Comparison of a new immobilized Fe3+ catalyst with homogeneous Fe3+–H2O2 system for degradation of 2,4‐dinitrophenol

BACKGROUND: Heterogeneous Fenton catalysts have been used to treat various organic pollutants in an aqueous environment. The present study has investigated the degradation of 2,4‐dinitrophenol (2,4‐DNP), a priority pollutant generated by such industries as pharmaceuticals, pesticides, pigments and dyes. Degradation of 2,4‐DNP (100 mg L^?1) was studied using Fe³⁺ loaded on Al₂O₃ as a heterogeneous catalyst in the presence of H₂O₂, and the efficiency compared with the homogeneous Fe³⁺/H₂O₂ based Fenton‐like process. The effect of different parameters for both processes, such as catalyst loading, H₂O₂ concentration, initial solution pH, initial substrate concentration and temperature were investigated and the optimum operating conditions determined. RESULTS: Under optimal operating conditions of the homogeneous system ([Fe³⁺] 125 mg L^?1; [H₂O₂] 250 mg L^?1; pH 3; room temperature), 92.5% degradation was achieved in 35 min for an initial 2,4‐DNP concentration of 100 mg L^?1. In the case of immobilized Fe (Fe³⁺–Al₂O₃ catalyst), degradation improved to 98.7% under the condition 10 wt% [Fe³⁺–Al₂O₃] 1 g L^?1 catalyst loading; [H₂O₂] 250 mg L^?1; pH 3; at room temperature for the same duration. CONCLUSIONS: This study demonstrated the stability and reusability of the prepared heterogeneous catalyst. This process is a viable technique for treatment of aqueous solutions containing contaminants. Copyright © 2012 Society of Chemical Industry     

The Fenton Chemistry and Its Combination with Coagulation for Treatment of Dye Solutions

Abstract

Aqueous solutions of Acid Blue 74, Acid Orange 10, and Acid Violet 19 were subjected to Fenton/Fenton‐like oxidation and its combination with lime coagulation. The analysis indicated no dependence of chemical oxidation efficacy on dye concentration in the range of 0.1–1 g L^?1. Complete or nearly complete (higher than 95%) color removal of all treated samples was observed. Dye:H₂O₂ weight ratio of 1∶2 proved optimal for treatment of all dye solutions by means of Fenton/Fenton‐like oxidation. Moderate doses of hydrogen peroxide led to the improvement of biodegradability of dye solutions. No formation of any toxic intermediates during the oxidation of Acid Orange 10 and Acid Violet 19 was detected. Only a slight toxicity increase was observed after Acid Blue 74 degradation by Fenton chemistry. H₂O₂/Fe³⁺ system with pH adjusted to 3 proved the most effective oxidation process. The combination of Fenton chemistry and subsequent lime coagulation was the most feasible treatment method of removing COD and UV₂₅₄ and UV_max absorbance of dye solutions. Combined oxidation and coagulation was more effective for Acid Blue 74 and Acid Orange 10 elimination than for Acid Violet 19.     

The sonochemical decolorisation of textile azo dye CI Reactive Orange 127

In the present study, Fenton and sono‐Fenton processes were applied to the oxidative decolorisation of synthetic textile wastewater including CI Reactive Orange 127 and polyvinyl alcohol. Process optimisation [pH, ferrous ion (Fe²⁺) and hydrogen peroxide (H₂O₂)], kinetic studies and their comparison were carried out for both of the processes. The sono‐Fenton process was performed by indirect sonication in an ultrasonic water bath, which was operated at a fixed 35‐kHz frequency and 80 W power. The optimum conditions were determined as [Fe²⁺] = 20 mg l^?1, [H₂O₂] = 15 mg l^?1 and pH = 3 for the Fenton process and [Fe²⁺] = 25 mg l^?1, [H₂O₂] = 5 mg l^?1 and pH = 3 for the sono‐Fenton process. The colour removals were 89.9% and 91.8% by the Fenton and sono‐Fenton processes, respectively. The highest decolorisation was achieved by the sono‐Fenton process because of the production of some oxidising agents as a result of sonication. Consequently, ultrasonic irradiation in the sono‐Fenton process slightly increased the colour removal to 91.8%, while decreasing the hydrogen peroxide dosage to one‐third of that of the Fenton process.     

