阴极脱氯协同多孔Ti/BDD电极阳极电催化氧化对氯苯酚

本文主要研究阴极脱氯协同阳极(多孔Ti/BDD 电极)电催化氧化对于对氯苯酚的电化学降解过程. 在有无阳离子交换膜电解槽体系下电化学降解对氯苯酚的实验结果表明,对氯苯酚的矿化主要在阳极区进行;无隔膜电解槽体系下,对氯苯酚在阴极还原形成的氯离子迁移到阳极,在阳极表面进一步生成了具有强催化氧化作用的活 性氯,与阳极产生的羟基自由基协同降解对氯苯酚;在阳离子交换膜电解槽体系下,阴极产生的氯离子难以通过阳离子膜迁移至阳极区,无隔膜电解槽呈现出更好的降解效率. 结合高效液相色谱技术确定阳极室的中间产物为对苯二酚、邻苯二酚、对苯醌和苯酚等,阴极室的主要产物是苯酚,并根据中间产物提出了对氯苯酚的降解路径.     

电生成Fenton试剂及其对染料降解脱色的研究

以可溶性铁为阳极,多孔石墨电极为阴极,Na2SO4为支持电解质.通电后,铁从阳极溶解生成二价亚铁离子Fe2+,氧在阴极上还原为过氧化氢H2O2,于电解现场发生Fenton反应,产生羟基自由基即Fenton试剂.在低电流密度(10mA/cm2)下,可有效地抑制阴、阳两极副反应的发生,所产生的羟基自由基浓度足以有效地进行染料废水的降解与脱色,脱色率达100%,CODcr去除率达80%.     

异相Fenton光催化对有毒有机污染物的降解

以蒙脱石-K10(Montmorillonite K10)作为Fe3 的载体制备异相Fenton催化剂(Mot-Fe),并用此催化剂在可见光(λ>420 nm)照射下研究其降解染料罗丹明B(Rhoda-mine B,RhB)和2,4-二氯苯酚(2,4-Dichlorophenol,DCP)。研究表明,选定的Mot-Fe/H2O2体系能有效地降解RhB,反应300 min脱色完全,总有机碳(TOC)去除率达85.2%,反应过程中主要涉及到.OH自由基的产生和参与。可见光照射下,对DCP/Mot-Fe/H2O2体系,TOC的去除率达到51.6%。催化剂具有比较好的稳定性,能够重复使用。     

应用于水溶液介质中喹啉氧化的电芬顿工艺实验设计方法(英文)

采用碳毡阴极和铂阳极的电芬顿工艺研究了喹啉模型分子8-羟基喹啉硫酸盐（8-HQS）在水溶液介质中的降解行为. 由于电化学诱导芬顿药剂（H2O2,Fe2+）产生大量的羟基活性基（OH）,成为与有机物发生反应直到有机物完全矿化的强有力氧化剂,因此,电芬顿工艺具有很强的氧化能力. 采用正交实验设计确定了水溶液介质中8-HQS降解的操作参数. 结果表明,电流密度和8-HQS的初始浓度是影响降解速度的主要因素. 8-HQS浓度随着电解时间而减少,说明8-HQS的氧化遵循准一级反应动力学. 通过竞争动力学方法确定的由OH引起8-HQS氧化的绝对反应速度常数为1.62×109 mol^-1·L·s^-1. 通过Doehlert 矩阵研究了8-HQS矿化的最佳实验参数,由此确定最佳条件下电芬顿工艺能导致8-HQS在水溶液中的准完全矿化（总有机成分去除率95%）. 对8-HQS水溶液的处理,使得8-HQS矿化前的最终产物为短链羧酸. 同时研究了电芬顿处理中短链羧酸的演变行为. 溶液毒性演变的跟踪研究发现,中间产物的毒性比8-HQS强,但溶液的毒性在中间产物矿化后可以完全消除.     

