nitrophenols and 2-nitrophenol

Two anthracene-based zirconium metal-organic frameworks (UiO-68-AN-fcu and UiO-68-AN-hcp) with blue emission were synthesized by the solvothermal reaction of ZrCl

Topics: Coloring Agents; Ligands; Metal-Organic Frameworks; Nitrophenols; Zirconium

Topics: 2,4-Dinitrophenol; Gases; Humans; Mercaptoethanol; Nitrophenols

This investigation implemented the nanomaterial rGOTiO

Topics: Catalysis; Graphite; Light; Models, Theoretical; Nanostructures; Nitrophenols; Photolysis; Titanium; Water Pollutants, Chemical

Two new adsorbents, namely avocado-based hydrochar and LDH/bone-based biochar, were developed, characterized, and applied for adsorbing 2-nitrophenol. The pore volume and surface diffusion model (PVSDM) was numerically solved for different geometries and applied to interpret the adsorption decay curves. Both adsorbents presented interesting textural and physicochemical characteristics, which achieved maximum adsorption capacities of 761 mg/g for biochar and 562 mg/g for hydrochar. The adsorption equilibrium data were well fitted by Henry isotherm. Besides, thermodynamic investigation revealed endothermic adsorption with the occurrence of electrostatic interactions. PVSDM predicted the adsorption decay curves for different adsorbent geometries at different initial concentrations of 2-nitrophenol. The surface diffusion was the main intraparticle mass transport mechanism. Furthermore, the external mass transfer and surface diffusion coefficients increased with the increase of 2-nitrophenol concentration.

Topics: Adsorption; Charcoal; Hydrogen-Ion Concentration; Kinetics; Nitrophenols; Solutions; Thermodynamics; Water Pollutants, Chemical

The present study reports the development of an electrochemical sensor based on sulfobutylether-β-cyclodextrin modified reduced graphene oxide hybrid (SBCD-rGO) for simultaneous detection of nitrophenol isomers. First, SBCD-rGO hybrid was synthesized and detailed characterized. Afterwards, a sensor was fabricated via the modification of glassy carbon electrode (GCE) with SBCD-rGO, and its electrochemical detection performances were also investigated. Then, the constructed electrochemical sensor was applied to detect nitrophenol isomers by voltammetry analysis. The results suggested that the sensitivities were 389.26, 280.88 and 217.19 μA/mM for p-nitrophenol (p-NP), m-nitrophenol (m-NP), and o-nitrophenol (o-NP), respectively, and their corresponding detection limits were all about 0.05 μM. Significantly, the combination of voltammetry analysis with the constructed sensor and data analysis by multiple linear regression realized the simultaneous detection of nitrophenol isomers.

Topics: beta-Cyclodextrins; Carbon; Electrochemical Techniques; Electrodes; Graphite; Isomerism; Limit of Detection; Nanostructures; Nitrophenols; Reproducibility of Results

This work developed an effective model of the cooperative removal process of organic compounds on biologically active carbon. This model involves the determination of the dynamics of adsorption efficiency and degradation of specific classes of target organic substances but also the dynamics of non-target filling of pores with products of vital microbial activity. It is possible to quantitatively assess the contributions of adsorption, biodegradation and self-bioregeneration in the process of biologically active carbon functioning and the changes in the activated carbon porous properties during the process. The model developed was applied to assess the efficiency of filtration of 2-nitrophenol through a biologically active carbon bed for 38 months. The activated carbon adsorption capacity for removing 2-nitrophenol was preserved after three years of the bed service due to the effective biodegradation that resulted in self-bioregeneration of the sorbent. Nontarget losses of porosity (filling with bioproducts) increased with increasing duration of system operation, and by the end of the experiment, these losses amounted to 61% of the pore volume of the fresh sorbent.

Topics: Adsorption; Biodegradation, Environmental; Charcoal; Filtration; Models, Chemical; Nitrophenols; Organic Chemicals; Porosity

Topics: Acacia; Anti-Infective Agents; Candida albicans; Catalysis; Coloring Agents; Dynamic Light Scattering; Environmental Pollutants; Kinetics; Metal Nanoparticles; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Nitrogen; Nitrophenols; Organic Chemicals; Photoelectron Spectroscopy; Plant Extracts; Secondary Metabolism; Silver; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Static Electricity; Temperature; Thermogravimetry; X-Ray Diffraction

The potential of rice husks and straw as adsorbents after being processed by subcritical water hydrolysis (SWH) was investigated. The influences of temperature (453, 493 and 533 K) and liquid/solid ratio (7.5 and 15 g water/g biomass) on the rice straw and rice husks characteristics and on the adsorption capacity of 2-nitrophenol were evaluated at pH 4 and 7. Adsorption kinetics, equilibrium and thermodynamic parameters were also studied. The adsorption capacity was favored at pH 7. Pseudo-first-order model was suitable to predict the kinetic curves for 2-nitrophenol concentrations of 25, 50, 75 and 100 mg/L and the isotherm data obeyed the Freundlich model. Overall, the thermodynamic results revealed a spontaneous and exothermic process. The maximum adsorption capacity (92.97 ± 1.31 mg/g) was obtained for rice straw that has undergone an SWH at 453 K and 7.5 g water/g straw. The integration of processes to valorize co-products can make the production of cellulosic bioethanol more feasible.

Topics: Adsorption; Biomass; Hot Temperature; Hydrogen-Ion Concentration; Hydrolysis; Kinetics; Nitrophenols; Oryza; Thermodynamics; Water

The induced degradation and detoxification of 2-nitrophenol (2-NP) in aqueous media by gamma irradiation were carefully evaluated in this study. Gamma radiation at absorbed doses as low as 20 kGy was able to degrade 2-NP to reach a removal of at least 85% across the investigated range of concentration (50-150 ppm). 2-NP breaks down to aromatic-based compounds with increasing number of byproducts upon increasing the radiation treatment from the absorbed dose of 50% decomposition (D

Topics: Gamma Rays; Hydrogen Peroxide; Nitrophenols; Organic Chemicals

Quantifying the extent of biodegradation of nitroaromatic compounds (NACs) in contaminated soils and sediments is challenging because of competing oxidative and reductive reaction pathways. We have previously shown that the stable isotope fractionation of NACs reveals the routes of degradation even if it is simultaneously caused by different bacteria. However, it is unclear whether compound-specific isotope analysis (CSIA) can be applied in situations where multiple pollutants are biodegraded by only one microorganism under multi-substrate conditions. Here we examined the C and N isotope fractionation of 2-nitrophenol (2-NP) and 3-nitrophenol (3-NP) during biodegradation by Pseudomonas putida B2 through monooxygenation and partial reductive pathways, respectively, in the presence of single substrates vs. binary substrate mixtures. Laboratory experiments showed that the reduction of 3-NP by Pseudomonas putida B2 is associated with large N and minor C isotope fractionation with C and N isotope enrichment factors, ε

Topics: Biodegradation, Environmental; Carbon Isotopes; Chemical Fractionation; Chromatography, High Pressure Liquid; Geologic Sediments; Isomerism; Kinetics; Nitrogen Isotopes; Nitrophenols; Oxidation-Reduction; Pseudomonas putida; Soil; Soil Pollutants

The ortho-nitrophenol (ONP)-utilizing Alcaligenes sp. strain NyZ215, meta-nitrophenol (MNP)-utilizing Cupriavidus necator JMP134 and para-nitrophenol (PNP)-utilizing Pseudomonas sp. strain WBC-3 were assembled as a consortium to degrade three nitrophenol isomers in sequential batch reactors. Pilot test was conducted in flasks to demonstrate that a mixture of three mononitrophenols at 0·5 mol l. Nitroaromatic compounds are readily spread in the environment and pose great potential toxicity concerns. Here, we report the simultaneous degradation of three isomers of mononitrophenol in a single system by employing a consortium of three bacteria, both in flasks and lab-scale sequential batch reactors. The results demonstrate that simultaneous biodegradation of three mononitrophenol isomers can be achieved by a tailor-made microbial consortium immobilized in sequential batch reactors, providing a pilot study for a novel approach for the bioremediation of mixed pollutants, especially isomers present in wastewater.

Topics: Bacteria; Biodegradation, Environmental; Bioreactors; Isomerism; Microbial Consortia; Nitrophenols; Pilot Projects; Real-Time Polymerase Chain Reaction; Wastewater; Water Pollutants, Chemical

The nitrophenols (NPs) are water-soluble compounds. These compounds pose a significant health threat since they are priority environmental pollutants. In this study, 2-Nitrophenol (2NP) and 2,4-dinitrophenol (DNP) were examined for embryo and early life stage toxicity in zebrafish (Danio rerio). Acute toxicity and teratogenicity of 2NP and DNP were tested for 4 days using zebrafish embryos. The typical lesions observed were no somite formation, incomplete eye and head development, tail curvature, weak pigmentation (≤48 hours postfertilization (hpf)), kyphosis, scoliosis, yolk sac deformity, and nonpigmentation (72 hpf). Also, embryo and larval mortality increased and hatching success decreased. The severity of abnormalities and mortalities were concentration- and compound-dependent. Of the compounds tested, 2,4-DNP was found to be highly toxic to the fish embryos following exposure. The median lethal concentrations and median effective concentrations for 2NP are 18.7 mg/L and 7.9 mg/L, respectively; the corresponding values for DNP are 9.65 mg/L and 3.05 mg/L for 48 h. The chorda deformity was the most sensitive endpoint measured. It is suggested that the embryotoxicity may be mediated by an oxidative phosphorylation uncoupling mechanism. This article is the first to describe the teratogenicity and embryotoxicity of two NPs to the early life stages of zebrafish.

Topics: 2,4-Dinitrophenol; Animals; Blastula; Embryo, Nonmammalian; Embryonic Development; Larva; Lethal Dose 50; Nitrophenols; Pigmentation; Somites; Spine; Survival Analysis; Tail; Teratogens; Toxicity Tests, Acute; Uncoupling Agents; Water Pollutants, Chemical; Yolk Sac; Zebrafish

There has been some dispute regarding reaction products formed at physiological peroxynitrite fluxes in the nanomolar range with phenolic molecules, when used to predict the behavior of protein-bound aromatic amino acids like tyrosine. Previous data showed that at nanomolar fluxes of peroxynitrite, nitration of these phenolic compounds was outcompeted by dimerization (e.g. biphenols or dityrosine). Using 3-morpholino sydnonimine (Sin-1), we created low fluxes of peroxynitrite in our reaction set-up to demonstrate that salicylaldehyde displays unique features in the detection of physiological fluxes of peroxynitrite, yielding detectable nitration but only minor dimerization products. By means of HPLC analysis and detection at 380nm we could identify the expected nitration products 3- and 5-nitrosalicylaldehyde, but also novel nitrated products. Using mass spectrometry, we also identified 2-nitrophenol and a not fully characterized nitrated dimerization product. The formation of 2-nitrophenol could proceed either by primary generation of a phenoxy radical, followed by addition of the NO2-radical to the various resonance structures, or by addition of the peroxynitrite anion to the polarized carbonyl group with subsequent fragmentation of the adduct (as seen with carbon dioxide). Interestingly, we observed almost no 3- and 5-nitrosalicylic acid products and only minor dimerization reaction. Our results disagree with the previous general assumption that nitration of low molecular weight phenolic compounds is always outcompeted by dimerization at nanomolar peroxynitrite fluxes and highlight unique features of salicylaldehyde as a probe for physiological concentrations of peroxynitrite.

Topics: Aldehydes; Chromatography, High Pressure Liquid; Humans; Leukocytes; Molecular Structure; Nitrophenols; Peroxynitrous Acid

In this work, covalent triazine frameworks (CTFs) were introduced in stir bar sorptive extraction (SBSE) and a novel polydimethylsiloxane(PDMS)/CTFs stir bar coating was prepared by sol-gel technique for the sorptive extraction of eight phenols (including phenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dimethylphenol, p-chloro-m-cresol and 2,4-dichlorophenol, 2,4,6-trichlorophenol) from environmental water samples followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. The prepared PDMS/CTFs coated stir bar showed good preparation reproducibility with the relative standard deviations (RSDs) ranging from 3.5 to 5.7% (n=7) in one batch, and from 3.7 to 9.3% (n=7) among different batches. Several parameters affecting SBSE of eight target phenols including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.08-0.30 μg/L. The linear range was 0.25-500 μg/L for 2-nitrophenol, 0.5-500 μg/L for phenol, 2-chlorophenol, 4-nitrophenol as well as 2,4-dimethylphenol, and 1-500 μg/L for p-chloro-m-cresol, 2,4-dichlorophenol as well as 2,4,6-trichlorophenol, respectively. The intra-day relative standard deviations (RSDs) were in the range of 4.3-9.4% (n=7, c=2 μg/L) and the enrichment factors ranged from 64.9 to 145.6 fold (theoretical enrichment factor was 200-fold). Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/CTFs stir bar showed better extraction efficiency for target phenol compounds. The proposed method was successfully applied to the analysis of phenols in environmental water samples and good relative recoveries were obtained with the spiking level at 2, 10, 50 μg/L, respectively.

Topics: Chlorophenols; Chromatography, High Pressure Liquid; Dimethylpolysiloxanes; Hydrogen-Ion Concentration; Limit of Detection; Nitrophenols; Osmolar Concentration; Phenols; Reproducibility of Results; Rivers; Spectrophotometry, Ultraviolet; Triazines; Water Pollutants, Chemical

The STEP (Solar Thermal Electrochemical Process) for Advanced Oxidation Processes (AOPs, combined to STEP-AOPs), fully driven by solar energy without the input of any other forms of energy and chemicals, is introduced and demonstrated from the theory to experiments. Exemplified by the persistent organic pollutant 2-nitrophenol in water, the fundamental model and practical system are exhibited for the STEP-AOPs to efficiently transform 2-nitrophenol into carbon dioxide, water, and the other substances. The results show that the STEP-AOPs system performs more effectively than classical AOPs in terms of the thermodynamics and kinetics of pollutant oxidation. Due to the combination of solar thermochemical reactions with electrochemistry, the STEP-AOPs system allows the requisite electrolysis voltage of 2-nitrophenol to be experimentally decreased from 1.00 V to 0.84 V, and the response current increases from 18 mA to 40 mA. STEP-AOPs also greatly improve the kinetics of the oxidation at 30 °C and 80 °C. As a result, the removal rate of 2-nitrophenol after 1 h increased from 19.50% at 30 °C to 32.70% at 80 °C at constant 1.90 V. Mechanistic analysis reveals that the oxidation pathway is favorably changed because of thermal effects. The tracking of the reaction displayed that benzenediol and hydroquinone are initial products, with maleic acid and formic acid as sequential carboxylic acid products, and carbon dioxide as the final product. The theory and experiments on STEP-AOPs system exemplified by the oxidation of 2-nitrophenol provide a broad basis for extension of the STEP and AOPs for rapid and efficient treatment of organic wastewater.

