纳米Fe0/Fe3O4复合体系对溶液中PCB77的降解研究

研究了纳米Fe0与纳米Fe3O4单一与复合体系对溶液中PCB77的降解动力学,以及影响降解效率的不同因素.结果表明,投加纳米Fe0对PCB77有显著的降解效果,反应240 min后PCB77残留率为8.94％；投加纳米Fe0同时配以不同比例的纳米Fe3O4能明显影响PCB77的降解速率,纳米Fe0/Fe3O4投加比例为1∶0.1、1∶0.2和1∶1时,PCB77的残留率分别为6.46％、10.23％和38.20％.溶液pH对纳米Fe0/Fe3O4复合体系降解PCB77具有较大的影响,当溶液pH为6.8时,纳米Fe0/Fe3O4复合体系降解PCB77的效果最好.纳米Fe0Fe3O4复合体系对PCB77的降解是一个还原脱氯的过程,随着PCB77残留率的减小,氯离子浓度不断增大,同时反应体系中氧化还原电位不断降低.研究结果将为环境中残留PCBs提供一种高效去除方法,并为PCBs污染水体和土壤的修复提供理论依据.

Degradation Kinetics of PCB77 in Aqueous Solution by Nanometer-sized Fe0 and Fe3O4 System

The degradation kinetics of 3,3’,4,4’-tetrachlorobiphenyl(PCB77) by nanometer-sized Fe0,Fe3O4 system and different factors that affected the degradation efficiency were studied.The results showed that nanometer-sized Fe0 could degrade PCB77 in aqueous solution efficiently.When the initial concentration of PCB77 was 5 g·L-1 and the dose of nanometer-sized Fe0 was 5 g·L-1,the residual rate of PCB77 in aqueous solution was 8.94% after 240 minutes.Different doses of nanometer-sized Fe0 and Fe3O4 could influence the PCB77 degradation rate significantly.When the nanometer-sized Fe0/Fe3O4 dosing ratios were 1:0.1,1:0.2 and 1:1,residual rates of PCB77 in aqueous solution were 6.46%,10.23% and 38.20%,respectively.The solution pH also had a great influence on PCB77 degradation by nanometer-sized Fe0 and Fe3O4 system.From our experiments when the pH value was 6.8,degradation efficiency of PCB77 by nanometer-sized Fe0 and Fe3O4 system was highest among different pH condition.Degradation of PCB77 by nanometer-sized Fe0 and Fe3O4 system was a dechlorination process and the chlorion concentration increased with the decreasing residual rate of PCB77.Meanwhile,oxidation-reduction potential was declined accordingly.The research will not only provide an efficient method for removing residual PCBs in the environment,but also support the restoration theory of PCBs contaminated soil and water.