TiO2膜电极光电催化降解苯甲酸的机理研究

利用自制纳米TiO2薄膜作电极, 对苯甲酸光电催化降解过程进行了系统研究. 同时利用扫描电镜(SEM)、X射线衍射图谱(XRD)和光电流-电压响应谱分析光催化剂的微观性质和光电性能. 选取较高的pH 10.5, 以利于苯甲酸降解中间产物的检测(GC/MS). 通过对比光电催化与单一的TiO2光催化体系中苯甲酸的降解动力学、总有机碳(TOC)的去除率、降解产物的生成(GC/MS)及活性自由基物种的产生(ESR), 提出光电催化降解苯甲酸的具体反应路径和氧化机理. 羟基化的苯甲酸在羟基自由基与活性氧自由基的共同作用下, 经由含六个碳原子的二酸(顺式己二烯二酸), 被进一步氧化成小分子酸和CO2.     

TiO2膜电极光电催化降解苯甲酸的机理研究

利用自制纳米TiO2薄膜作电极, 对苯甲酸光电催化降解过程进行了系统研究. 同时利用扫描电镜(SEM)、X射线衍射图谱(XRD)和光电流-电压响应谱分析光催化剂的微观性质和光电性能. 选取较高的pH 10.5, 以利于苯甲酸降解中间产物的检测(GC/MS). 通过对比光电催化与单一的TiO2光催化体系中苯甲酸的降解动力学、总有机碳(TOC)的去除率、降解产物的生成(GC/MS)及活性自由基物种的产生(ESR), 提出光电催化降解苯甲酸的具体反应路径和氧化机理. 羟基化的苯甲酸在羟基自由基与活性氧自由基的共同作用下, 经由含六个碳原子的二酸(顺式己二烯二酸), 被进一步氧化成小分子酸和CO2.     

掺硼金刚石电极电催化氧化酚类有机物的取代基效应

本文主要以当前水环境中存在酚类有机污染物为研究对象,探讨酚类有机污染物在掺硼金刚石(BDD)电极上的取代基效应,具体研究具有不同位置及种类官能团的取代酚类有机污染物在BDD电极上的电催化氧化过程,通过化学需氧量和浓度变化考察有机污染物在电催化降解过程中的降解趋势,深入分析电极种类、官能团位置与种类与电催化氧化活性之间的联系的同时,研究阳极材料电催化氧化有机污染物的机理及动力学。结果表明,有机物在电极表面的电催化过程以电产生羟基自由基为媒介,对苯二酚在不同电极上的电催化活性与电极析氧电位及表面产生羟基自由基量有着重要的联系,BDD电极拥有最强的电催化氧化活性;不同取代基团的对位取代酚在BDD电极上的电化学降解实验显示电催化反应速率受取代官能团自身的电子效应制约,有机物矿化过程中羟基自由基首先进攻苯环的对位发生取代反应,同时取代基脱离苯环过程成为整个取代酚类电化学降解过程的决速步骤,且有机物的电催化反应速率与取代基特征Hammett常数σ呈近似线性关系。     

可见光/Fenton光催化降解有机染料

采用Fenton试剂(Fe³⁺/H₂O₂)在可见光条件下(λ＞450nm)光催化降解目标染料化合物罗丹明B(RhodamineB,RhB).在pH＜3.0体系中用可见光照射,能使RhB染料在光敏化作用下有效降解,反应160min后矿化率达到71.8%.采用ESR和溴甲酚绿(Bromocresolgreen,BCG)法跟踪测定活性氧化物种,通过对RhB降解过程的紫外-可见光谱、红外光谱分析及总有机碳量(TOC)跟踪测定,结果表明,Fe³⁺/H₂O₂/RhB体系在可见光照射下主要的活性氧化物种为羟基自由基,能有效地降解RhB.     

S2O2-8派生氧化法催化降解水中的甲基橙

 S2O2-8在Ag+的催化作用下可生成 SO-4· 和Ag2+, SO-4· 和Ag2+ 具有极强的氧化能力,其电极电位分别为E0Ag2+/Ag+=1.989 V, E0SO-4·/SO2-4=3.64 V. 本文研究了S2O2-8+Ag+体系中甲基橙的降解情况,并用紫外光谱、总有机碳(TOC)和高效液相色谱/质谱对降解过程进行了表征. 在pH=1的S2O2-8+Ag+体系中,反应8 min时, 5 μmol/L的甲基橙色度去除率达100%. 2 h后,水样中有悬浮物出现,过滤后样品TOC去除率为8.6%; 在同样条件下, Fenton法对甲基橙TOC去除率为10%. 在促使有机物矿化方面, S2O2-8+Ag+法与Fenton法的效果基本相同.     