Topics: Electrochemistry; Electrolysis; Nitrophenols; Oxidation-Reduction; Solar Energy; Sunlight; Temperature; Wastewater; Water Pollutants, Chemical

To investigate green synthesis of gold nanoparticles (AuNPs) by Trichosporon montevideense, and to study their reduction of nitroaromatics.. AuNPs had a characteristic absorption maximum at 535 nm. Scanning electron microscopy images revealed that the biosynthesized nanoparticles were attached on the cell surface. X-ray diffraction analysis indicated that the particles formed as face-centered cubic (111)-oriented crystals. The average size of AuNPs decreased from 53 to 12 nm with increasing biomass concentration. The catalytic reduction of 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, o-nitrophenylamine and m-nitrophenylamine (0.1 mM) by NaBH4 had reaction rate constants of 0.32, 0.44, 0.09, 0.24 and 0.39 min(-1) with addition of 1.45 × 10(-2) mM AuNPs.. An eco-friendly approach for synthesis of AuNPs by T. montevideense is reported for the first time. The biogenic AuNPs could serve as efficient catalysts for hydrogenation of various nitroaromatics.

Topics: Catalysis; Gold; Green Chemistry Technology; Hydrogenation; Metal Nanoparticles; Nitrophenols; Trichosporon

The present study deals about the vicinity of phytochemicals present in the Phyllanthus emblica (P. emblica) seed extract. The bio-active compounds present in the methanolic seed extract have been identified using Gas Chromatography Mass Spectroscopy (GC-MS)·The antioxidant activity of P. emblica seed extract was evaluated using assistance of DPPH (2,2-Diphenyl-1-picrylhydrazyl) assay. The determination of total phenol and flavonoid substance were contemplated. Further blood clot lysis activity was also done to check the percentage of clot lysis in methanolic seed extract. The result proved that seed extract has potential application. The GCMS results of P. emblica suggest that Octyl-β-d-Glucopyranoside is present in major quantity. The work has been designed towards the degradation of 2-nitrophenol and 4-nitrophenol using P. emblica methanolic seed extract. The progress of nitrophenol degradation has been observed in UV-visible spectroscopy. At 5min duration, the 4-nitrophenol has been degraded up to 82.42%. This may be due to the presence of secondary metabolites such as alkaloids, carbohydrate and phenols in the P. emblica seed extract. The seed extract showed good scavenging activity which resulted in IC50 value of 85.92μg/mL. The total phenol and flavonoid content present in the extract were 48.242 and 12.72mg/mL. Also the seed extract showed good lysis when compared to the standard streptokinase.

Topics: Catalysis; Free Radical Scavengers; Gas Chromatography-Mass Spectrometry; Glucosides; Light; Nitrophenols; Photolysis; Phyllanthus emblica; Plant Extracts; Seeds; Spectrophotometry, Ultraviolet

Topics: Adsorption; Aminophenols; Azo Compounds; Catalysis; Cellulose; Chitosan; Coloring Agents; Metal Nanoparticles; Nanocomposites; Nickel; Nitrophenols; Paper

Ce2O3 nanoparticle decorated CNT nanocomposites (Ce2O3.CNT NCs) were prepared by a wet-chemical method in basic medium. The Ce2O3.CNT NCs were examined using FTIR, UV/Vis, Field-Emission Scanning Electron Microscopy (FESEM), X-ray electron dispersive spectroscopy (XEDS), X-ray photoelectron spectroscopy (XPS), and powder X-ray diffraction (XRD). A selective 2-nitrophenol (2-NP) sensor was developed by fabricating a thin-layer of NCs onto a flat glassy carbon electrode (GCE, surface area = 0.0316 cm2). Higher sensitivity including linear dynamic range (LDR), long-term stability, and enhanced electrochemical performances towards 2-NP were achieved by a reliable current-voltage (I-V) method. The calibration curve was found linear (R2 = 0.9030) over a wide range of 2-NP concentration (100 pM ~ 100.0 mM). Limit of detection (LOD) and sensor sensitivity were calculated based on noise to signal ratio (~3N/S) as 60 ± 0.02 pM and 1.6×10-3 μAμM-1cm-2 respectively. The Ce2O3.CNT NCs synthesized by a wet-chemical process is an excellent way of establishing nanomaterial decorated carbon materials for chemical sensor development in favor of detecting hazardous compounds in health-care and environmental fields at broad-scales. Finally, the efficiency of the proposed chemical sensors can be applied and utilized in effectively for the selective detection of toxic 2-NP component in environmental real samples with acceptable and reasonable results.

Topics: Carbon; Cerium; Electrochemical Techniques; Electrodes; Environment; Limit of Detection; Metal Nanoparticles; Microscopy, Electron, Scanning; Nanocomposites; Nanotubes, Carbon; Nitrophenols; Photoelectron Spectroscopy; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; X-Ray Diffraction

The determination and remediation of three phenolic compounds bisphenol A (BPA), ortho-nitrophenol (o-NTP), parachlorophenol (PCP) in wastewater is reported. The analysis of these molecules in wastewater was done using gas chromatography (GC) × GC time-of-flight mass spectrometry while activated carbon derived from maize tassel was used as an adsorbent. During the experimental procedures, the effect of various parameters such as initial concentration, pH of sample solution, eluent volume, and sample volume on the removal efficiency with respect to the three phenolic compounds was studied. The results showed that maize tassel produced activated carbon (MTAC) cartridge packed solid-phase extraction (SPE) system was able to remove the phenolic compounds effectively (90.84-98.49%, 80.75-97.11%, and 78.27-97.08% for BPA, o-NTP, and PCP, respectively). The MTAC cartridge packed SPE sorbent performance was compared to commercially produced C18 SPE cartridges and found to be comparable. All the parameters investigated were found to have a notable influence on the adsorption efficiency of the phenolic compounds from wastewaters at different magnitudes.

Topics: Adsorption; Benzhydryl Compounds; Charcoal; Chlorophenols; Gas Chromatography-Mass Spectrometry; Inflorescence; Nitrophenols; Phenols; Solid Phase Extraction; Wastewater; Water Pollutants, Chemical; Water Quality; Zea mays

Recent studies have shown that manganese dioxide (MnO2) can significantly accelerate the oxidation kinetics of phenolic compounds such as triclosan and chlorophenols by potassium permanganate (Mn(VII)) in slightly acidic solutions. However, the role of MnO2 (i.e., as an oxidant vs catalyst) is still unclear. In this work, it was demonstrated that Mn(VII) oxidized triclosan (i.e., trichloro-2-phenoxyphenol) and its analogue 2-phenoxyphenol, mainly generating ether bond cleavage products (i.e., 2,4-dichlorophenol and phenol, respectively), while MnO2 reacted with them producing appreciable dimers as well as hydroxylated and quinone-like products. Using these two phenoxyphenols as mechanistic probes, it was interestingly found that MnO2 formed in situ or prepared ex situ greatly accelerated the kinetics but negligibly affected the pathways of their oxidation by Mn(VII) at acidic pH 5. The yields (R) of indicative products 2,4-dichlorophenol and phenol from their respective probes (i.e., molar ratios of product formed to probe lost) under various experimental conditions were quantified. Comparable R values were obtained during the treatment by Mn(VII) in the absence vs presence of MnO2. Meanwhile, it was confirmed that MnO2 could accelerate the kinetics of Mn(VII) oxidation of refractory nitrophenols (i.e., 2-nitrophenol and 4-nitrophenol), which otherwise showed negligible reactivity toward Mn(VII) and MnO2 individually, and the effect of MnO2 was strongly dependent upon its concentration as well as solution pH. These results clearly rule out the role of MnO2 as a mild co-oxidant and suggest a potential catalytic effect on Mn(VII) oxidation of phenolic compounds regardless of their susceptibility to oxidation by MnO2.

Topics: Catalysis; Chlorophenols; Kinetics; Manganese Compounds; Nitrophenols; Organic Chemicals; Oxidants; Oxidation-Reduction; Oxides; Phenols; Potassium Permanganate; Triclosan; Water; Water Pollutants, Chemical

Despite knowing the fact that vanadium pentoxide is slightly soluble in aqueous medium, its photocatalytic activity was evaluated for the degradation of phenol and its derivatives (2-hydroxyphenol, 2-chlorophenol, 2-aminophenol and 2-nitrophenol) in natural sunlight exposure. The prime objective of the study was to differentiate between the homogeneous and heterogeneous photocatalysis incurred by dissolved and undissolved V2O5 in natural sunlight exposure. V2O5 was synthesized by chemical precipitation procedure using Triton X-100 as morphology mediator and characterized by DRS, PLS, Raman, FESEM and XRD. A lower solubility of ∼ 5% per 100ml of water at 23 °C was observed after calcination at 600 °C. The study revealed no contribution of the dissolved V2O5 in the photocatalytic process. In sunlight exposure, V2O5 powder exhibited substantial activity for the degradation, however, a low mineralization of phenolic substrates was observed. The initial low activity of V2O5 followed by a sharp increase both in degradation and mineralization in complete spectrum sunlight exposure, was further investigated that revealed the decrease in the bandgap and the reduction in the particle size with the interaction of UV photons (<420 nm) as this effect was not observable in the exposure of visible region of sunlight. The role of the chemically different substituents attached to an aromatic ring at 2-positions and the secondary interaction of released ions during the degradation process with the reactive oxygen species (ROS) was also explored.

Topics: Aminophenols; Catalysis; Catechols; Chlorophenols; Chromatography, High Pressure Liquid; Electrochemistry; Electrons; Hydrogen-Ion Concentration; Ions; Microscopy, Electron, Scanning; Nitrophenols; Particle Size; Phenol; Photochemistry; Photons; Reactive Oxygen Species; Semiconductors; Solubility; Spectrophotometry, Ultraviolet; Sunlight; Vanadium Compounds; X-Ray Diffraction

Anthropogenic activities are the main source of nitrophenols and chlorophenols in the atmosphere. Nitro and chlorophenols have a high potential to form ozone and secondary organic aerosol, thus investigations on the major photo oxidation pathways of these compounds are important to assess their contribution to urban air pollution and human health. Presented here are rate coefficients determined at atmospheric pressure and (298 ± 2) K using a relative kinetic method for the reactions of chlorine atoms with 2-chlorophenol (2ClP), 2-nitrophenol (2NP) and four methyl-2-nitrophenol (2-nitrocresol, nM2NP (n = 3,4,5,6)) isomers. The following rate coefficients (in units of cm(3) molecule(-1) s(-1)) have been obtained: (5.9 ± 1.5) × 10(-12) for 2ClP, (6.8 ± 2.3) × 10(-12) for 2NP, and (14.0 ± 4.9) × 10(-11), (4.3 ± 1.5) × 10(-11), (1.94 ± 0.67) × 10(-11) and (2.68 ± 0.75) × 10(-11) for the four methyl-2-nitrophenol isomers 3M2NP, 4M2NP, 5M2NP, and 6M2NP, respectively. This study represents the first kinetic investigation for the reaction of chlorine atoms with all the nitrophenols. In addition, to assist in the interpretation of the results, rate coefficients for the reactions of Cl atoms with the cresol ortho, meta, and para isomers have been determined for the first time. The rate coefficient for the reaction with 2ClP is in good agreement with previous data and the relative reactivity of 2NP, 4M2NP, 5M2NP, and 6M2NP can be rationalized based on known substituent effects. The rate coefficient for 3M2NP is anomalously large; the observation of significant NO2 production in only this reaction suggests that an ipso substitution mechanism is the cause of the enhanced reactivity.

Topics: Air Pollutants; Chlorine; Chlorophenols; Cresols; Isomerism; Nitrophenols; Phase Transition; Volatile Organic Compounds

To overcome the drawback of poor solar light utilization brought about by the narrow photoresponse range of TiO₂, a silver and sulfur co-doped TiO₂was synthesized. Using the prepared catalyst, solar photocatalytic degradation of 2-nitrophenol (2-NP) by a TiO₂-based catalyst was studied for the first time. Effects of the co-doping on the structural, optical and morphological properties of the synthesized nanoparticles were investigated by different characterization methods: X-ray diffraction, N2 adsorption-desorption measurements, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, UV-visible diffuse reflectance spectroscopy and Fourier transform infrared spectroscopy. Solar experiments showed that the co-doping with silver and sulfur significantly increased the photocatalytic activity. In various initial concentrations of 2-NP more than 99% of the contaminant was decomposed by Ag-S/TiO₂in less than 150 minutes, while the degradation efficiency was much less in the presence of bare TiO₂. Kinetic studies suggested that solar photocatalytic degradation of 2-NP is consistent with the Langmuir-Hinshelwood model. The rate constant of the reaction and adsorption constant of the modified photocatalyst were found to be 2.4 and 4.1 times larger than that of bare TiO₂, respectively.

Topics: Catalysis; Coloring Agents; Kinetics; Nitrophenols; Photolysis; Silver; Sulfur; Sunlight; Titanium; Water Pollutants, Chemical

The water-soluble 3-n-propyl-4-picolinium silsesquioxane chloride (Si4Pic(+)Cl(-)) polymer was prepared, characterized and used as a stabilizing agent for the synthesis of gold nanoparticles (nAu). The ability of Si4Pic(+)Cl(-) to adsorb anionic metal complexes such as AuCl4(-) ions allowed well-dispersed nAu to be obtained with an average particle size of 4.5nm. The liquid suspension of nAu-Si4Pic(+)Cl(-) was deposited by the drop coating method onto a glassy carbon electrode (GCE) surface to build a sensor (nAu-Si4Pic(+)Cl(-)/GCE) which was used for the detection of o-nitrophenol (o-NP) and p-nitrophenol (p-NP). Under optimized experimental conditions the reduction peak current increased with increasing concentrations of both nitrophenol isomers in the range of 0.1-1.5μmolL(-1). The detection limits were 46nmolL(-1) and 55nmolL(-1) for o-NP and p-NP, respectively. These findings indicate that the nAu-Si4Pic(+)Cl(-) material is a very promising candidate to assemble electrochemical sensors for practical applications in the field of analytical chemistry.

