Wang Hui, Wang Jian Long
Laboratory of Environmental Technology, INET, Tsinghua University, Beijing 100084, PR China.
J Hazard Mater. 2008 Jun 15;154(1-3):44-50. doi: 10.1016/j.jhazmat.2007.09.102. Epub 2007 Sep 29.
By using a self-made carbon/polytetrafluoroethylene (C/PTFE) O2-fed as the cathode and Ti/IrO2/RuO2 as the anode, the degradation of three organic compounds (phenol, 4-chlorophenol, and 2,4-dichlorophenol) was investigated in the diaphragm (with terylene as diaphragm material) electrolysis device by electrochemical oxidation process. The result indicated that the concentration of hydrogen peroxide (H2O2) was 8.3 mg/L, and hydroxyl radical (HO) was determined in the cathodic compartment by electron spin resonance spectrum (ESR). The removal efficiency for organic compounds reached about 90% after 120 min, conforming to the sequence of phenol, 4-chlorophenol, and 2,4-dichlorophenol. And the dechlorination degree of 4-chlorophenol exceeded 90% after 80 min. For H2O2, HO existed in the catholyte and reduction dechlorination at the cathode, the mineralization of organics in the cathodic compartment was better than that in the anodic compartment. The degradation of organics was supposed to be cooperative oxidation by direct or indirect electrochemical oxidation at the anode and H2O2, HO produced by oxygen reduction at the cathode. High-performance liquid chromatography (HPLC) allowed identifying phenol as the dechlorination product of 4-chlorophenol in the cathodic compartment, and hydroquinone, 4-chlorocatechol, benzoquinone, maleic, fumaric, oxalic, and formic acids as the main oxidation intermediates in the cathodic and anodic compartments. A reaction scheme involving all these intermediates was proposed.
以自制的碳/聚四氟乙烯（C/PTFE）作为氧气供给型阴极，Ti/IrO₂/RuO₂作为阳极，在以涤纶为隔膜材料的隔膜电解装置中，通过电化学氧化过程研究了三种有机化合物（苯酚、4-氯苯酚和2,4-二氯苯酚）的降解情况。结果表明，过氧化氢（H₂O₂）浓度为8.3 mg/L，通过电子自旋共振光谱（ESR）在阴极室检测到了羟基自由基（HO）。120分钟后有机化合物的去除效率达到约90%，符合苯酚、4-氯苯酚和2,4-二氯苯酚的顺序。80分钟后4-氯苯酚的脱氯程度超过90%。对于H₂O₂、HO存在于阴极电解液中且在阴极发生还原脱氯，阴极室中有机物的矿化程度优于阳极室。有机物的降解被认为是阳极的直接或间接电化学氧化与阴极氧还原产生的H₂O₂、HO协同氧化的结果。高效液相色谱（HPLC）能够鉴定出苯酚是阴极室中4-氯苯酚的脱氯产物，对苯二酚、4-氯邻苯二酚、苯醌、马来酸、富马酸、草酸和甲酸是阴极室和阳极室中的主要氧化中间体。提出了一个涉及所有这些中间体的反应方案。
