betadex and phenanthrene

The remediation of a genuinely PAH-contaminated soil was performed, for the first time, through a new and complete investigation, including PAH extraction followed by advanced oxidation treatment of the washing solution and its recirculation, and an analysis of the impact of the PAH extraction on soil respirometry. The study has been performed on the remediation of genuine PAH-contaminated soil, in the following three steps: (i) PAH extraction with soil washing (SW) techniques, (ii) PAH degradation with an electro-Fenton (EF) process, and (iii) recirculation of the partially oxidized effluent for another SW cycle. The following criteria were monitored during the successive washing cycles: PAH extraction efficiency, PAH oxidation rates and yields, extracting agent recovery, soil microbial activity, and pH of soil. Two representative extracting agents were compared: hydroxypropyl-beta-cyclodextrin (HPCD) and a non-ionic surfactant, Tween(®) 80. Six PAH with different numbers of rings were monitored: acenaphthene (ACE), phenanthrene (PHE), fluoranthene (FLA), pyrene (PYR), benzo(a)pyrene (BaP), and benzo(g,h,i)perylene (BghiP). Tween(®) 80 showed much better PAH extraction efficiency (after several SW cycles) than HPCD, regardless of the number of washing cycles. Based on successive SW experiments, a new mathematical relation taking into account the soil/water partition coefficient (Kd*) was established, and could predict the amount of each PAH extracted by the surfactant with a good correlation with experimental results (R(2) > 0.975). More HPCD was recovered (89%) than Tween(®) 80 (79%), while the monitored pollutants were completely degraded (>99%) after 4 h and 8 h, respectively. Even after being washed with partially oxidized solutions, the Tween(®) 80 solutions extracted significantly more PAH than HPCD and promoted better soil microbial activity, with higher oxygen consumption rates. Moreover, neither the oxidation by-products nor the acidic media (pH approximately 3) of the partially oxidized solution inhibited the general soil microbial activity during the washing cycle.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Benzo(a)pyrene; beta-Cyclodextrins; Environmental Pollution; Environmental Restoration and Remediation; Phenanthrenes; Polycyclic Aromatic Hydrocarbons; Polysorbates; Pyrenes; Soil; Soil Pollutants; Solutions; Surface-Active Agents

The explicit-solvent molecular dynamic (MD) simulation and adaptive biased forces (ABF) methods were employed to systemically study the structural and thermodynamic nature of the β-cyclodextrin (βCD) monomer, phenanthrene (Phe) monomer, and their inclusion complexes in both the aqueous and membrane environments, aiming at clarifying the atomic-level mechanisms underlying in the CD-enhanced degradation of polycyclic aromatic hydrocarbons (PAHs) by bacteria. Simulations showed that βCD and Phe monomers could associate together to construct two distinctive assemblies, i.e, βCD1-Phe1 and βCD2-Phe1, respectively. The membrane-involved equilibrium simulations and the data of potential of mean forces (PMFs) further confirmed that Phe monomer was capable of penetrating through the membranes without confronting any large energy barrier, whereas, the single βCD and βCD-involved assemblies were unable to pass across the membranes. These observations clearly suggested that βCD only served as the carrier to enhance the bioavailability of Phe rather than the co-substrate in the Phe biodegradation process. The Phe-separation PMF profiles indicated that the maximum of the Phe uptake by bacteria would be achieved by the "optimal" βCD:Phe molar ratio, which facilitated the maximal formation of βCD1-Phe1 inclusion and the minimal construction of βCD2-Phe1 complex.