OXIDATION OF C.I. ACID ORANGE 7 WITH OZONE AND HYDROGEN PEROXIDE IN A HOLLOW FIBER MEMBRANE REACTOR

The degradation of C.I. Acid Orange 7 by ozone combined with hydrogen peroxide was carried out in a hollow fiber membrane reactor, and batch recirculation mode of aqueous phase was employed. The effect of initial pH, hydroxyl radical scavenger, hydrogen peroxide concentration, liquid recirculation rate, gas flow rate, and gaseous ozone concentration on the decolorization of C.I. Acid Orange 7 was investigated. The results showed that the decolorization of C.I. Acid Orange 7 fits the pseudo-half-order kinetic model. The rate constant increased with the increase of initial pH, hydrogen peroxide concentration, liquid recirculation rate, gas flow rate, and gaseous ozone concentration. The presence of hydroxyl radical scavenger inhibited the decolorization rate by over 50%. The combination of ozone with hydrogen peroxide achieved a higher COD removal efficiency than ozone alone in the membrane reactor.     

Degradation of C.I. Acid Red 88 aqueous solution by combination of Fenton's reagent and ultrasound irradiation

BACKGROUND: Pollution caused by industrial wastewater has become a common problem for many countries. In particular, dye pollutions from industrial effluents disturb human health and ecological equilibrium. The discharge of highly colored synthetic dye effluents is aesthetically displeasing and can damage the receiving water body by impeding penetration of light. Azo dyes can be reduced to more hazardous intermediates on anaerobic conditions. Therefore, an effective and economic treatment of effluents containing a diversity of textile dyes has become a necessity for clean production technology for textile industries. Herein we wish to report the degradation of Acid Red 88 by the combination of Fenton's reagent and ultrasound irradiation. RESULTS: The results show that the combination of ultrasonic irradiation and Fenton's reagent is effective for the degradation of Acid Red 88 aqueous solution. Furthermore, it can achieve better results than either Fenton's reagent or ultrasound alone. The optimum conditions for the degradation of Acid Red 88 aqueous solution were 1.96 mmol L^?1 H₂O₂, 0.108 mmol L^?1 Fe²⁺, pH 3.0, and ultrasonic irradiation frequency of 40 kHz. A degradation efficiency of 98.6% was achieved within 135 min. CONCLUSION: We have provided an efficient and convenient procedure for the degradation of Acid Red 88 aqueous solution. In the present procedure, the azo linkage of Acid Red 88 is broken and some carbonyl compounds are formed, but the complete mineralization of dye cannot be achieved. Copyright © 2008 Society of Chemical Industry     

Degradation of benzene,toluene ethylbenzene and p‐xylene (BTEX) in aqueous solutions using UV/H2O2 system

The homogeneous degradation of benzene (B), toluene (T), ethylbenzene (E) and p‐xylene (X) (BTEX) was studied in aqueous solutions, at pH 3.0, of hydrogen peroxide (5.8 mM ) under UV irradiation in a photoreactor equipped with a 300 nm lamp of light intensity 3.5 × 10^?5 Ein L^?1 min^?1. BTEX was substantially degraded by the H₂O₂/UV system, with >90% disappearing in 10 min of irradiation. The decomposition of BTEX was studied either as single or as multi‐component systems. The effects of irradiation time, amounts of H₂O₂ in molar ratios, rate of degradation and competition between components were thoroughly examined. It can be stated that the rate of BTEX degradation in mixture was higher than those for the individual components due to external effects of the absorption of UV light by the mixture, and their effects on enhancing the formation of OH^? radicals. The appropriate figure of merit, the electrical energy per mass (EE/M), was estimated at various molar ratios and it was confirmed that the best value was the one depicted for p‐xylene (0.065 kWh kg^?1). A theoretical model for the degradation pathway was proposed. Copyright © 2004 Society of Chemical Industry     

Effect of dye auxiliaries on the kinetics of advanced oxidation UV/H2O2 of Acid Orange 7 (AO7)