阳极TiO2/g-C3N4与阴极WO3/W纳米催化剂之间扩大的异质结自偏压系统去除污染物

电化学或光电化学半导体催化剂广泛应用于降解污水中的有机与无机污染物,有望实现低能耗且高效的污染物降解.目前,已有多种异质结半导体光催化剂的研究报道,并且大多数的研究结果显示催化剂活性有明显提高,但仍存在着光激发后电子与空穴的复合问题.光电化学系统的构建可减少电子与空穴的复合,因光催化阳极与光催化阴极之间费米能级的不同,在两极之间形成异质结,产生内电场,自生偏压驱动电子流动.已有诸多研究报道将TiO2催化剂与g-C3N4复合形成异质结,提高光催化活性.由于g-C3N4(~–1.12 eV vs.NHE)导带位置相比于TiO2(~–0.2 eV vs.NHE)更负,因此在两者之间可形成内部偏压,驱动电子由g-C3N4转移至TiO2.WO3/W导带位置(~+0.2 eV vs.NHE)比TiO2与g-C3N4更正,因此自生内偏压促进电子由阳极流动至阴极.我们研究组发展了一种在无光条件下的自偏压电化学燃料电池系统,异质结间的电子流动可活化氧气产生自由基,自由基可用于阳极污染物的降解,但阴极未降解污染物.本文在上述研究基础上,应用TiO2/g-C3N4异质结与WO3/W分别作为阳极与阴极催化剂,构建自偏压催化燃料电池系统,在无光条件下催化阳极与阴极之间自发电子转移,活化氧气产生自由基,同时实现低能耗阳极室内污染物如罗丹明B和三氯生的氧化,且电子用于阴极室内硝态氮的还原.通过在空气中原位加热与氧化钨丝制得WO3/W阴极,由扫描电镜图可知在钨丝表面形成三氧化钨纳米粒子,此结构增大了催化剂的表面积以及催化剂与电解液的接触面积,有利于电荷转移.用循环伏安曲线(CV)与电流时间曲线(I-t)表征了电极的电化学性质.CV测试结果表明,相比于硫酸钠电解液,WO3/W阴极在含有硝态氮的电解液中存在还原峰,且紫外照射比无光条件下的电流略大,说明此电极在无光条件下可用于还原硝态氮,有光更利于激发催化剂产生电子与空穴降解和去除污染物.在硫酸钠电解液中,无光照条件下(同室),I-t曲线表明TiO2/g-C3N4相比于WO3/W电极可产生更大电流,因此选择TiO2/g-C3N4作为阳极,WO3/W作为阴极.在含污染物电解液中,无光照条件下,Pt片作为对电极时(同室),I-t曲线中的电流在曝气时比未曝气时小,说明电极上产生的部分电子用于活化氧气产生自由基,因此转移到外电路的电子减少,电流变小;相反,当TiO2/g-C3N4阳极置于阳极室,WO3/W阴极置于阴极室时(两室),阳极鼓入空气,阴极曝氮气时,电流比两室均未曝气时大,说明此系统有利于电子产生与转移,用于氧化还原去除污染物.相比于传统方法,此系统通过阳极室内曝空气与活化分子氧形成自由基,无需外加偏压,在有光与无光条件下,均可实现对阳极室与阴极室内不同污染物的同时去除或降解,同时提出了此系统中的降解机理.     