Topics: Catalysis; Electrochemical Techniques; Gold; Metal Nanoparticles; Nitrophenols; Organosilicon Compounds; Polymers; Solubility; Water; Water Pollutants, Chemical

In an effort to enhance the photocatalytic activity of ZnO in natural sunlight, V2O5-ZnO nanocomposites were synthesized by co-precipitation technique. The characterization of the synthesized powders by FESEM, XRD and UV-visible diffuse reflectance spectroscopy (DRS) revealed that the both V2O5 and ZnO retain their individual identity in the composites but the increasing concentration of V2O5 affect the particle size of ZnO. As estimated by photoluminescence spectroscopy, in comparison to pure ZnO, the presence of V2O5 significantly suppressed the charge carrier's recombination process. The photocatalytic activity of the synthesized powders was evaluated for the degradation/mineralization of three potential nitrophenol pollutants (2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol). The synthesized composites showed significantly higher activity for both degradation and mineralization of nitrophenols compared to pure ZnO. The progress of the degradation process was evaluated by HPLC while mineralization was monitored by TOC analysis. The degradation/mineralization route was estimated by identifying the intermediates using GC-MS. The correlation of the experimental data revealed that the position of NO2 group in 2- and 4-nitrophenol significantly affect the rate of degradation. The identification of hydroxyl group containing intermediates in the degradation of 4-NP confirmed the formation and vital role of hydroxyl radicals in degradation process. The rapid mineralization of nitrophenol substrates pointed out superoxide anions as major contributors in degradation and mineralization process. The assessment of the release of relevant ions (NO2(-), NO3(-), ONOO(-) and NH4(+)) during the degradation process assisted in identifying the plausible interaction sites.

Topics: 2,4-Dinitrophenol; Chemical Precipitation; Environmental Restoration and Remediation; Nitrophenols; Photolysis; Vanadium Compounds; Water Pollutants, Chemical; Water Pollution, Chemical; Zinc Oxide

The reduction of nitroaromatic compounds (listed as a priority pollutant) in natural subsurface environments typically coexists with dissimilatory reduction of iron oxides effected by dissolved organic matter (DOM). Investigating the impact of the DOM that influences those reduction processes is crucial for understanding and predicting the geochemical fate of these environmental species. This study investigated the impact of different molecular weight DOM fractions (DMWDs) on the 2-nitrophenol (2-NP) reduction by S. putrefaciens 200 (SP200) and α-Fe2O3 with lactate (excluding electron donor interference). Kinetic measurements demonstrated that 2-NP reduction rates were affected by the redox reactivity of active species under DMWDs (denoted as L-DOM, M-DOM, and H-DOM). The enhanced reduction rates are consistent with the negative shifts in peak oxidation potential values, the increases in HA-like/FA-like values, aromaticity index values and electron transfer capacity values. L-DOM acted mainly as ligands to complex Fe(II), whereas the significant role of H-DOM in reductive reactions should be acting as an electron shuttle, transferring electrons from SP200 to Fe(III) and 2-NP and from biogenic Fe(II) to 2-NP, further accelerating the 2-NP reductions. Those observations provide valuable insights into the role of DOM in the biogeochemical redox processes and the remediation of contaminated soil in a natural environment.

Topics: Electrochemistry; Electrons; Ferric Compounds; Ferrous Compounds; Nitrophenols; Oxidation-Reduction; Shewanella putrefaciens

The rapid detection of Listeria monocytogenes contamination in food is essential to prevent food-borne illness in humans. The aim of this study was to differentiate non-contaminated milk from milk contaminated with L. monocytogenes using enzyme substrates coupled with the analysis of volatile organic compounds (VOCs). The method is based on the activity of β-glucosidase and hippuricase enzymes and the detection of a specific VOC i.e. 2-nitrophenol and 3-fluoroaniline, respectively. VOCs were extracted, separated and detected by headspace-solid phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME GC-MS). This approach required the inclusion of the selective agent's cycloheximide, nalidixic acid and acriflavine HCl in the growth medium to inhibit interfering bacteria. The VOCs were liberated by L. monocytogenes provided that samples contained at least 1-1.5×10(2) CFU ml(-1) of milk prior to overnight incubation. This approach shows potential for future development as a rapid method for the detection of L. monocytogenes contaminated milk.

Topics: Amidohydrolases; Aniline Compounds; Animals; beta-Glucosidase; Fluorobenzenes; Food Microbiology; Gas Chromatography-Mass Spectrometry; Listeria monocytogenes; Milk; Nitrophenols; Solid Phase Extraction; Volatile Organic Compounds

We are interested in the free energies of transferring nonpolar solutes into aqueous NaCl solutions with salt concentrations upwards of 2 M, the Hofmeister regime. We use the semi-explicit assembly (SEA) computational model to represent these electrolyte solutions. We find good agreement with experiments (Setschenow coefficients) on 43 nonpolar and polar solutes and with TIP3P explicit-solvent simulations. Besides being much faster than explicit solvent calculations, SEA is more accurate than the PB models we tested, successfully capturing even subtle salt effects in both the polar and nonpolar components of solvation. We find that the salt effects are mainly due to changes in the cost of forming nonpolar cavities in aqueous NaCl solutions, and not mainly due to solute-ion electrostatic interactions.

Topics: Computer Simulation; Electrolytes; Models, Chemical; Models, Molecular; Nitrophenols; Sodium Chloride; Solubility; Solvents; Static Electricity; Thermodynamics; Water

The gas-phase oxidation mechanism of phenol initiated by OH radical was investigated using DFT and ab initio calculations. The initiation of the reaction is dominated by OH addition to ortho-position, forming P2, which subsequently combines with O2 at the ipso-position to form P2-1-OO adduct. A concerted HO2 elimination process from P2-1-OO was found to be much faster than the common ring closure to bicyclic intermediates. The HO2 elimination process from P2-1-OO forms 2-hydroxy-3,5-cyclohexadienone (HCH) as the main product and is also responsible for the experimental fact that the rate constants for reaction between P2 and O2 are about 2 orders of magnitude higher than those between other aromatic-OH adducts and O2. It was speculated that HCH would isomerize to catechol, which is thermodynamically more stable than HCH and was the experimentally observed main product, possibly through heterogeneous processes. Reaction of P2 with NO2 proceeded by addition to form P2-n-NO2 (n = 1, 3, 5), followed by HONO elimination from P2-1/3-NO2 to form catechol. The barriers for HONO elimination and catechol formation are below the separate reactants P2 and NO2, being consistent with the experimental observation of catechol in the absence of O2, while H2O elimination from P2-1/3-NO2 to form 2-nitrophenol (2NP) is hindered by high barriers. The most likely pathway for 2NP is the reaction of phenoxy radical and NO2.

Topics: Atmosphere; Catechols; Gases; Hydroxyl Radical; Kinetics; Models, Chemical; Nitrogen Dioxide; Nitrophenols; Oxidation-Reduction; Phenol; Phenols; Quantum Theory; Thermodynamics

Inorganic-framework molecularly imprinted TiO2/WO3 nanocomposites with molecular recognitive photocatalytic activity were first prepared successfully by a facile one-step sol-gel method using 2-nitrophenol and 4-nitrophenol as template molecules, and tetrabutyl orthotitanate as titanium source as well as the precursor of functional monomer which could complex with template molecules. The template molecules could be completely removed by means of high-temperature calcination, avoiding the traditional extraction procedures that are time- as well as solvent-consuming. Compared to nonimprinted TiO2/WO3, the molecularly imprinted TiO2/WO3 shows a much higher adsorption capacity and selectivity toward the template molecules. The enhancement in terms of adsorption capacity and selectivity can be attributed to the chemical interaction between target molecules and imprinted cavities, as well as size matching between imprinted cavities and target molecules. The photocatalytic activity of molecularly imprinted TiO2/WO3 toward the target molecules is more than two times that of non-imprinted TiO2/WO3, a result of selective adsorption of target molecules on molecularly imprinted TiO2/WO3. The formation pathway of intermediate products in 2-nitrophenol and 4-nitrophenol degradation process was provided. Moreover, molecularly imprinted TiO2/WO3 exhibits high stability. The results indicate that inorganic-framework molecularly imprinted TiO2/WO3 nanocomposites have a promising prospect in the treatment of wastewater for irrigation.

Topics: Catalysis; Light; Molecular Imprinting; Nanocomposites; Nitrophenols; Oxides; Photolysis; Recycling; Titanium; Tungsten; Waste Disposal, Fluid; Water Pollutants, Chemical

Dissolved organic matter (DOM) is widespread in aquatic and terrestrial environments. Iron is the most abundant transition metal in the Earth's crust. The biogeochemistry of iron and the strength of Fe(II) as a reducing agent while adsorbed on minerals are affected by DOM. This study investigated the effects of Fe(II)/DOM interactions on the reduction of 2-nitrophenol (2-NP) in TiO2 suspensions. Kinetic measurements demonstrated that rates (k) of 2-NP reduction by adsorbed Fe(II) species are affected by adding DOM (denoted O-DOM), and the obtained k values under the impact of the Fe(II)/DOM interaction with different molecular weight DOM fractions [including MW<3500Da (L-DOM), 350014000Da (H-DOM)] showed significant differences. The enhanced rates of 2-NP reduction contributed to increases in the amount of adsorbed Fe(II) species and negative shifts in peak oxidation potential values (EP) in CV tests. For different molecular weight DOM fractions, increases in k (O-DOM

Topics: Adsorption; Electrochemistry; Electron Transport; Iron; Kinetics; Molecular Weight; Nitrophenols; Suspensions; Titanium

Pollutant interactions during the aerobic biodegradation of phenolic mixtures with either 2-nitrophenol (2-NP) or 3-nitrophenol (3-NP) by a NP-adapted microbial consortium in simulated wastewater were studied in a packed-bed bench scale bioreactor continuously operated in a flow mode. Phenol/2-NP and phenol/3-NP mixtures with varied phenol/nitrophenol ratios were shown to exhibit different biodegradability patterns. The presence of 2-NP led to a much lower overall elimination capacity and lower process stability in comparison to mixtures with 3-NP. In contrast to the expected greater degradation of a more biodegradable substrate in mixtures, phenol was degraded with a lower efficiency at higher phenol concentrations than NPs, although this difference became less pronounced with the gradual biofilm adaptation to phenol. This unusual substrate interaction, which appears to be common in the biotreatment of substituted phenol mixtures, was explained by prior biofilm adaptation to less degradable substrates, NPs. The biofilm composition was significantly altered during the long-term reactor operation. Although eukaryotes were not present in the inoculum, four fungal species were isolated from the biofilm after 1.5 years of operation. Of the initially present strains, only Chryseobacterium sp. and several Pseudomonas species persisted till the end of operation.

Topics: Bacterial Physiological Phenomena; Biodegradation, Environmental; Biofilms; Bioreactors; Chromatography, High Pressure Liquid; Nitrophenols; Phenol; Waste Disposal, Fluid; Wastewater; Water Pollutants, Chemical

Monooxygenation is an important route of nitroaromatic compound (NAC) biodegradation and it is widely found for cometabolic transformations of NACs and other aromatic pollutants. We investigated the C and N isotope fractionation of nitrophenol monooxygenation to complement the characterization of NAC (bio)degradation pathways by compound-specific isotope analysis (CSIA). Because of the large diversity of enzymes catalyzing monooxygenations, we studied the combined C and N isotope fractionation and the corresponding (13)C- and (15)N-apparent kinetic isotope effects (AKIEs) of four nitrophenol-biodegrading microorganisms (Bacillus spharericus JS905, Pseudomonas sp. 1A, Arthrobacter sp. JS443, Pseudomonas putida B2) in the pH range 6.1-8.6 with resting cells and crude cell extracts. While the extent of C and N isotope fractionation and the AKIE-values varied considerably for the different organisms, the correlated C and N isotope signatures (δ(15)N vs δ(13)C) revealed trends, indicative of two distinct monooxygenation pathways involving hydroxy-1,4-benzoquinone or 1,2- and 1,4-benzoquinone intermediates, respectively. The distinction was possible based on larger secondary (15)N-AKIEs associated with the benzoquinone pathway. Isotope fractionation was neither masked substantially by nitrophenol speciation nor transport across cell membranes. Only when 4-nitrophenol was biodegraded by Pseudomonas sp. 1A did isotope fractionation become negligible, presumably due to rate-limiting substrate binding steps pertinent to the catalytic cycle of flavin-dependent monooxygenases.

Topics: Arthrobacter; Bacillus; Benzoquinones; Biocatalysis; Biodegradation, Environmental; Carbon Isotopes; Chemical Fractionation; Environmental Pollutants; Kinetics; Metabolic Networks and Pathways; Mixed Function Oxygenases; Nitrogen Isotopes; Nitrophenols; Pseudomonas putida

A new approach for the calculation of resonance Raman spectra is presented. The new method is based on dynamic polarizabilities from real-time time-dependent density functional theory, and its estimations are compared to two established techniques for the prediction of resonance Raman spectra. These established methods either use dynamic polarizabilities from linear-response time-dependent density functional theory or employ excited-state gradients. The three different ways to calculate resonance Raman spectra are investigated using the example of ortho-nitrophenol. The three methods give very similar results, respectively, for the four different exchange-correlation functionals applied. Thus, the new approach is validated for the calculation of resonance Raman intensities and advantages as well as disadvantages are discussed.

Topics: Nitrophenols; Quantum Theory; Spectrum Analysis, Raman; Time Factors

A differential pulse polarography (DPP) for the simultaneous determination of 2-nitrophenol and 4-nitrophenol was proposed. It was found that under optimum experimental conditions (pH = 5, scan rate = 5 mV/s, pulse amplitude = -50 mV), 2-nitrophenol and 4-nitrophenol had well-defined polarographic reduction waves with peak potentials at -317 and -406 mV, respectively. In the mixture of two compounds overlapping polarographic peaks were observed. In this study, support vector regression (SVR) was applied to resolve the overlapped polarograms. Furthermore, a comparison was made between the performance of SVR and partial least square (PLS) on data set. The results demonstrated that SVR is a better well-performing alternative for the analysis and modeling of DPP data than the commonly applied PLS technique. The proposed method was used for the determination of 2-nitrophenol and 4-nitrophenol in industrial waste water.

Topics: Environmental Monitoring; Industrial Waste; Nitrophenols; Polarography; Water Pollutants, Chemical

In the present study, the FT-IR and FT-Raman spectra of 3-methyl-2-nitrophenol (C(7)H(7)O(3)N) (3M2NP) have been recorded in the range of 4000-100 cm(-1). The fundamental modes of vibrational frequencies of 3M2NP are assigned. All the geometrical parameters have been calculated by HF and DFT (LSDA and B3LYP) methods with 6-31G(d,p) and 6-311G(d,p) basis sets. Optimized geometries of the molecule have been interpreted and compared with the reported experimental values for phenol and some substituted phenol. The harmonic and anharmonic vibrational wave numbers, IR intensities and Raman activities are calculated at the same theory levels used in geometry optimization. The calculated frequencies are scaled and compared with experimental values. The scaled vibrational frequencies at LSDA/B3LYP/6-311G(d,p) seem to coincide with the experimentally observed values with acceptable deviations. The impact of substitutions on the benzene structure is investigated. The molecular interactions between the substitutions (OH, CH(3) and NO(2)) are also analyzed. A detailed interpretation of the infrared spectra of was also reported more precisely. Charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap are calculated and presented. On the basis of the thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations between standard heat capacities (C) standard entropies (S), and standard enthalpy changes (H) and temperatures.

