新型双功能复合电极的制备及其加速水中有机污染物降解作用的研究

介绍了新型复合电极的制备方法、其双功能特性以及在提高水中有机污染物(如苯胺)降解速度所起的作用,并对其作用机制进行了讨论.实验结果表明,由空气电极和TiO₂光催化剂组成的复合电极,当其工作电位控制在0.05V(vs.SCE)左右时,既具有良好的光电效应,又具有以较高效率合成H₂O₂的特性,使溶液中的有机分子获得来自光催化氧化与光化学氧化两方面的联合降解作用,从而显著地提高了有机分子的氧化降解速度.     

TiO2担载在新型载体上的光催化电极

介绍了一种将TiO₂光催化剂担载在新型载体上的光催化电极.新型载体是用炭质材料和聚四氟乙烯制备的,它具有电合成H₂O₂的功能.在电流密度为15mA/cm²时,光催化电极不仅具有高达80%的电合成H₂O₂的电流效率,而且该电极的电位处在0.02V(SCE)左右,使载体表面的TiO₂光催化剂获得了约+0.47V的阳极偏压(相对平带电势),对增加TiO₂光催化反应效率十分有益.在具有新型光催化电极的光反应体系中,水中的有机分子受到来自溶液中大量·OH自由基(H₂O₂被紫外光分解的中间产物)的均相氧化(即光化学氧化),以及来自TiO₂表面光生空穴的复相氧化(即光催化氧化).在光化学氧化和光催化氧化的联合作用下,有机分子的矿物化反应速度显著提高.     

球磨微米硫化零价铁活化双氧水降解有机污染物的研究

报道了机械球磨方法制备的微米硫化零价铁（S-ZVI）可以快速活化H₂O₂降解各类有机污染物.S-ZVI/H₂O₂降解苯酚的单位比表面积反应速率常数是ZVI/H₂O₂的5倍以上,且苯酚的降解不存在初始抑制阶段.探针化合物乙醇的淬灭反应结合电子顺磁共振（EPR）实验证明S-ZVI/H₂O₂体系产生的氧化活性物质为·OH.反应前后S-ZVI颗粒的扫描电子显微镜（SEM）和X射线衍射（XRD）表征结合电化学测试和苯酚降解结果表明S-ZVI中FeS取代ZVI表面的钝化膜（铁氧化物）,加速了电子从Fe⁰传递到H₂O₂,更快地释放Fe²⁺,引发Fenton反应.在这过程中FeS主要作为电子的导体而非Fe²⁺的释放源.     

有机农药异丙隆的级联生物降解体系的构建

构建了一个酶促氧化结合活性淤泥处理的级联生物降解有机农药异丙隆的体系.首先,建立了氯过氧化物酶（CPO）催化H₂O₂氧化降解异丙隆的酶处理体系.在最佳反应条件下,异丙隆的降解率可在10 min内达到100%.反应在室温下进行,pH=3.0,所需H₂O₂浓度为0.2 mmol/L,酶用量极少,仅7 nmol/L.降解体系高效、温和、绿色,无二次污染,极具应用潜力.CPO酶促氧化降解异丙隆的产物用HPLC-MS测定,并进一步根据主要产物推测了降解的途径.结果表明,异丙隆经CPO催化H₂O₂氧化处理后,被分解成较小的4-异丙基苯胺和4-乙基苯胺苄基正离子碎片分子.如果将CPO-H₂O₂酶促氧化作为一种前处理手段,后续与活性淤泥微生物降解过程结合,通过这种二级处理方法可实现含异丙隆污水的化学需氧量（COD）的有效去除,达到含异丙隆污水深度治理的目的.进一步以绿藻Chlorella pyrenoidosa的生长抑制率为评价指标对异丙隆酶催化氧化降解的产物进行了毒性评估,结果表明,随着底物降解率的逐渐增大,降解产物对绿藻的生长抑制率逐渐减小,说明经酶法降解后得到的产物与异丙隆相比毒性降低.     