BACKGROUND: The effect of four dye‐auxiliary chemicals, typically employed in acid dyeing, on the performance of UV/H₂O₂ decolouration of the model non‐biodegradable dye C.I. Acid Orange 7 (AO7) was investigated. The initial concentration of AO7 was 0.150 g L^?1, while the concentration of the auxiliary compounds (NaCl, Na₂SO₄, Na₂CO₃ and CH₃COOH) was varied in the range 1–10 g L^?1. RESULTS: The negative influence of the presence of the dye‐auxiliary compounds studied on the decolouration rate of AO7 decreased in the following order: CH₃COOH > Na₂SO₄ > NaCl > Na₂CO₃. Results were quantified in terms of the observed kinetic rate constant, k_obs (s^?1), of AO7 decolouration as a function of dye auxiliary chemical concentration. The decolouration rate of AO7 decreased as the concentration of dye‐auxiliary compound increased in the range 1–5 g L^?1, while higher concentrations had a minor effect. Upon addition of 5 g L^?1 of CH₃COOH, NaCl and Na₂SO₄, the kinetic rate constant decreased by 39%, 30% and 12%, respectively. CONCLUSIONS: It was concluded that the presence of NaCl, Na₂SO₄ and above all of CH₃COOH should be considered in the design of the treatment of real dye‐bath effluents by UV/H₂O₂. Copyright © 2008 Society of Chemical Industry     

High‐Energy Pollen‐Like Porous Fe2O3/Al Thermite: Synthesis and Properties

A pollen‐like porous Fe₂O₃/Al thermite was prepared by a templated method, with aluminium nanoparticles (Al‐NPs) embedded in the porous channels. The thermite prepared by reduced pressure released the largest exothermic heat during DSC testing period compared with Fe₂O₃/Al thermites prepared by ultrasonic mixing and physical mixing. The exothermic heats in the range of 773 K to 1273 K are 3742.3 J g⁻¹, 2279.0 J g⁻¹, 1981.1 J g⁻¹, and 2621.0 J g⁻¹ for pollen‐like Fe₂O₃/Al by reduced pressure, pollen‐like Fe₂O₃/Al by ultrasonic mixing, pollen‐like Fe₂O₃/Al by physical mixing, and commercial Fe₂O₃/Al by ultrasonic mixing, respectively. The reactivity between Fe₂O₃ and Al‐NPs was efficiently improved, corresponding to its enlarged contact surface area between Al‐NPs and the porous pollen‐like Fe₂O₃, and the reduced pre‐combustion sintering. Furthermore, pollen‐like Fe₂O₃/Al has good compatibility with both RDX and HMX and it is not compatible with Cl‐20 and GAP.     

Heterogeneous Fenton degradation of Orange II by immobilization of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles onto Al-Fe pillared bentonite

A novel catalyst, Fe₃O₄ nanoparticle decorated Al-Fe pillared bentonite (Fe₃O₄/Al-Fe-P-B), was prepared by in situ precipitation oxidization method. The catalyst was characterized by SEM, XRD and Raman spectroscopy. The Fe₃O₄ nanoparticles mainly exist on the surface or enter into the pore of bentonite, with better dispersing and less coaggregation. The catalytic activity of Fe₃O₄/Al-Fe-P-B was investigated in the degradation of Orange II (OII) by heterogeneous Fenton-like process. The effects of initial concentration of hydrogen peroxide, catalyst loading, temperature and initial pH on the degradation of OII were investigated. The Fe₃O₄/Al-Fe-P-B showed higher degradation efficiency of OII than bare Fe₃O₄ or Al-Fe-P-B in the degradation experiment. The enhanced catalytic activity of Fe₃O₄/Al-Fe-P-B in heterogeneous Fenton system was due to the synergistic effect between Al-Fe-P-B and Fe₃O₄. The novel catalyst can achieve solid-liquid separation easily by sample magnetic separation and has a good reusability and stability.     

Efficiency and Mechanism of Ciprofloxacin Hydrochloride Degradation in Wastewater by Fe3o4/Na2S2O8

ABSTRACT

The nanosized Fe₃O₄ catalyst was synthesized via a modified reverse coprecipitation method and characterized by means of a scanning electron microscope (SEM) and an X-ray diffraction (XRD) analysis instrument. The degradation efficiency and reaction rate of Fe₃O₄ in activating sodium persulfate used to degrade ciprofloxacin were determined from the catalyst dosage, oxidant concentration, and initial pH. The results showed that under the optimum conditions of a catalyst dosage of 2.0 g·L^?1, a sodium persulfate concentration of 1.0 g·L^?1, and an initial pH of 7, the degradation rate of ciprofloxacin was 93.73%, the removal rate of total organic carbon was 78%, and the first-order reaction constant was 0.06907 min^?1 within 40 min. It was also demonstrated that the reactive oxygen species in the Fe₃O₄/sodium persulfate catalytic system were mainly composed of SO₄^– and supplemented by OH· and HO₂· using probe compounds such as ethanol, tertiary butanol, and benzoquinone.     