Topics: Bacteria; beta-Cyclodextrins; Biodegradation, Environmental; Cell Membrane; Lipid Bilayers; Molecular Dynamics Simulation; Phenanthrenes; Soil Pollutants; Water

It is necessary to find an effective soil remediation technology for the simultaneous removal of hydrophobic organic contaminants and heavy metals from contaminated soils. In this work, a novel cysteine-β-cyclodextrin (CCD) was synthesized by the reaction of β-cyclodextrin with cysteine, and the structure of CCD was confirmed by (1)H-NMR, (13)C-NMR, FT-IR spectroscopy and elemental analysis. Pot-culture experiments were conducted to investigate the effects of CCD on the phytoremediation of soil co-contaminated with phenanthrene and lead. The results showed that CCD can enhance the phytoremediation of soil co-contaminated with phenanthrene and lead. When CCD was added to the co-contaminated soil, the concentrations of phenanthrene and Pb in roots and shoots of ryegrass (Lolium perenne L.) significantly increased, the presence of CCD is beneficial to the accumulation of phenanthrene and Pb in ryegrass, and the residual concentrations of phenanthrene and Pb in soils significantly decreased. Under the co-contamination of 500 mg Pb kg(-1) and 50 mg PHE kg(-1), the bioconcentration factor of phenanthrene and Pb in the presence of CCD was increased by 1.43-fold and 4.47-fold, respectively. After CCD was added to the contaminated soils, the residual concentration of phenanthrene and Pb in unplanted soil was decreased by 18 and 25%, respectively. However, for the planted soil, the residual concentration of phenanthrene and Pb was decreased by 48 and 56%, respectively. CCD may improve the bioavailability of phenanthrene and Pb in co-contaminated soil; CCD enhanced phytoremediation technology may be a good alternative for the removal of hydrophobic organic contaminants and heavy metals from contaminated soils.

Topics: beta-Cyclodextrins; Biodegradation, Environmental; Cysteine; Lead; Lolium; Phenanthrenes; Plant Roots; Polycyclic Aromatic Hydrocarbons; Soil; Soil Pollutants; Spectroscopy, Fourier Transform Infrared

The potential bioavailability of phenanthrene aged in soil was determined by using a self-dying reporter bacterium, and the results were compared to two physicochemical measures, Tenax TA(®) bead-assisted desorption, and hydroxypropyl-β-cyclodextrin (HPCD) extraction. The reporter bacterium, capable of degrading phenanthrene as a sole carbon and energy source, was genetically reconstructed to die when it degrades phenanthrene. Therefore, population change of the reporter cells can be viewed as the quantification of bioavailable phenanthrene. When Ottawa sand was used as an aging matrix, the amounts of bioavailable phenanthrene (i.e. little gradual decrease) were similar, regardless of aging time, and consistent between the reporter bacterium and the two physicochemical measures. However, decrease in bioavailable phenanthrene with aging was readily evident in sandy loam with organic matter of 11.5%, with all three measures. More importantly, when the reporter bacterium was used, a rapid and significant decrease in the bioavailable fraction from 1.00 to 0.0431 was observed. The extent of decrease in bioavailable fraction was less than 40% in the two physicochemical measures, but was nearly 100% in the reporter bacterium, during the first 3 months of aging. Our results suggest that the phenanthrene fraction available to bacterial degradation, and probably the fraction that really manifests toxicity, may be much smaller than the fractions predicted with the physicochemical measures.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; beta-Cyclodextrins; Biodegradation, Environmental; Biological Availability; Organisms, Genetically Modified; Phenanthrenes; Polymers; Soil; Soil Pollutants; Sphingomonas

Organic matter (OM) plays a vital role in controlling polycyclic aromatic hydrocarbon (PAH) bioavailability in soils and sediments. In this study, both a hydroxypropyl-β-cyclodextrin (HPCD) extraction test and a biodegradation test were performed to evaluate the bioavailability of phenanthrene in seven different bulk soil/sediment samples and two OM components (humin fractions and humic acid (HA) fractions) separated from these soils/sediments. Results showed that both the extent of HPCD-extractable phenanthrene and the extent of biodegradable phenanthrene in humin fraction were lower than those in the respective HA fraction and source soil/sediment, demonstrating the limited bioavailability of phenanthrene in the humin fraction. For the source soils/sediments and the humin fractions, significant inverse relationships were observed between the sorption capacities for phenanthrene and the amounts of HPCD-extractable or biodegradable phenanthrene (p < 0.05), suggesting the importance of the sorption capacity in affecting desorption and biodegradation of phenanthrene. Strong linear relationships were observed between the amount of HPCD-extractable phenanthrene and the amount degraded in both the bulk soils/sediments and the humin fractions, with both slopes close to 1. On the other hand, in the case of phenanthrene contained in HA, a poor relationship was observed between the amount of phenanthrene extracted by HPCD and the amount degraded, with the former being much less than the latter. The results revealed the importance of humin fraction in affecting the bioavailability of phenanthrene in the bulk soils/sediments, which would deepen our understanding of the organic matter fractions in affecting desorption and biodegradation of organic pollutants and provide theoretical support for remediation and risk assessment of contaminated soils and sediments.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Adsorption; beta-Cyclodextrins; Biodegradation, Environmental; Biological Availability; Environmental Pollution; Geologic Sediments; Humic Substances; Phenanthrenes; Polycyclic Aromatic Hydrocarbons; Soil; Soil Pollutants

