remazol-black-b and titanium-dioxide

CdS/TiO2 NPs-decorated carbon nanofibers were prepared by a simple electrospinning method followed by the calcination under argon atmosphere. As-synthesized nanocomposites exhibited a strong photocatalytic activity for decomposition of methylene blue (MB), reactive black 5, and reactive orange 16 under visible light radiation for many successive cycles. Moreover, in the dark, the carbon content revealed very good adsorption behavior as 95% of the dye was removed within 5 min, however less adsorption capacity was observed upon successive cycles. Therefore, the enhanced photocatalytic performance for the introduced nanofibers might be attributed to the adsorption characteristic of carbon nanofiber and the known photocatalytic activities of the TiO2 and CdS photocatalysts.

Topics: Adsorption; Azo Compounds; Cadmium Compounds; Carbon; Catalysis; Coloring Agents; Light; Methylene Blue; Nanofibers; Naphthalenesulfonates; Photolysis; Sulfides; Titanium

Decolorization and mineralization of reactive dyes by intimately coupled TiO₂-photocatalysis and biodegradation (ICPB) on a novel TiO₂-coated biofilm carrier were investigated in a photocatalytic circulating-bed biofilm reactor (PCBBR). Two typical reactive dyes--Reactive Black 5 (RB5) and Reactive Yellow 86 (RY86)--showed similar first-order kinetics when being photocatalytically decolorized at low pH (~4-5) in batch experiments. Photocatalytic decolorization was inhibited at neutral pH in the presence of phosphate or carbonate buffer, presumably due to electrostatic repulsion from negatively charged surface sites on TiO₂, radical scavenging by phosphate or carbonate, or both. Therefore, continuous PCBBR experiments were carried out at a low pH (~4.5) to maintain high photocatalytic efficiency. In the PCBBR, photocatalysis alone with TiO₂-coated carriers could remove target compound RB5 and COD by 97% and 47%, respectively. Addition of biofilm inside macroporous carriers maintained a similar RB5 removal efficiency, but COD removal increased to 65%, which is evidence of ICPB despite the low pH. ICPB was further proven by finding microorganisms inside carriers at the end of the PCBBR experiments. A proposed ICPB pathway for RB5 suggests that a major intermediate, a naphthol derivative, was responsible for most of the residual COD, while most of the nitrogen in the azo-bonds (-N=N-) was oxidized to N₂.

Topics: Azo Compounds; Biodegradation, Environmental; Biofilms; Bioreactors; Buffers; Carbonates; Coated Materials, Biocompatible; Coloring Agents; Hydrogen-Ion Concentration; Molecular Structure; Naphthalenesulfonates; Phosphates; Photobleaching; Photosensitizing Agents; Static Electricity; Titanium; Triazines; Ultraviolet Rays; Water Pollutants, Chemical

Titanium dioxide (TiO(2)) nanoparticle powders have been extensively studied to quickly photodegrade some organic pollutants; however, the effect of the particle size of TiO(2) nanoparticle aggregates on degradation remains unclear because microscale aggregates form once the nanoparticle powders enter into water.. The degradation of azo dye by different particle sizes of TiO(2) nanoparticle aggregates controlled by NaCl concentrations was investigated to evaluate the particle size effect. Removal reactions of reactive black 5 (RB5) with TiO(2) nanoparticles followed pseudo-first-order kinetics.. The increase of TiO(2) dosage from 40 to 70 mg/L enhanced the degradation. At doses around 100 mg/L TiO(2), degradation rates decreased which could be the result of poor UV light transmittance at high-particle concentrations. At average particle sizes of TiO(2) nanopowders less than around 500 nm, the degradation rates increased with decreasing particle size. As the average particle size exceeded 500 nm, the degradation rates were not significantly changed.. For the complete degradation experiments, the mineralization rates of total organic carbon disappearance are generally following the RB5 decolorization kinetic trend. These findings can facilitate the application of TiO(2) nanoparticles to the design of photodegradation treatments for wastewater.

