Solar photodegradation of dichloroacetic acid and 2,4-dichlorophenol using an enhanced photo-Fenton process

The photo-Fenton process using potassium ferrioxalate as a mediator was investigated for the photodegradation of dichloracetic acid (DCA) and 2,4-dichlorophenol (DCP) in aqueous medium using solar light as source of irradiation. The influence of the solution depth, the light intensity and the effect of stirring the solution during irradiation process were evaluated using DCA as a model compound. A negligible influence of stirring the solution was observed when the concentration of ferrioxalate (FeOx) was 0.8 mM and solution depth was 4.5 or 14 cm. The optimum FeOx concentration determined for solution depths between 4.5 and 14 cm was 0.8 mM considering total organic carbon (TOC) removal during DCA irradiation. The high efficiency of the photo-Fenton process was demonstrated on summer days, when only 10 min of exposition (around noon) were sufficient to completely destroy the organic carbon of a 1.0 mM DCA solution in the presence of 0.8 mM FeOx and 6.0 mM H2O2 using a solution depth of 4.5 cm. It was observed that the photodegradation efficiency increases linearly with the solar light intensity up to values around 15 Wm(-2) but this linear relationship does not hold above this value showing a square root dependence. The photodegradation of a solution of DCP/FeOx showed a lower TOC removal rate than that observed for DCA/FeOx, achieving approximately 90% after 35 min irradiation under 19 W m(-2), while under this light intensity, the same TOC removal of DCA/FeOx was achieved in only 10 min irradiation.     

Oxidation of TNT by photo-Fenton process

A series of photo-Fenton reactions have been performed for the degradation of 2,4,6-trinitrotoluene (TNT) in a 4.2-l reactor. The degradation reaction rate of TNT followed a pseudo-first-order behavior; and the rate constants for 2.4mW cm(-2)UV only, 2.4mW cm(-2)UV/H(2)O(2), Fenton, photo-Fenton (2.4mW cm(-2)) and photo-Fenton (4.7mW cm(-2)) were 0.002min(-1), 0.007min(-1), 0.014min(-1), 0.025min(-1) and 0.037min(-1), respectively. Increasing the intensity of UV light, and the concentrations of ferrous ions and hydrogen peroxide promoted the oxidation rate under the experimental conditions in this study. The weighting factor (f), the Fe(II)-promoted efficiency (r) and the promoted-UV light efficiency (p) were calculated to clarify their effects on the TNT oxidation. Moreover, the inhibition effect of hydroxyl radical was also observed in both Fenton and photo-Fenton oxidation when the concentration of Fe(II) were higher than 2.88mM. Solid phase micro-extraction was first applied to the separation of the organic byproducts from TNT oxidation. GC/MS was employed to identify the byproducts during the Fenton and photo-Fenton oxidation of TNT. These compounds were clarified as 1,3,5-trinitrobenzene, 1-methyl-2,4-dinitrobenzene 2,5-dinitrobenzoic acid and 1,3-dinitrobenzene. By these byproducts, the mechanisms of the methyl group oxidation, decarboxylation, aromatic ring breakage, and hydrolysis can be recognized and demonstrated. The pathway of TNT oxidation by photo-Fenton process was also proposed in this study.     

强化UV/Fenton法降解水中苯酚的研究

研究了UV/Fenton法处理含苯酚废水时H2 O2 和FeSO4 加入量及苯酚初始浓度对酚去除效果的影响及C2 O2 -4 对UV/Fenton法的增强效果。 [H2 O2 ]=2 0mmol/L ,[FeSO4 ]=5mmol/L ,反应 2 0min ,苯酚初始浓度为 5 0mg/L时 ,酚去除率达 99%。UV/Fenton体系中引入C2 O2 -4 后可有效提高对紫外和可见光的利用率 ,进而提高了对高浓度苯酚废水去除效果     

电-Fenton法处理制药中间体废水的研究

采用电-Fenton法对麻醉药瑞芬太尼合成过程中的中间体1-苄基-4-氨甲酰基-4-苯胺基哌啶(简称酰胺,AMIDE)模拟废水进行了降解研究,结果表明,在以石墨为阴极、铁为阳极的模式下,当pH为3、电解电压为3 V、投加H_2O_2浓度为10 mmol/L时,室温下电解浓度为20 mg/L的酰胺废水60 min后,酰胺的去除率高于99%,TOC去除60%。通过紫外光谱(UV)、红外光谱(IR)及HPLC检测酰胺的降解产物,说明电-Fenton法能使废水中目标化合物的环结构破坏,快速而完全地转化为小分子,但不能使其全部矿化。本研究可为电-Fenton法在处理该类药物合成废水中的实际应用提供重要的理论依据。     