Surface modified electrospun polyester (PET) nanofibers with cyclodextrin polymer (CDP) were produced (PET/CDP). CDP formation onto electrospun PET nanofibers was achieved by polymerization between citric acid (CTR, crosslinking agent) and cyclodextrin (CD). Three different types of native CD (α-CD, β-CD and γ-CD) were used to form CDP. Water-insoluble crosslinked CDP coating was permanently adhered onto the PET nanofibers. SEM imaging indicated that the nanofibrous structure of PET mats was preserved after CDP surface modification process. PET/CDP nanofibers have shown rougher/irregular surface and larger fiber diameter when compared to untreated PET nanofibers. The surface analyses of PET/CDP nanofibers by XPS elucidated that CDP was present on the fiber surface. DMA analyses revealed the enhanced mechanical properties for PET/CDP where PET/CDP nanofibers have shown higher storage modulus and higher glass transition temperature compared to untreated PET nanofibers. The surface area of the PET/CDP nanofibers investigated by BET measurements showed slight decrease due to the presence of CDP coating compared to pristine PET nanofibers. Yet, it was observed that PET/CDP nanofibers were more efficient for the removal of phenanthrene as a model polycyclic aromatic hydrocarbon (PAH) from aqueous solution when compared to pristine PET nanofibers. Our findings suggested that PET/CDP nanofibers can be a very good candidate as a filter material for water purification and waste treatment owing to their very large surface area as well as inclusion complexation capability of surface associated CDP.

Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Cellulose; Cyclodextrins; gamma-Cyclodextrins; Nanofibers; Phenanthrenes; Polyesters; Surface Properties; Water Pollutants, Chemical; Water Purification

It has become apparent that the threat of an organic pollutant in soil is directly related to its bioavailable fraction and that the use of total contaminant concentrations as a measure of potential contaminant exposure to plants or soil organisms is inappropriate. In light of this, non-exhaustive extraction techniques are being investigated to assess their appropriateness in determining bioavailability. To find a suitable and rapid extraction method to predict phenanthrene bioavailability, multiple extraction techniques (i.e., mild hydroxypropyl-β-cyclodextrin (HPCD) and organic solvents extraction) were investigated in soil spiked to a range of phenanthrene levels (i.e., 1.12, 8.52, 73, 136, and 335 μg g( - 1) dry soil). The bioaccumulation of phenanthrene in earthworm (Eisenia fetida) was used as the reference system for bioavailability. Correlation results for phenanthrene suggested that mild HPCD extraction was a better method to predict bioavailability of phenanthrene in soil compared with organic solvents extraction. Aged (i.e., 150 days) and fresh (i.e., 0 day) soil samples were used to evaluate the extraction efficiency and the effect of soil contact time on the availability of phenanthrene. The percentage of phenanthrene accumulated by earthworms and percent recoveries by mild extractants changed significantly with aging time. Thus, aging significantly reduced the earthworm uptake and chemical extractability of phenanthrene. In general, among organic extractants, methanol showed recoveries comparable to those of mild HPCD for both aged and unaged soil matrices. Hence, this extractant can be suitable after HPCD to evaluate risk of contaminated soils.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Animals; beta-Cyclodextrins; Biological Availability; Chemical Fractionation; Environmental Monitoring; Oligochaeta; Phenanthrenes; Plants; Soil; Soil Pollutants; Time Factors