Topics: Coloring Agents; Metal Nanoparticles; Naphthalenesulfonates; Particle Size; Photolysis; Titanium; Water Pollutants, Chemical

Mesoporous TiO2 microparticles (TiO2-11) were prepared through the micelle hydrothermal method using a 1:1 M ratio of 1-tetradecylamine:Ti(OiPr)4. TiO2-11 microparticles exhibited significantly higher decolorization percentage of Remazol Black 5 (RB5) and Remazol Brilliant Orange (3R) dyes than other TiO2 microparticles formed with different molar ratios of 1-tetradecylamine:Ti(OiPr)4, and P25 and anatase TiO2. The results showed that the decolorization of the dyes by the microparticles was affected by the different irradiation wavelengths, catalyst dosages, dye concentrations, initial pH values, as well as electron acceptors. The kinetic experiments with varying initial pH values were in accordance with the second-order model. In addition, the adsorption study of the dyes in the dark fitted well with the Langmuir isotherm model. With the addition of 20 mmol/mL of three electron acceptors, H2O2, KBrO3, and (NH4)2S2O8, the decolorization of the RB5 and 3R dyes increased by 54% and 35%, 59% and 41%, and 36% and 33%, respectively. Hence, this technique for the preparation of the mesoporous TiO2 microparticles can facilitate more efficient decolorization of dyes in an aqueous solution.

Topics: Adsorption; Azo Compounds; Benzenesulfonates; Kinetics; Naphthalenesulfonates; Photochemical Processes; Titanium; Water Pollutants; Water Purification

Immobilization of TiO(2) is a promising approach that produces antifouling and photocatalytic membranes that could help advance wastewater treatment and re-use processes. In this study, poly(acrylic acid) (PAA) was plasma-grafted on commercial poly(vinylidene fluoride) (PVDF) to introduce functional groups on the membrane surface that can support the nanoparticles. It was found that plasma treatment at 100 W for 120 s followed by liquid grafting with 70% aqueous AA at 60°C for 2h maximized the number of TiO(2) binding sites. Membrane hydrophilicity was tremendously enhanced by the self-assembly of TiO(2), following a direct proportionality to TiO(2) loading. The membrane with 0.5% TiO(2) loading maintained the highest pure water flux and the best protein antifouling property. UV irradiation triggered the photodegradation of strongly bound foulants, but at least 1.5% TiO(2) and 30 min cumulative irradiation were necessary to completely recover the membrane's original performance. The TiO(2)-modified membranes removed 30-42% of 50mg/l aqueous Reactive Black 5 (RB5) dye. The fabricated membranes demonstrate huge potential for use in membrane reactors with high hydrophilicity, fouling mitigation, and photocatalytic capability.

Topics: Acrylic Resins; Catalysis; Coloring Agents; Membranes, Artificial; Metal Nanoparticles; Naphthalenesulfonates; Photolysis; Polyvinyls; Titanium; Ultraviolet Rays; Waste Disposal, Fluid; Water Pollutants, Chemical

Spray pyrolysis procedure for preparation of nanostructured TiO(2) films with higher photocatalytic effectiveness and longer exploitation life is presented in this study. Thin films of active nanocrystalline TiO(2) were obtained from titanium isopropoxide, stabilized with acetyl acetone and characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The activity of sprayed nanostructured TiO(2) is tested for photocatalytic degradation of Reactive Black 5 dye with concentrations up to 80 ppm. Interesting result of the work is the reduction of toxicity after photocatalytic treatment of RB5 with TiO(2), which was confirmed by the lower percentage of mortality of Artemia salina. It was proved that the film thickness, conditions of post deposition treatment and the type of the substrate affected significantly the photocatalytic reaction. Taking into account that the parameters are interdependent, it is necessary to optimize the preparation conditions in order to synthesize photocatalytic active films.

Topics: Animals; Artemia; Azo Compounds; Catalysis; Coloring Agents; Nanostructures; Naphthalenesulfonates; Oxidation-Reduction; Photochemical Processes; Temperature; Textiles; Titanium

This study utilises a UV/TiO(2) system to decolorise C.I. Reactive Black 5 (RB5). The effects of TiO(2) dosage, pH, RB5 concentration and light power on the decolorisation efficiency using the UV/TiO(2) system were determined. IO(4)(-) was employed as an oxidant to increase the photodegradation efficiency of UV/TiO(2). The decolorisation rate constants (k) of RB5 in the UV/TiO(2) system are consistent with pseudo-first-order kinetics. The k values of 0.1, 0.5, 1.0 and 2.0 g/l TiO(2) were 0.53, 0.52, 0.69 and 0.68 h(-1), respectively. The rate constant increases with decreasing pH from 10 to 4. The decolorisation rate approximates linear relationship with RB5 concentration, as given by k=1.05[1/RB5](0.98); it varies nonlinearly with light power, as given by k=0.178[power](0.63). The experimental results reveal that the rate of decolorisation obtained using UV/TiO(2)/IO(4)(-) exceeds that obtained using UV/TiO(2).