Highly stable Fe/γ‐Al2O3 catalyst for catalytic wet peroxide oxidation

BACKGROUND: A highly stable Fe/γ‐Al₂O₃ catalyst for catalytic wet peroxide oxidation has been studied using phenol as target pollutant. The catalyst was prepared by incipient wetness impregnation of γ‐Al₂O₃ with an aqueous solution of Fe(NO₃)₃· 9H₂O. The influence of pH, temperature, catalyst and H₂O₂ doses, as well as the initial phenol concentration has been analyzed. RESULTS: The reaction temperature and initial pH significantly affect both phenol conversion and total organic carbon removal. Working at 50 °C, an initial pH of 3, 100 mg L^?1 of phenol, a dose of H₂O₂ corresponding to the stoichiometric amount and 1250 mg L^?1 of catalyst, complete phenol conversion and a total organic carbon removal efficiency close to 80% were achieved. When the initial phenol concentration was increased to 1500 mg L^?1, a decreased efficiency in total organic carbon removal was observed with increased leaching of iron that can be related to a higher concentration of oxalic acid, as by‐product from catalytic wet peroxide oxidation of phenol. CONCLUSION: A laboratory synthesized γ‐Al₂O₃ supported Fe has shown potential application in catalytic wet peroxide oxidation of phenolic wastewaters. The catalyst showed remarkable stability in long‐term continuous experiments with limited Fe leaching, < 3% of the initial loading. Copyright © 2010 Society of Chemical Industry     

Kinetic study of the manganese‐based catalytic hydrogen peroxide oxidation of a persistent azo‐dye

BACKGROUND: The discharge of synthetic dyes by the textile industry into the environment poses concerns due to their persistence and toxicity. New efficient treatment processes are required to effectively degrade these dyes. The aim of this work was to study the degradation of a persistent dye (Drimarene Brilliant Reactive Red K‐4BL, C.I.147) using H₂O₂ oxidation catalysed by an Mn(III)‐saltren catalyst and to develop a kinetic model for this system. RESULTS: Dye oxidation with H₂O₂ was significantly improved by the addition of the catalyst. As the pH was increased from 3 to 10, the oxidation rates increased significantly. The kinetic model developed in this study was found to adequately explain the experimental results. In particular, dye oxidation can be described at high pH by pseudo‐first‐order kinetics. A Michaelis–Menton type equation was developed from the model and was found to adequately describe the effect of H₂O₂ and catalyst concentrations on the apparent pseudo‐first‐order rate constant. Optimum catalyst and H₂O₂ concentrations of 500 mg L^?1 and 6.3 g L^?1, respectively, were found to give maximum reaction rates. CONCLUSION: Catalytic H₂O₂ oxidation was found to be effective for the removal of persistent dye and the results obtained in this work are of significance for design and scale‐up of a treatment process. Copyright © 2009 Society of Chemical Industry     

Advanced treatment of phenol by H2O2/UV/activated carbon coupling: Influence of homogeneous and heterogeneous phase

In this work, a heterogeneous catalytic wet peroxide process combining activated carbon (AC) and hydrogen peroxide (H₂O₂)/ultraviolet radiation was applied for the aqueous‐phase removal of phenol. The influence of the pH and peroxide concentration were determined according to a factorial plan. The kinetic contribution of radical mechanisms () was estimated using a radical scavenger (tert‐butyl alcohol). The degradation kinetics was modelled by a global pseudo‐first‐order kinetic model based on the sum of the effects during the treatment process. The results showed that these two variables significantly affected the percentage removal. The peroxide concentration exerted a positive effect (i.e., as the H₂O₂ concentration increased, the percentage removal also increased). Additionally, as the pH value increased, the degradation accelerated, and the kinetic constant (k_homogeneous) increased from 0.00938 min^?1 to 0.02772 min^?1. The results obtained in the presence of AC demonstrated the ability of AC to ameliorate the degradation of phenol; for example, was 45.69 % to 41.35 %.