电Fenton联用电絮凝处理晚期垃圾渗滤液

采用电Fenton联用电絮凝工艺处理晚期垃圾填埋场的渗滤液,研究最佳工艺处理条件,并考察处理前后出水的理化指标及对斑马鱼胚胎毒性的变化.结果表明,在三电极电解体系中分别以铸铁为阴阳电极、甘汞为参比电极,操作电压1V、2mLH2O2和pH =3时,300 mL渗滤液经电Fenton工艺处理60 min后,出水COD去除效率接近90％,其余指标亦显著改善,但对斑马鱼胚胎发育仍显示一定毒性;之后在操作电压1V和溶液近中性时,联用电絮凝工艺继续处理30min,出水COD可达到国家排放标准,斑马鱼胚胎凝结率、孵化率、心包水肿和脊柱畸形发生率均与空白组无显著差异.结合理化分析与生物毒性评价,证实2种电化学工艺联用是一种经济有效的渗滤液处理工艺.     

甲酸刻蚀缺陷MOFs电芬顿高效降解磺胺甲恶唑

采用甲酸刻蚀MIL-88B(Fe)制备了一系列缺陷MOFs并用于催化降解水中磺胺甲恶唑(SMX)为代表的抗生素污染物,通过SEM、XPS、XRD分析手段对材料的形貌和结构进行了表征和分析,考察了pH、电流、SMX初始浓度等因素对SMX去除的影响,探究了SMX催化降解反应的动力学特性以及缺陷MOFs材料的可循环利用性和稳定性,探究了SMX催化降解反应的电流利用效率与能耗,通过自由基淬灭实验推测了SMX催化降解反应发生机理。结果证明,缺陷MOFs材料催化降解SMX性能优于未经刻蚀的MIL-88B(Fe),对于10 mg·L⁻¹ SMX,在电流为40 mA、电压为 3.5 V、持续通氧气、搅拌的条件下,反应120 min后,5 mmol甲酸刻蚀制得的5A-MIL-88(Fe)对SMX的去除率可达98.72%。以5A-MIL-88(Fe)作为催化剂,协同电芬顿(Fenton)反应构建的处理体系为水中抗生素污染物高效去除提供参考。     

电-Fenton法处理页岩气压裂返排液

页岩气开发压裂返排液处理是近年的研究热点,本文采用电-Fenton氧化技术对压裂返排液絮凝出水进行深度处理研究,主要考察了H2O2投加量、pH值、电压和反应时间对COD去除效果的影响。通过正交实验和单因素影响实验,确定电-Fenton氧化处理絮凝出水的适宜条件为：H2O2投加量为40 mL·L-1、pH=3、电压6 V和反应时间60 min。在此条件下,出水COD为71.3 mg·L-1,COD去除率达到62.5%。实验结果表明化学絮凝-电-Fenton氧化是页岩气压裂返排液达标外排的一种适宜处理工艺。     

电-Fenton法预处理干法腈纶生产废水

以Ti金属网为阴极,Ti基RuO2涂层形稳电极为阳极,采用外加H2O2和Fe2+的方式,研究了电-Fenton氧化预处理干法腈纶生产废水的工艺,考察了H2O2投加量、Fe2+投加量、pH值和电流强度等因素对污染物降解过程的影响,分析了废水可生化性和污染物变化规律。结果表明,电-Fenton法可以有效降解废水中有机污染物,使废水COD迅速降低,在初始pH值为3.0,Fe2+投加量为5.0 mmol/L,H2O2投加量为60.0 mmol/L,电流强度0.2 A的条件下,反应120 min后COD去除率可以达到44.0%以上;反应过程中H2O2的投加方式对电-Fenton法的处理效果具有明显影响,H2O2分6次投加可以使COD去除率由一次性投加时的44.8%提高至54.1%;处理后废水的BOD5/COD由0.29升高至0.68;GC-MS结果表明,经电-Fenton法预处理后,废水中多数芳香族化合物和特征污染物能被有效降解。     

