电芬顿法降解苯酚废水的研究

对以空气扩散电极为阴极,铁板为阳极的电化学体系降解苯酚模拟废水进行了研究。采用分光光度法测定苯酚浓度,研究了pH值、电解时间和电流密度对苯酚去除率的影响。结果表明,电芬顿体系对含酚废水有很强的降解能力,初始浓度为300 mg/L的苯酚溶液,在电流密度20 mA/cm2条件下电解180 min,苯酚去除率99.5%,COD(Chemical Oxygen Demand)去除率85.1%。     

混凝污泥的资源化回收及其电化学性能

将混凝污泥碳化后制成电极材料,通过红外光谱和X射线衍射对污泥的官能团结构与晶型进行表征,采用循环伏安和线性扫描伏安法研究不同碳化温度下所制电极材料的电化学性能,并应用于电芬顿体系催化降解双酚A。结果表明,混凝污泥的主要成分为含碳和铁元素的复合物,高温碳化后污泥的结晶度增强。所制电极在电芬顿体系中显示出良好的电催化活性。外部投加Fe2+条件下,经900℃碳化的电极材料为阴极对双酚A的去除率最高,电解130 min后去除率高达99.2%。表明在电化学芬顿法废水处理中有一定的应用前景。     

玻璃碳阴极电芬顿降解孔雀石绿研究

采用玻璃碳作为阴极,Ti/RuO_2作为阳极,开展了电芬顿降解孔雀石绿染料废水的研究。研究了电解质浓度、氧气曝气量、电流、pH等条件对玻璃碳阴极电芬顿降解孔雀石绿的影响。结果表明:在pH=3.0、电解质浓度0.1 mol/L、氧气曝气量100 mL/min、电流强度30 mA条件下,初始浓度为200 mg/L的孔雀石绿经过60 min处理,降解率达到99.11%。     

电芬顿降解活性艳红X3B的阳极影响因素

以钛基氧化锡纳米涂层(DSA)电极作为阳极,以活性炭纤维(ACF)作为阴极,与石墨板(GE)电极进行组合,形成三组不同的电极对,用于比较研究电芬顿反应中的阳极影响因素。降解模拟染料活性艳红X3B,其脱色率和矿化率均为:电极体系a(阴极/ACF,阳极/DSA)>b(阴极/ACF,阳极/GE)>c(阴极/GE,阳极/DSA)。其中最优电极体系a反应90 min完全脱色,180 min内矿化率和平均电流效率分别为75.3% 和56.7%。XRD和SEM表征表明:DSA电极和ACF电极在电芬顿反应中具有稳定的化学结构。循环伏安扫描的结果表明三组电极体系均无明显的阳极直接氧化反应发生。采用荧光法检测了活性氧化物种,发现三组电极体系生成羟基自由基的数量与其降解效果完全一致。本研究证明DSA 对于电芬顿反应有促进作用,并且这一促进作用是通过催化H₂O₂生成·OH 这一间接途径来实现的。     

构建电促铁还原型芬顿氧化法降解水中4-硝基酚

以钛基氧化物涂层材料(Ti/SnO_2-Sb_2O_5-IrO_2)为阳极,碳纳米管修饰的石墨材料(GE-CNT)为阴极构建电化学系统,促进芬顿反应过程中Fe~(3+)还原,从而减少芬顿氧化法中铁盐加量和铁泥产生量。研究表明:GE-CNT具有良好的还原Fe~(3+)性能,其优化的阴极还原电位约为0.30 V(vs.Ag/AgCl),该电位下反应120 min时Fe~(3+)还原率达到85.7%。以Fe~(3+)为催化剂降解4-硝基酚的结果,证实了电化学还原Fe~(3+)促进芬顿反应的有效性。对比考察了电促铁还原型芬顿氧化法与普通芬顿氧化法降解4-硝基酚的效果,优化的条件下两者可获得近似的降解效果,但前者优化的H_2O_2与Fe~(2+)摩尔比为40∶1,而后者为20∶1。因此,相对于普通芬顿氧化法,电促铁还原型芬顿氧化法可显著减少芬顿反应初始Fe~(2+)投加量。     

