Li Yu-Ping, Cao Hong-Bin, Liu Chen-Ming, Zhang Yi
Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, P.O. Box 353, Beijing 100080, China.
J Hazard Mater. 2007 Sep 5;148(1-2):158-63. doi: 10.1016/j.jhazmat.2007.02.021. Epub 2007 Feb 15.
The electrochemical behaviors of nitrobenzene at a pyrolytic graphite electrode modified with carbon nanotubes (CNTs) were studied using cyclic voltammetry and constant-potential electrolysis technique, and the CNT-modified electrode was characterized with Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) measurements. A CNT-modified packed-bed flow reactor was also constructed for electrocatalytic reduction of nitrobenzene. The results showed that CNTs exhibited high activity for nitrobenzene reduction to aniline and the electrochemical reduction of nitrobenzene at CNT-modified electrode followed the pathway of nitrobenzene-->phenylhydroxylamine-->aniline. CNTs had been functionalized with profuse carboxylic group and other oxygen-containing groups, became open with some lacuna on the wall, and were distributed symmetrically on the electrode with forming a three-dimensional layer, resulting in the high catalytic-activity for nitrobenzene reduction to aniline. The removal of nitrobenzene was over 95% with electrolysis for 50 min at -1.20 V in pH 5 solution using the CNT-modified packed-bed flow reactor, and no other product was obtained except aniline. The removal of nitrobenzene was over 95% with electrolysis for 80 min at -1.20 V in pH 7 solution and was 87% with electrolysis for 120 min in pH 9 solution. A little phenylhydroxylamine besides aniline was obtained during the initial electrolysis stage, and then all reduced to aniline. The average current efficiency at pH 5, 7 and 9 was 46, 51 and 63%, respectively. The electrolysis products were mineralized easily through aerobiotic biodegradation.
采用循环伏安法和恒电位电解技术研究了硝基苯在碳纳米管（CNT）修饰的热解石墨电极上的电化学行为，并用傅里叶变换红外光谱（FTIR）、高分辨率透射电子显微镜（HRTEM）和扫描电子显微镜（SEM）对CNT修饰电极进行了表征。还构建了一个CNT修饰的填充床流动反应器用于硝基苯的电催化还原。结果表明，CNT对硝基苯还原为苯胺具有高活性，硝基苯在CNT修饰电极上的电化学还原遵循硝基苯→苯胲→苯胺的途径。CNT已被大量羧基和其他含氧基团官能化，管壁上有一些空隙并变得开放，且在电极上对称分布形成三维层，从而对硝基苯还原为苯胺具有高催化活性。使用CNT修饰的填充床流动反应器，在pH 5溶液中于-1.20 V下电解50 min，硝基苯的去除率超过95%，除苯胺外未得到其他产物。在pH 7溶液中于-1.20 V下电解80 min，硝基苯的去除率超过95%；在pH 9溶液中电解120 min，去除率为87%。在电解初始阶段除得到苯胺外还得到少量苯胲，随后全部还原为苯胺。在pH 5、7和9时的平均电流效率分别为46%、51%和63%。电解产物易于通过好氧生物降解进行矿化。
