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1.
The removal of metsulfuron methyl (MeS)—a sulfonyl urea herbicide from contaminated water was investigated by advanced oxidation process (AOP) using Fenton method. The optimum dose of Fenton reagent (Fe 2+/H 2O 2) was 10 mg/L Fe 2+ and 60 mg/L H 2O 2 for an initial MeS concentration ([MeS] 0) range of 0–80 mg/L. The Fenton process was effective under pH 3. The degradation efficiency of MeS decreased by more than 70% at pH > 3 (pH 4.5 and 7). The initial Fe 2+ concentration ([Fe 2+] 0) in the Fenton reagent affected the degradation efficiency, rate and kinetics. The degradation of MeS at optimum dose of Fenton reagent was more than 95% for [MeS] 0 of 0–40 mg/L and the degradation time was less than 30 min. The determination of residual MeS concentration after Fenton oxidation by UV spectrophotometry was affected by the interferences from Fenton reagent. The estimation of residual MeS concentration after Fenton oxidation by high pressure/performance liquid chromatograph (HPLC) was interference free and represented the actual concentration of MeS and does not include the by-products of Fenton oxidation. The degradation kinetics of MeS was modelled by second order reactions involving 8 rate constants. The two reaction constants directly involving MeS were fitted using the experimental data and the remaining constants were selected from previously reported values. The model fit for MeS and the subsequent prediction of H 2O 2 were found to be within experimental error tolerances. 相似文献
2.
Oxidation with O 3/H 2O 2 and Fe 2+/H 2O 2 are optional for the degradation of herbicides and pesticides in water. The choice of which process will be applied depends upon the degree of degradation of organic micropollutants and the process conditions related to the formation of oxidation by-products, and also on the total costs and the safety and reliability of the process. Under real conditions, atrazine and some phenylureaherbicides were oxidized with O 3/H 2O 2. Comparable experiments under conditions of different pH, iron and DOC content were performed with Fe 2+/H 2O 2, in order to gain information on the influence of these parameters. The oxidation results of both processes as well as the formation of bromate as one of the oxidation by-products are described. It was found that 80% of atrazine and >99% of some phenylureaherbicides could be degraded with O 3/H 2O 2 at pH 7.8 (H 2O 2/O 3 ratio 3.7 g/g). Under these conditions, bromate was formed up to 5 μg/1. Comparable results were obtained with Fe 2+/H 2O 2 at a pH value of 5.5, whereas the formation of bromate was kept below 0.2 μg/L. 相似文献
3.
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 Fe 3+ loaded on Al 2O 3 as a heterogeneous catalyst in the presence of H 2O 2, and the efficiency compared with the homogeneous Fe 3+/H 2O 2 based Fenton‐like process. The effect of different parameters for both processes, such as catalyst loading, H 2O 2 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 ([Fe 3+] 125 mg L ?1; [H 2O 2] 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 (Fe 3+–Al 2O 3 catalyst), degradation improved to 98.7% under the condition 10 wt% [Fe 3+–Al 2O 3] 1 g L ?1 catalyst loading; [H 2O 2] 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 相似文献
4.
The kinetics of the dependence of pH, oxalate, and hydrogen peroxide concentrations on the degradation performance of the herbicide 2,4‐dichlorophenoxyethanoic acid (2,4‐D) was studied in a novel ferrous oxalate/H 2O 2/UV system. The formation and destruction of the primary intermediate, 2,4‐dichlorophenol (2,4‐DCP), was also monitored in the study. A rate enhancement of about 2.9 times was found when 1.2 mM of oxalate was added to the conventional Fe 2+/H 2O 2/UV process. However, excess oxalate suppressed the reaction due to the scavenging and light attenuation effects. The 2,4‐D transformation at a lower initial pH was faster than that at a higher pH, and the different reaction mechanisms were investigated. In addition to the decay rates, the yield of the intermediate 2,4‐DCP was also affected by the initial solution pH. The increment of hydrogen peroxide concentration did not increase the initial decay rates of 2,4‐D, yet it improved the overall removal of 2,4‐D and elevated the formation of the corresponding intermediate (2,4‐DCP). Copyright © 2004 Society of Chemical Industry 相似文献
5.