Removal of polyvinylamine sulfonate anthrapyridone dye by application of heterogeneous electro-Fenton process

Diversity and rapidly multiplication of the pollutants incite as to improve the conventional treatments wastewater methods. One of the bottlenecks often faced is the presence into wastewater of organic pollutants with complex structures that requests the design of efficient processes. Thus, this work investigates the removal of polyvinylamine sulfonate anthrapyridone (PSA) dye which complex structure makes difficult its degradation by conventional technologies. For that, a heterogeneous oxidative process using pyrite as sustainable catalyst was designed. Initially, the performance of the system BBD-carbon felt as anode and cathode, respectively for the production of H₂O₂ was determined in comparison with system boron-doped diamond nickel foam. The carbon felt electrode provided the highest oxidant production, and it was selected for the treatment of the polymeric dye. Several oxidative processes were evaluated, and the best degradation levels were obtained by application of electro-Fenton-pyrite process. In addition, it was determined that dye removal followed a kinetic model of pseudo-first-order achieving the highest efficiency by operation at optimum dosage of pyrite 2 g/L and 200 mA of current intensity. Depending on the optimal experimental conditions, these values lead to a nearly complete mineralization (total organic carbon removal of 95%) after 6 h. Furthermore, the reusability of pyrite was evaluated, by removal of PSA in four cycles.

     

矿化垃圾床＋三维电极／电Fenton法处理老龄垃圾渗滤液

提出以二级矿化垃圾床为预处理单元,串联三维电极／电Fenton处理老龄垃圾渗滤液的组合工艺。矿化垃圾床处理后渗滤液中COD、氨氮、总磷、色度的去除率分别为80．55％、88．47％、98．32％和87．53％。通过单因素实验和正交实验,确定了三维电极／电Fenton法最佳工艺条件。经该组合工艺后,渗滤液中COD、氨氮、总磷和色度的最高去除率分别可达97．08％、95．24％、99．55％和96．92％,其中COD、总磷、色度这3个指标低于《生活垃圾填埋场污染控制标准》（GB16889．2008）表2规定的排放标准,为该组合工艺在实际中的应用提供重要理论依据。     

Degradation of clofibric acid in acidic aqueous medium by electro-Fenton and photoelectro-Fenton

Acidic aqueous solutions of clofibric acid (2-(4-chlorophenoxy)-2-methylpropionic acid), the bioactive metabolite of various lipid-regulating drugs, have been degraded by indirect electrooxidation methods such as electro-Fenton and photoelectro-Fenton with Fe(2+) as catalyst using an undivided electrolytic cell with a Pt anode and an O(2)-diffusion cathode able to electrogenerate H(2)O(2). At pH 3.0 about 80% of mineralization is achieved with the electro-Fenton method due to the efficient production of oxidant hydroxyl radical from Fenton's reaction between Fe(2+) and H(2)O(2), but stable Fe(3+) complexes are formed. The photoelectro-Fenton method favors the photodecomposition of these species under UVA irradiation, reaching more than 96% of decontamination. The mineralization current efficiency increases with rising metabolite concentration up to saturation and with decreasing current density. The photoelectro-Fenton method is then viable for treating acidic wastewaters containing this pollutant. Comparative degradation by anodic oxidation (without Fe(2+)) yields poor decontamination. Chloride ion is released during all degradation processes. The decay kinetics of clofibric acid always follows a pseudo-first-order reaction, with a similar rate constant in electro-Fenton and photoelectro-Fenton that increases with rising current density, but decreases at greater metabolite concentration. 4-Chlorophenol, 4-chlorocatechol, 4-chlororesorcinol, hydroquinone, p-benzoquinone and 1,2,4-benzenetriol, along with carboxylic acids such as 2-hydroxyisobutyric, tartronic, maleic, fumaric, formic and oxalic, are detected as intermediates. The ultimate product is oxalic acid, which forms very stable Fe(3+)-oxalato complexes under electro-Fenton conditions. These complexes are efficiently photodecarboxylated in photoelectro-Fenton under the action of UVA light.     