Topics: Absorption; Electrons; Entropy; Models, Chemical; Molecular Conformation; Nitrophenols; Quantum Theory; Solvents; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis, Raman; Vibration

The novel surface molecularly imprinted polymer (MIP) with 2-nitrophenol (2-NP) as the template has been prepared and used as the adsorbent for the solid-phase extraction (SPE). The selectivity of the polymer was checked toward several selected nitrophenols (NPs) such as 2-NP, 3-nitrophenol (3-NP), 4-nitrophenol (4-NP) and 2,4,6-trichlorophenol (2,4,6-TCP). Under the optimized conditions, high sensitivity (detection limits: 0.07-0.12 ng/mL) and good reproducibility of analytes (2.3-4.8% for four cycles) were achieved. Then, the method was applied for the analysis of selected phenols in spiked tap, lake and river water samples. High recoveries (>83.3%) for nitrophenols (NPs) were obtained, but lower recoveries (<63.4%) were achieved for 2,4,6-TCP. The method was found to be linear in the range of 1-300 ng/mL with correlation coefficients (R(2) ) greater than 0.99 and repeatability relative standard deviation (RSD) below 7.2% in all cases. For analysis of 120 mL water samples, the method detection limits (LODs) ranged from 0.10 to 0.22 ng/mL and the limit of quantification (LOQs) from 0.33 to 0.72 ng/mL. These results showed the suitability of the MIP-SPE method for the selective extraction of a group of structurally related isomeric compounds.

Topics: Adsorption; Molecular Imprinting; Nitrophenols; Polymers; Solid Phase Extraction; Stereoisomerism; Surface Properties; Water Pollutants, Chemical

Coupling of long-chain ionic liquid (LCIL)-based sweeping and micelle to solvent stacking (MSS) in CZE for anionic compounds was proposed. N-Cetyl-N-methylpyrrolidinium bromide (C16MPYBr) was used as a novel cationic surfactant. The capillary column was conditioned with poly(1-vinyl-3-butylimidazolium) bromide, a kind of polymeric ionic liquid, to obtain the anodic electroosmotic flow (EOF). There is a micellar solution (MS) zone which is prepared with C16MPYBr before the sample zone. The micelles penetrated into the sample zone, swept and transported the analytes toward the micelle to solvent boundary (MSSB). Meanwhile, a sufficient amount of methanol in the background solution (BGS) resulted in the reversal of effective electrophoretic mobility of analytes and completed the MSS. Under optimal conditions, good linearity (0.9988–0.9999) was obtained for model analytes in a wide linear range with limits of detection (LODs) from 0.025 to 0.25 mg/L. The intraday and interday repeatabilities (%RSD, n=5, 10) were acceptable in the range from 2.12 to 7.29%. 34 and 25 times increases in peak area sensitivity for benzoic acid (BA) and 2-nitrophenol (2-NP) and 60 times increase in peak height sensitivity for 4-chlorophenol (4-CP) were obtained. The proposed method is applied to analyze two spiked environmental water samples obtaining satisfactory recoveries.

Topics: Benzoic Acid; Cations; Chlorophenols; Ionic Liquids; Micelles; Nitrophenols; Solvents; Surface-Active Agents; Water Pollutants, Chemical

We investigated the biodegradation of 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), and 2,4-dinitrophenol (2,4-DNP) in the rhizosphere of Spirodela polyrrhiza plants by conducting degradation experiments with three river water samples supplemented with each nitrophenol (NP). We then isolated NP-degrading bacteria both from the S. polyrrhiza roots and from the river water. In the river water samples, removal of the three NP was accelerated in the presence of S. polyrrhiza plants. The three NPs persisted in an autoclaved solution with sterile plants suggests that NP removal was accelerated largely by bacterial NP biodegradation rather than by adsorption and uptake by the plants. We isolated 8 strains of NP-degrading bacteria: 6 strains from the S. polyrrhiza roots and 2 strains from river water without the plants. The 2-NP- and 2,4-DNP-degrading bacteria were isolated only from the S. polyrrhiza roots. The 4-NP-degrading bacteria different from those isolated from the river water samples were also found on S. polyrrhiza roots. The 2-NP- and 4-NP-degrading strains isolated from the roots utilized the corresponding NP (0.5 mmol/L) as the sole carbon and energy source. The 2,4-DNP-degrading strains isolated from the roots showed substantial 2,4-DNP-degrading activity, but the presence of other carbon and energy sources was required for their growth. The isolated NP-degrading bacteria from the roots must have contributed to the accelerated degradation of the three NPs in the rhizosphere of S. polyrrhiza. Our results suggested that rhizoremediation with S. polyrrhiza may be effective for NP-contaminated surface water.

Topics: 2,4-Dinitrophenol; Araceae; Bacteria; Biodegradation, Environmental; Glucose; Molecular Sequence Data; Nitrophenols; Rhizosphere; Rivers; RNA, Ribosomal, 16S

Forty-seven surface water samples were collected from the main stream and 22 tributaries in area of the Three Gorges Reservoir, 15 phenolic compounds in these samples were analyzed using GC/MS. The results showed that the concentrations of phenolic compounds in the samples from the main stream and tributaries were 52.47 ng x L(-1) and 87.99 ng x L(-1), respectively. The concentrations of non-chlorinated phenols were higher than those of chlorinated phenols in the main stream and tributaries, and so the non-chlorinated phenols were the predominant compounds in these surface water samples. Phenol, o-cresol and 2-nitrophenol were the predominant compounds accounted for 79.1%, 3.7% and 3.6% in the samples from the main stream, respectively. Phenol, o-cresol, 2,6-dichlorophenol and 2-nitrophenol were the main compounds accounted for 77.5%, 5.4%, 3.8% and 2.2% in the samples from the tributaries, respectively. As compared the concentrations of phenol and 2-nitrophenol with the standard limits in The National Environmental Health Risk List, the levels of phenol and 2-nitrophenol were much lower than the standard limits, suggesting negligible risk of phenol and 2-nitrophenol in these samples.

Topics: China; Cresols; Environmental Monitoring; Nitrophenols; Phenol; Phenols; Rain; Rivers; Seasons; Water Pollutants, Chemical; Water Supply

The Fe(III)/Fe(II) couple can play a significant role in the abiotic reduction of 2-nitrophenol (2-NP) at the cathode chamber of a microbial fuel cell (MFC). Experimental results demonstrate that Fe(II) addition to the cathode chamber contributes to a significant increase in the reaction rate of 2-NP removal and the power performance of MFC. Observed pseudo first-order rate constants and power densities are heavily dependent on the identity of the Fe(II)-complexing ligands. The Fe(II) complex coordinated with citrate results in the highest rate constant up to 0.12 h(-1) as compared to other organically complexed iron species including Fe(II)-EDTA, Fe(II)-acetate and Fe(II)-oxalate, and iron species uncomplexed with any organic ligands. In addition, the presence of Fe(II)-citrate species leads to a maximum volumetric power density of 1.0 W m(-3), which is the highest value among those obtained with other iron species for the similar MFC system.

Topics: Bioelectric Energy Sources; Electricity; Electrodes; Electrons; Iron; Kinetics; Ligands; Nitrophenols; Oxidation-Reduction; Time Factors

For the first time, an ionic liquid based three-phase liquid-liquid-liquid solvent bar microextraction (IL-LLL-SBME) was developed for the analysis of phenols in seawater samples. The ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF(6)]), was used as the intermediary solvent for LLL-SBME, enhancing the extraction efficiency for polar analytes. In the procedure, the analytes were extracted from the aqueous sample into the ionic liquid intermediary and finally, back-extracted into an aqueous acceptor solution in the lumen of the hollow fiber. The porous polypropylene membrane acted as a filter to prevent potential interfering materials from being extracted, and no additional cleanup was required. After extraction, the acceptor solution could be directly injected into a high-performance liquid chromatographic system for analysis. Six phenols, 2-nitrophenol, 4-chlorophenol, 2,3-dichlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol were selected here as model compounds for developing and evaluating the method. The most influential extraction parameters were evaluated, including the ionic liquid, the composition of donor solution and acceptor solution, the extraction time and the extraction temperature, the effect of ionic strength, and the agitation speed. Under the most favorable extraction parameters, the method showed good linearity (from 0.05-50 to 0.5-50 μg/L, depending on the analytes) and repeatability of extractions (RSD below 8.3%, n=5). The proposed method was compared to conventional three-phase LLL-SBME and ionic liquid supported hollow fiber protected three-phase liquid-liquid-liquid microextraction, and showed higher extraction efficiency. The proposed method was demonstrated to be a simple, fast, and efficient method for the analysis of phenols from environmental water samples.

Topics: Chemical Fractionation; Chlorophenols; Chromatography, High Pressure Liquid; Imidazoles; Ionic Liquids; Linear Models; Nitrophenols; Reproducibility of Results; Seawater; Temperature

Nitrophenols and methylnitrophenols have been identified as photolytic precursors of nitrous acid, HONO, but their gas-phase absorption has not previously been reported. In this study, the absorption cross sections of 2-nitrophenol, 3-methyl-2-nitrophenol, and 4-methyl-2-nitrophenol were measured from 320 to 450 nm using incoherent broad-band cavity-enhanced absorption spectroscopy (IBBCEAS). The benzaldehyde absorption spectrum was measured to validate the approach and was in good agreement with literature spectra. The nitrophenol absorption cross sections are large (ca. 10(-17) cm(2) molecule(-1)) and blue-shifted about 20 nm compared to previously measured solution spectra. Besides forming HONO, nitrophenol absorption influences other photochemistry by reducing the available actinic flux. The magnitudes of both effects are evaluated as a function of solar zenith angle, and nitrophenol absorption is shown to lower the photolysis rates of O(3) and NO(2).

Topics: Atmosphere; Kinetics; Nitrophenols; Oxygen; Photolysis; Spectrophotometry, Ultraviolet; Ultraviolet Rays

The mutagenic activities of 5-methyl-2-nitrophenol (5M2NP), a chlorination by-product of butamifos, its structural isomer 2-methyl-5-nitrophenol (2M5NP), and related compounds were evaluated by the Ames assay. The mutagenic activities of 5M2NP and 2M5NP were negative or not particularly high. However, those of their chlorinated derivatives were increased in Salmonella typhimurium strain TA100 and the overproducer strains YG1026, and YG1029 in the absence and/or presence of a rat liver metabolic activation system (S9 mix), particularly for YG1029. The mutagenic activities of 6-chloro-2-methyl-5-nitrophenol (6C2M5NP) in YG1029 in the absence and presence of S9 mix were 70000 and 110000 revertants mg(-1), respectively. When nitro functions of 6C2M5NP and 4-chloro-5-methyl-2-nitrophenol (4C5M2NP) were reduced to amino functions, their mutagenic activities were markedly decreased. The mutagenic activities of 5M2NP and 4C5M2NP were lower than those of 2M5NP and 6C2M5NP, respectively. Thus, it was shown that substituent position is a key factor for the mutagenic activities of methylnitrophenols (MNPs) and related compounds. The mutagenic activities of the extracts of 2M5NP in chlorination increased early during the reaction time and then decreased. The main chlorination by-product contributing to the mutagenic activities of the extracts of 2M5NP in chlorination was 6C2M5NP. The results of chlorination of 2M5NP suggested that MNPs were present as their dichlorinated derivatives or further chlorination by-products in drinking water.

Topics: Animals; Carcinogens; DNA, Bacterial; Halogenation; Hydrogen-Ion Concentration; Microsomes, Liver; Mutagenicity Tests; Mutagens; Nitrophenols; Organothiophosphorus Compounds; Rats; Salmonella typhimurium; Structure-Activity Relationship

SEIRA, SERS, TPD and DFT were used to study 4-nitrophenol (4NP), 3-nitrophenol (3NP) and 2-nitrophenol (2NP) adsorption on nanoscale silver films/powder. SERS and DFT demonstrated that 4NP adsorbed as the 4-nitrophenolate ion. SEIRA results revealed that a 4NP multilayer condensed differently using deposition solvents with and without polar bonds. 3NP and 2NP adsorption were not altered by the polar properties of the solvent. The nanoscale properties of the silver films/powder were shown to impact how the polar properties of the deposition solvent altered nitrophenol adsorption. In the SEIRA spectra of 4NP and 3NP a C=O stretch was observed above 1700cm(-1) using a highly volatile n-pentane deposition solvent. No other solvent yielded such a peak for 4NP or 3NP adsorption including n-heptane. 2NP had a C=O stretch regardless of deposition solvent. A C=O stretch confirmed nitrophenol ionization in the monolayer and pointed toward the significance of resonance in NP adsorption. 2NP never formed a multilayer at high exposures as demonstrated using TPD and SEIRA. Results of this work will have environmental implications and will aid biochemical and industrial applications where phenolic compounds are employed.

Topics: Adsorption; Isomerism; Models, Molecular; Nanostructures; Nitrophenols; Silver; Spectrum Analysis

In order to investigate nitro-substitutent's effect on degradation of phenols at boron-doped diamond (BDD) anodes, cyclic voltammetries of three nitrophenol isomers: 2-nitrophenol (2NP), 3-nitrophenol (3NP) and 4-nitrophenol (4NP) were studied, and their bulk electrolysis results were compared with phenol's (Ph) under alkaline condition. The voltammetric study showed nitrophenols could be attacked by hydroxyl radicals and nitro-group was released from the aromatic ring. Results of bulk electrolysis showed degradation of all phenols were fit to a pseudo first-order equation and followed in this order: 2NP>4NP>3NP>Ph. Molecular structures, especially carbon atom charge, significantly influenced the electrochemical oxidation of these isomers. Intermediates were analyzed during the electrolysis process, and were mainly catechol, resorcinol, hydroquinone, and carboxylic acids, such as acetic acid and oxalic acid. A simple degradation pathway was proposed. Moreover, a linear increasing relationship between degradation rates and Hammett constants of the studied phenols was observed, which demonstrated that electrochemical oxidation of these phenols was mainly initiated by electrophilic attack of hydroxyl radicals at BDD anodes.

Topics: Boron; Diamond; Electrochemical Techniques; Electrodes; Electrolysis; Environmental Restoration and Remediation; Hydroxyl Radical; Nitrophenols; Oxidation-Reduction; Phenols

The extent of cometabolic bioregeneration of activated carbons loaded with 2-nitrophenol was investigated in lab-scale batch activated sludge reactors. Bioregeneration was quantified by measuring the deterioration in adsorption capacity of a fresh activated carbon after a pre-loading and a subsequent bioregeneration sequence. Activated carbons loaded with 2-nitrophenol could be partially bioregenerated cometabolically in the presence of phenol as the growth substrate. The occurrence of exoenzymatic bioregeneration was also possible during cometabolic bioregeneration of thermally activated carbon. However, cometabolic bioregeneration of chemically activated carbon was higher in accordance with higher desorbability. Rather than biodegradation, desorption was the rate-limiting step in bi-solute bioregeneration of phenol and 2-nitrophenol. The absence of oxidative coupling reactions leads to sufficient reversible adsorption, which eventually makes 2-nitrophenol an ideal compound in terms of bioregenerability.