Enhanced electrocatalytic oxidation of dyes in aqueous solution using cobalt phthalocyanine modified activated carbon fiber anode

Cobalt tetra(2,4-dichloro-1,3,5-triazine)aminophthalocyanine(CoPc)was immobilized covalently on activated carbon fiber(ACF)felt to obtain CoPc-modified ACF(CoPc-ACF)catalyst,and an electrocatalytic oxidation system using CoPc-ACF as the anode was constructed.The electrocatalytic oxidation of Acid Red 1(AR1)was investigated in aqueous solution by an UV-vis spectrophotometer and UPLC.The results indicated that AR1 could be eliminated efficiently in this electrocatalytic oxidation system.In addition,the results of FTIR,TOC and GC-MS suggested that the electrocatalytic oxidation experienced the decoloration achieved by destroying the azo linkage and the further mineralization due to the cleavages of benzene ring and naphthalene ring.The intermediates were mainly small molecular compounds such as maleic acid and succinic acid,etc.Repetitive tests showed that CoPc-ACF can maintain high electrocatalytic activity over several cycles.The further EPR spin-trap experiments indicated that the hydroxyl radicals did not dominate the reaction in this electrocatalytic system,which was completely different from the traditional electro-Fenton system.Based on the non-radical reaction mechanism,the CoPc-modified ACF electrocatalyst has potential application in treating actual dyestuffs wastewaters,which are accompanied with high concentration of hydroxyl radical scavengers such as chlorine ions and additives in the textile printing and dyeing industry.     

Efficient electrochemical incineration of phenol on activated carbon fiber as a new type of particulates

The feasibility of activated carbon fibers (ACFs) used as a new type of particle electrodes in 3-dimensional (3D) electrode for the electrochemical degradation of phenol wastewater was investigated for the first time. The surface morphology, textual properties and electrochemical behaviors of ACF were studied by scanning electron microscopy (SEM), N₂-BET sorption and cyclic voltammograms (CVs), respectively. Compared with the commercialized granular activated carbon (GAC), ACF particle electrodes exhibited higher electrochemical oxidation performance on the mineralization of target pollutant. The identification of intermediates indicated most of oxidation products were adsorbed onto the ACFs. The detection of hydrogen peroxide and hydroxyl radicals in the reaction system suggested that the reaction mechanism was direct anodic oxidation of pollutant on ACFs if the cathode did not contact the ACFs. The operative parameters including initial concentration of substrate, applied current density and the initial aqueous pH have been scientifically studied in search of the optimum condition. Based upon the obtained results, the ACFs longevity was tested in solution at pH 2.0, revealing relatively high electrooxidation capacity and long catalyst lifetime of ACFs in acid solution.     

生物电化学系统降解多环芳烃萘及微生物群落研究

采用单室空气阴极微生物燃料电池(MFC)反应器构型, 以不同浓度萘为基底物质, 考察MFC的产电性能、 萘降解率、 化学需氧量(COD)和总有机碳含量(TOC)降解率及MFC阴阳极微生物活性和多样性. 结果表明, 循环伏安曲线受不同浓度萘的影响变化较为明显, 随着萘浓度的增大, 最大功率密度呈下降趋势, 且萘对MFC的阴极电极电势影响较大; 当萘的浓度为15 mg/L时, MFC最大功率密度可达(645.841±28.08) mW/m ²; 对萘的降解率高达100%, 且MFC对COD和TOC的降解率随着萘浓度的提高而增大, 但是增大的速率逐渐减小. 对MFC阳极微生物膜进行高通量测序发现, Geobacter是优势菌属, 相对丰度达81%, 阴极主要以Aquamicrobium为主.     

TiO2/UV/O2和TiO2/UV/N2体系降解水中对氯硝基苯

以商用TiO₂P25为催化剂,分别在TiO₂/UV/O₂和TiO₂/UV/N₂两种体系下进行降解对氯硝基苯(pCNB)试验.采用ESR对两种体系下光催化反应形成的·OH进行测定,利用LC-MS对两种体系下反应形成的中间产物进行了定性和定量分析,最后对pCNB降解过程中氯和硝基的存在形式进行了研究.结果表明:TiO₂/UV/O₂体系的催化降解效果要明显优于TiO₂/UV/N₂体系;两种反应体系都有·OH产生,并且TiO₂/UV/O₂体系产生的·OH的量多于TiO₂/UV/N₂体系产生的·OH的量;TiO₂/UV/O₂体系形成的中间产物的种类要多于TiO₂/UV/N₂体系形成的,苯环上的氢、氯、硝基均可被·OH取代形成对硝基酚(pNP)、5-氯-2-硝基酚(5-C-2-PN)等酚类物质;两种体系下均有Cl^-和NO₂^-存在,其中Cl^-生成势与pCNB的去除势一致,只有TiO₂/UV/O₂体系中存在NO₃^-.     