The decomposition of polycyclic aromatic hydrocarbons in a creosote oily solution and in synthetic solutions containing naphthalene
and pyrene was investigated in the presence of an amphoteric surfactant using electrooxidation by comparison to Fenton oxidation
process. Electrolysis was carried out using a parallelepipedic electrolytic 1.5-L cell containing five anodes (expanded titanium
covered with ruthenium) and five cathodes (stainless steel) alternated in the electrode pack, whereas Fenton oxidation process
was carried out in 500 mL Erlenmeyer glass-flasks in which H 2O 2 and Fe 2+ were added. Using electrochemical oxidation, the sum concentration of 16 polycyclic aromatic hydrocarbons investigated could
be optimally diminished by up to 80–82% by applying a current density of 9.23 mA cm −2 and a pH of 4.0 or 7.0 for 90-min reaction period. By comparison, the best yield (46%) of Fenton oxidation process for polycyclic
aromatic hydrocarbons degradation was recorded by using H 2O 2/Fe 2+ molar ratio of 11.0 and a pH of 4.0. 相似文献
6.
This study investigated the combination of chemical and ultrasonic regeneration (Sono-Fenton), used for regenerating granular activated carbon (GAC) saturated with Rhodamine B (RB). This process was modeled and optimized using response surface methodology (RSM) based on central composite design (CCD). Effective parameters on regeneration efficiency such as pH, concentration of hydrogen peroxide (H 2O 2), and time of ultrasonic irradiation were optimized and modeled using the reduced quadratic method. The fitness of the model was checked by the determination coefficient (R 2?=?0.9978). At optimum condition, the effective parameters of pH?=?3.84, concentration of H 2O 2?=?38.28 (mM), and time of ultrasonic irradiation?=?23.11(min), maximum regeneration efficiency (87.88%) was achieved, the results of which were obtained after four-time sequential adsorption–regeneration cycles were acceptable. Desorption and degradation of RB were conducted through the generation of active species, including hydroxyl radicals and high-energy ultrasound. The regeneration efficiency was increased using this combination method. In conclusion, the Sono-Fenton method is suggested to be used more widely in regeneration processes. 相似文献
7.
传统Fenton反应存在对液相pH要求较高、Fe 3+回收困难以及难以重复使用等问题。基于"活性离子固载化,酸性环境局部化"的设计思路,通过对活性炭(AC)表面酸化改性,制备得到载铁活性炭(Fe/AC)催化剂。研究了Fe/AC制备工艺与其性能之间的关系,结果表明,在载Fe 3+量44.05 mg·g -1、煅烧温度200℃的制备工艺下可得到催化活性较高、稳定性好的Fe/AC催化剂。用性能优良的Fe/AC催化H 2O 2降解双酚A(BPA),其较佳催化反应条件为:反应时间60 min、反应温度20℃、溶液pH值为4.0≤pH≤8.0、Fe 3+/H 2O 2摩尔比为0.007~0.012、30% H 2O 2用量为0.04 ml H 2O 2·(mg BPA) -1。本工作制备得到的Fe/AC催化剂具有较好的重复使用性能,在实际废水处理领域具有较大的应用前景。 相似文献
8.
