摘要
以负载Pd催化剂的活性碳纤维作为扩展阴极,对吸附在活性碳纤维上的五氯苯酚进行了电催化还原脱氯研究。考察了电解质浓度、催化剂含量、电流密度等主要因素对还原脱氯效率的影响。结果表明,电解质浓度0.25mol·L-1,温度40℃,电流密度25mA·cm-2,催化剂Pd的含量5%,反应4h,五氯苯酚的降解率可达到94.3%。通过中间产物的分析对电催化还原脱氯反应机理进行了初步探讨。
The activated carbon fiber （ACF） could be used as a kind of three-dimensional electrode materials, for it has a uniform structure with a three-dimensional reticulation framework, high porosity, good liquid permeability and conductivity, as well as a large special surface area. In present study, the working electrode was prepared using palladium electrochemical deposition on activated carbon fiber （Pd/ ACF）, and adsorption/electroreduction process was employed for electrocatalytic dechlorination of pentachlorophenol （PCP） on the surface of ACF. First, PCP was adsorbed onto Pd/ACF from the solution, and then was dechlorinated at a constant current. The primary factors affecting electrodechlorination efficiency were investigated under constant current. The parameters concerned include concentration of electrolyte, temperature, current density and catalyst amount. The results show that 94.3% PCP was dechlorinated in 4 hours under the optimum conditions： tetramethyl-ammonium chloride （TMAC1） 0.25 mol·L^-1; temperature of 40℃, applied current density 25 mA·cm^- 2 and Pd amount 5 % . Complete dechlorination of 200 mg·L^-1 PCP with a current efficiency 9.1% was realized. The experimental results also indicate that the electrocatalytic reduction on the Pd/ACF can effectively dechlorinate PCP, and the dechlorination reaction proves in good conformity with the first order kinetics at the beginning of 200 min. In addition, the extracts from the Pd/ACF electrode and electrolyte solution were analyzed by GC/MS after 3 h of electrolysis and five kinds of main dechlorination products were detected including tetrachlorophenols （ TetraCP ）, trichlorophenols （ TriCP ）, dichlorophenols （DiCP）, chlorophenols （CPL） and phenol （ PNL）. After 4 h, only phenol and small amount of chlorophenols were detected. On the basis of the above results, PCP was gradually degraded, and was completely dechlorinated to PNL at last. Therefore, electroeatalytic dechlorination on the Pd/ACF can dechlorinate PCP to phenol, whose toxicity is lower.
出处
《安全与环境学报》
CAS
CSCD
2005年第4期51-54,共4页
Journal of Safety and Environment
基金
国家自然科学基金重点项目(20337020)
关键词
环境工程
钯
活性炭纤维
电催化还原
五氯苯酚
environmental engineering
palladium
activated carbon fiber
electroreduction
pentachlorophenol