The observed strong sorption of polycyclic aromatic hydrocarbons (PAHs) to black carbon (BC) presents potential implications for PAH bioaccessibility in soils. The effects of BC on the desorption kinetics and mineralization of phenanthrene in four soils was investigated after 1, 25, 50, and 100 d soil-PAH contact time, using sequential hydroxypropyl-β-cyclodextrin (HPCD) extractions in soils amended with 0, 0.1, 1, and 5% (dry wt. soil) activated charcoal (AC, a form of BC). The rapidly (%F(rap)) and slowly (%F(slow)) desorbing phenanthrene fractions and their rate constants were determined using a first-order two-compartment (biphasic) desorption model. A minimum 7.8-fold decrease in %F(rap) occurred when AC was increased from 0 to 5%, with a corresponding increase in %F(slow). Desorption rate constants followed the progression k(rap) (% h(-1)) > k(slow) (% h(-1)) and were in the order of 10(-1) to 10(-2) and 10(-3) to 10(-4), respectively. Linear regressions between %F(rap) and the fractions degraded by a phenanthrene-degrading inoculum (%F(min)) indicated that slopes did not approximate 1 at concentrations greater than 0% AC; %F(min) often exceeded %F(rap), indicating a fraction of sorbed phenanthrene (%F(slow)) remained microbially accessible. Therefore, HPCD-desorption kinetics alone may not be an adequate basis for the prediction of the bioaccessibility of PAHs to microorganisms or bioremediation potential in AC-amended soils.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; beta-Cyclodextrins; Biodegradation, Environmental; Charcoal; Dose-Response Relationship, Drug; Environmental Pollutants; Environmental Restoration and Remediation; Kinetics; Linear Models; Phenanthrenes; Pseudomonas

The impact of fullerene soot (FS), single-walled (SWCNTs) and multi-walled (MWCNTs) carbon nanotubes on the behaviour of two (14)C-PAHs in sterile soil was investigated. Different concentrations of carbon nanomaterials (0, 0.05, 0.1 and 0.5%) were added to soil, and (14)C-phenanthrene and (14)C-benzo[a]pyrene extractability assessed over 80 d through dichloromethane (DCM) and hydroxypropyl-β-cyclodextrin (HPCD) shake extractions. Total (14)C-PAH activity in soils was determined by combustion, and mineralisation of (14)C-phenanthrene was monitored over 14 d, using a catabolically active pseudomonad inoculum. No significant loss of (14)C-PAH-associated activity from CNM-amended soils was observed over the 'aging' period. CNMs had a significant impact on HPCD-extractability of (14)C-PAHS; extractability decreased with increasing CNM concentration. Additionally, (14)C-phenanthrene mineralisation was inhibited by the presence of CNMs at concentrations of ≥ 0.05%. Differences in overall extents of (14)C-mineralisation were also apparent between CNM types. It is suggested the addition of CNMs to soil can reduce PAH extractability and bioaccessibility, with PAH sorption to CNMs influenced by CNM type and concentration.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Benzo(a)pyrene; beta-Cyclodextrins; Fullerenes; Methylene Chloride; Nanotubes, Carbon; Phenanthrenes; Pseudomonas; Soil Microbiology; Soil Pollutants; Soot

Preparation of glycine-β-cyclodextrin (GCD) was carried out by the reaction of β-cyclodextrin with glycine in the presence of KOH and epichlorohydrin. The enhanced solubilization behavior of phenanthrene and lead carbonate by GCD was studied, and the desorption behavior of phenanthrene and lead from co-contaminated soil was also investigated. The results showed that GCD has obvious solubilization for phenanthrene and lead carbonate. The solubility of phenanthrene in 30 g/L of GCD was enhanced about 30-fold. And the apparent aqueous solubilities of lead carbonate are also obviously increased with increasing GCD concentration, when the concentration of GCD reached 20 g/L, the aqueous lead concentration was 2945 mg/L. GCD could simultaneously increase the apparent aqueous solubility of phenanthrene and complex with lead. The desorption process of GCD for phenanthrene and lead from co-contaminated soil followed the pseudo-second-order kinetic model. The removal efficiencies of phenanthrene and lead in soil increased dramatically with increasing GCD concentrations. At concentration of 40 g/L, GCD has a removal efficiency of 85.8% and 78.8% for lead and phenanthrene, respectively, from the combined contaminated soil. The use of GCD as an extractant to enhance the removal of heavy and hydrophobic organic contaminants (HOCs) from co-contaminated soils appears as a promising remediation method.