Au单晶电极上H2O2的氧化反应研究

本文利用旋转圆盘电极系统研究了酸性介质中H₂O₂在Au(100)和Au(111)电极表面的电化学行为. 实验发现在Au电极上H₂O₂难以发生还原,但是当电位稍微正于H₂O₂氧化为O₂的平衡电势时即可发生氧化. 在Au(111)上H₂O₂氧化的起始电位比在Au(100)正0.1 V左右. Au(100)上的双桥位位点能增强反应中间体*OOH的吸附,可能是导致Au(100)上H₂O₂氧化反应超电势比Au(111)低的主要原因. 在较正电位区(E>1.2 V), 当电极表面被氧物种覆盖时,H₂O₂在两个电极上的氧化都会受到一定程度的抑制,这种影响在Au(111)上比Au(100)上更加明显,这与Au(111)上氧物种的生成与逆向还原可逆性差的趋势一致. 最后还将Au与Pt单晶电极上H₂O₂氧化的行为进行了对比分析.     

过氧化氢调控藜芦醇介导木素过氧化物酶催化氧化邻苯三酚红研究

木素过氧化物酶(LiP)催化H₂O₂氧化邻苯三酚红(PR)反应的氧化产物受H₂O₂与PR的摩尔比控制, H₂O₂与PR的摩尔比不同, 所得降解产物不一样. 分析表明, H₂O₂在LiP催化氧化PR过程中的双重作用(即低浓度的H₂O₂是LiP的激活剂, 高浓度的H₂O₂是LiP的抑制剂)是导致上述现象的根本原因. 藜芦醇(VA)对LiP催化氧化PR的反应有促进作用, 尤其是当H₂O₂与PR的摩尔比较高时这种促进作用更为明显; 然而PR对LiP催化氧化VA的反应却有抑制作用. 后者可以用来解释为什么在用白腐菌降解染料时在培养液中常常检测不到LiP的藜芦醇活力. 分析表明, VA的存在不但促进了LiP酶中间体LiP(II)和/或LiP(III)向LiP的转化, 使LiP的催化循环加速, VA生成的VA^＋·也间接氧化了染料PR, 从而使PR的氧化速率提高.     

活性炭催化过氧化物高级氧化技术降解水中有机污染物*

活性炭（AC）能够催化过氧化氢(H₂O₂）释放出强氧化性的羟基自由基•OH。过二硫酸盐（PS）与H₂O₂结构上相似,因此PS也有可能被AC催化产生强氧化性的硫酸根自由基SO4−•。AC催化无机过氧化物（H₂O₂或PS）将发展成为一类新型高级氧化技术。AC催化H₂O₂联合体系包括AC/H2O2,AC/Fenton,AC/H₂O₂/紫外光,,AC/H₂O₂/微波,AC/湿式H₂O₂氧化;AC催化AC/PS联合体系包括 AC/PS,AC/PS/金属离子, AC/PS/ 微波。AC过氧化联合体均可高效降解水中有机污染物。本文在首次综述AC/过氧化物联合体系处理有机污染物研究现状的基础上,分析了AC和过氧化物的相互作用,并对该类高级氧化技术的发展前景进行了展望。     

自然水体生物膜体系中过氧化氢浓度的影响因素

以过氧化氢(H₂O₂)为自然水体生物膜产生的活性氧(ROS)的代表, 通过模拟实验, 研究了水-自然水体生物膜体系中光/暗变化、 生物膜的避光预处理与数量、 有机配体和pH值对体系中H₂O₂浓度的影响. 结果表明, 光照可快速增加体系中H₂O₂浓度, 光照转为无光时体系H₂O₂浓度下降(约为光照时的2/3); 避光预处理会显著降低体系中H₂O₂的产生速率和浓度; 生物膜数量的增减会导致体系H₂O₂浓度的相应增减; 有机配体的存在会使体系内H₂O₂浓度下降(约1/2~1/3); pH=7和5的体系中H₂O₂的浓度高于pH=9的体系(高出约1.5倍). 上述各因素主要通过影响生物膜生产H₂O₂、 H₂O₂自然分解和生物膜去除H₂O₂ 3种作用来影响体系H₂O₂浓度.     