Anodic-Cathodic Electrocatalytic Degradation of Phenol with Oxygen Sparged in the Presence of Iron(Ⅱ)

IntroductionAs typical contaminants,phenolic pollutants,are toxic and are found in oil refinery and coke,chemical and plastic industries. Conventionaltreatment processes such as activated carbonadsorption,extraction and biological treatment cannot make the pollutants complete mineralization orwill lead to recontamination. Recently,electrochemical techniques have been extensivelyapplied to such a kind of wastewater treatment,mainly because of their amenability to automation,high efficiency and …     

Degradation of Phenol by Hydroxyl Radicals on Different Coating Lead Dioxide Electrodes

Lead dioxide electrodes on Ti substrates were prepared by thermal-deposition or electro-deposition. The amount of hydroxyl radicals generated at the electrodes prepared by the above-mentioned two methods was compared with that at the electrodes mingled with Bi or La prepared by electro-deposition. The experimental results indicate that the highest concentration of hydroxyl radicals generated by thermal-deposition, electro-deposition mingled with nothing, electro-deposition mingled with Bi or La was 0.781, 1.048, 1.838 or 2.044 μmol/L, respectively. When phenol was electrolyzed on the four electrodes at a current density of 30 mA/cm2, the removal efficiency of phenol after electrolysis for 1.5 h was 87.30%, 93.55%, 97.95% or 98.70%, TOC removal efficiency after electrolysis for 5 h was 86.76%, 94.26%, 98.53% or 99.60%, respectively. Through the degradation experiments of phenol, the amount of hydroxyl radicals was responsible for the removal efficiency of phenol. The electro-catalytic characteristics were investigated by SEM, the generation amount of hydroxyl radicals, the degradation degree of phenol and the stability and conductivity of the electrodes were also investigated. The experimental results indicate that the four electrodes all show good electro-catalytic characteristics; the electro-catalytic characteristics of the electrode mingled with La were superior to those of the other three ones, and the electrochemical degradation of phenol followed one-step reaction dynamics.     

Ru0.7Si0.3O2/Ti电极电催化氧化处理硝基苯废水

制备了Ru0.7Si0.3O2/Ti电极,并以该电极作为氧化阳极,不锈钢为阴极,电催化氧化降解废水中硝基苯。 实验结果表明,当硝基苯初始质量浓度为220 mg/L时,最佳条件为：电流密度25×10-3 A/cm2;Na2SO4作为电解质时加入量为8 g/L;溶液初始pH=2。 在此最佳条件下,硝基苯去除率大于85%,TOC去除率大于50%,表明Ru0.7Si0.3O2/Ti阳极能有效去除废水中有机污染物;对中间产物的检测结果表明,硝基苯的降解是阴阳两极协同作用的结果。     

Fe~(2+)协同热活化过一硫酸氢钾盐诱导自由基脱除NO的研究

在气液撞击流反应器中,研究了Fe~(2+)协同热活化过一硫酸氢钾盐诱导自由基脱除模拟烟气中的NO。考察了主要工艺参数(溶液温度、Fe~(2+)浓度、过一硫酸氢钾盐浓度、溶液pH值、NO入口浓度)对NO脱除效率的影响。分析检测了反应产物和自由基。基于不同系统的对比研究、反应产物检测和活性自由基的捕获,揭示了NO脱除过程的机制和反应路径。结果表明,提高溶液温度、Fe~(2+)浓度和过一硫酸氢钾盐浓度均提高了NO的脱除效率,而提高溶液pH值和NO入口浓度均降低了NO的脱除效率。Fe~(2+)和热对活化过一硫酸氢钾盐产生自由基有显著的协同效应。自由基氧化是NO脱除的主要路径,而过一硫酸氢钾盐直接氧化是次要的脱除路径。Fe~(2+)和热的协同活化体系具有比其他体系高得多的NO脱除率。     

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.