Abstract Some advanced oxidation processes (AOP's) such as Fenton H 2O 2/Fe 2+, photo assisted Fenton UV/H 2O 2/Fe 2+, UV photolysis, and photo assisted Fenton—like UV/O 2/Fe 2+ have been tested for the degradation of Gemfibrozil in aqueous solution in a batch system and then in a membrane reactor. A nanofiltration/reverse osmosis type cross‐linked polyamide, UTC‐60 (Toray) membrane (19 cm 2) was used. In the batch degradation tests, the gemfibrozil, used at 5 mg/L, was degraded by employing the four AOP's but numerous peaks of intermediates were observed at the HPLC. Indeed DOC analyses showed poor mineralization in the case of photolysis (3.1%) and UV/O 2/Fe (10%), while it was 62% using the photo assisted Fenton and 24% using the Fenton. Thus in the membrane reactor only the Fenton and the photo assisted Fenton were tested. Obtained results showed a drug degradation higher than 92%, a mineralization higher than 55%, and a membrane retention of the catalyst in solution higher than 95%. 相似文献
9.
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 (Fe 2+) and hydrogen peroxide (H 2O 2)], 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 [Fe 2+] = 20 mg l ?1, [H 2O 2] = 15 mg l ?1 and pH = 3 for the Fenton process and [Fe 2+] = 25 mg l ?1, [H 2O 2] = 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. 相似文献
10.
Ultrasonic degradation of Basic Red 29 (BR29) textile dye in the presence of Co 2+-H 2O 2 system was investigated in this study. The effects of presence of ultrasonic power, concentrations of cobalt (II) acetate (Co(II)Act) and H 2O 2, temperature and initial pH on the BR29 degradation were examined. Initial dye concentration of 20 mg/L BR29 was used in the study as a model solution. In sonication experiments, an ultrasonic bath at a frequency of 40 kHz was employed. Best experimental conditions were also obtained in the studies as follows: 1000 mg/L Co(II)Act, 1000 mg/L H 2O 2, 40 °C and original pH of 6.70.According to the results, after 30 min of sonication in the presence of Co 2+-H 2O 2 dye removal efficiency of practically 100% was achieved. It was also found that US enhanced the degradation rate of BR29. 相似文献
11.
The effect of UV radiation on the removal of formic, oxalic and maleic acids from water by metallic ion (Fe 2+ or Cu 2+)/H 2O 2 and metallic ion/O 3 was studied and compared. The results showed that metallic ion/O 3/UV has higher efficiency than metallic ion/H 2O 2/UV for oxalic acid removal. UV radiation significantly increases the efficiency of metallic ion/H 2O 2 for formic and maleic acids removal while its effect on the efficiency of metallic ion/O 3 for formic acid removal is minor . However, at pH 2, O 3 alone showed higher efficiency than metallic ion/H 2O 2/UV for formic acid removal. Contrary to the relative efficiency of metallic ions in the previous systems, Cu 2+ exhibited higher rate than Fe 2+ for the removal of the degradation products of maleic acid by O 3. UV radiation exhibited a minor effect on the efficiency of Cu 2+/O 3, while it exhibited a large effect on the efficiency of Fe 2+/O 3 for the removal of the degradation products of maleic acid. 相似文献
12.
The Fenton oxidation is rarely used industrially due to its high operating cost, large chemical consumption, excessive sludge production, and operability only within a narrow pH range. Therefore, there is a need to evaluate the Fenton oxidation to maximize its ability to degrade high-strength dye wastewater at reduced operating cost. Optimization tools are among the most commonly used tool to maximize the degradation of pollutants. The current study aims at evaluating the applicability of response surface methodology (RSM) and adaptive neuro-fuzzy inference system (ANFIS) to optimize the degradation of Remazol brilliant blue through the Fenton oxidation. The effects of four operating parameters including dye concentration, retention time, and mass ratios of Dye:Fe 2+ and H 2O 2:Fe 2+ were evaluated by applying RSM. According to the RSM results, color and chemical oxygen demand (COD) removal of 99.9% and 84%, respectively, were obtained at 120?min at the COD value of 795?mg/L, mass ratios of Dye:Fe 2+?=?16, H 2O 2:Fe 2+?=?15 and pH?=?3. ANFIS was also used to evaluate the most influential operating parameters on the COD removal based on the RSM results. The ANFIS results showed that the mass ratio of H 2O 2:Fe 2+ had the most significant contribution to the COD removal. High R2 values (≥90%) indicated that the predictions of RSM and ANFIS models for COD removal were acceptable. In conclusion, this study demonstrated that RSM and ANFIS were able to determine the most significant operating parameters and optimum ratios of pollutant:oxidant:catalyst, which reduced the operating cost directly. 相似文献
13.