Topics: Coloring Agents; Hydrogen-Ion Concentration; Naphthalenesulfonates; Periodic Acid; Time Factors; Titanium; Ultraviolet Rays; Waste Disposal, Fluid; Water Pollutants, Chemical; Water Purification

The photocatalytic degradation of two commercial textile azo dyes, namely C.I Reactive Black 5 and C.I Reactive Red 239, has been studied. TiO(2) P25 Degussa was used as catalyst and photodegradation was carried out in aqueous solution under artificial irradiation with a 125 W mercury vapor lamp. The effects of the amount of TiO(2) used, UV-light irradiation time, pH of the solution under treatment, initial concentration of the azo dye and addition of different concentrations of hydrogen peroxide were investigated. The effect of the simultaneous photodegradation of the two azo dyes was also investigated and we observed that the degradation rates achieved in mono and bi-component systems were identical. The repeatability of photocatalytic activity of the photocatalyst was also tested. After five cycles of TiO(2) reuse the rate of colour lost was still 77% of the initial rate. The degradation was followed monitoring the change of azo dye concentration by UV-Vis spectroscopy. Results show that the use of an efficient photocatalyst and the adequate selection of optimal operational parameters may easily lead to a complete decolorization of the aqueous solutions of both azo dyes.

Topics: Azo Compounds; Catalysis; Coloring Agents; Environmental Restoration and Remediation; Hydrogen Peroxide; Hydrogen-Ion Concentration; Industrial Waste; Naphthalenesulfonates; Photolysis; Recycling; Textiles; Titanium; Ultraviolet Rays; Waste Disposal, Fluid; Water Purification

The photocatalytic degradation of Reactive Black 5 (RB 5), a di-azo dye was investigated over M/TiO2 (M = Ag, Au and Pt) photocatalysts irradiated with UV and visible light. TiO2 was prepared by sol-gel technique (Syn-TiO2). Photodeposition of metal salt precursors over Syn-TiO2 was carried out so as to obtain 1 wt% of M/TiO2 catalysts. The photodecolourization and photodegradation reactions were also compared with commercial TiO2 (Degussa P25) catalyst. Kinetic studies for the decolourization of RB 5 showed that it followed pseudo first order. Recycling of catalysts was performed to check the economic feasibility of the photocatalytic process. In order to check the applicability of M/TiO2 catalyst in the treatment of industrial effluent, real textile effluent was collected from an industry and subjected to photodegradation and the results are presented. Enhanced activity of M/TiO2 catalyst under visible light irradiation highlights its importance in the field of photocatalysis.

Topics: Catalysis; Metals; Naphthalenesulfonates; Photochemistry; Photolysis; Titanium

The modified PVDF membranes were prepared by adding different amounts of TiO(2) particles (0-4 wt.%) into the casting solution. The TiO(2) entrapped PVDF membranes (0-4% PVDF/TiO(2)) were tested for its antibacterial property by using Escherichia Coliform (E. Coli), photoactive property using Reactive Black 5 (RB5) dye and self cleaning (antifouling) properties by fouling using 1% BSA solution. Results showed that TiO(2) addition significantly affects the pore size and hydrophilicity of the PVDF/TiO(2) membrane. This also improves the flux and permeability of modified PVDF/TiO(2) membrane. The results of antibacterial study showed that the composite PVDF/TiO(2) membrane removes E. Coli at a very faster rate than neat PVDF membrane and membrane with 4% TiO(2) possess highest antibacterial property. The RB5 dye removal using PVDF/TiO(2) occurs under UV by photolysis and photocatalysis mechanisms. The rate of RB5 dye color removal was faster as compared to the rate of aromatic ring structure. The resistance study showed 2% TiO(2) membrane having lower fouling resistance as compared to others. The fouling resistance caused by loosely bound protein (R(c)) was lower than the strongly bound protein (R(f)). The performance of fouled membranes flux and TMP can be recovered to its initial value by simple UV treatment.

Topics: Anti-Bacterial Agents; Catalysis; Escherichia; Kinetics; Membranes, Artificial; Naphthalenesulfonates; Photochemical Processes; Polyvinyls; Titanium; Ultraviolet Rays

Reactive black 5 (RB5), an azo dye, was degraded by using UV-irradiated TiO(2) coated on non woven paper with SiO(2) as a binder. The adsorption capacity of the photocatalyst was studied at natural pH, superior to pH(pzc) of the binder, for various ionic strengths. Different salts such as NaCl, KCl, CaCl(2), LiCl, Ca(NO(3))(2) were used to increase the ionic strength. The presence of salt increased the adsorption capacity. The electrostatic interactions between dye and oxide surface charges (TiO(2)/SiO(2)) is very important in the adsorption phenomena. The effect of the ionic strength of the solution on photocatalyst degradation was studied. The rate of degradation was increased by the presence of salts in the range of the experimental conditions. The increase of the initial decolorization rate was observed in the following order: Ca(2+)>K(+)>Na(+)>Li(+). Experiments with different anions (Cl(-), NO(3)(-)) had shown that nitrate was an indifferent electrolyte for the adsorption and photodegradation of the dye on SiO(2)/TiO(2).