Topics: Adsorption; Bioreactors; Charcoal; Conservation of Natural Resources; Nitrophenols; Sewage

We present a novel method for identification of unlabeled analytes using fluorescent carrier ampholytes and isotachophoresis (ITP). The method is based on previous work where we showed that the ITP displacement of carrier ampholytes can be used for detection of unlabeled (nonfluorescent) analytes. We here propose a signal analysis method based on integration of the associated fluorescent signal. We define a normalized signal integral which is equivalent to an accurate measure of the amount of carrier ampholytes which are focused between the leading electrolyte and the analyte. We show that this parameter can be related directly to analyte effective mobility. Using several well characterized analytes, we construct calibration curves relating effective mobility and carrier ampholyte displacement at two different leading electrolyte (LE) buffers. On the basis of these calibration curves, we demonstrate the extraction of fully ionized mobility and dissociation constant of 2-nitrophenol and 2,4,6-trichlorophenol from ITP experiments with fluorescent carrier ampholytes. This extraction is based on no a priori assumptions or knowledge of these two toxic chemicals. This technique allows simultaneous identification of multiple analytes by their physiochemical properties in a few minutes and with no sample preparation.

Topics: Calibration; Chlorophenols; Electrophoresis; Fluorescence; Nitrophenols

Pseudomonas sp. strain NyZ402, a native soil organism that grows on para-nitrophenol (PNP), was genetically engineered for the simultaneous degradation of methyl parathion (MP) and ortho-nitrophenol (ONP) by integrating mph (methyl parathion hydrolase gene) from Pseudomonas sp. strain WBC-3 and onpAB (ONP 2-monooxygenase and ONP o-benzoquinone reductase genes) from Alcaligenes sp. strain NyZ215 into the genome of strain NyZ402. Methyl parathion hydrolase (MPH), ONP 2-monooxygenase (OnpA) and o-benzoquinone reductase (OnpB) were constitutively expressed in the engineered strain NyZ-MO. Strain NyZ-MO was free of exogenous antibiotic resistance gene markers and the introduced genes were genetically stable. Degradation experiments showed that strain NyZ-MO could utilize MP or ONP as the sole carbon and energy source, and mineralize 0.1 mM MP-0.1 mM ONP simultaneously. This method may serve as a useful strategy for the construction of engineered strains in the degradation of multiple environmental pollutants.

Topics: Alcaligenes; Anti-Bacterial Agents; Drug Resistance, Bacterial; Genetic Engineering; Methyl Parathion; Mixed Function Oxygenases; Nitrophenols; Oxidoreductases; Phosphoric Monoester Hydrolases; Pseudomonas

In this study the interaction between new benzimidazole molecules, 2-(2-nitrophenyl)-1H-benzimidazole (NB) and N-benzoyl-2-(2-nitrophenyl)-benzimidazole (BNB), with dsDNA and ssDNA was assessed at pH 7.4. Using differential pulse voltammetry at glassy carbon electrode, both molecules were electrochemically reduced due to the presence of a nitro group in their structures. When DNA was added to the solution, the electrochemical signal of NB and BNB decreased and shifted to more negative potentials. The interaction mode was electrostatic when ionic strength was low. Under this condition DNA-nitro complexes were characterized and binding constant values of 8.22 x 10(4)M(-1) and 3.08 x 10(6)M(-1) for NB and BNB with dsDNA were determined. On the other hand, only NB was able to interact when a high concentration of NaCl was used. Finally, a glassy carbon electrode modified with carbon nanotubes and DNA was tested in order to determine the nitrocompound in solution. The electrochemical reduction of the nitrocompound adsorbed on GCE/CHIT-CNT/DNA was used as an analytical signal. Using 10 min as accumulation time, a linear dependence was observed between 20 and 80 microM nitrocompound concentrations and the electrode response. Detection and quantification limits in the range of microM were determined.

Topics: Benzimidazoles; Carbon; Chemistry Techniques, Analytical; DNA; DNA, Single-Stranded; Electrochemistry; Electrodes; Hydrogen-Ion Concentration; Nitrophenols; Osmolar Concentration; Reproducibility of Results; Sensitivity and Specificity

A couple of new fluorescent probes, based on diethoxycarbonyl glycoluril, were synthesized and characterized by (1)H NMR, X-ray crystal structure. The probes were found to be relatively highly fluorescence with quantum yields of 0.20 and 0.18, respectively, at room temperature in THF solution. Both of the proposed probes were tested using different phenolic compounds, showing very high selectivity and sensitivity for 2-nitrophenol by forming a 1:1 complex in THF-MeOH (9:1, v/v). Additionally, the sensors could be used for the qualitative analysis of 2-nitrophenol in real water samples.

Topics: Chromatography, High Pressure Liquid; Crystallography, X-Ray; Environmental Monitoring; Fluorescent Dyes; Humans; Hydrogen; Magnetic Resonance Spectroscopy; Models, Chemical; Molecular Conformation; Nitrophenols; Solvents; Spectrophotometry, Ultraviolet; Temperature; Water; X-Ray Diffraction

We report a novel system to analyze atmospheric nitrophenols (NPs). Rain or air sample extracts (1 mL) are preconcentrated on a narrow bore (2 mm) aliphatic anion exchanger. In the absence of strong retention of NPs exhibited by aromatic ion exchangers, retained NPs are eluted as a plug by injection of 100 microL of 0.1 M Na(2)SO(4) on to a short (2 x 50 mm) reverse phase C-18 column packed with 2.2 mum particles. The salt plug passes through the C-18 column unretained while the NPs are separated by an ammonium acetate buffered methanol-water eluent, compatible with mass spectrometry (MS). The eluted NPs are measured with a long path Teflon AF-based liquid core waveguide (0.15 x 1420 mm) illuminated by a 403 nm light emitting diode and detected by a monolithic photodiode-operational amplifier. The waveguide is rendered chemically active by suspending it over concentrated ammonia that permeates into the lumen. The NPs ionize to the yellow anion form (lambda(max) approximately 400 nm). The separation of 4-nitrophenol, 2,4-dinitrophenol, 2-methyl-4-nitrophenol, 3-methyl-4-nitrophenol, and 2-nitrophenol (these are the dominant NPs, typically in that order, in both rain and air of Houston and Arlington, TX, confirmed by tandem MS) takes just over 5 min with respective S/N = 3 limits of detection (LODs) of 60, 12, 30, 67, and 23 pg/mL compared to MS/MS LODs of 20, 49, 11, 20, and 210 pg/mL. Illustrative air and rain data are presented.

Topics: 2,4-Dinitrophenol; Air; Air Pollutants; Chromatography, Liquid; Cresols; Mass Spectrometry; Nitrophenols; Rain; Spectrophotometry

A three-phase hollow fiber liquid-phase microextraction method coupled with CE was developed and used for the determination of partition coefficients and analysis of selected nitrophenols in water samples. The selected nitrophenols were extracted from 14 mL of aqueous solution (donor solution) with the pH adjusted to pH 3 into an organic phase (1-octanol) immobilized in the pores of the hollow fiber and finally backextracted into 40.0 microL of the acceptor phase (NaOH) at pH 12.0 located inside the lumen of the hollow fiber. The extractions were carried out under the following optimum conditions: donor solution, 0.05 M H(3)PO(4), pH 3.0; organic solvent, 1-octanol; acceptor solution, 40 microL of 0.1 M NaOH, pH 12.0; agitation rate, 1050 rpm; extraction time, 15 min. Under optimized conditions, the calibration curves for the analytes were linear in the range of 0.05-0.30 mg/L with r(2)>0.9900 and LODs were in the range of 0.01-0.04 mg/L with RSDs of 1.25-2.32%. Excellent enrichment factors of up to 398-folds were obtained. It was found that the partition coefficient (K(a/d)) values were high for 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol and 2,6-dinitrophenol and that the individual partition coefficients (K(org/d) and K(a/org)) promoted efficient simultaneous extraction from the donor through the organic phase and further into the acceptor phase. The developed method was successfully applied for the analysis of water samples.

Topics: 1-Octanol; 2,4-Dinitrophenol; Chromatography, Liquid; Electrophoresis, Capillary; Limit of Detection; Nitrophenols; Solvents; Uncoupling Agents; Water

A number of approaches have been proposed for screening level ecological risk assessment. In this paper, we first established a mass spectrum library including 50 phenols using retention time locking (RTL) technology and deconvolution reporting software (DRS). Distribution of phenols in surface water of the Taihu Lake was screened. Among the 22 identified phenols, 14 phenols were quantified. The concentrations of total phenols ranged 675.2-3346.1 ng L(-1). The distributions of ecological effect quotients (EEQs) of 14 phenols were characterized in terms of the exposure concentration distributions (ECDs) and species sensitivity distributions (SSDs). Those phenols with EEQs exceeding the threshold proposed by Water Environment Research Foundation of Alexandria were selected as priorities. As a result, 2-nitrophenol (2-NP), p-chloro-m-xylenol (PCMX) and pyrocatechol were determined as potential ecological risk stressors in surface water of the Taihu Lake. Results of the present study suggested that the proposed approach is feasible for the screening level ecological risk assessment.

Topics: Catechols; Fresh Water; Nitrophenols; Phenols; Risk Assessment; Water Pollutants, Chemical; Xylenes

This Study describes the feasibility of anaerobic degradation of United States Environmental Protection Agency (USEPA) listed 4-chloro-2-nitrophenol (4C-2-NP), 2-chloro-4-nitrophenol (2C-4-NP), 2-chloro-5-methylphenol (2C-5-MP) from a simulated wastewater using four identical 7L bench scale hybrid up flow anaerobic sludge blankets (HUASBs) at five different hydraulic retention times (HRTs) under thermophilic condition (55+/-3 degrees C). The substrate to co-substrate ratios were maintained between 1:33.3 and 1:166.6. Continuous monitoring of parameters like pH, volatile fatty acids (VFAs) accumulation, oxidation reduction potential, chemical oxygen demand (COD), alkalinity, gas productions, methane percentages were carried out along with compound reduction to asses the efficiency of biodegradation. The compound reduction was estimated by using spectrophotometric methods and further validated with high-performance liquid chromatography (HPLC). Optimum HRT values were observed at 24h. Optimum ratio of substrate (phenolic compounds) to co-substrate (glucose) was 1:100. Scanning electron micrographs show that the granules were composed of thermophilic Methanobrevibacter and thermophilic Methanothrix like bacteria.

Topics: Anaerobiosis; Biodegradation, Environmental; Bioreactors; Laboratories; Methanobrevibacter; Methanosarcinaceae; Nitrophenols; Sewage

The ability of biological and non-biological adsorbents to remove 2-nitrophenol (2-NP) and 2-chlorophenol (2-CP) from aqueous solutions in batch experiments at room temperature was compared. The marine seaweeds Macrocystis integrifolia Bory (S1) and Lessonia nigrescens Bory (S2) were cross-linked with CaCl(2) to enhance their mechanical properties. Natural bentonite was chemically exchanged with hexadecyltrimethylammonium bromide (B1) and bencyltriethylammonium chloride (B2) to increase their affinity towards organic compounds as well. The adsorption capacity of all of the adsorbents strongly depends on solution pH, whereas equilibrium assays showed a mixed mechanism according to the Langmuir and Freundlich isotherms. The maximum adsorption capacity of 2-NP follows the trend: S1>S2>B2>B1 within the range of 97.37 and 18.64 mg g(-1) whereas for 2-CP, it ranged between 24.18 and 9.95 mg g(-1) with the trend: S1>S2>B2 approximately B1. The importance of the octanol-water partition coefficient as the main factor on the adsorption of these compounds on two different kinds of adsorbents is discussed.

Topics: Adsorption; Calcium Chloride; Cetrimonium; Cetrimonium Compounds; Chlorophenols; Nitrophenols; Octanols; Phenols; Seaweed; Water; Water Pollutants, Chemical; Water Purification

This study was aimed at elucidating the role of adsorbed Fe(II) on minerals in the reductive transformation of 2-nitrophenol (2-NP) by using electrochemical methods. The studies of Fe(ll) adsorption and 2-NP reduction kinetics showed that the identity of minerals such as gamma-Al2O3 and TiO and the solution pH were crucial factors to determine the Fe(ll) adsorption behavior and to influence the rate constant (k) of 2-NP reduction. Furthermore, two electrochemical methods, cyclic voltammetry (CV) and electrochemical impedance spectrometry (EIS), were applied to characterize the Fe(II) reactivity with both the mineral-coated and mineral-free electrodes. The electrochemical evidence confirmed that the peak oxidation potential (Ep) of complex Fe(II) can be significantly affected by the solution pH;the enhanced reductive transformation of 2-NP can be related to the reduced Ep of surface-complex Fe(II) and the reduced charge transfer resistance (R(CT)) of the Fe(III)/Fe(II) couple. All these relationships were studied quantitatively. At pH 6.7, the measured Ep and R(CT) decreased in the order TiO2/GC < gamma-Al2O3/ GC < GC (Ep, 0.140 < 0.190 < 0.242 V; R(CT), 0.30 < 0.41 < 0.78 komega), while the 2-NP reduction on different minerals were in the order TiO2 > gamma-Al2O3 > nonmineral (k x 10-2, 7.91 > 0.64 > 0.077 min(-l)).

Topics: Adsorption; Aluminum Oxide; Electric Impedance; Electrochemistry; Electrodes; Environment; Hydrogen-Ion Concentration; Iron; Kinetics; Minerals; Models, Chemical; Nitrophenols; Oxidation-Reduction; Surface Properties; Titanium

Photodissociation dynamics of o-nitrophenol in the gas phase at different photolysis wavelengths (361-390 nm) is investigated, and the nascent OH radical is observed by the single-photon laser-induced fluorescence technique. At all the photolysis wavelengths, the OH radicals are formed in vibrationally cold state (upsilon(")=0) and have similar rotational state distributions. The average rotational temperature for all the photolysis wavelengths is approximately 970+/-120 K, corresponding to a rotational energy of 1.9+/-0.2 kcal mol(-1). The spin orbit and Lambda-doublet states of the OH fragments formed in the dissociation are measured to have nonstatistical distributions. To get an insight into the dissociative mechanism leading to OH formation in the photolysis of o-nitrophenol, the potential energy surfaces of the OH-forming channels are mapped by ab initio theoretical calculations. According to both experimental and theoretical results, a possible mechanism for OH formation is proposed.