光照下自然水体生物膜产生H2O2及其对十二烷基苯磺酸钠降解的影响

通过模拟实验研究了不同活性的自然水体生物膜在光照条件下生成过氧化氢(H₂O₂)的反应. 并研究了光照对自然水体生物膜体系中十二烷基苯磺酸钠(SDBS)降解的影响, 结合无生物膜H₂O₂溶液中SDBS的降解实验, 验证了H₂O₂对SDBS降解的作用. 结果表明, 具有生物活性的生物膜可以生成H₂O₂, 而无活性和光合作用受到抑制的生物膜则不能生成H₂O₂; 光照条件下, 生物膜体系中SDBS的降解量明显高于无光照条件下的; 光照和Fe²⁺对H₂O₂降解SDBS有促进作用.     

非均相芬顿体系协同去除复合双污染物:化学转化,pH影响和机理分析

系统研究了ZVI(零价铁粉)-Fenton体系协同去除铜离子和亚甲基蓝(MB)污染物过程中, ZVI微表面发生的化学转化以及目标污染物降解机理. 分别利用扫描电子显微镜(SEM), X射线能谱(EDS), X射线衍射(XRD), X射线光电子能谱(XPS)和傅里叶变换红外光谱(FTIR)等技术, 对比分析了反应前后以及不同体系之间ZVI表面结构, Fe和Cu化学转移的变化. 结果表明, 在ZVI/H₂O₂体系中反应后ZVI表面腐蚀产物较多, 主要为Fe₃O₄和Fe₂O₃. 在ZVI/H₂O₂-Cu体系中, 虽ZVI腐蚀作用更加剧烈, 但ZVI表面残留的腐蚀产物较少, 且腐蚀产物中Fe₃O₄含量的占比增加. Cu ²⁺主要还原产物为Cu ⁰, 同时还伴随着CuO的生成. pH影响实验表明, ZVI/H₂O₂-Cu体系不仅强化了MB的降解, 有效地去除了总溶解铜离子(TCu), 同时还扩大ZVI-Fenton体系的有效pH范围(pH=2.5~5.5). 叔丁醇捕获自由基实验表明, 羟基自由基是氧化降解MB的主要活性物质. 最后针对ZVI-Fenton体系协同去除复合双目标污染物的机理进行研究分析.     

新颖的PW11O39Fe(Ⅲ)(H2O)4-/H2O2类光-Fenton体系光催化降解苯胺

将Keggin型铁取代杂多阴离子PW11O39Fe(Ⅲ)(H2O)4-[PW11Fe(Ⅲ)(H2O)]构成的类光-芬顿体系用于水体生物难降解有机污染物苯胺(ArNH2)的降解。 研究了在紫外光照射和H2O2存在下,PW11Fe(Ⅲ)(H2O)对ArNH2降解的均相光催化作用。 考察了ArNH2、H2O2和PW11Fe(Ⅲ)(H2O)浓度对光催化降解反应速率的影响。 实验结果表明,0.1 mmol/L PW11Fe(Ⅲ)(H2O)+0.2 mmol/L H2O2+0.1 mmol/L ArNH2的中性溶液在300 W汞灯照射下反应60 min,ArNH2的降解率达100%,总有机碳(TOC)去除约52%。 同时讨论了PW11Fe(Ⅲ)(H2O)光催化H2O2产生羟基自由基的分子机制,并比较了酸性和中性条件下苯胺的光催化降解效果。     

光催化与光化学联合降解苯胺

水中许多难于被其它方法降解的有机污染物（例如卤代烃、表面活性剂、多氯联苯、染料等）能在ＴｉＯ２的光催化作用下发生矿物化的降解反应,被氧化为ＣＯ２、Ｈ２Ｏ等简单的无机物,对环境不会带来二次污染［１～３］．近年来有关ＴｉＯ２纳米晶（或微晶）膜的制备与光催...     

