电化学还原-氧化工艺降解4-氯酚的毒性研究

采用紫外光还原法制备了Pd-Fe/石墨烯催化阴极,并以Ti/IrO_2/RuO_2为阳极,构成三电极体系(双阴极)和两电极体系(单阴极)的电化学还原-氧化降解工艺,分别对4-氯酚进行降解.采用离子色谱、高效液相色谱、TOC仪对4-氯酚降解过程中中间产物及其浓度进行测定.根据公式计算降解过程中理论计算毒性值,应用发光细菌法测定降解过程中的实际毒性值,对理论计算毒性值与实际毒性值进行比较,分析不同体系下降解过程中毒性的变化规律.结果表明,两种工艺体系在最佳降解条件下,阴极室毒性均呈下降的趋势,由于降解过程中在阳极室生成高毒性的苯醌,阳极室毒性均先升高后降低.通过相关性分析得到,两种体系理论计算毒性与实际毒性在P=0.01水平下,相关性系数均为1,显著相关,表明降解过程中实际毒性的测定结果真实可靠.降解至120 min时,三电极体系毒性小于两电极体系,表明三电极体系优于两电极体系.据此提出实际毒性测定方法在电化学还原-氧化工艺降解氯酚类有机废水毒性测试的工业应用中有着广泛的前景.

Toxicity of 4-Chlorophenol Solution Under Electrochemical Reduction-oxidation Process

The Pd-Fe/graphene multi-functional catalytic cathode was prepared by UV-assisted photocatalytic reduction. The catalytic cathode and a Ti/IrO₂/RuO₂ anode consisting of both three-electrode system (two cathodes) and two-electrode system (one cathode) were designed for the degradation of 4-chlorophenol in aid of electrochemical reducing and oxidizing processes. The concentrations of the intermediates and products were monitored by high performance liquid chromatography (HPLC), total organic carbon (TOC), and ion chromatography (IC). The theoretical toxicity was calculated according to the formula. The actual toxicity of the solution during the degradation process was detected using the luminescent bacteria. The comparison of the actual toxicity and theoretical toxicity was performed to analyze the trend of the two systems. The results showed that the toxicity of the solution in anode compartment first increased and then decreased, but the toxicity in cathode compartment decreased during the whole degradation for both systems. This trend could be attributed to the intermediate formed, benzoquinone. Through the analysis of correlation, the correlation coefficient was 1 of the theoretical toxicity and actual toxicity at the level of P=0.01, which indicated the result of toxicity was reliable. The toxicity of three-electrode system was lower than that of two-electrode system after 120 min. The three-electrode system was considered to be better than the two-electrode system. Therefore, the detection of actual toxicity in electrochemical reducing and oxidizing process for the degradation of chlorophenols in the actual industry has wide application prospect.