EDTA优化纳米Pd/Fe对2,4-D的催化脱氯研究

Catalytic dechlorination of 2,4-D in aqueous solution by nanoscale Pd/Fe in the presence of EDTA

采用EDTA优化纳米Pd/Fe催化脱氯水中2,4-二氯苯氧乙酸(2,4-D),并考察了EDTA投加浓度、pH、钯化率、温度等因素对2,4-D还原的影响.结果表明,EDTA的加入络合了纳米Pd/Fe在催化脱氯过程中生成的铁离子,抑制纳米Pd/Fe颗粒表面钝化层的形成,提高了体系的反应活性.适宜的EDTA浓度、低pH、高钯化率、低温等有利于2,4-D的还原脱氯.当EDTA浓度为25.0 mmol·L-1,纳米铁含量为1.0 g·L-1,初始pH=4.3、钯化率为0.5%,温度为25.0℃,搅拌速率为200 r·min^(-1)时,反应50 min,10.0 mg·L-1的2,4-D去除率及苯氧乙酸(PA)生成率均达到100%.

The present study aims to investigate catalytic reduction of 2,4-Dichlorophenoxyacetic acid（ 2,4-D） by nanoscale Pd / Fe in the presence of EDTA in aqueous solution and to study the effects of EDTA concentration,solution pH,Pd loading and temperature on dechlorination. EDTA could chelate iron ions that were generated by nano zero valent iron（ n ZVI） in the reaction process,and prevent the formation of passivation layer on the surface of n ZVI,therefore enhancing the reactivity of the Pd / Fe nanoparticles. Under the optimized operational conditions（ EDTA = 25.0 mmol·L^-1,n ZVI dosage1.0 g·L^-1,pH= 4.3,0.5% Pd loading,25.0 ℃,200 r·min^-1）,10.0 mg·L^-12,4-D was completely converted to phenoxyacetic acid（ PA） in 50 min.The results demonstrate that the dechlorination of 2,4-D by nanoscale Pd / Fe was significantly enhanced with EDTA.