Electro-fenton and photoelectro-fenton degradation of sulfanilic acid using a boron-doped diamond anode and an air diffusion cathode

The mineralization of sulfanilic acid has been studied by electro-Fenton (EF) and photoelectro-Fenton (PEF) reaction with UVA light using an undivided electrochemical cell with a boron-doped diamond (BDD) anode and an air diffusion cathode able to generate H(2)O(2). Organics were then oxidized by hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton's reaction between generated H(2)O(2) and added Fe(2+). The UVA irradiation in PEF enhanced the production of hydroxyl radicals in the bulk, accelerating the removal of organics and photodecomposed intermediates like Fe(III)-carboxylate complexes. Partial decontamination of 1.39 mM sulfanilic acid solutions was achieved by EF until 100 mA cm(-2) at optimum conditions of 0.4 mM Fe(2+) and pH 3.0. The increase in current density and substrate content led to an almost total mineralization. In contrast, the PEF process was more powerful, yielding almost complete mineralization in less electrolysis time under comparable conditions. The kinetics for sulfanilic acid decay always followed a pseudo-first-order reaction. Hydroquinone and p-benzoquinone were detected as aromatic intermediates, whereas acetic, maleic, formic, oxalic, and oxamic acids were identified as generated carboxylic acids. NH(4)(+) ion was preferentially released in both treatments, along with NO(3)(-) ion in smaller proportion.     

Mineralization of metoprolol by electro-Fenton and photoelectro-Fenton processes

Solutions of about 0.25 mM of the β-blocker metoprolol tartrate (100 mg L(-1) total organic carbon) with 0.5 mM Fe(2+) in the presence and absence of 0.1 mM Cu(2+) of pH 3.0 have been comparatively degraded under electro-Fenton (EF) and photoelectro-Fenton (PEF) conditions. The electrolyses were carried out with two systems: (i) a single cell with a boron-doped diamond (BDD) anode and an air-diffusion cathode (ADE) for H(2)O(2) electrogeneration and (ii) a combined cell with a BDD/ADE pair coupled with a Pt/carbon felt (CF) cell. Overall mineralization was reached in all PEF treatments using both systems due to the efficient production of hydroxyl radical ((?)OH) from Fenton's reaction induced by UVA light and the quick photolysis of Fe(III) carboxylate complexes formed. In EF, the combined cell was much more potent than the single one by the larger (?)OH generation from the continuous Fe(2+) regeneration at the CF cathode, accelerating the oxidation of organics. However, almost total mineralization in EF was feasible using the combined cell in the presence of 0.1 mM Cu(2+), because of the parallel quick oxidation of Cu(II) carboxylate complexes by (?)OH. Metoprolol decay always followed a pseudo-first-order reaction. Aromatic products related to consecutive hydroxylation/oxidation reactions of metoprolol were detected by gas chromatography-mass spectrometry. The evolution of the aromatic 4-(2-methoxyethyl)phenol and generated carboxylic acids was followed by HPLC. The degradation rate and mineralization degree of metoprolol tartrate were limited by the removal of Fe(III) and Cu(II) complexes of ultimate carboxylic acids such as formic, oxalic, and oxamic. NH(4)(+) ion and to a lesser extent NO(3)(-) ion were released in all treatments, being quantified by ionic chromatography.     

Application of Catalytic Wet Air Oxidation to Treatment of Landfill Leachate on Co／Bi Catalyst

Catalytic wet air oxidation(CWAO) was employed to reduce the organic compounds in landfill leachate and the effects of temperature, oxygen pressure, catalyst dosage, and concentration of the organic compounds on the TOC and CODcr removal rates were studied. The degradation kinetics of landfill leachate was also investigated and an exponential experiential model consisting of four influential factors was established to describe the reduction of the organic compounds in the landfill leachate. Meanwhile, the GC-MS technique was used to detect the components of the organic intermediates for the inference of the decomposition mechanisms of the organic compounds in landfill leachate. The results reveal that the reaction temperature and the catalyst dosage are the most important factors affecting the degradation reaction of the organic compounds and that the principal intermediates confirmed by GC-MS are organic acids at a percentage of more than 88% with no aldehydes or alcohols detected. The decomposition mechanisms of the organic compounds in landfill leachate were inferred based on the GC-MS information as follows;the activated gas phase O2 captured the hydrogen of the organic pollutants to produce free radicals, which then initiated the catalytic reaction. So most of the organic compounds were oxidized into CO2 and H2O ultimately. In general, catalytic wet air oxidation over catalyst Co3O4/Bi2O3 was a very promising technique for the treatment of landfill leachate.     