Topics: Adsorption; beta-Cyclodextrins; Glycine; Lead; Phenanthrenes; Soil Pollutants; Solubility; Spectrometry, Fluorescence; Spectroscopy, Fourier Transform Infrared

A second-order multivariate calibration approach, based on a combination of PARAFAC with time-resolved room temperature phosphorescence (RTP), has been applied to resolve a binary mixture of Phenanthrene and 1,10-Phenanthroline, as model compounds. The RTP signals were obtained in aqueous beta-cyclodextrin solutions, in the presence of several heavy atom containing compounds. No deoxygenation was necessary to obtain the phosphorescence signals, which adds simplicity to the method. The resolution of the model compounds was possible in base to the differences in the delay-time of the RTP signals of the investigated analytes, opening a new approach for second-order data generation and subsequent second order multivariate calibration.

Topics: beta-Cyclodextrins; Complex Mixtures; Luminescent Measurements; Phenanthrenes; Phenanthrolines; Solutions

Soil was spiked with [9-(14)C]phenanthrene and [1-(14)C]hexadecane at 50 mg kg(-1) and aged for 1, 25, 50, 100 and 250 d. At each time point, the microcosms were amended with aqueous solutions of cyclodextrin (HP-beta-CD) at a range of concentrations (0-40 mM). Mineralisation assays and aqueous HP-beta-CD extractions were performed to assess the effect of the amendments on microbial degradation. The results showed that amendments had no significant impact on the microbial degradation of either of the (14)C-contaminants. Further, HP-beta-CD extractions were correlated with the mineralisation of the target chemicals in each of the soil conditions. It was found that the HP-beta-CD extraction was able to predict mineralisation in soils which had not been amended with cyclodextrin; however, in the soils containing the HP-beta-CD, there was no predictive relationship. Under the conditions of this study, the introduction of HP-beta-CD into soils did not enhance the biodegradation of the organic contaminants.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Alkanes; Bacteria; beta-Cyclodextrins; Biodegradation, Environmental; Carbon Radioisotopes; Environmental Restoration and Remediation; Isotope Labeling; Phenanthrenes; Soil Microbiology; Soil Pollutants

An organic polymeric monolithic disk was prepared by situ polymerization of glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA) in a binary porogenic solvent consisting 1-propanol and 1,4-butanediol, then modified by a reaction with beta-cyclodextrin (beta-CD). The beta-CD modified disk can be used as a solid substrate and solid phase extraction (SPE) membrane for solid phase extraction-room temperature phosphorescence (SPE-RTP). The room temperature phosphorescence (RTP) behaviors of 14 organic compounds on the beta-CD modified disk were examined. The results indicated that phenanthrene, 7,8-benzoquinoline, carbazole, fluorene, 3-indoleacetic acid and 1-naphthylacetic acid can emit strong RTP, and the limits of detection (LOD) were found to be 6.5 x 10(-10)-3.0 x 10(-9) mol mL(-1). Used as solid phase extraction membrane, the modified disk could selectively enrich compounds with three rings such as phenanthrene, 7,8-benzoquinoline, carbazole and fluorene. After solid phase extraction, LODs of four compounds were decreased to 4.0 x 10(-12)-6.4 x 10(-11) mol mL(-1). The method was applied to the determination of fluorene and phenanthrene in biosamples with satisfactory results.