柠檬酸强化钢渣湿法烧结烟气脱硫及机理

在鼓泡反应器中考察了添加柠檬酸强化钢渣湿法烧结烟气脱硫的影响因素,包括钢渣粒度,吸收浆液浓度、进口二氧化硫浓度、停留时间,pH值,柠檬酸与钢渣的浸泡时间等,结果表明,柠檬酸浓度为2.0 mmol/L、钢渣浓度为4%、二氧化硫进口浓度为1 500 mg/m3、烟气停留时间为7 s、钢渣强化时间为2 h、钢渣粒度>200目,脱硫率达到90%以上。经4 mmol/L的柠檬酸强化后的钢渣浆液脱硫率比单纯钢渣浆液提高18.41%,达到90.99%的脱硫率,且有效反应时间延长50%,达到60 min以上。柠檬酸的加入,一方面促进了钢渣碱性组分溶解,另一方面在吸收液中形成柠檬酸和柠檬酸盐缓冲体系,增加了气液界面SO2浓度,提高了SO2的气液传质速率。     

Changes of turbidity during the phenol oxidation by photo-Fenton treatment

Turbidity presented by phenol solutions oxidized with Fenton reagent shows the tendency of a first order intermediate kinetics. Thus, turbidity can be considered a representative parameter of the presence of intermediate oxidation species, which are generated along the decomposition of toxic and reluctant contaminants, such as phenol. Moreover, that parameter presents a linear dependence with the catalyst dosage, but is also determined by the initial contaminant load. When analyzing the oxidation mechanism of phenol, it is found that the maximum turbidity occurs when the treatment is carried out at oxidant to phenol molar ratios R?=?4.0. These oxidation conditions correspond to the presence of a reaction mixture mainly composed of dihydroxylated rings, precursors of the muconic acid formation. The oxidation via “para” comprises the formation reactions of charge transfer complexes (quinhydrone), between the para-dihydroxylated intermediates (hydroquinone) and the para-substituted quinones (p-benzoquinone), which are quite unstable and reactive species, quickly decomposed into hydroxyhydroquinones. Working with oxidant ratios up to R?=?6.0, the maximum observed value of turbidity in the oxidized solutions is kept almost constant. It is found that, in these conditions, the pyrogallol formation is maximal, what is generated through the degradation of ortho-species (catechol and ortho-benzoquinone) and meta-substituted (resorcinol). Operating with ratios over R?=?6.0, these intermediates are decomposed into biodegradable acids, generating lower turbidity in the solution. Then, the residual turbidity is a function of the molar ratio of the ferrous ions vs. moles of oxidant utilized in the essays, that lets to estimate the stoichiometric dosage of catalyst as 20 mg/L at pH?=?3.0, whereas operating in stoichiometric conditions, R?=?14.0, the residual turbidity of water results almost null.     

微波强化氧化处理垃圾渗滤液工艺研究

考察了最优作用方式下单独微波、单独氧化剂以及两者的结合工艺对垃圾渗滤液的处理效果。单独微波工艺在功率为700 W,辐射10 min,COD、氨氮、磷和色度去除率分别为37.66%、96.14%、40%和80%,BOD5/COD由0.16增加到0.43。渗滤液先微波再氧化,氨氮去除率增加显著,节省了氧化剂用量。微波后渗滤液在pH=5,T=50℃,NaClO=24 mL/L时COD、氨氮、磷和色度去除率分别为98.63%、99.67%、97.25%和98%,BOD5/COD=0.8。总处理效率:微波-NaClO微波-Fenton微波-KMnO4微波-H2O2,微波-Fenton处理效率低于微波-NaClO主要取决微波后滤液中小表观分子质量增加导致氧化剂的混凝作用减弱,其次受反应后pH值变化的影响。     

阳极氧化联合电-Fenton氧化深度处理垃圾渗滤液

采用多孔碳素阴极、Ti/SnO2-Sb2O5-IrO2阳极构建电化学氧化系统用于渗滤液的深度处理。研究结果表明,所构建的电化学氧化系统通过阳极氧化和电-Fenton氧化2种机制降解有机污染物;处理过程中阴极表面形成的沉淀物对TOC和COD的衰减也产生了影响。在阴极电位为-1.0 V、Fe2+ 初始浓度为0.5 mmol/L的条件下,电化学处理120 min获得了58% 的TOC去除;处理480 min COD去除率为55%,NH3-N去除率为99%,TN去除率为60%,色度几乎被完全去除。GC-MS分析结果表明,渗滤液中以腐殖质类物质为主的有机化合物被降解为分子量相对较小的有机物,直至完全矿化。联合阳极氧化和电-Fenton氧化机制的电化学处理方法为垃圾渗滤液深度处理提供了新的选择。     