玻璃碳阴极电芬顿降解孔雀石绿研究

采用玻璃碳作为阴极,Ti/RuO_2作为阳极,开展了电芬顿降解孔雀石绿染料废水的研究。研究了电解质浓度、氧气曝气量、电流、pH等条件对玻璃碳阴极电芬顿降解孔雀石绿的影响。结果表明:在pH=3.0、电解质浓度0.1 mol/L、氧气曝气量100 mL/min、电流强度30 mA条件下,初始浓度为200 mg/L的孔雀石绿经过60 min处理,降解率达到99.11%。     

双极Electro-Fenton法降解水中苯酚的研究

设计了一种双极电化学芬顿方法(Bipolar Electro—Fenton;BEF)并对水中的苯酚进行了降解研究。采用热压法制备了多孔气体扩散碳电极。在无分隔槽反应装置中,以多孔气体扩散碳电极为阴极将氧气还原产生过氧化氢,铁板作阳极产生Fe2 ,直接利用两电极产物发生芬顿(Fenton)反应对苯酚进行降解。TOC、COD的检测结果表明,BEF法中所采用的气体扩散电极对苯酚的降解程度较通常废水处理中以石墨为阴极的电芬(Electro-Fenton;EF)更为彻底;而且BEF法对苯酚的降解速率比传统芬顿法更快。     

碳毡电极用于电芬顿脱色性能及机理研究

为了探究CF电极在电芬顿脱色中的应用性能及机理，通过对阴极材料的对比，建立了以碳毡为阴极的电芬顿降解体系，探讨了不同操作参数如废液pH、O₂流量、电压、Fe²⁺浓度等因素对活性红195染料废水的脱色率、COD去除率的影响。根据实验结果，采用碳毡做阴极，Fe²⁺浓度为20 mg/L,pH为3、O₂流量60 mL/min、电压3 V条件下，反应3 h染料几乎完全脱色，COD去除率可达73.31%；利用猝灭实验初步探讨了染料降解的主要机制，·OH的生成及其强氧化作用是染料降解的主要因素；利用UV-Vis及GC-MS对染料降解机理进行了分析，发现反应前30 min降解速度最快；电极稳定性实验及扫描电子显微镜(SEM)形貌分析证明了碳毡阴极具有良好的电化学稳定性。     

基于Ti/SnO2阳极的电化学法降解对硝基苯酚

为探寻硝基芳香族有机污染物的高效降解技术,采用溶胶凝胶法制备了钛基锡系阳极,且掺杂Sb、La等元素对该电极材料进行了改性,并把该系列电极用于电化学处理模拟对硝基苯酚废水。通过SEM和XRD对电极形貌进行表征,分析了元素掺杂改善电极性能的机理,考察了电解条件对电化学降解对硝基苯酚效果的影响,探究了电场因素对电化学体系降解废水的影响机制。通过紫外吸收光谱分析推断了对硝基苯酚在电化学作用下可能的降解历程。研究结果表明：同时掺杂La和Sb的电极降解对硝基苯酚效果最好;在电解电压12 V、极板间距25 mm、pH值为7、电解质浓度0.5 mol/L的条件下电解120 min,对硝基苯酚的降解率可达92.8%,可见应用掺杂La、Sb的Ti/SnO2电极材料的电化学法降解对硝基苯酚优势相当明显。     

碳纤维类材料用于电芬顿体系电极的研究现状

电芬顿技术作为先进氧化技术的一种，基于电化学原理间接性地产生·OH自由基，可以高效快速地去除水中的有机污染物。碳纤维类材料因其比表面积大、密度低、耐腐蚀等优点而被常用作电芬顿体系的电极材料。本文首先介绍了电芬顿技术的基本原理，对近年来碳纤维类材料用于电芬顿电极的研究现状进行了归纳总结，分析了碳纤维材料用于电芬顿电极时的改性手段及应用方式。着重分析了其用于电芬顿阴极时的改性机理与改性方式，并指出了其应用优势与局限性。同时也对碳纤维类材料在电芬顿阳极的应用进行了总结。最后，针对碳纤维类材料用于电芬顿体系时的产业化问题、能耗问题、电极的多功能化等问题进行了分析和展望，为碳纤维类材料应用于电芬顿体系的深入研究提供参考。     

