Fenton's Reagent Dosage Research Articles

Degradation of naproxen by combination of Fenton reagent and ultrasound irradiation: optimization using response surface methodology

A central composite factorial design methodology was employed to optimize the degradation of naproxen (NPX) by the combination of Fenton reagent and ultrasound (US) irradiation. In this study, the variables considered for the process optimization were the hydrogen peroxide, ferrous ion and NPX initial concentrations, while ultrasonic power amplitude was adjusted at 90% and initial pH was 3. An appropriate quadratic model was developed in order to plot the response surface and contour curves. Optimum dosage of Fenton reagent for NPX removal was found to be hydrogen peroxide concentration = 9.98 mmol L⁻¹, ferrous ion concentration = 4.83 mg L⁻¹ while NPX concentration was equal to 20 mg L⁻¹. A degradation efficiency of 100% was achieved within 10 min under US.

Photo-Fenton degradation of non-ionic surfactant and its mixture with cationic or anionic surfactant

The oxidative degradation of non-ionic surfactants by the photo-Fenton process has been examined. The photo-Fenton degradation kinetics of mixtures of non-ionic surfactant and other type surfactants has been also investigated since mixtures of non-ionic and ionic surfactants are commonly used to utilize their synergistic effects in many practices. Effects of operating parameters such as dosages of Fenton reagents (iron and hydrogen peroxide) and UV light intensity on the degradation of commercial non-ionic surfactant Sannonic SS-90 (polyoxyethylene alkyl ether) were studied. Although the dosages of the Fenton reagents increased the degradation rate up to the optimum dosages, further addition of the reagents could not enhance the degradation rate. Excess dosages of Fe and H2O2 caused excess OH radicals which could be a scavenger of OH radicals and as a result could not enhance the degradation of the surfactant. The increase in UV light intensity resulting in the faster photo-Fenton process or the enhancement of OH radical formation rate led to the increase in degradation rate of non-ionic surfactant. Although the existence of the anionic surfactant (sodium dodecylbenzene sulphonate) would inhibit the degradation of the non-ionic surfactant due to the formation of complex with Fe ion, the existence of cationic surfactant (dodecyltrimethyl ammonium chloride) affected insignificantly the photo-Fenton degradation process of the non-ionic surfactant.

Removal of VOCs in waste gas by the photo‐Fenton reaction: effects of dosage of Fenton reagents on degradation of toluene gas in a bubble column

AbstractBACKGROUNDVolatile organic compounds (VOCs) are major pollutants in the atmosphere of all urban and industrial areas, and the development of an effective treatment process for VOCs is highly desirable. Advanced oxidation processes (AOPs) are a promising technology for air pollution control. In this study, the AOP photo‐Fenton oxidative reaction in the liquid phase was applied to chemical absorption and degradation of toluene in waste gas.RESULTSFor toluene levels of 0.25 mg L−1 in waste gas flowing at 5.0 Lmin−1 the maximum removal and mineralization of toluene in the waste gas were more than 90% with H2O2 dosage above 150 mg L−1 and Fe dosage above 10 mg L−1. The Toluene photodegradation efficiency increased with increasing dosages of Fenton reagents, however, beyond a certain dosage further improvements were insignificant. The photo‐Fenton reaction in the liquid‐phase could improve the overall toluene absorption rate by increasing the driving force for mass transfer and as a result enhance the removal of toluene from exhaust gas.CONCLUSIONToluene in waste gas was successfully removed and mineralized by the photo‐Fenton process. The mineralization of toluene was strongly linked with the iron redox cycle and H2O2 decomposition driven by the Fenton reagents and UV light. The proposed chemical absorption process based on photo‐Fenton photocatalytic oxidation in the liquid phase was shown to be very effective for the degradation of VOCs in waste gas. Copyright © 2012 Society of Chemical Industry

Decolorization of Methylene Blue Dye Wastewater by Fenton’s Reagent

Using ·OH from Fenton’s reagent, the strong oxidation treatment of methylene blue dye wastewater can destruct the chromophore in organic compounds, and yield CO2, H2O and small molecule inorganic compounds by oxidative degradation finally. The influence of Fenton's reagent dosage, initial pH, and reaction time on the degradation effect was studied. The experimental results show that the decolorization rate of 100mL 20mg/L methylene blue dye wastewater can achieve 96% in the conditions of 0.02g FeSO4·7H2O, 1mL 30% H2O2, initial pH at 3.0 ~4.0, reaction time is 30 min, at room temperature. This treatment of dye wastewater is easy to operate and with good effect.