Magnetic field assisted Fenton reactions for the enhanced degradation of methyl blue

Magnetic field was tentatively introduced into Fenton reactions system for the degradation and discoloration of methyl blue as the represent of organic chemical dye,which was a bio-refractory organic pollutant in industry wastewater.It was found that under optimal Fenton reaction conditions,with the assistant of magnetic field in Fenton reactions,the degradation rate of methyl blue,the decomposition rate of H_2O_2 and the conversion rate of Fe~(2+)were accelerated,the extent of them would be improved by ...     

Preparation and characterization of polyaniline/manganese dioxide composites and their catalytic activity

This paper is devoted to the preparation of polyaniline/MnO2 (PANI/MnO2) composites via chemical oxidation of aniline in H2SO4 medium using beta-MnO2 as an oxidant. The parameters affecting the polymerization reaction are considered. These parameters are [aniline], amount of beta-MnO2, stirring time, and polymerization temperature. SEM, FT-IR, XRD, and TGA techniques are used to characterize the resulting composites. XRD measurements reveal the distortion of the crystal structure of beta-MnO2 after the polymerization reaction. Thus, the XRD pattern of PANI is predominating. The crystalline composites are obtained using higher molar ratio of [Ox]/[ANI] and at higher temperature. Increasing the amount of beta-MnO2 led to an increase in the acidic character of the obtained composites due to adsorption of excess H+ on the oxide surface. The thermal stability of the composites decreased with increasing both [aniline] and stirring time, while it increased with increasing amount of beta-MnO2. The applications of the composites in the oxidative degradation of Direct Red 81, Acid Blue 92, and Indigo Carmine dyes exhibited good catalytic activity in the presence of H2O2 as an oxidant. The reactions followed first-order kinetics and the rate constants were determined. The degradation reaction involved the catalytic action of the PANI counterpart of the composite toward H2O2 decomposition, which can lead to the generation of HO radicals as a highly efficient oxidant attacking the target dyes. The detailed kinetic studies and the mechanism of these catalytic reactions are under consideration in our group.     

新型复合电极对偶氮染料分子的光催化降解

介绍了具有合成H2O2和光催化性能的双功能新型复合电极,并用X射线衍射、扫描电镜等方法进行了表征.双功能复合电极是将TiO2光催化剂负载在活性碳(AC)和具有合成H2O2性能的新型载体空气电极上形成的.在复合电极作阴极的光反应器中,* OH和TiO2光催化剂的存在实现了光化学氧化与光催化氧化在同一电极/溶液界面上的联合作用.实验结果表明,复合电极对提高偶氮染料分子活性艳红(K-2BP)的氧化降解速度起了重要作用,仅反应3 min,脱色率可达49%;反应80 min,偶氮染料分子COD去除率可达47%.     

Upgrading and expanding the electro-Fenton and related processes

The Fenton-based electrochemical advanced oxidation processes are currently recognized as the most effective technologies to achieve fast and complete degradation of target organic contaminants in water. Electro-Fenton was the pioneering process, but a larger mineralization is attained via UV and solar photoelectro-Fenton processes due to the occurrence of key photoreduction reactions. In practice, the decontamination effectiveness turns out to be limited as solution pH increases and the two-electron oxygen reduction reaction occurring at the cathode becomes inefficient or insufficient. Here, we focus on the current opinion in two crucial features of the reviewed processes: (i) trends in cathodic H₂O₂ electrogeneration, showing the oxygen reduction reaction upgrading upon use of new and/or more sustainable electrocatalysts, cathode configurations and reactor designs; and (ii) advances in iron-based catalysts, with the main purpose of expanding the application to a much wider pH range, eventually surpassing the classical acidic limitation associated to conventional Fenton's reaction.