The first part of this study examined the effect of operating conditions on Fenton pretreatment of an antibiotic wastewater containing amoxicillin and cloxacillin. The optimum H 2O 2/COD and H 2O 2/Fe 2+ molar ratios were 2.5 and 20, respectively. Under the optimum operating conditions, complete degradation of the antibiotics occurred in 1 min. In the second part of this study, a bench-scale SBR was operated for 239 days and fed with Fenton-treated wastewater under different operating conditions. BOD 5/COD ratio below 0.40 of the Fenton-treated wastewater had negative effect on the SBR performance. Hydraulic retention time (HRT) of 12 h was found suitable for the SBR and increasing HRT to 24 and 48 h did not significantly improve the SBR efficiency. Statistical analysis (two-way ANOVA) was made on the results to optimize the H 2O 2/Fe 2+ molar ratio and Fenton reaction time and it was found possible to reduce the Fe 2+ dose and increase the Fenton reaction time. Under the best operating conditions (H 2O 2/COD molar ratio 2.5, H 2O 2/Fe 2+ molar ratio 150, Fenton reaction time 120 min and HRT 12 h), the combined Fenton-SBR process efficiency was 89% for sCOD removal and the SBR effluent met the discharge standards. Combined Fenton-SBR is a feasible process for antibiotic wastewater treatment. 相似文献
14.
Recently, the application of metal oxides such as Fe3O4 nanoparticles have wide interest for environmental remediation and treatment of wastewater especially contaminated with azo dyes owing to its high degradation efficacy and low toxicity. The recovery of magnetic catalysts without losing their efficiency is an essential feature in the catalytic applications. The aim of this article is to investigate and synthesis of magnetically retrievable Fe3O4/polyvinylpyrrolidone/polystyrene (Fe3O4/PVP/PS) nanocomposite for the catalytic degradation of azo dye acid red 18 (AR18). Fe3O4/PVP/PS nanocomposite was prepared in two steps. Firstly, PVP/PS microsphere was synthesized by γ-irradiation polymerization of styrene in presence of PVP solution. Secondly, deposition of Fe3O4 nanoparticles on PVP/PS microsphere was achieved by the alkaline co-precipitation of Fe3+/Fe2+ ions. The chemical structural and morphological properties of PVP/PS microsphere and Fe3O4/PVP/PS nanocomposite were examined by XRD, TEM, DLS, FTIR, EDX and VSM techniques. TEM results showed homogeneous morphology, spherical shaped and well-dispersed Fe3O4 nanoparticles with average particle size of 26 nm around PVP/PS microspheres. The VSM measurements of Fe3O4/PVP/PS nanocomposite exhibit excellent magnetic response of saturation magnetization 26.38 emu/g which is suitable in magnetic separation. The effect of the synthesized Fe3O4/PVP/PS nanocomposite on the catalytic degradation of AR18 in presence of hydrogen peroxide (H2O2) as a heterogeneous Fenton-like catalyst was examined. The catalyst Fe3O4/PVP/PS/H2O2 played basic role in promoting the oxidation degradation efficiency of AR18 of initial concentration 50 mg/L to 94.4% in 45 min with excellent recyclability till the sixth cycles under the best conditions of pH 3, 2% v/v H2O2 and 0.3 g catalyst amount. Furthermore, the Fe3O4/PVP/PS/H2O2 hybrid catalyst system supports high capability for oxidation degradation of mixture of different dyes. The Fe3O4/PVP/PS nanocomposite catalyst had high magnetic and recyclability characters which are acceptable for the treatment of wastewater contaminated by various dyes pollutants. 相似文献
15.