Mineralization of an azo dye Acid Red 14 by photoelectro-Fenton process using an activated carbon fiber cathode

The mineralization of an azo dye Acid Red 14 (AR14) by the photoelectro-Fenton (PEF) process was studied in an undivided electrochemical reactor with a RuO₂/Ti anode and an activated carbon fiber (ACF) cathode able to electrochemically generate H₂O₂. Anodic oxidation and UV irradiation of AR14 were also examined as comparative experiments. Results indicate that the electro-Fenton process yielded about 60–70% mineralization of AR14, while the photoelectro-Fenton could mineralize AR14 more effectively (more than 94% total organic carbon (TOC) removal) even at low current densities assisted with UV irradiation after 6 h electrolysis. The mineralization current efficiency (MCE) of the PEF process increased with the increasing AR14 concentrations. In addition, the initial solution pH ranging from 1.49 to 6.72 had little influence on the TOC removal probably due to the formation of organic carboxylic acids which balanced the pH increase caused by the cathodic generation of hydrogen gas. The ACF cathode showed a long-term stability during multiple experimental runs for degradation of AR14, indicating its good potential for practical application in treating refractory organic pollutants in aqueous solutions.     

An experimental comparison of a graphite electrode and a gas diffusion electrode for the cathodic production of hydrogen peroxide

This work studies the production of hydrogen peroxide through the cathodic reduction of oxygen in acidic medium, by comparing the results obtained using a commercial graphite and a gas diffusion electrode. A low pH was required to allow the application of hydrogen peroxide generation to an electro-Fenton process. The influence of applied potential and the gas flow composition were investigated. The gas diffusion electrode demonstrates a higher selectivity for hydrogen peroxide production, without significantly compromising the iron regeneration, thus making its successful application to a cathodic Fenton-like treatment, possible. Unlike the graphite cathode, the gas diffusion cathode also proved to be effective in the air flow.     

电芬顿体系中铁铈双金属催化剂降解邻苯二甲酸二丁酯研究

以MCM-41为载体,采用水热-焙烧法制备了Al修饰双金属催化剂Fe-Ce/Al-MCM-41并进行了XRD、BET和FT-IR表征;以水体中的邻苯二甲酸二丁酯(DBP)为处理对象,在铂丝-碳毡电芬顿体系中研究了催化氧化降解DBP的效果和影响因素,探讨了降解机理。结果表明,铁、铈双金属催化剂在电芬顿体系降解邻苯二甲酸二丁酯中具有良好的催化活性,铝离子的加入能够提高催化剂的催化性能;最佳实验条件为pH=3、催化剂投加量0.5 g/L、电流强度I=0.15 A、通氧流量0.2 L/min、反应120 min、初始浓度10 mg/L,此时DBP去除率为97.1%,在酸性或中性条件下去除率稳定在92.1%以上,碱性条件下DBP去除率降低,电流强度和通氧量达到饱和后对DBP降解率影响很小,并且催化剂投加过量会导致催化效果降低。此电芬顿体系中·OH的氧化反应是降解DBP的主要途径。     

联合阴极电Fenton和阳极氧化降解高相对分子质量聚丙烯酰胺

采用浸渍-高温煅烧法制备了Fe3O4/石墨毡复合电极,联合阴极电Fenton和阳极氧化法降解聚丙烯酰胺(PAM)。以CODCr和溶液的相对粘度为指标,分别比较阴极电Fenton法、阳极氧化法及联合法对PAM的降解性能。与单一方法相比,联合法对PAM表现出强化降解效果,降解后溶液的CODCr降低了45.6%,相对粘度由2.19降低到1.04。采用凝胶渗透色谱(GPC)、傅里叶变换红外光谱(FT-IR)、X射线光电子能谱分析(XPS)对PAM的降解产物进行表征分析。结果表明,在降解过程中PAM的碳主链缩短,侧链基团大量脱落,并有醚键生成。据此推测PAM在电催化氧化中的降解机理为碳主链的断裂与重新缩合的过程,因此,PAM降解产物中仍存在部分高分子聚合物。所生成的聚合物具有较强的可生化降解性,可被好氧活性污泥进一步降解。     