Topics: Computer Simulation; Hydroxyl Radical; Lasers; Nitrophenols; Photolysis; Quantum Theory; Rotation; Spectrometry, Fluorescence; Surface Properties; Temperature; Vibration

2-Nitrophenol (2-NP) is the major detoxification metabolite of an important industrial pollutant and a potent carcinogen, 2-nitroanisole (2-NA). Characterization of the products of 2-NP metabolism by rat hepatic microsomes containing cytochromes P450 (CYPs) and identification of the major CYP enzymes participating in this process are aims of this study.. HPLC with UV detection was employed for the separation and characterization of 2-NP metabolites. Inducers and inhibitors of CYPs and rat recombinant CYPs were used to characterize the enzymes participating in 2-NP oxidation.. Rat hepatic microsomes oxidize 2-NP to its hydroxylated metabolite, 2,5-dihydroxynitrobenzene (2,5-DNB). No nitroreductive metabolism leading to the formation of o-aminophenol was evident when using rat hepatic microsomes. Selective CYP inhibitors and hepatic microsomes of rats pre-treated with specific CYP inducers were used to characterize CYPs oxidizing 2-NP in rat livers. Based on these studies, we attribute most of 2-NP oxidation in rat liver to CYP2E1 and 3A, followed by CYP2D and 2C. Among recombinant rat CYP enzymes tested in this study, CYP2E1 and 2C11 were the most effective enzymes oxidizing 2-NP. Oxidation of 2-NP by rat CYP2E1 exhibits the Michaelis-Menten kinetics, having the Km value of 0.35 mM.. The results found in this study, the first report on the metabolism of 2-NP by rat hepatic microsomes and rat CYP enzymes, demonstrate that CYP2E1 is the major enzyme oxidizing this compound in rat liver.

Topics: Animals; Anisoles; Chromatography, High Pressure Liquid; Cytochrome P-450 Enzyme Inhibitors; Cytochrome P-450 Enzyme System; Humans; Inhibitory Concentration 50; Kinetics; Microsomes, Liver; Nitrophenols; Oxidation-Reduction; Rats; Recombinant Proteins; Ultraviolet Rays

Resolution of overlapped chromatographic peaks is generally accomplished by modeling the peaks as Gaussian or modified Gaussian functions. It is possible, even preferable, to use actual single analyte input responses for this purpose and a nonlinear least squares minimization routine such as that provided by Microsoft Excel Solver can then provide the resolution. In practice, the quality of the results obtained varies greatly due to small shifts in retention time. I show here that such deconvolution can be considerably improved if one or more of the response arrays are iteratively shifted in time.

Topics: Algorithms; Chromatography, Ion Exchange; Data Interpretation, Statistical; Nitrophenols; Normal Distribution; Software

This study examined o-nitrophenol removal from aqueous solutions by electrochemical oxidation employing a modified electrode. The modified electrode was produced by electrodepositing lead oxide onto a titanium substrate. Following electrochemical oxidation of o-nitrophenol-containing solutions, the remaining o-nitrophenol concentration and chemical oxygen demand (COD) values were determined. The optimum parameters were current density of 40 mA cm(-2), pH of 2.47, 60 min of electrolysis time, 4 g L(-1) NaCl electrolyte solution and temperature of 30 degrees C. Under these optimum conditions of electrochemical degradation using a lead oxide/titanium modified electrode complete removal of o-nitrophenol and COD was achieved.

Topics: Electrodes; Electrolysis; Hydrogen-Ion Concentration; Lead; Nitrophenols; Oxidation-Reduction; Oxides; Sodium Chloride; Temperature; Titanium; Waste Disposal, Fluid; Water Pollutants, Chemical; Water Purification

A wavelet-based latent variable regression (WLVR) method was developed to perform simultaneous quantitative analysis of overlapping spectrophotometric signals. The quality of the noise removal was improved by combining wavelet thresholding with principal component analysis (PCA). A method for selecting the optimum threshold was also developed. Eight error functions were calculated for deducing the number of factor. The latent variables were made by projecting the wavelet-processed signals onto orthogonal basis eigenvectors. Two-programs WMRA and WLVR, were designed to perform wavelet thresholding and simultaneous multicomponent determination. Experimental results showed the WLVR method to be successful even where there was severe overlap of spectra.

Topics: 2,4-Dinitrophenol; Indicators and Reagents; Least-Squares Analysis; Models, Theoretical; Multivariate Analysis; Nitrophenols; Principal Component Analysis; Regression Analysis; Signal Processing, Computer-Assisted; Software; Spectrophotometry; Spectrophotometry, Ultraviolet

A simple, novel and sensitive spectrophotometric method was described for simultaneous determination of nitrophenol isomers mixtures. All factors affecting on the sensitivity were optimized and the linear dynamic range for determination of nitrophenol isomers were found. The simultaneous determination of nitrophenol mixtures by using spectrophotometric methods is a difficult problem, due to the spectral interferences. The partial least squares modeling was used for the multivariate calibration of the spectrophotometric data. The orthogonal signal correction was used for preprocessing of data matrices and the prediction results of model, with and without using orthogonal signal correction, were statistically compared. The experimental calibration matrix was designed by measuring the absorbance over the range 300-520 nm for 21 samples of 1-20, 1-20 and 1-10 microg ml(-1) of m-nitrophenol, o-nitrophenol and p-nitrophenol, respectively. The RMSEP for m-nitrophenol, o-nitrophenol and p-nitrophenol with and without OSC were 0.3682, 0.5965, 0.3408 and 0.7351, 0.9962, 1.0055, respectively. The proposed method was successfully applied for the determination of m-nitrophenol, o-nitrophenol and p-nitrophenol in synthetic and real matrix samples such as water.

Topics: Industrial Waste; Least-Squares Analysis; Nitrophenols; Rivers; Spectrophotometry; Water Pollutants, Chemical; Water Supply

Alcaligenes sp. strain NyZ215 was isolated for its ability to grow on ortho-nitrophenol (ONP) as the sole source of carbon, nitrogen, and energy and was shown to degrade ONP via a catechol ortho-cleavage pathway. A 10,152-bp DNA fragment extending from a conserved region of the catechol 1,2-dioxygenase gene was obtained by genome walking. Of seven complete open reading frames deduced from this fragment, three (onpABC) have been shown to encode the enzymes involved in the initial reactions of ONP catabolism in this strain. OnpA, which shares 26% identity with salicylate 1-monooxygenase of Pseudomonas stutzeri AN10, is an ONP 2-monooxygenase (EC 1.14.13.31) which converts ONP to catechol in the presence of NADPH, with concomitant nitrite release. OnpC is a catechol 1,2-dioxygenase catalyzing the oxidation of catechol to cis,cis-muconic acid. OnpB exhibits 54% identity with the reductase subunit of vanillate O-demethylase in Pseudomonas fluorescens BF13. OnpAB (but not OnpA alone) conferred on the catechol utilizer Pseudomonas putida PaW340 the ability to grow on ONP. This suggests that OnpB may also be involved in ONP degradation in vivo as an o-benzoquinone reductase converting o-benzoquinone to catechol. This is analogous to the reduction of tetrachlorobenzoquinone to tetrachlorohydroquinone by a tetrachlorobenzoquinone reductase (PcpD, 38% identity with OnpB) in the pentachlorophenol degrader Sphingobium chlorophenolicum ATCC 39723.

Topics: Alcaligenes; Bacterial Proteins; Catechol 1,2-Dioxygenase; Molecular Sequence Data; Multigene Family; Nitrophenols; Open Reading Frames; Oxidation-Reduction; Oxidoreductases; Oxygenases; Phylogeny; Sequence Analysis, DNA

A voltammetric and spectroelectrochemical ESR study of the reduction processes of five substituted 4-R-2-nitrophenols (R = -H, -OCH(3), -CH(3), -CN, -CF(3)) in acetonitrile was performed. In the potential range considered here (-0.2 to -2.5 V vs Fc+/Fc), two reduction signals (Ic and IIc) were detected; the first one was associated with the formation of the corresponding hydroxylamine via a self-protonation pathway. The voltammetric analysis at the first reduction signal showed that there are differences in the reduction pathway for each substituted 4-R-2-nitrophenol, being the E1/2 values determined by the inductive effect of the substituent in the meta position with respect to the nitro group, while the electron-transfer kinetics was determined by the protonation rate (k(1)+ ) of the anion radical electrogenerated. However, at potential values near the first reduction peak, no ESR signal was recorded from stable radical species, indicating the instability of the radical species in solution. Nevertheless, an intense ESR spectrum generated at the second reduction peak was detected for all compounds, indicating the monoelectronic reduction of the corresponding deprotonated 4-R-2-nitrophenols. The spin-coupling hyperfine structures revealed differences in the chemical nature of the electrogenerated radical; meanwhile, the -CF(3) and -CN substituents induced the formation of a dianion radical structure, and the -H, -CH(3), and -OCH(3) substituents provoked the formation of an anion radical structure due to protonation by acetonitrile molecules of the initially electrogenerated dianion radical. This behavior was confirmed by analyzing the ESR spectra in deuterated acetonitrile and by performing quantum chemical calculations of the spin densities at each site of the electrogenerated anionic radicals.

Topics: Acetonitriles; Electrochemistry; Electron Spin Resonance Spectroscopy; Molecular Structure; Nitrophenols; Oxidation-Reduction; Protons; Solvents

In the present study we estimated the localization of ortho-nitrophenol (ONP) within model membranes through its efficiency to quench and to modify the anisotropy of DPH and TMA-DPH fluorescence. These fluorescent probes are known to sense the hydrocarbon core and the polar head group region of membranes, respectively. TMA-DPH fluorescence in MLVs was more efficiently quenched than DPH (K(q,TMA-DPH)=2.36 and K(q,DPH)=1.07 mM ns(-1)). Moreover, these results demonstrated the interfacial localization of ONP and may contribute to understand membrane-mediated mechanisms of ONP-induced toxicity and the behavior of ONP as a product of several enzymatic reactions occurring in the presence of lipid-water interfaces.

Topics: Diphenylhexatriene; Fluorescence Polarization; Fluorescent Dyes; Lipid Bilayers; Nitrophenols; Phospholipids; Spectrometry, Fluorescence

The nitration process of salicylic acid for the production of the important intermediate 5-nitrosalicylic acid is studied from thermokinetic and safety points of view. Investigations carried out by considering, as process deviations, the loss of the thermal control point out the possibility of runaway phenomena due to the occurrence of polynitration reactions. Isothermal experiments are carried out in various conditions to assess the involved reaction network and reaction kinetics.

Topics: Acetic Acid; Kinetics; Nitrates; Nitric Acid; Nitrophenols; Safety; Salicylic Acid; Temperature

The effect of nitrophenolic shock loads on the performance of three bench-scale upflow anaerobic sludge blanket (UASB) reactors was studied using synthetic wastewater. Reactors R1, R2 and R3 were fed with 30 mg/L concentration of 2-nitrophenol (2-NP), 4-nitrophenol (4-NP) and 2,4-dinitrophenol (2,4-DNP), respectively, along with methanol (COD = 2000 mg/ L), sodium nitrate (NO3(-)-N=200mg/L), and other nutrients. The reactors were in continuous operation for more than 2 years before the shock loading study was performed. Five nitrophenolic shock loadings of 45, 60, 75, 90 and 120mg/L d were administrated by increasing the influent nitrophenolic concentration to 45, 60, 75, 90 and 120mg/L, respectively, while keeping hydraulic retention time as 24h. The shocks were given continuously for a period of 4 days before switching back to normal nitrophenolic loading (30mg/Ld). The reactors were allowed to recover to normal performance level before administrating the next nitrophenolic shock load. The study showed that the nitrophenolic shock load of as high as 120 mg/L d did not affect the reactors performance irreversibly. After resuming the normal nitrophenolic loading, it took almost 3-18 days for the reactors to recover from the shock effect. The study was further extended to assess the maximum possible mixed nitrophenolic loading (2NP:4NP:2,4:DNP = 1:1:1) to which 2,4-DNP acclimated granular sludge containing reactor (R3) can be exposed without hampering the reactor (R3) performance irreversibly. The reactor was able to achieve pseudo-steady-state at a mixed nitrophenolic loading of 180 mg/L d with more than 90% removal of all the three nitrophenols, but failed at a mixed nitrophenolic loading of 225 mg/Ld.

Topics: 2,4-Dinitrophenol; Anaerobiosis; Bioreactors; Nitrophenols; Sewage; Time Factors; Waste Disposal, Fluid; Water Pollutants, Chemical; Water Purification

The decomposition of 2-nitrophenol in aqueous solutions by ozone and UV/ozone processes was found to be technically feasible under adequate experimental conditions. Formation of nitrate ions was observed following the decomposition of 2-nitrophenol by ozone and UV/ ozone processes. Increasing ozone dosage and UV light intensity accelerated the decomposition rate of 2-nitrophenol in an aqueous solution. The species distribution of 2-nitrophenol under various solution conditions plays a significant role in determining decomposition behavior. In most experiments conducted in this study, the decomposition of 2-nitrophenol by ozone and UV/ozone processes was favored to occur in alkaline conditions. The addition of 2-butanol accelerated the rate of gaseous ozone transfer to an aqueous phase by reducing the surface tension of aqueous solution and therefore enhancing the decomposition rate of 2-nitrophenol by ozone and UV/ozone processes.

Topics: Hazardous Substances; Hydrogen-Ion Concentration; Kinetics; Nitrophenols; Ozone; Photolysis; Solutions; Time Factors; Ultraviolet Rays; Waste Disposal, Fluid; Water

We had demonstrated that membrane adsorption or penetration differentially modulated beta-Galactosidase (beta-Gal) activity against soluble substrates (Coll. and Surf., 24, 21, 2002). In a heterogeneous media, not only the enzyme but also the rest of the chemical species taking part in a chemical reaction would eventually interact with the available surfaces. The aim of the present work was to investigate if, in addition to changes in the intrinsic mechanism of the reaction at the lipid-water interface, the kinetics of enzyme-catalyzed reactions could be significantly affected by the partitioning of the substrate (ortho-nitro-phenyl galactopyranoside (ONPG)), the product (ortho-nitro-phenol (ONP)) and the enzyme (E. coli beta-Gal) towards the membrane. Multilamellar vesicles of sPC were used as model membranes. Membrane-water partition coefficients (Pm/w) were determined according to the theory and methodology developed previously (J. Neurosci. Meth. 36, 203, 1991). The values of Pm/w obtained (PONPG =0, PONP =50 and P beta-Gal = 118) were applied to a two-compartment model, which assumed a free access of the substrate to the enzyme and a nucleophile-like activatory effect exerted, within the membrane compartment, by the lipid-water interface. This model: (i) reproduced the lipid concentration-dependence we had observed previously in Vmax, (ii) predicted the values of k4 = 3.54 x 10(7) s-1 and the extinction coefficient of the aglycone in the membrane phase, 4012 M(-1) cm-1, with p < 0.0001 and p < 0.02, respectively, as well as for P beta-Gal =117 (which was poor (p=0.6716) but gave a numerical value within the same order of magnitude that the experimental value) and (iii) emphasized the importance of the more efficient reaction mechanism in the membrane phase compared with that in the aqueous phase (k4>>k3).