     

Photoreactor design and CFD modelling of a UV/H2O2 process for distillery wastewater treatment

A pseudo‐kinetic model for the treatment of a distillery wastewater by the ultraviolet irradiation and hydrogen peroxide process in a continuous tubular photoreactor is developed. There is a scarcity of information on modelling of organic degradation rates based on chemical oxygen demand (COD) and total organic carbon (TOC) in advanced oxidation technologies (AOTs). In this study, the COD and TOC are used as surrogate parameters to design a photoreactor instead of individual concentrations of species. The rate constants for the reaction between COD and TOC with hydroxyl radicals were determined to be 4.9 × 10⁹ and 5.0 × 10⁶ M^?1 s^?1, respectively. A laminar flow model was simulated to estimate the velocity and residence time of the medium in a cylindrical photoreactor. The model was validated by the experimental data published in the open literature for different concentrations of H₂O₂ (1, 10, and 100 mM), COD (589, 709, and 850 mg O₂ L^?1), and TOC (190, 200, and 192 mg C L^?1). The optimal value of the inlet hydrogen peroxide concentration was predicted to be 400 mg L^?1. Axial and radial concentration distributions of species in the photoreactor were also obtained. At different photoreactor radii (from 50 to 200 mm), the values of radial local volumetric rate of energy absorption (LVREA) were estimated. It was found that a higher LVREA was achieved in the photoreactor space at smaller radii. © 2011 Canadian Society for Chemical Engineering     

Oxidation of Acid Red-151 Aqueous Solutions by the Peroxone Process and its Kinetic Evaluation

Oxidation of an azo dye solution, namely, Acid Red 151 by the peroxone process was investigated experimentally at different pH values, initial dye and ozone concentrations, and the initial molar ratios (r) of hydrogen peroxide to ozone. At pH 2.5 in this process, the obtained color and chemical oxygen demand (COD) removals were higher than those at pH of 7 and 10. The best value of r yielding the highest treatment efficiency at each pH was determined as 0.5. The application of the “initial rates method” to the kinetic data for peroxone oxidation of aqueous Acid Red 151 solutions showed that the individual orders with respect to O₃ and dye were one, the total order of the reaction being two. The rate constants based on the initial rates of dye degradation were determined as 98.9, 77.3 and 65.7 mM^?1min^?1 at the pH values of 2.5, 7 and 10, respectively.     

Graft copolymerization of 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid onto carboxymethylcellulose (sodium salt) by H2O2/Fe+2 redox pair

The effect of the reaction conditions on the grafting parameters during grafting of 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid onto sodium carboxymethylcellulose using H₂O₂/Fe⁺² redox pair are studied at 30°C. The grafting ratio, add on, and conversion initially increase with the H₂O₂ concentration in the range of (10.0–15.0) × 10^?2 mol dm^?3. Thereafter, these parameters decrease with the H₂O₂ concentration. The grafting ratio, add on, and conversion increase when increasing the ferrous ion concentration from (0.5 to 4.0) × 10^?2 mol dm^?3 and decrease with a further increase in the concentration. It is observed that the grafting ratio and add on increase with the monomer concentration, whereas the conversion decrease. The hydrogen ions seem to be facilitating the grafting reaction up to a certain concentration and after this concentration seem to be retarding the process. The grafting ratio, add on, and conversion decrease with the sodium carboxymethylcellulose concentration. When increasing the time period from 60 to 90 min, the grafting parameters increase but decrease thereafter. Similarly, when increasing the temperature from 25 to 30°C, the grafting parameters increase and decrease thereafter. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4819–4825, 2006     

Photodegradation of four fluoroquinolone compounds by titanium dioxide under simulated solar light irradiation

BACKGROUND; In this study, simultaneous photocatalytic degradation of four fluoroquinolone (FQ) compounds (i.e. ofloxacin, norfloxacin, ciprofloxacin and enrofloxacin) was investigated in TiO₂ suspensions under simulated solar light irradiation. Effects of experimental variables including pH, TiO₂ dosage, initial substrate concentration and hydrogen peroxide (H₂O₂) on the degradation processes were also investigated. RESULTS: The antibiotics degradation was pH‐influenced. The photocatalytic reaction followed the pseudo‐first‐order model, with reaction rate constants (k) 0.026, 0.027, 0.022 and 0.026 min^?1 for ofloxacin, norfloxacin, ciprofloxacin and enrofloxacin, respectively. Complete elimination of four FQs was achieved in a reaction system composed of 0.5 g L^?1 of TiO₂ and 82.5 mg L^?1 of H₂O₂ at pH 6 after 90 min irradiation. Mineralization of FQs during TiO₂ photocatalysis was slower than the FQs conversion, and the antibacterial activity of the four FQs was completely removed by TiO₂ under simulated solar light irradiation. CONCLUSION: The four FQs can be simultaneously degraded and mineralized with commercially available TiO₂ under simulated solar light irradiation. Microbiological analysis showed that the antibacterial activity of the four FQs was completely removed. These results are helpful for antibiotics removal in the environment, and for exploring new technology for wastewater treatment. Copyright © 2012 Society of Chemical Industry     