A coupled O 3/Fenton process is applied to study the degradation ef?ciency of organic pollutants. The C.I. Acid Blue 80 (AB80), a kind of anthraquinone dye, is used as target contaminant. The results show that the combination of ozonation and Fenton process is a highly effective way of removing color from wastewater. Response surface methodology is applied to optimize the working conditions and the effects and interactions among initial pH (X 1), mole ratio of H 2O 2/Fe 2+ (X 2) and ozone flux (X 3) are investigated. Regression equations determines that the best condition is that initial pH = 2.85, [H 2O 2]/[Fe 2+] = 18.10 and ozone flux = 55.70 L.h ?1. It turns out the relative error of 1.32% with the predicted model when the actual value which is 88.76% in the best condition, compared to the predictive value of 88.95% under same condition. UV-Vis and FT-IR analysis are used as an assisted technique to study degradation mechanism during the oxidation process. The intermediate products are determined by gas chromatography/mass spectrometry (GC/MS) analysis and the plausible degradation pathway is proposed. 相似文献
16.
Dark- and photo-Fenton type processes, Fe 2+/H 2O 2, Fe 3+/H 2O 2, Fe 0/H 2O 2, UV/Fe 2+/H 2O 2, UV/Fe 3+/H 2O 2 and UV/Fe 0/H 2O 2, were applied for the treatment of model colored wastewater containing two reactive dyes, C.I. Reactive Blue 49 and C.I. Reactive Blue 137, and degradation kinetics were compared. Dye degradation was monitored by the means of UV/VIS, adsorbable organic halides (AOX) and total organic carbon (TOC) analysis, thus determining decolorization and dechlorination of triazine structure, as well as mineralization of model colored wastewater. Both dark- and photo-Fenton type processes were proven to be very efficient for color removal; ≥98% was achieved in all cases. Significant improvements in the mineralization of studied dyes were achieved by the assistance of UV light, as it was expected. It was demonstrated that the degradation kinetic of applied dyes depended on the presence of UV light, as well as type of iron catalyst and dye structure. On bases of the obtained experimental results, the mathematical models were developed describing dye degradation kinetics in all studied systems. Since UV light was used in order to enhance the efficiency of dark-Fenton type processes, mathematical model describing dye degradation by UV photolysis providing the values of quantum yields for each of the dye was developed and incorporated in model for photo-Fenton type processes. A sensitivity analysis for the evaluation of importance of each reaction used in mathematical models was also performed. 相似文献
17.
BACKGROUND: Microwave‐enhanced advanced oxidation processes with and without the addition of ferrous sulfate (MW/H 2O 2/Fe 2+‐AOP and MW/H 2O 2‐AOP respectively) were studied for reduction of solids and solubilisation of nutrients from secondary sewage sludge. RESULTS: For the MW/H 2O 2/Fe 2+‐AOP the yields of solubilisation of orthophosphate and ammonia decreased with increasing temperature. The best results (88.1 mg L ?1 for orthophosphate and 22.7 mg L ?1 for ammonia) were obtained at a treatment temperature of 40 °C. In contrast, the MW/H 2O 2‐AOP had an advantage when it was operated at higher temperatures of 60 and 80 °C. The highest yields of solubilisation were obtained at 60 °C for orthophosphate (81.1 mg L ?1) and at 80 °C for both ammonia (35.0 mg L ?1) and soluble chemical oxygen demand (1954 mg L ?1). Over the temperature range used in this study, the MW/H 2O 2‐AOP gave a better performance than the MW/H 2O 2/Fe 2+‐AOP. CONCLUSION: For sewage sludge treatment the MW/H 2O 2‐AOP is more effective than the MW/H 2O 2/Fe 2+‐AOP in terms of solid reduction and nutrient solubilisation. It will also be more cost‐effective, as it does not require iron addition in the process. Copyright © 2008 Society of Chemical Industry 相似文献
18.