Advanced landfill leachate treatment with least sludge production using modified Fenton process

This research was undertaken to investigate various operating conditions of Fenton treatment process for minimizing the sludge production and maximizing COD as well as colour removal from landfill leachate. Sample was collected from Matuaill and fill site, one of the major landfill sites of Dhaka City Corporation. For optimum pH value of 5 and optimum dosages of Fenton reagents having H2O2/Fe2+ molar ratio of 1.3 the highest removal of COD and colour were found 68% and 87% respectively with massive sludge production of 75%. The COD and colour removal efficiencies with a three-step dosing of reagents were 11% and 7% higher respectively with 17% less sludge production than those with single dosing of individual Fenton treatment process. Also recycling of Fenton sludge enhanced COD removal efficiency by 6% having similar colour removal efficiency and reduced sludge production significantly by 38%. With all optimum parameters, the highest removal of COD and colour were found 84% and 93% respectively with sludge production of 30% through multiple dosing of Fenton reagents with sludge recirculation. Conversely, pretreatment with extended aeration before Fenton process provided the achievement of 89% COD and 97% colour removals having less sludge volume reduction.

Oxidation and coagulation removal of humic acid using Fenton process

The treatment of humic acid (HA) in water with Fenton reagents was carried out and the roles of oxidation and coagulation in removing HA during treatment were investigated. The removal efficiencies of HA by oxidation and coagulation were tested under various operating conditions: reaction time, initial pH, dosages of Fenton reagents, [H 2O 2]/[Fe 2+] molar ratio, initial HA concentration and reaction temperature. It is demonstrated that Fenton process can effectively remove HA. The values of 27.6% mineralization of HA and 78.9% reduction of UV absorbance at 254 nm (UV 254) by oxidation after 120 min reaction time indicated that HA was not completely oxidized to carbon dioxide but rather transformed to some organic intermediates. Moreover, the oxidation occurred mainly at the first 60 min and predominated the HA removal efficiency. Under the most favorable conditions (initial pH 4.0, H 2O 2 160 mM, Fe 2+ 40 mM, reaction time 120 min, reaction temperature 30 °C), 93.3% of UV 254 was reduced, the reduction of UV 254 by oxidation and coagulation were 78.9% and 14.4%, respectively. Results highlighted the synergistic roles of oxidation and coagulation in Fenton treatment of HA.

Sono-Fenton oxidation of formic acid/formate ions in an aqueous solution: From an experimental design to the mechanistic modeling

In order to establish an efficient oxidation process for the mineralization of a model wastewater containing formate species, the effects of some operating parameters such as Fenton reagent dosages and volume of the treated system were observed during the treatment by the ultrasonic assisted Fenton and modified Fenton processes. The mineralization kinetics was also examined based on the experimental data. The overall mineralization kinetics was found to be in the accordance with the first-order reaction kinetics. The results obtained within this work indicate an efficient mineralization, achieved by studied sonochemical oxidation processes. With the appropriate combination of operating parameters it is reasonable to expect a mineralization extent of 94%, corresponding to the complete degradation of formate species with the consequent formation and the degradation of oxalic acid in the system. The detailed mathematical model describing the ongoing process in the studies batch system was developed on the basis of a mechanistic reaction scheme, given in the frame of this work. The model has been validated, pointing at the significance of the assumed reactions and the accuracy of the corresponding rate constants.

Degradation of Recalcitrant Organics from Winery Wastewater by Fenton's Reaction

The advanced treatment of wine vinasses was investigated experimentally using the Fenton reaction. The relationship between the dosage of Fenton reagent and the resulting degradation of residual re...

