Electrochemical oxidation of 1H,1H,2H,2H-perfluorooctane sulfonic acid (6：2 FTS) on DSA electrode：Operating parameters and mechanism

The 6:2 FTS was the substitute for perfluorooctane sulfonate(PFOS) in the chrome plating industry in Japan. Electrochemical oxidation of 6:2 FTS was investigated in this study. The degradabilities of PFOS and 6:2 FTS were tested on the Ti/SnO2–Sb2O5–Bi2O3anode. The effects of current density,potential,and supporting electrolyte on the degradation of 6:2 FTS were evaluated. Experimental results showed that 6:2 FTS was more easily degraded than PFOS on the Ti/SnO2–Sb2O5–Bi2O3anode. At a low current density of 1.42 mA/cm2,6:2 FTS was not degraded on Ti/SnO2–Sb2O5–Bi2O3,while the degradation ratio increased when the current density ranged from 4.25 to 6.80 mA/cm2. The degradation of 6:2 FTS at current density of 6.80 mA/cm2 followed pseudo first-order kinetics with the rate constant of 0.074 hr-1. The anodic potential played an important role in the degradation of 6:2 FTS,and the pseudo first-order rate constants increased with the potential. The surface of Ti/SnO2–Sb2O5–Bi2O3was contaminated after electrolysis at constant potential of 3 V,while the fouling phenomenon was not observed at 5 V. The fouled anode could be regenerated by incinerating at 600°C. The intermediates detected by ultra-performance liquid chromatography coupled with a triple-stage quadrupole mass spectrometer(UPLC–MS/MS) were shorter chain perfluorocarboxylic acids. The 6:2 FTS was first attacked by hydroxyl radical,and then formed perfluorinated carboxylates,which decarboxylated and removed CF2 units to yield shorter-chain perfluorocarboxylic acids.     

Pd/C气体扩散电极用于电化学降解4-氯酚的研究

采用氢气还原法制备Pd/C催化剂,利用XRD、TEM及XPS对该催化剂进行了表征,并利用此催化剂制备成新型的Pd/C气体扩散阴极;在隔膜电解体系中对4-氯酚进行降解,比较了不同通气方式下的去除效果.结果表明,所制备的催化剂中Pd以无定形态存在并高度分散在活性炭表面,形状比较规则,粒径在4.1 nm左右;制备的0.5%Pd/C催化剂表面的Pd摩尔分数达到1.29%;制备的Pd/C气体扩散阴极既对4-氯酚具有还原脱氯作用(通入H2时),又促进O2还原生成H2O2(通入O2时).采用先通氢气后通空气的方式对4-氯酚有很好的去除效果,反应60min后4-氯酚的转化率和脱氯率接近100%,120 min后阴极室COD去除率达到87.4%.因此,采用Pd/C气体扩散阴极可通过还原.氧化相结合的方法对氯酚类有机物进行降解.     

网状Ti/TiO2电极光电催化氧化若丹明B

用阳极氧化法制备出一种网状Ti/TiO₂电极,扫描电镜和拉曼光谱对电极表面TiO₂膜的形貌和晶体结构的检测结果表明:膜的结构和性能受阳极氧化过程中氧化速率的影响,在控制实验条件下,锐钛型TiO₂是其主要结晶形态.若丹明B的光电催化降解和光催化降解的实验结果表明:外加偏压可以有效地提高有机物的光催化降解效率.TOC的测定结果显示,在光电催化氧化过程中,若丹明B几乎完全矿化.若丹明B在光电催化降解过程中,生色基团的破坏与脱乙基作用同时发生.     

离子电极连续测定食醋中的碘氟

采用柠檬酸－KOH为离子强度调节剂,用碘电极、氟电极直接测定食醛中碘氟的量。方法简便、快速。本方法碘氯 的最低检出限分别为4.3ug/L和24ug/L.     