Photocatalytic degradation of 4-chlrophenol (4-CP) using UVA-LED assisted persulfate and hydrogen peroxide activated by the nZVI (Nano Zero Valent Iron) in a batch photocatalytic reactor was investigated. The reaction involved a lab-scale photoreactor irradiated with UVA-LED light emitted at 390 nm. The efficiency of the reaction was evaluted in terms of 4-CP degradation and mineralization degree at different pH of solution, initial concentrations of nZVI, persulfate, hydrogen peroxide and 4-CP. In UVA-LED/H 2O 2/nZVI process, complete degradation of 4-CP (>99%) and 75% mineralization was achieved at pH of 3, hydrogen peroxide concentration of 0.75 mM, nZVI dosage of 1mM and initial 4-CP concentration of 25mg/L at the reaction time of 30 min. The optimum conditions obtained for the best 4-CP degradation rate were at an initial concentration of 25mg/ l, persulfate concentration of 1.5mM, nZVI dosage of 1mM, pH of 3 and reaction time of 120min for UVA-LED/persulfate/nZVI process. It was also observed that the 4-CP degradation rate is dependent on initial 4-CP concentrations for both processes. The pseudo-first-order kinetic constant at 25mg/L initial concentration of 4-CP was found to be 1.4×10 ?1 and 3.8×10 ?2 in UVA-LED/H 2O 2/nZVI and UVA-LED/persulfate/nZVI processes, respectively. Briefly, the UVA-LED/H 2O 2/nZVI process enhanced the degradation rate of 4-CP by 3.67-times in comparison to UVA-LED/persulfate/nZVI process at 30min contact time, which serves as a new and feasible approach for the degradation of 4-CP as well as other organic contaminants containing wastewater. 相似文献
19.
Pristine activated carbon (AcC) was oxidized by H 2O 2 under ultrasonic conditions. Compared with pristine AcC, the H 2O 2-oxidized AC possesses higher accumulation ability to trace levels of Cd 2+. Based on this, a highly sensitive, simple and rapid electrochemical method was developed for the determination of Cd 2+. In 0.01 mol L −1 HClO 4 solution, Cd 2+ was effectively accumulated at the surface of H 2O 2-oxidized AcC modified paste electrode, and then reduced to Cd under −1.10 V. During the following potential sweep from −1.10
to −0.50 V, reduced Cd was oxidized and a sensitive stripping peak appears at −0.77 V. The stripping peak current of Cd 2+ changes linearly with concentration over the range 5.0 × 10 −8 to 5.0 × 10 −6 mol L −1. The limit of detection was found to be 3.0 × 10 −8 mol L −1 for 2-min accumulation. Finally, this new sensing method was successfully used to detect Cd 2+ in waste water samples. 相似文献
20.
The effectiveness factor, E
f, (fraction of the electrode surface that participates effectively in the investigated reaction) of fast (Fe 3+/Fe 2+), moderate (Cl 2/Cl −) and slow (O 2/H 2O) redox couples has been estimated using IrO 2-based electrodes with different loading. The method of choice was linear sweep voltammetry (measurement of the anodic peak
current) for the Fe 3+/Fe 2+ redox couple and steady-state polarization (determination of the exchange current) for the O 2 and Cl 2 evolution reactions. The results have shown that the effectiveness factor depends strongly on the kinetics of the investigated
redox reaction. For the Fe 3+/Fe 2+ redox couple, effectiveness factors close to zero (max 4%) have been obtained contrary to the O 2 evolution reaction where effectiveness factors close to 100% can be achieved, all being independent of IrO 2 loading. For the Cl 2 evolution reaction, intermediate values of the effectiveness factor have been found and they decrease strongly, from 100%
down to about 60%, with increasing loading. 相似文献
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