Topics: beta-Cyclodextrins; Epoxy Compounds; Fluorenes; Luminescent Measurements; Methacrylates; Phenanthrenes; Polymers; Solid Phase Microextraction

A number of soil extraction techniques have been proposed to determine the microbial degradability of organic contaminants in soil. Exhaustive methods using organic solvents have little relevance to the concentration of contaminants actually available to microorganisms. The present study investigated the relationship between sequential hydroxypropyl-beta-cyclodextrin (HPCD) extractions and microbial mineralization of [14C]phenanthrene in four soils over time. The desorption of [14C]phenanthrene was assessed at 24-h intervals over 10 d and compared to cumulative mineralization of the [14C]phenanthrene using an enriched pseudomonad inoculum. The cumulative total of [14C]phenanthrene extracted by HPCD exceeded the mineralization asymptote by more than 20%. The overall total extents mineralized after both single and multiple degrader inoculations, however, were statistically similar to that extracted after the first 24 h by HPCD; the ratios of extractable to mineralizable [14C]phenanthrene consistently approached one. Furthermore, a good linear correlation between mineralized and extracted phenanthrene was observed (single: r2 = 0.99, gradient = 0.90, intercept = 3.09; multiple: r2 = 0.95, gradient = 1.01, intercept = -0.48), suggesting that a single HPCD extraction accurately and reproducibly predicts the total fraction of phenanthrene available for microbial mineralization in all soils tested in the present study.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Adsorption; beta-Cyclodextrins; Biodegradation, Environmental; Biological Availability; Carbon Isotopes; Dose-Response Relationship, Drug; Phenanthrenes; Reproducibility of Results; Soil; Soil Microbiology; Soil Pollutants; Time Factors

During the past century, increased biomass burning and fossil fuel consumption have drastically increased the input of black carbon (BC) into the environment, and that has been shown to influence the behavior of organic contaminants in soil. A study was conducted to investigate the effects of BC on the relationship between aqueous hydroxypropyl-beta-cyclodextrin (HPCD) extraction and microbial mineralization (bioaccessibility) of 14C-phenanthrene (10 mg kg(-1)) in four soils amended with 0, 0.1, 0.5, 1, 2.5, and 5% (% dry wt soil) activated charcoal, a type of BC. Mineralisation was monitored over 20 d incubation, within respirometric assays, using an inoculum containing a phenanthrene-degrading pseudomonad and compared to HPCD extraction (24 h) using 50 mM aqueous solution; analyses were conducted after 1, 25, 50, and 100 d soil-phenanthrene contact time. Statistical analyses revealed that for each soil the addition of BC led to significant (P < 0.001) reductions in both HPCD extractability and microbial mineralization. Linear correlations for BC concentrations of 0% (r2 = 0.95; slope = 0.89) and 0.1% (r2 = 0.67; slope = 0.95) revealed a highly significant (P < 0.01) relationship between HPCD extractability and total mineralization (20 d), indicating a direct prediction of phenanthrene bioaccessibility by HPCD. However, in soils amended with 0.5, 1, 2.5, and 5% BC exhibited r2 values ranging 0.51-0.13 and slopes of 2.19-12.73. This study has shown that BC strongly sorbs phenanthrene causing reductions in extractability and, to a lesser extent, bioaccessibility to degrading microorganisms.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Bacteria; beta-Cyclodextrins; Biodegradation, Environmental; Carbon; Carbon Isotopes; Environmental Restoration and Remediation; Minerals; Phenanthrenes; Regression Analysis; Soil

There is currently considerable scientific interest in finding a chemical technique capable of predicting bioavailability; non-exhaustive extraction techniques (NEETs) offer such potential. Hydroxypropyl-beta-cyclodextrin (HPCD), a NEET, is further validated through the investigation of concentration ranges, differing soil types, and the presence of co-contaminants. This is the first study to demonstrate the utility of the HPCD-extraction technique to predict the microbial availability to phenanthrene across a wide concentration range and independent of soil-contaminant contact time (123 d). The efficacy of the HPCD-extraction technique for the estimation of PAH microbial availability in soil is demonstrated in the presence of co-contaminants that have been aged for the duration of the experiment together in the soil. Desorption dynamics are compared in co-contaminant and single-PAH contaminated spiked soils to demonstrate the occurrence of competitive displacement. Overall, a single HPCD-extraction technique proved accurate and reproducible for the estimation of PAH bioavailability from soil.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Adsorption; Bacteria; beta-Cyclodextrins; Biodegradation, Environmental; Environmental Monitoring; Phenanthrenes; Poaceae; Polycyclic Aromatic Hydrocarbons; Pyrenes; Soil Microbiology; Soil Pollutants; Time; Trees