Topics: beta-Galactosidase; Catalysis; Chemical Phenomena; Chemistry, Physical; Escherichia coli; Kinetics; Membranes, Artificial; Models, Theoretical; Nitrophenols; Nitrophenylgalactosides; Octanols; Sensitivity and Specificity; Surface Properties; Water

Field studies have shown that the powerful phytotoxic agent 2,4-dinitrophenol is very likely to form in the atmospheric aqueous phase upon nitration of 2-nitrophenol or 4-nitrophenol. However, until now, the nitration pathway and the relative importance of the two mononitrophenols as sources of 2,4-dinitrophenol were not known. The present study shows that 2,4-dinitrophenol formation from mononitrophenols can take place upon photolysis and photooxidation of nitrite/nitrous acid (NO2-/HONO) and that nitrogen dioxide plays a key role in the process. A possible pathway might be the reaction between light-excited mononitrophenols (both 2- and 4-isomers) and nitrogen dioxide, in the presence of oxygen. As an alternative, nitration might involve *NO3 + *NO2. Possible sources of nitrogen dioxide in the atmospheric aqueous phase are dissolution from the gas phase and oxidation of NO2-. In the latter case, however, it is necessary that NO2- oxidation is faster than the oxidation of mononitrophenols. This would happen, for instance, in the presence of hematite under irradiation. Radiation absorption and scattering by hematite would also inhibit the direct photolysis of nitrophenols. The formation rate and the yield of 2,4-dinitrophenol are slightly higher when starting from 2-nitrophenol than those from 4-nitrophenol, but they are compensated by the higher concentration of 4-nitrophenol in the atmospheric aqueous phase.

Topics: 2,4-Dinitrophenol; Atmosphere; Gas Chromatography-Mass Spectrometry; Nitrogen Dioxide; Nitrophenols; Photolysis; Rain; Ultraviolet Rays

We developed a new sensing motif for the detection and quantification of creatinine, which is an important small molecule marker of renal dysfunction. This novel sensor motif is based on our intelligent polymerized crystalline colloidal array (IPCCA) materials, in which a three-dimensional crystalline colloidal array (CCA) of monodisperse, highly charged polystyrene latex particles are polymerized within lightly cross-linked polyacrylamide hydrogels. These composite hydrogels are photonic crystals in which the embedded CCA diffracts visible light and appears intensely colored. Volume phase transitions of the hydrogel cause changes in the CCA lattice spacings which change the diffracted wavelength of light. We functionalized the hydrogel with two coupled recognition modules, a creatinine deiminase (CD) enzyme and a 2-nitrophenol (2NPh) titrating group. Creatinine within the gel is rapidly hydrolyzed by the CD enzyme in a reaction which releases OH(-). This elevates the steady-state pH within the hydrogel as compared to the exterior solution. In response, the 2NPh is deprotonated. The increased solubility of the phenolate species as compared to that of the neutral phenols causes a hydrogel swelling which red-shifts the IPCCA diffraction. This photonic crystal IPCCA senses physiologically relevant creatinine levels, with a detection limit of 6 microM, at physiological pH and salinity. This sensor also determines physiological levels of creatinine in human blood serum samples. This sensing technology platform is quite general. It may be used to fabricate photonic crystal sensors for any species for which there exists an enzyme which catalyzes it to release H(+) or OH(-).

Topics: Acrylic Resins; Aminohydrolases; Biosensing Techniques; Creatinine; Humans; Latex; Nitrophenols; Polystyrenes

Concentration-dependent inhibition of the photosynthetic electron transport chain (photosystem I (PS I), photosystem II (PS II) and whole chain reaction) and ATP content was observed in Nostoc muscorum and Chlorella vulgaris grown with o-nitrophenol, m-nitrophenol, or 2,4-dinitrophenol. Although the extents of inhibition of the photosynthetic electron transport chain in both organisms were similar, PS II was more sensitive than PS I and whole chain reaction to the nitrophenols. Depletion of the ATP pool was noted in nitrophenol-grown cultures, probably as a consequence of nearly complete inhibition of the photosynthetic electron transport chain.

Topics: 2,4-Dinitrophenol; Adenosine Triphosphate; Biodegradation, Environmental; Chlorella; Culture Media; Cyanobacteria; Electron Transport; Nitrophenols; Photosynthesis; Photosystem I Protein Complex; Photosystem II Protein Complex; Uncoupling Agents

The aim of this study is to evaluate the efficiency of a new solid-phase extraction cartridge, Spe-ed Advanta, in the extraction and preconcentration of four phenolic compounds (phenol, 2-chlorophenol, 2-nitrophenol, and 2,4-dichlorophenol) from water. The solid phase is a polystyrene-divinylbenzene resin modified with carboxylic groups, these polar groups improve the contact between the matrix and the aqueous solutions in the extraction of polar analytes. We studied several elution solvents in order to find the most efficient one. Sample concentration, sample volume, and sample pH are also investigated as well as the best method for drying the cartridge. Recoveries achieved with the new phase are compared with those obtained with Isolute ENV+, a non-modified polystyrene-divinylbenzene stationary bed. The best experimental conditions were then used for determination of the phenols in spiked environmental waters.

Topics: Chlorophenols; Chromatography, Gas; Chromatography, High Pressure Liquid; Indicators and Reagents; Nitrophenols; Phenols; Water Pollutants, Chemical

We design novel chromophoric amphiphiles 6a-c, which lead to pH-dependent membrane fusion of egg phosphatidylcholine (eggPC) liposome containing them. Lipids 6a-c comprise double alkyl chains, a single chain with a 2-nitrophenol group as a pH trigger, and dipeptide (Asp-Asp) between them. The pKa values of 2-nitrophenol groups of 6a-c in liposome are larger than that of hydrophilic compound 9 in an aqueous solution. Absorption spectra indicate that the fields around 2-nitrophenol of 6a-c situated in liposome membranes are more hydrophobic than that of 9 in an aqueous solution, whereas the environments around deprotonated 2-nitrophenolate of 6b and 6c are not so hydrophobic as that of 6a. This means that protonated 2-nitrophenol groups of 6a-c are embedded in bilayer membranes. Deprotonated 2-nitrophenol groups of 6b and 6c must be located in less hydrophobic circumstances, while that of 6a is still embedded in bilayer membranes because of its larger hydrophobicity. Absorption spectra and (1)H NMR spectra respectively suggest that protonated 2-nitrophenol groups of 6a and those of 6c might take face-to-face associations in bilayer membranes.

Topics: Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Hydrogen-Ion Concentration; Hydrophobic and Hydrophilic Interactions; Kinetics; Lipid Bilayers; Liposomes; Membrane Fusion; Membrane Lipids; Nitrophenols; Nuclear Magnetic Resonance, Biomolecular; Phosphatidylcholines

The sorption and desorption of 2-nitrophenol (2-NP), 4-nitrophenol (4-NP) and 2,4-dinitrophenol (2,4-DNP) on live anaerobic granular sludge was studied at five different sorbate (nitrophenols) concentrations between 10 x 10(3) - 90 x 10(3) microg l(-1). Experiments were conducted at room temperature (29 +/- 2 degrees C) and at an initial pH of 7.5. The maximum uptake capacity of live anaerobic granular sludge was found to b e 1,427, 1,511 and 1,865 microg g(-1) VSS for 2-NP, 4-NP and 2,4-DNP, respectively. The equilibrium data of three nitrophenols obeyed both Freundlich and linear isotherm models. Sorption was observed to be partially reversible. About 20-89%, 36-90% and 29-80% desorption was observed for 10 x 10(3) - 90 x 10(3) microg l(-1) sorbate concentrations of 2-NP, 4-NP and 2,4-DNP, respectively.

Topics: 2,4-Dinitrophenol; Adsorption; Bacteria, Anaerobic; Coloring Agents; Models, Theoretical; Nitrophenols; Sewage; Temperature

The conversion of exogenous monatomic phenols (O-[1-(14)C]nitrophenol, 2,4-[1-14C]dinitrophenol, and alpha-[1-14C]naphthol) in pea seedlings has been investigated. It has been found that in the pea seedlings glycosylation of these phenols does not occur, but the main pathway of their detoxication is conjugation with the low-molecular-weight peptides. Approximately 80% of phenols absorbed by seedlings form phenol-peptide conjugates. The part of exogenous monatomic phenols is irreversibly bound to proteins via quinone-protein interaction. The amino acid content of the peptides involved in the conjugation process has been established. Penetration into the plant of monatomic exogenous phenols with a high dissociation constant leads to the stimulation of peptide formation.

Topics: 2,4-Dinitrophenol; Amino Acids; Environmental Pollutants; Inactivation, Metabolic; Naphthols; Nitrophenols; Peptides; Phenols; Pisum sativum; Protein Binding; Seeds

Although 2-nitrophenol has been identified as an important environmental chemical there is scarcity in the literature regarding the temperature dependence of its Henry's law coefficient, H. Here a bubble purge method was used to measure H for 2-nitrophenol over the temperature range 278-303 K. A novel approach in the data treatment allowed correction of the data for non-equilibrium partitioning in the apparatus to obtain the true equilibrium H value. The experimentally derived temperature-dependent expression for H of 2-nitrophenol is lnH (M atm(-1)) = (6290/T (K)) - 16.6. The standard enthalpy and entropy of gas-to-liquid transfer for 2-nitrophenol in aqueous solution are -52.3 +/- 8.1 kJ mol(-1) and -138 +/- 28 J mol(-1) K(-1), respectively. (Errors are 95% confidence intervals.)

Topics: Chemical Phenomena; Chemistry, Physical; Environmental Pollutants; Gases; Kinetics; Models, Chemical; Nitrophenols; Temperature

This work concerns the kinetic study of heterogeneous photocatalytic processes on copper adsorbed on aluminium-pillared montmorillonite. Photomineralization of 2-nitrophenol in aqueous medium was investigated as a function of the following experimental parameters: initial concentration of pollutant, light intensity, initial concentration of hydroperoxide, catalyst concentration, pH and temperature. The kinetic expression obtained can be described by the formula: V(NP) = k(0)exp(-Ea/RT)I(beta) x (K(NP)[NP]K(H2O2)[H2O2]/ [1+K(NP)[NP]0)(1+K(H2O2)[H2O2])] The apparent overall activation energy obtained for 2-nitrophenol was 28 kJ mol(-1). By fitting the above equation with the experimental data and values for beta (1.94), K(H2O2) (32.291 mol(-1)) and K(NP) (47.25 x 10(2)l mol(-1)), the kinetic equation can predict the concentration of 2-nitrophenol during the entire degradation process at pH 5 and a catalyst concentration of 0.5 g l(-1).

Topics: Aluminum; Bentonite; Catalysis; Copper; Hydrogen-Ion Concentration; Kinetics; Light; Models, Theoretical; Nitrophenols; Photochemistry; Temperature

A novel lipid analog with two long alkyl (C16) chains, an aspartate skeleton, a connecting alkyl (C8) chain, and 2-nitrophenol trigger group is synthesized by an efficient synthetic route, which can induce liposome fusion at physiological pH.

Topics: Hydrogen-Ion Concentration; Lipids; Liposomes; Magnetic Resonance Spectroscopy; Membrane Fusion; Nitrophenols; Spectrophotometry, Infrared

Topics: Child; Clinical Enzyme Tests; Cystic Fibrosis; Humans; Nitrophenols; Reagent Kits, Diagnostic; Sodium; Sweat

The effective concentrations (EC), which cause a certain percentage of inhibition in growth yield, of four nitrophenolics (o-nitrophenol, m-nitrophenol, p-nitrophenol (PNP), and 2,4-dinitrophenol) and the major metabolites of PNP reduction (p-nitrosophenol and p-aminophenol) toward growth of two microalgae (Chlorella vulgaris and Scenedesmus bijugatus) and two cyanobacteria (Nostoc muscorum and Nostoc linckia), all isolated from soil, were determined following linear regression analysis. The EC50 values of the selected toxicants toward the test organisms were in the range of 32 to 227 micrograms ml-1. Such a wide range in EC figures emphasizes the need for a prior determination of EC values of a toxicant before establishing its toxicity pattern toward a nontarget microorganism.

Topics: 2,4-Dinitrophenol; Chlorella; Cyanobacteria; Eukaryota; Lethal Dose 50; Linear Models; Nitrophenols; Soil Microbiology; Structure-Activity Relationship

A major industrial chemical accident occurred on 22 February 1993 at Hoechst AG Frankfurt/Germany. Approximately 11.8 tons of a chemical mixture (mostly chlorinated nitroarenes) were emitted, resulting in heavy contamination of Schwanheim, a nearby housing area. Urine samples were collected from the inhabitants of the affected area a few days after the accident and were analyzed for o-nitrophenol (ONP) as a representative metabolite to assess the actual uptake of the pollutants. As a result, ONP was found in urines of control subjects from elsewhere, an observation hitherto not described in the literature. Mean ONP excretion was about three times higher in the Schwanheim population than in the controls. The results show not only a higher accident-related but also a higher permanent ONP-excretion of the population of Schwanheim, pointing to a permanent environmental pollution in Schwanheim. Both results, the hitherto unknown ONP excretion in controls and regional differences in ONP excretion, require further investigation.

Topics: Accidents; Adolescent; Adult; Chemical Industry; Child; Child, Preschool; Environmental Monitoring; Environmental Pollution; Female; Germany; Humans; Male; Nitrophenols

A major chemical accident occurred on 22 February 1993 at plant Griesheim of Hoechst AG Frankfurt/Germany during which approximately 11.8 tons of a chemical mixture containing mostly chlorinated nitroarenes were emitted leading to serious contaminations in Schwanheim/Goldheim, a nearby housing area. Numerous inhabitants of the contaminated area complained of irritation of eyes, skin and mucous membranes, headache and nausea, and 92 persons with moderate symptoms were reported to the National Health Department. Urine samples were collected from the inhabitants of the affected area a few days after the accident and analysed for o-nitrophenol as a representative metabolite to assess the actual uptake of pollutants. O-nitrophenol, however, was also detected in the urine of not knowingly exposed control subjects, an observation not hitherto described in literature. The median levels of o-nitrophenol were three times higher in the exposed population than in the controls. Taking into account the data on pollution measured in the environment, the reported intoxication symptoms, the results of biomonitoring, and the published literature on the components of the mixture, the following conclusions were drawn: (1) The exposure was not high enough to cause severe acute toxic effects. (2) Although the emitted mixture contained carcinogenic components according to animal experiments, the transient exposure to these chemicals does not increase the tumour risk to any measurable extent, i.e. demonstrable by epidemiological methods, especially if weighed against the permanent exposure to "normal" urban pollution.