Topics: Adsorption; Catalysis; Hydrogen-Ion Concentration; Naphthalenesulfonates; Osmolar Concentration; Paper; Photochemistry; Silicon Dioxide; Textile Industry; Titanium; Water Purification

The combined electrochemical oxidation-solar-light/immobilized TiO2 film process was conducted to degrade an azo dye, Reactive Black 5 (RB5). The toxicity was also monitored by the Vibrio fischeri light inhibition test. The electrochemical oxidation rapidly decolorized RB5 (55, 110 microM) with a supporting electrolyte of 2 gl(-1) NaCl at current density 277Am(-2) and pH 4. However, TOC mineralization and A(310) removal were low. Additionally, the treated solution showed high biotoxicity. RB5 at 110 microM significantly retarded the de-colorization efficiency by using the solar-light/immobilized TiO2 film process. The combined electrochemical oxidation-solar-light/immobilized TiO2 process effectively increased the removal of color, A(310), and TOC. The toxicity was also significantly reduced after 3h of solar irradiation. The results indicated that the low-cost combined process is a potential technique for rapid treatment of RB5.

Topics: Aliivibrio fischeri; Electrochemistry; Naphthalenesulfonates; Photochemistry; Photolysis; Sunlight; Titanium

The degradation of reactive black 5 (RB 5), a representative diazo dye found in textile effluents, by means of ultraviolet irradiation (9W UVA) over TiO(2) suspensions, ultrasound irradiation (80kHz, 135W) and their combined application was investigated. Several commercial TiO(2) catalysts were screened and an anatase Hombicat UV 100 sample exhibited considerable activity in terms of solution decoloration, COD and ecotoxicity reduction. Photocatalytic degradation increased with increasing TiO(2) loading (in the range 0.05-1g/L) and decreasing dye concentration (in the range 120-20mg/L) and solution pH (in the range 9-2.6). At the typical conditions employed in this study (60mg/L dye, 0.25mg/L catalyst, ambient pH=5.8, oxygen sparging), complete decoloration was achieved after 60min of reaction. Addition of H(2)O(2) up to 0.01M hindered degradation, scavenging the photogenerated holes and hydroxyl radicals. Ultrasound irradiation resulted in low decoloration, e.g. less than 10% after 60min at 60mg/L dye and oxygen sparging and slightly improved under an argon atmosphere. The simultaneous application of ultraviolet and ultrasound irradiation resulted in increased decoloration compared to that achieved by photocatalysis and sonolysis operating separately; moreover, the overall sonophotocatalytic effect was greater than the additive effect of the two processes, implying possible synergy.

Topics: Catalysis; Coloring Agents; Hydrogen-Ion Concentration; Light; Models, Molecular; Naphthalenesulfonates; Solutions; Titanium; Ultrasonics; Water Pollutants, Chemical

The textile effluent is a major industrial polluter because it is highly colored, containing about 15% unfixed dyes as well as high levels of salts that can potentially be discharged into the environment. Photocatalytic oxidation using an thin gap annular UV reactor with TiO2 was used to break down the colour of a synthetic effluent ranging up to 400 ppm in dye concentration of Reactive Black 5 and up to 80 g/L in NaCl. Results show that the reaction kinetics was dominated by the TiO2 loading, the initial dye concentration, and the dissolved oxygen concentration; with the other parameters showing less significant effects. High rates of decolorization were found, with a linear fit to the Langmuir-Hinshelwood equation yielding a reaction rate constant (k) of 2.45 ppm/min, and an adsorption equilibrium constant (K) of 0.048 ppm(-1) based on color removal. The presence of the combination of high dissolved oxygen (15 ppm) and sodium chloride (up to 80 g/L) was found to enhance the decolorization and mineralization rates of the reactive dye. However, pH was found to not significantly affect the degradation rate. Since textile effluent is strongly alkaline, this result is significant, as no solution neutralisation is required and direct treatment of the effluent is possible.

Topics: Catalysis; Coloring Agents; Naphthalenesulfonates; Oxidation-Reduction; Oxygen; Photochemistry; Textile Industry; Titanium; Water Pollution; Water Purification