The characteristics of host-guest complexation between beta-cyclodextrin (beta-CD) and phenanthrene derivatives (phenanthrene, n-propyl, n-butyl and n-hexyl-phenanthrene) were investigated by fluorescence spectrometry. Linear and non-linear regression methods were used to estimate the formation constants (K1). A 1:1 stoichiometric ratio and an effect of n-alkyl chain length on the formation constant were observed for the binary inclusion complex between guest and beta-CD. The formation constant dramatically increases with the length of n-alkyl, it starts from the value of 140 l mol(-1) for the phenanthrene to reach the value of 580 l mol(-1) for hexyl-phenanthrene. The effect of the temperature on the fluorescence intensity of each complex (guest-host) was also studied; and then the thermodynamic parameters were calculated. The main inclusion site seems to be aromatic moiety for short chain molecules, and it moves toward the alkyl chain part, as the chain becomes longer.

Topics: beta-Cyclodextrins; Macromolecular Substances; Molecular Structure; Phenanthrenes; Spectrometry, Fluorescence; Thermodynamics

A study was conducted to investigate the effect of hydroxypropyl-beta-cyclodextrin (HPCD) on the aging and biodegradation of phenanthrene (PHE) in soil. Soil was spiked with PHE at 25 mgPHE/kgSOIL and HPCD at a range of concentrations from 0 to 3.5 gHPCD/kgSOIL and aged for 1, 84, and 322 d. At each time point, a variety of analyses were performed to assess the loss and aging of the PHE in the soil. Methods included determination of total PHE remaining, dichloromethane (DCM) and butan-1-ol (BuOH) extractions, and determination of PHE extractable by an aqueous HPCD shake extraction. Mineralization assays were also carried out to assess the availability of the PHE to a PHE-degrading bacterial inoculum. It was found that the presence of HPCD in the soils increased PHE loss from the aged soil systems, particularly at the higher application rates. Dichloromethane and BuOH extractabilities were reduced with aging and increasing HPCD concentration, as was the amount of PHE that was extractable using an aqueous HPCD shake extraction or that was available for mineralization. The DCM and BuOH extraction yielded similar results, and both greatly overestimated the availability of the PHE to the degraders, whereas the HPCD extraction results were very similar to that of PHE biodegradation. This study indicates that cyclodextrins have potential for use as alternatives to surfactants in enhancing the desorption/solubilization and degradation of recalcitrant organic contaminants in soil.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Bacteria; beta-Cyclodextrins; Biodegradation, Environmental; Carbon Radioisotopes; Cyclodextrins; Dose-Response Relationship, Drug; Environmental Pollution; Phenanthrenes; Soil Microbiology; Time Factors

Objective of this study was to evaluate the effects of hydroxypropyl-beta-cyclodextrin (HPCD) on the removal of phenanthrene from solid phase. Batch tests for the phenanthrene distribution between aqueous and solid phase were conducted in the presence of HPCD. Column tests and numerical simulations were conducted to evaluate the roles of HPCD cavities and interaction rates between water, HPCD, and solid phase in the enhanced removal of phenanthrene. Experimental results showed that HPCD was effective in removing sorbed phenanthrene from subsurface environment, primarily due to its negligible sorption to the solid phase and the partitioning of phenanthrene into HPCD cavities. From the numerical simulations, it was found that rate-limited partitioning of phenanthrene into HPCD cavities was most influential factor in the enhanced elution of phenanthrene. Sorption and desorption rate of phenanthrene between aqueous and solid phase was very fast or near equilibrium state. Interaction rates of contaminant between water, HPCD, and solid phase could be affected by other factors such as soil types and organic matter contents. Results from this study implied that HPCD flushing could be effectively applied for the removal of hydrophobic organic pollutants existing in the soils as sorbed or NAPL state.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Adsorption; beta-Cyclodextrins; Cyclodextrins; Humans; Phenanthrenes; Soil; Soil Pollutants; Surface-Active Agents