Box-Behnken响应面分析法对双阳极电Fenton法处理垃圾渗滤液工艺的优化

采用双阳极电Fenton法处理垃圾渗滤液,并在阴极曝气。应用Box-Behnken响应面分析法对电Fenton法处理的结果进行了优化,将Fe2+投加量、电压、和反应时间3个因素进行实验设计,得到二次响应曲面模型。响应面分析表明,Fe2+投加量与反应时间的交互作用对COD去除率影响最大,其次是电压与反应时间的交互作用。优化后的结果:Fe2+投加量、电压、和反应时间分别为3 219.2 mg/L、6.11 V和180 min。模型方差分析得到F值和R2分别为24.2和0.977,说明该二次方程是显著的,模型在整个回归区域内拟合好,能够很好地反映电Fenton法处理垃圾渗滤液的过程。     

超声波、Fenton试剂与絮凝联用进一步处理焦化废水的实验研究

焦化废水是一种较难处理的工业废水,目前采用的生化方法很难使COD达到国家规定的排放标准.对超声、Fenton与絮凝联合应用处理生化后的焦化废水进行了实验研究,并探讨了三者联合应用的最佳组合反应条件及单因素对COD的影响趋势.结果表明,三者联合应用处理焦化废水COD的最佳反应条件为:Fe2 40 mg/L,H2O2 55 mg/L,FeCl3 5.4 mg/L,PAM 1.2mg/L,超声波频率为34.19 kHz.在此反应条件下,COD去除率达到77.7%;各单因素对COD去除率的影响顺序为Fe2 ＞H2O2＞PAM＞超声波频率＞FeCl3.     

Transformation characteristics of refractory pollutants in plugboard wastewater by an optimal electrocoagulation and electro-Fenton process

The treatment of the plugboard wastewater was performed by an optimal electrocoagulation and electro-Fenton. The organic components with suspended fractions accounting for 30% COD were preferably removed via electrocoagulation at initial 5 min. In contrast, the removal efficiency was increased to 76% with the addition of H(2)O(2). The electrogenerated Fe(2+) reacts with H(2)O(2) and leads to the generation of (·)OH, which is responsible for the higher COD removal. However, overdosage H(2)O(2) will consume (·)OH generated in the electro-Fenton process and lead to the low COD removal. The COD removal efficiency decreased with the increased pH. The concentration of Fe(2+) ions was dependent on the solution pH, H(2)O(2) dosage and current density. The changes of organic characteristics in coagulation and oxidation process were differenced and evaluated using gel permeation chromatography, fluorescence excitation-emission scans and Fourier transform infrared spectroscopy. The fraction of the wastewater with aromatic structure and large molecular weight was decomposed into aliphatic structure and small molecular weight fraction in the electro-Fenton process.     

电-Fenton法预处理青霉素废水的降解规律研究

研究电-Fenton法预处理青霉素钠(penicillin G sodium,PGN)模拟废水的降解规律,分析预处理过程中PGN浓度、COD、TOC的变化情况及BOD5/COD改善情况.当T=20℃、pH=3时,投加0.5g/L FeSO4、0.2 mL/L H2O2,于0.3 A电流下降解浓度为100 mg/L的PGN废水,120 min后PGN去除97.9%,COD去除76.7%,TOC去除59.8%,BOD5/COD由0升至0.4,有效提高了废水的可生化性.以红外光谱(infrared spectrogram,IR)和液相色谱-质谱联用(Liquid chromatogramMass chromatogram,LC-MS)检测青霉素钠的降解产物,说明青霉素钠抑菌的关键结构b-内酰胺环被破坏,抗菌性消失,有助于生物处理有效去除.     

微絮凝-反渗透耦合过程深度处理邻苯二甲酸二辛酯化工废水

高浓度DOP有机化工废水生物毒性强,采用常规处理手段难完全降解,对环境存在较高危害性.采用微絮凝-反渗透耦合过程对DOP化工厂二级生化出水进行深度处理研究,考察了絮凝预处理的最佳条件,比较了BW30和CPA2两种反渗透复合膜对该实际废水的处理性能,并利用电子扫描电镜分析了废水处理过程中膜表面结构的变化.结果表明:絮凝预...