Decolorization of dark brown colored coffee effluent by solar photo-Fenton reaction: Effect of solar light dose on decolorization kinetics

The decolorization of dark brown colored coffee effluent by solar photo-Fenton process has been studied. Effects of accumulated solar light energy and dosage of Fenton reagents (iron and hydrogen peroxide) on the color removal have been examined. With increasing Fe dosage the rate of the decolorization increased but the enhancement was not pronounced beyond 10 mg L −1. Although addition of H 2O 2 increased the decolorization rate up to around 1000 mg L −1 of H 2O 2, further addition of H 2O 2 could not enhance the color removal. At excess dosages of Fenton reagents, the color removal was not improved due to their scavenging of hydroxyl radicals. It was found that the pseudo-first order decolorization kinetic constant based on the accumulated solar energy is a sole parameter unifying solar photo-Fenton decolorization processes under the different weather conditions. The kinetic constant can be readily used to calculate the amount of solar energy required to achieve a certain degree of color removal. The mineralization was rather slower as compared with the decolorization. The decolorization capability with solar irradiation was found to be comparable to UV light irradiation. The present results suggest that abundant solar energy driving decolorization of coffee effluent by photo-Fenton reaction is highly efficient.

Treatment of water-based printing ink wastewater by Fenton process combined with coagulation

Attempts were made in this study to examine the efficiency of Fenton process combined with coagulation for treatment of water-based printing ink wastewater. Parameters affecting the Fenton process, such as pH, dosages of Fenton reagents and the settling time, were determined by using jar test experiments. 86.4% of color and 92.4% of chemical oxygen demand (COD) could be removed at pH 4, 50 mg/l H 2O 2, 25 mg/l FeSO 4 and 30 min settling time. The coagulation using polyaluminium chloride (PAC) and ferrous sulfate (FeSO 4) was beneficial to improve the Fenton process treated effluent in reducing the flocs settling time, enhancing color and COD removal. The overall color, COD and suspended solids (SS) removal reached 100%, 93.4% and 87.2% under selected conditions, respectively. Thus this study might offer an effective way for wastewater treatment of water-based ink manufacturer and printing corporation.

Physical and oxidative removal of organics during Fenton treatment of mature municipal landfill leachate

Municipal landfill leachate, especially mature leachate, may disrupt the performance of moderately-sized municipal activated sludge wastewater treatment plants, and likewise tend to be recalcitrant to biological pretreatment. Recently, Fenton methods have been investigated for chemical treatment or pre-treatment of mature leachate. In this paper, the results of laboratory tests to determine the roles of oxidation and coagulation in reducing the organic content of mature leachate during Fenton treatment are presented. The efficiencies of chemical oxygen demand (COD) oxidation and coagulation were tested, and the ratio of COD removal by oxidation to that by coagulation was assessed, under various operating conditions. Low initial pH, appropriate relative and absolute Fenton reagent dosages, aeration, and stepwise addition of reagents increased COD removal by oxidation and the importance of oxidation relative to coagulation. Simultaneous aeration and stepwise reagent addition allowed comparable treatment without initial acidification pH, due to the generation of acidic organic intermediates and the continuous input of CO 2. On the other hand, high COD oxidation efficiency and low ferrous dosage inhibited COD removal by coagulation. At significantly high oxidation efficiency, overall COD reduction decrease slightly due to low coagulation efficiency. Under the most favorable conditions (initial pH 3, molar ratio [H 2O 2]/[Fe 2+] = 3, [H 2O 2] = 240 mM, and six dosing steps), 61% of the initial COD was removed, and the ratio of COD removal oxidation to coagulation was 0.75. Results highlighted the synergistic roles of oxidation and coagulation in Fenton treatment of mature leachate, and the role of oxidation in controlling the efficiency of removal of COD by coagulation.

Degradation of 4-nitrophenol in aqueous medium by electro-Fenton method

The degradation of 4-nitrophenol by electro-Fenton (E-Fenton) method was carried out in batch recirculation mode. The effect of operating conditions such as electrical current, Fenton's reagent dosage, Fe(II) to H 2O 2 molar ratio, and H 2O 2 feeding time on the efficiency of E-Fenton process was investigated. It was found that E-Fenton method showed the synergetic effect on COD removal. The increase of Fenton's reagent dosage, Fe(II) to H 2O 2 molar ratio, and the electrical current would lead to the increase of COD removal efficiency. Continuous addition of hydrogen peroxide was more effective than the addition of hydrogen peroxide in a single step and there existed an optimal H 2O 2 feeding time for COD removal. The reaction system was modeled as a plug flow reactor (PFR) in series with a continuous stirred tank reactor (CSTR), and the pseudo-first order rate constant of COD removal was determined from the model based on the experimental data.

