Electrochemical degradation of 4-chlorophenol using a novel Pd/C gas-diffusion electrode
Electrochemical degradation of 4-chlorophenol using a novel Pd/C gas-diffusion electrode
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DOI：
10.1016/j.apcatb.2007.07.004
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发表时间：
2007-11
影响因子：
22.1
通讯作者：
Hui Wang;Jianlong Wang
中科院分区：
文献类型：
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作者：
Hui Wang;Jianlong Wang
采用氢还原法制备了Pd/C催化剂，并将其用于Pd/C气体扩散电极。采用X射线衍射（XRD）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）和循环伏安（CV）等技术对其进行了表征。在隔膜电解装置中，分别以Pd/C气体扩散电极和碳/聚四氟乙烯（C/PTFE）气体扩散电极为阴极，采用两种不同的进气方式，研究了4-氯苯酚的电化学降解。结果表明，平均粒径为4.0nm的钯颗粒高度分散在活性炭中，呈无定形结构，Pd/C催化剂表面钯含量达到1.3at.%。先通入氢气后通入空气有利于提高4-氯酚的去除率。Pd/C气体扩散阴极不仅可以通入氢气还原4-氯酚脱氯，还可以通入空气加速O2的双电子还原生成H2 O2。因此，使用Pd/C气体扩散阴极对4-氯苯酚的去除效率优于C/PTFE气体扩散阴极。60 min后，4-氯苯酚的去除率和脱氯度均达到100%左右，120 min后，4-氯苯酚的化学需氧量（COD）平均去除率超过70%。高效液相色谱（HPLC）分析表明，苯酚为脱氯产物，对苯二酚、苯醌、马来酸、富马酸、丙烯酸、丙二酸、草酸、乙酸和甲酸为主要氧化中间产物。提出了一个涉及所有这些中间体的反应途径。
Pd/C catalyst was prepared by hydrogen reduction method and used for the Pd/C gas-diffusion electrode. It was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) techniques. The electrochemical degradation of 4-chlorophenol was investigated in a diaphragm electrolysis device, by two different feeding gas modes, using the Pd/C gas-diffusion electrode and the carbon/polytetrafluoroethylene (C/PTFE) gas-diffusion electrode as a cathode, respectively. The results indicated that Pd particles with an average size of 4.0nm were highly dispersed in the activated carbon with an amorphous structure; Pd content on the surface of the Pd/C catalyst reached 1.3 at.%. Furthermore, feeding with hydrogen gas firstly and then with air was in favor of improving 4-chlorophenol removal efficiency. The Pd/C gas-diffusion cathode can not only reductively dechlorinate 4-chlorophenols by feeding hydrogen gas, but also accelerate the two-electron reduction of O2to hydrogen peroxide (H2O2) by feeding air. Therefore, the removal efficiency of 4-chlorophenol by using the Pd/C gas-diffusion cathode was better than that of the C/PTFE gas-diffusion cathode. And both the removal efficiency and the dechlorination degree of 4-chlorophenol reached about 100% after 60min, and the average removal efficiency of 4-chlorophenol in terms of chemical oxygen demand (COD) exceeded 70% after 120min. The analysis of high-performance liquid chromatography (HPLC) identified that phenol was the dechlorination product, and hydroquinone, benzoquinone, maleic, fumaric, crylic, malonic, oxalic, acetic and formic acids were the main oxidation intermediates. A reaction pathway involving all these intermediates was proposed.