Photoelectrochemical degradation of Methylene Blue with -PbO2 electrodes driven by visible light irradiation

-PbO2 electrodes were prepared by electro-deposition and characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and linear sweep voltammetry. We confirmed pure -PbO2 crystals were on the electrode and it had a high oxygen evolution potential. The photoactivity and photoelectrochemical (PEC) properties of the -PbO2 electrode were investigated under visible light irradiation ( > 420 nm) for the decolorization of Methylene Blue. Pseudo first-order kinetics parameter (Kapp) for dye decolorization using the -PbO2 electrode achieved 6.71×10?4 min?1 under visible light irradiation, which indicated its excellent visible light-induced photoactivity. The Kapp of the PEC process was as much as 1.41×10?3 min?1 and was 1.71 times that of visible light irradiation or electrolysis even in the presence of the -PbO2 electrode. A significant synergetic effect was observed in the PEC system. We also employed TiO2 modified -PbO2 electrodes in this test, which revealed that the TiO2 immobilized on the -PbO2 electrode inhibited the visible light-induced PEC efficiency despite the amount of TiO2 used for electrode preparation. The -PbO2 electrode was also superior to the dimensionally stable anode (Ti/Ru0:3Ti0:7O2) in visible light-induced photoactivity and PEC efficiency.     

紫外光协助下DSA电极对1,4-苯醌的强化开环作用研究

以商品化DSA电极为光电极,以1,4-苯醌为模型污染物进行了光电催化降解,考察了外加电解质、外加电场强度和初始pH条件等因素的影响.结果表明,光电催化氧化过程的TOC去除率是单独光催化氧化和电催化氧化过程之和的1.25倍,光电催化降解过程具有更高的降解效率,证明光催化氧化和电催化氧化过程的耦合产生了一定的协同作用.外加电解质和外加电场均能在一定浓度和强度范围内有效提高光电催化降解效率.酸性和中性pH条件利于1,4-苯醌的开环矿化.探讨了光电催化氧化机制,指出以电化学氧化作用为主导的光助电催化氧化过程能够高效产生羟基自由基,降解效率可调,在水处理中更具实用价值.     

膨胀石墨流态化电极处理酸性含镉废水的研究

该法电流效率４０％－５０％,除镉速度４０．７ｍｇ／ｍｉｎ,能耗６－１０ｋＷ·ｈ／（ｋｇ·ｄ）。处理后废水中Ｃｄ＾２＋浓度可降至１０ｐｐｍ以下,虽未能达到国家排放标准（０．１ｐｐｍ）,但从镉的回收方面来看还是有效的。实验确定了处理酸性含镉废水的适宜条件,同时探讨了从废水中回收金属镉的方法。     

VB6在CNT修饰电极的电化学行为及检测

研究了维生素B6在碳纳米管修饰玻碳电极(CNT/GC)的电化学行为。实验表明,碳纳米管对维生素B6有良好的电催化作用;在磷酸盐缓冲溶液中,维生素B6有2个氧化峰(Epa1=0.20V,Epa2=0.44V)和2个还原峰(Epc1=-0.33V,Epc2=-0.66V),在CNT/GC电极上的氧化还原较复杂;在5.0×10-6—8.0×10-5mol/L浓度范围内,氧化峰电流与维生素B6的浓度呈线性关系,最低检测限(3σ/slope)为1.8×10-6mol/L。     

不同剂量Er元素掺杂PbO2电极的制备表征及其降解磺胺类抗生素

本研究利用电沉积法制备PbO2电极,在制备表面活性层时加入不同剂量的稀土元素Er进行改性,得到0％Er-PbO2、0.5％Er-PbO2、 1.0％Er-PbO2、 2.0％Er-PbO2、 4.0％Er-PbO2等5种电极,运用SEM、EDS、XRD、LSV等手段对制备得到的电极进行表征分析.选择磺胺甲基嘧啶为目标污...     

电化学催化降解水中有机污染物的研究进展

电化学去催化降解废水中的有机污染物已引起广泛兴趣。在电极的作用下，电化学反应和化学催化作用结合，可导致有机分子的电催化降解。选用合适的电极材料可以加速电化学反应速率，有助于有机物的电化学转化，本文讨论了提高电催化降解速率的方法，指出了在该领域的研究中存在的问题和发展方向。