Treatment of landfill leachate by Fenton's reagent in a continuous stirred tank reactor

The treatment of landfill leachate by Fenton process was carried out in a continuous stirred tank reactor (CSTR). The effect of operating conditions such as reaction time, hydraulic retention time, pH, H 2O 2 to Fe(II) molar ratio, Fenton's reagent dosage, initial COD strength, and temperature on the efficacy of Fenton process was investigated. It is demonstrated that Fenton's reagent can effectively degrade leachate organics. Fenton process reached the steady state after three times of hydraulic retention. The oxidation of organic materials in the leachate was pH dependent and the optimal pH was 2.5. The favorable H 2O 2 to Fe(II) molar ratio was 3, and organic removal increased as dosage increased at the favorable H 2O 2 to Fe(II) molar ratio. Temperature gave a positive effect on organic removal.

Removal of COD from landfill leachate by electro-Fenton method

The treatment of landfill leachate by electro-Fenton (E-Fenton) method was carried out in a batch electrolytic reactor. The effect of operating conditions such as reaction time, the distance between the electrodes, electrical current, H 2O 2 to Fe(II) molar ratio, Fenton's reagent dosage and H 2O 2 feeding mode on the efficacy of E-Fenton process was investigated. It is demonstrated that E-Fenton method can effectively degrade leachate organics. The process was very fast in the first 30 min and then slowed down till it was complete in 75 min. There exists an optimal distance range between the electrodes so that an over 7% higher chemical oxygen demand (COD) removal was achieved than the electrodes positioned beyond this range. COD removal efficiency increased with the increasing current, but further increase of current would reduce the removal efficiency. Organic removal increased as Fenton's reagent dosage increased at the fixed H 2O 2 to Fe(II) molar ratio. COD removal was only 65% when hydrogen peroxide alone was applied to the electrolytic reactor, and the presence of ferrous ion greatly improved COD removal. COD removal efficiency increased with the increase of ferrous ion dosage at the fixed hydrogen peroxide dose and reached highest at the 0.038 mol/L of ferrous ion concentration. COD removal would decrease when ferrous ion concentration was higher than 0.038 mol/L. The stepwise or continuous addition of hydrogen peroxide was more effective than the addition of hydrogen peroxide in a single step. E-Fenton method showed the synergetic effect for COD removal as it achieved higher COD removal than the total COD removal by electrochemical method and Fenton's reagent.

Optimization of Fenton process for the treatment of landfill leachate

The treatment of landfill leachate by Fenton process was carried out in a batch reactor. The effect of operating conditions such as reaction time, pH, H 2O 2 to Fe(II) molar ratio, Fenton's reagent dosage, initial COD strength, feeding mode, the type of polymer, and temperature on the efficacy of Fenton process was investigated. It is demonstrated that Fenton's reagent can effectively degrade leachate organics. Fenton process was so fast that it was complete in 30 min. The oxidation of organic materials in the leachate was pH dependent and the optimal pH was 2.5. The favorable H 2O 2 to Fe(II) molar ratio was 1.5, and organic removal increased as dosage increased at the favorable H 2O 2 to Fe(II) molar ratio. The efficacy of Fenton process was improved by adding Fenton's reagent in multiple steps than that in a single step. Furthermore, the stepwise addition of both hydrogen peroxide and ferrous iron was more effective than that of hydrogen peroxide only. Sludge settling characteristics were much improved with the addition of the proper polymer. Temperature gave a positive effect on organic removal.

Fenton's Reagent Degradation of 2,4-Dinitrotoluene in Water–Acetone Mixtures

This article presents laboratory studies using Fenton's reagent (Fe+2 + H2O2) to degrade 2,4-dinitrotoluene (DNT) in water-acetone mixtures representative of contaminated soil extract solutions. Specifically, DNT degradation and kinetics as a function of Fenton's reagent dosage and variable acetone concentration (0-15.5 M) were examined. DNT degradation was successful (>98%) in water only, but was significantly impacted by acetone. At acetone concentrations greater than 3 M, the maximum DNT degradation was 20%. Greater than 65% DNT degradation, however, was measured at acetone concentrations less than or equal to 1.38 M. The presence of acetone also reduced DNT degradation kinetics. DNT degradation behavior in the presence of acetone suggests acetone is a significant hydroxyl radical scavenger; however, it may also contribute to DNT removal, possibly through secondary reactions involving acetone degradation products and oxygen. Comparison of model and experimental results show that DNT degradation is as much as 38% greater than predicted by direct reaction with hydroxyl radical alone.