The mechanism and application of the electro‐Fenton process for azo dye Acid Red 14 degradation using an activated carbon fibre felt cathode

BACKGROUND: The discharge of azo dyes into the environment poses concerns due to their limited biodegradability. The electro‐Fenton process (EF) is a good method to effectively degrade these dyes. The aim of this work was to study the mechanism and the feasibility of the EF reaction using an activated carbon fibre (ACF) cathode. In this study, two methods were used to measure the reactive species generated in anodic oxidation (AO), anodic oxidation with electrogenerated H₂O₂ (AO‐H₂O₂) and the EF process. Acid Red 14 (AR14) was chosen as a model pollutant. The effects of the operational parameters, pH and initial concentrations were investigated. A short‐term biodegradability test was also carried out to evaluate the EF process from a biological point of view. RESULTS: After 2 h EF reaction 118.7 µmol L^?1?OH were produced, which was much higher than that of the AO‐H₂O₂ (63.2 µmol L^?1) process. H₂O₂ is largely generated and Fe³⁺ efficiently reduced on the high surface area of the ACF cathode. The EF process provides more effective degradation of AR14 than the conventional Fenton process, and its current efficiency is significantly affected by the initial pH and the initial AR14 concentration. Following EF treatment, the biodegradability of AR14 is significantly increased. CONCLUSION: The higher formation of ^?OH in the EF process suggests it is an effective method for pollutant removal. This process also leads to increased biodegradability, which is expected to facilitate subsequent biological treatment. Copyright © 2010 Society of Chemical Industry     

Kinetics of hydrogenation of 4‐chloro‐2‐nitrophenol catalyzed by Pt/carbon catalyst

Hydrogenation of 4‐chloro‐2‐nitrophenol (CNP) was carried out at moderate hydrogen pressures, 7–28 atm, and temperatures in the range 298–313 K using Pt/carbon and Pd/γ‐Al₂O₃ as catalysts in a stirred pressure reactor. Hydrogenation of CNP under the above conditions gave 4‐chloro‐2‐aminophenol (CAP). Dechlorination to form 2‐aminophenol and 2‐nitrophenol is observed when hydrogenation of CNP is carried out above 338 K, particularly with Pd/γ‐Al₂O₃ catalyst. Among the catalysts tested, 1%Pt/C was found to be an effective catalyst for the hydrogenation of CNP to form CAP, exclusively. To confirm the absence of gas–liquid mass transfer effects on the reaction, the effect of stirring speed (200–1000 rpm) and catalyst loading (0.02–0.16 g) on the initial reaction rate at maximum temperature 310 K and substrate concentration (0.25 mole) were thoroughly studied. The kinetics of hydrogenation of CNP carried out using 1%Pt/C indicated that the initial rates of hydrogenation had first order dependence with respect to substrate, catalyst and hydrogen pressure in the range of concentrations varied. From the Arrhenius plot of ln rate vs 1000/T, an apparent activation energy of 22 kJ mol^?1 was estimated. © 2001 Society of Chemical Industry     

Photoassisted Fenton mineralisation of Acid Violet 7 by heterogeneous Fe(III)–Al2O3 catalyst

Photoassisted Fenton mineralisation of an azo dye Acid Violet 7 was studied in detail using a Fe(III) loaded Al₂O₃ as a heterogeneous catalyst in the presence of H₂O₂ and UV-A light. The catalyst ferrioxalate–Al₂O₃ is more efficient than ferricnitrate–Al₂O₃. 35% Fe³⁺ loaded Al₂O₃ shows maximum efficiency in the degradation. The effects of reaction parameters such as catalyst loading, H₂O₂ concentration, initial solution pH and initial dye concentration on photodegradation were investigated and the optimum conditions are reported.