新型光电催化反应器对甲基橙的脱色降解研究

以热氧化法制备的TiO2/Ti薄膜电极为阳极、石墨电极为阴极和饱和甘汞电极为参比电极,设计一种新型的光电化学催化反应器。研究了三种不同催化体系对甲基橙的降解率,同时研究了初始pH、反应时间对脱色率的影响,结果显示,光电化学催化体系对甲基橙的降解效果优于另外两种催化体系。当溶液初始pH=3.0,其他条件不变的情况下,双槽反应器阴阳两极槽甲基橙溶液的脱色率分别达到82.35%和91.30%,单槽反应器脱色率为85.00%。单双槽反应器均达到了＂双极双效＂的目的。     

Multi-cathode cell with flow-through electrodes for the production of iron(ii)-triethanolamine complexes

Nonregenerable reducing agents used in dye houses for the application of indigo, vat dyes and sulfur dyes can be substituted by indirect cathodic reduction techniques. An electrochemical cell for the indirect cathodic reduction of dispersed indigo dyestuff using an alkaline solution of the Fe(iii/ii)-triethanolamine complex as redox mediator was constructed and tested. The cell is built up as divided cell (cathode area 5–10m2, catholyte volume 12L, anolyte volume 1.5L) with several three dimensional cathode units (up to 10) in the same cathode compartment. The cathodes were connected to a common anode and to separately adjustable power supplies. The catholyte was circulated through the porous cathode units parallel to the current direction. Two different electrode materials (copper and stainless steel) and cathode constructions were tested, resulting in an optimized cell construction. The electrochemical cell was characterized by a series of batch electrolysis experiments. Results are given dealing with the cell voltage drop in the cathode, the product yield and the current efficiency at different current densities and cell current. After an optimization step the current efficiency reaches 70–80% at 2 A m–2 current density and 7.8×10–3moldm–3 Fe(ii)-complex. The cell current is 10A.     

Experimental design methodology applied to electro-Fenton treatment for degradation of herbicide chlortoluron

The degradation of herbicide chlortoluron in aqueous medium by electro-Fenton process using a carbon felt cathode and a platinum anode was studied. The great oxidation ability of this process is due to the large production of hydroxyl radical (OH) by electrochemically induced Fenton's reagent. Hydroxyl radicals are very powerful oxidizing agents which react on organics up to complete mineralization. The influence of some experimental parameters such as initial concentration, current intensity and processing time on the degradation and mineralization rate of chlortoluron by hydroxyl radicals has been investigated. The evolution of chlortoluron concentration with processing time shows a pseudo first order kinetics (k_abs = (4.8 ± 0.2) × 10⁹ mol⁻¹ L s⁻¹). A Doehlert matrix was applied for determination of the optimal working conditions. Optimal parameters for maximum mineralization efficiency (TOC removal ratio of 98%) was achieved after 8 h of treatment using a chlortoluron initial concentration of 0.125 mM and an applied current of 300 mA. The mineralization of aqueous chlortoluron solutions was confirmed by identification of the end-products such as carboxylic acids and inorganic ions. Their evolution during electro-Fenton treatment was studied.     

电化学氧化处理难降解废水的研究进展

综述了国内外电化学氧化处理难降解废水的研究现状,详细阐述了电化学氧化机理,包括阳极氧化技术和阴极还原技术,介绍了影响电化学氧化降解效率的主要因素,包括电极材料、电化学反应器、溶液的pH值、溶剂体系以及其它因素.从有机污染物电化学氧化机理的研究、电极材料的研制、电板结构的研究和高效电解反应器的开发、对特定的电化学氧化系统...