Topics: Accidents, Occupational; Adult; Air Pollutants, Occupational; Animals; Anisoles; Chemical Industry; Child; Environmental Exposure; Environmental Monitoring; Germany; Humans; Maximum Allowable Concentration; Mice; Nitrobenzenes; Nitrophenols; Rats

A novel method for enumerating Escherichia coli in foods is described. It is based on the production of o-nitrophenol (ONP) from o-nitrophenyl-beta-D-glucuronide as detected by an ion mobility spectrometer. The time taken for the detection of ONP in a food sample was inversely proportional to the logarithm of the initial E. coli population. Escherichia coli could be detected at a level of 10 g-1 within 9 h.

Topics: Animals; Colony Count, Microbial; Cooking; Escherichia coli; Evaluation Studies as Topic; Food Analysis; Food Microbiology; Ions; Meat; Nitrophenols; Spectrum Analysis

Two commercially available bacterial toxicity monitors are compared. As test organisms pure cultures of Pseudomonas putida are used in both systems. The bacteria are grown continuously in turbidostatic ("Toxalarm", LAR, Berlin, Germany) or chemostatic ("Stiptox-norm", Siepmann und Teutscher, Gross-Umstadt, Germany) regulated cultures in a selective culture medium in nonsterile devices. Toxic substances can be detected by continuously working bacterial respiration tests. Oxygen consumption is the measuring parameter. The bacterial test suspension is mixed continuously in a fixed proportion with air-saturated test water in a measuring cell. The separate culturing of the bacteria and the carrying out of the tests ensures that neither the bacterial culture is endangered by toxic substances nor the sensitivity can be changed by poison adaptation. Results of "Toxalarm"-tests with several chemicals (e.g. Atrazine, Lindane, 2-Nitro-phenol, Sodiumpentachlorophenolate) are presented. The registration of an alarm event (River Rhine) by "Stiptox-norm" is shown.

Topics: Animals; Atrazine; Bacteriological Techniques; Dose-Response Relationship, Drug; Environmental Monitoring; Equipment Failure; Hexachlorocyclohexane; Humans; Maximum Allowable Concentration; Nitrophenols; Oxygen Consumption; Pentachlorophenol; Pseudomonas; Water Pollutants, Chemical; Water Pollution, Chemical

Topics: Animals; Atrazine; Chlorophyta; Dose-Response Relationship, Drug; Electron Transport; Environmental Monitoring; Fluorescence; Hexachlorocyclohexane; Humans; Nitrophenols; Pentachlorophenol; Photosynthesis; Water Pollutants, Chemical; Water Pollution, Chemical

A new biological "early warning system" for continuous water control is presented that is based on the valve movements of the freshwater mussel Dreissena polymorpha. For two groups of up to 42 mussels, both the percentage of open mussels and the number of valve movements during a time interval are used to describe the activity behaviour of the zebra mussel. A main prerequisite of such a biomonitor should be the knowledge of the "normal" behaviour in correlation to changing environmental conditions. Preliminary results in Dreissena demonstrate the influence of the temperature, the daily cycle of light and the food concentration on both characteristics of the activity pattern. During toxicity tests, the mussels reacted significantly within 3-30 minutes after the addition of a toxicant. This was normally observed by both the decrease of the percentage of open mussels and the increase of the number of valve movements. Therefore--and against the background of the well-known "normal" behaviour--reliable limits for the detection of a harassing event can be defined. First experiments with Pentachlorophenol, Lindane, Atrazine and 2-Nitrophenol demonstrated to some extent a higher sensitivity compared to other "early warning systems".

Topics: Animals; Atrazine; Bivalvia; Dose-Response Relationship, Drug; Environmental Monitoring; Hexachlorocyclohexane; Motor Activity; Nitrophenols; Pentachlorophenol; Reference Values; Signal Processing, Computer-Assisted; Water Pollutants, Chemical; Water Pollution, Chemical

Three low molecular weight compounds were found in hexane:diethyl ether extracts of fed males of the African ticks, Amblyomma variegatum (tropical bont tick) and A. hebraeum (bont tick), namely, o-nitrophenol, methyl salicylate and 2,6-dichlorophenol. These same compounds were also fond in a rinse of fed A. variegatum males, but were absent or present in only trace amounts in a rinse of fed A. hebraeum males, o-Nitrophenol and methyl salicylate were present in much higher concentrations (i.e., amounts/tick) in A. variegatum than in A. hebraeum. 2,6-Dichlorophenol was also more abundant in A. variegatum than in A. hebraeum, but the differences were not as great as with the former two compounds. Extraction in hexane over a 3-week period revealed four additional compounds, benzaldehyde, benzyl alcohol, benzothiazole and nonanoic acid. The first three compounds were found in males of both species; nonanoic acid was found only in A. hebraeum males. Published reports consistently show strong attraction by o-nitrophenol and methyl salicylate for both sexes of the two bont tick species; 2,6-dichlorophenol and benzaldehyde have been reported to be attractive to both sexes of A. hebraeum. The possible roles of these compounds, as well as others occasionally reported from A. hebraeum and A. variegatum, as components of the aggregation/attachment pheromone or other pheromones is discussed.

Topics: Animals; Arachnid Vectors; Benzaldehydes; Benzothiazoles; Benzyl Alcohol; Benzyl Alcohols; Chlorophenols; Chromatography, Gas; Fatty Acids; Feeding Behavior; Female; Gas Chromatography-Mass Spectrometry; Heartwater Disease; Male; Nitrophenols; Salicylates; Sex Attractants; Sexual Behavior, Animal; Thiazoles; Tick Infestations; Ticks

1. In the activity of the high-Mr beta-glucosidase A (beta-D-glucoside glucohydrolase, EC 3.2.1.21) obtained from culture filtrates of Botryodiplodia theobromae Pat. on o-nitrophenyl beta-D-glucopyranoside as substrate, both Vmax. and Km increased non-linearly with increasing concentration of glycerol, and the Vmax./Km(app.) ratio decreased non-linearly with increasing concentration of glycerol. 2. No increase in rate was observed with phenyl beta-D-glucopyranoside as substrate in the presence of up to 250 mM-glycerol, indicating that glucosylation is rate-limiting with this substrate. 3. With o-nitrophenyl beta-D-glucopyranoside, p-nitrophenyl beta-D-glucopyranoside and phenyl beta-D-glucopyranoside as substrates, kappa cat. values of 793.7 s-1, 62.8 s-1 and 5.4 s-1 respectively were calculated. 4. With o-nitrophenyl beta-D-glucopyranoside and phenyl beta-D-glucopyranoside as substrate, alpha-deuterium kinetic isotope effects of 1.9 +/- 0.03 and 1.01 +/- 0.01 respectively were found; in the presence of 200 mM-glycerol the values were 1.21 +/- 0.03 and 1.02 +/- 0.01 respectively. 5. In the presence of a large excess of o-nitrophenyl beta-D-glucopyranoside [( S] = 35.7 Km), the amount of o-nitrophenol and also of the transglucosylation product formed by beta-glucosidase action increased non-linearly, whereas that of glucose formed decreased non-linearly with increasing glycerol concentration. 6. All these results were found to fit the data calculated from rate equations derived on the basis of the proposed mechanism of enzyme action involving two ion-pair intermediates and a covalent alpha-D-glucosyl-enzyme in the reaction sequence [Umezurike (1987) Biochem. J. 241, 455-462].

Topics: beta-Glucosidase; Deuterium; Glucose; Glucosidases; Glycerol; Hydrolysis; Kinetics; Mitosporic Fungi; Nitrophenols

Volatiles emitted by male Amblyomma hebraeum while feeding on a rabbit were quantitatively sampled by the dynamic solvent effect and analysed by capillary gas-liquid chromatography and mass spectrometry. Changes in emissions of 2-methyl propanoic acid, benzaldehyde and 2-nitrophenol paralleled reported increases in the attractiveness of males to conspecific ticks after 4-5 days of feeding. These compounds are therefore candidates for the bioassay of pheromonal activity.

Topics: Animals; Benzaldehydes; Butyrates; Feeding Behavior; Isobutyrates; Male; Methods; Nitrophenols; Pheromones; Rabbits; Sex Attractants; Ticks

A nitrophenol oxygenase which stoichiometrically converted ortho-nitrophenol (ONP) to catechol and nitrite was isolated from Pseudomonas putida B2 and purified. The substrate specificity of the enzyme was broad and included several halogen- and alkyl-substituted ONPs. The oxygenase consisted of a single polypeptide chain with a molecular weight of 58,000 (determined by gel filtration) or 65,000 (determined on a sodium dodecyl sulfate-polyacrylamide gel). The enzymatic reaction was NADPH dependent, and one molecule of oxygen was consumed per molecule of ONP converted. Enzymatic activity was stimulated by magnesium or manganese ions, whereas the addition of flavin adenine dinucleotide, flavin mononucleotide, or reducing agents had no effect. The apparent Kms for ONP and NADPH were 8 and 140 microM, respectively. 2,4-Dinitrophenol competitively (Ki = 0.5 microM) inhibited ONP turnover. The optimal pH for enzyme stability and activity was in the range of 7.5 to 8.0. At 40 degrees C, the enzyme was totally inactivated within 2 min; however, in the presence of 1 mM ONP, 40% of the activity was recovered, even after 10 min. Enzymatic activity was best preserved at -20 degrees C in the presence of 50% glycerol.

Topics: Catalysis; Catechols; Chemical Phenomena; Chemistry; Chromatography, Gel; Electrophoresis, Polyacrylamide Gel; Hydrogen-Ion Concentration; Molecular Weight; Nitrites; Nitrophenols; Oxygenases; Pseudomonas; Substrate Specificity; Ultracentrifugation

Fifty percent of an Amblyomma variegatum female population were able to find upwind-positioned targets containing the synthetic aggregation-attachment pheromone of this species or the pheromone component o-nitrophenol alone. The ticks were not attracted to the other components of the pheromone: methyl-salicylate and pelargonic acid. The mean time required for the ticks to reach a target at 1 m from the starting point was 3 min and 20 s.

Topics: Animals; Fatty Acids; Female; Nitrophenols; Pheromones; Salicylates; Ticks

The inhibition of human carbonic anhydrase II (carbonate hydro-lyase, EC 4.2.1.1) by tetrazole, 1,2,4-triazole, 2-nitrophenol, and chloral hydrate has been investigated. These inhibitors, together with phenol which has been studied previously (Simonsson, I., Jonsson, B.-H. and Lindskog, S. (1982) Biochem. Biophys. Res. Commun. 108, 1406-1412), can be classified in three groups depending upon the kinetic patterns of inhibition of CO2 hydration at pH near 9. The first group, represented by tetrazole and 2-nitrophenol, yields predominantly uncompetitive inhibition under these conditions in analogy with simple, inorganic anions. The second group, represented by 1,2,4-triazole and chloral hydrate gives rise to essentially noncompetitive inhibition patterns, whereas phenol, representing the third group, is a competitive inhibitor of CO2 hydration. These diverse inhibition patterns are discussed in terms of the kinetic mechanism scheme originally proposed by Steiner et al. (Steiner, H., Jonsson, B.-H. and Lindskog, S. (1975) Eur. J. Biochem. 59, 253-259.

Topics: Binding, Competitive; Carbonic Anhydrase Inhibitors; Chloral Hydrate; Humans; In Vitro Techniques; Kinetics; Nitrophenols; Tetrazoles; Triazoles

Partition (K) and permeance (P) coefficients have been determined for phenol, 2-nitrophenol, and 4-nitrophenol with isolated cuticles from mature tomato (Lycopersicon) and green pepper (Capsicum) fruits and from the adaxial surface of rubber (Ficus) leaves. Plant cuticular membranes (CM) are composed of a lipophilic, insoluble polymer matrix (MX) membrane and soluble cuticular lipids (SCL). Partition coefficients of the phenols (pH 3.0) for the system MX/buffer (MX/b) ranged from 43.6 to 164.9 and could be predicted from n-octanol/buffer (o/b) partition coefficients using the equation log KMX/b = 0.363 + 0.952 log Ko/b where (r = 0.986). In CM the K values were lower, especially for 4-nitrophenol, ranging from 32.4 to 110.8. The role of hydrogen bonding in partitioning of phenols into cuticles is discussed. Permeance coefficients for the cuticular membranes [P(CM)] ranged from 10(-10) (Ficus) to 10(-8) m sec-1 (Lycopersicon, Capsicum), with 2-nitrophenol permeating more rapidly than the other two phenols. Extraction of the SCL increased the permeance coefficients [P(MX)] by factors of approximately 5 (Lycopersicon), 50 (Capsicum), and 1000 (Ficus), respectively. The transport-limiting layer in plant cuticles acts as a diffusion and solubility barrier.

Topics: Absorption; Biological Transport; Capsicum; Cell Membrane; Cell Membrane Permeability; Diffusion; Nitrophenols; Phenol; Phenols; Plants; Plants, Medicinal

The effect of the mono- and di-nitrophenols and certain related compounds has been determined on the rate of oxygen consumption, the rate of carbon dioxide output and the rectal temperature of the Wistar albino rat.Of the compounds examined, only 2:4-dinitrophenol and its derivative, 3:5-dinitro-o-cresol, stimulated metabolic rate. 2-Nitrophenol and 2:3-, 2:6-, and 3:5-dinitrophenol produced no change in metabolic rate; 3-nitrophenol and 2:5-dinitrophenol had no action on carbon dioxide production although they caused a decrease in oxygen consumption. 4-Nitrophenol and 3:4-dinitrophenol increased only the rate of carbon dioxide output; 2-amino-4-nitrophenol increased the rate of carbon dioxide output and decreased the rate of oxygen consumption; 4-amino-2-nitrophenol caused depression of metabolic rate.It was confirmed that neither rectal temperature nor carbon dioxide output could replace rate of oxygen consumption as a reliable index of metabolic stimulant action. An apparatus is described which facilitates measurement of the oxygen consumption of small mammals.

Topics: Animals; Carbon Dioxide; Cresols; Dinitrophenols; Metabolism; Nitrophenols; Oxygen Consumption; Rats; Rats, Wistar

1. The pretreatment induction method of studying the formation of beta-galactosidase in E. coli B has been described. 2. It has been found that E. coli B cells have their maximum capacity to form beta-galactosidase, in response to a constant induction stimulus, when they are in the stationary phase of the growth cycle. 3. The concentration of inductor, the nature of the nitrogen source, the duration of the assimilatory phase, oxygen tension, and temperature are factors which affect, and may limit, the rate of beta-galactosidase formation. 4. When limitations imposed by these factors were removed, the time course of induced beta-galactosidase formation was strictly linear from the onset. 5. The implications of this finding were discussed and a new theory of the mechanism of enzyme formation has been proposed. 6. A very satisfactory method of synthesis of ortho-nitrophenol-alpha-D-galactoside has been described. This substance is a suitable chromogenic substrate for the specific determination of alpha-galactosidase activity. 7. Preliminary experiments using this substrate have confirmed the results of respiration studies and shown that in E. coli B alpha-galactosidase formation may be induced by beta- as well as by alpha-galactosides.

Topics: Escherichia coli; Glycoside Hydrolases; Nitrophenols; Temperature