纳米Fe、Si体系对3,3′,4,4′-四氯联苯的脱氯降解

研究了纳米Fe、Si体系降解3,3′,4,4′-四氯联苯(PCB77)的动力学差异.结果表明,纳米Fe0、纳米Fe3O4和纳米Si0对PCB77均有降解作用,该降解为还原脱氯反应.降解过程符合准一级反应动力学,反应速率常数Kobs分别为0.0177,0.0038,0.0045h-1.PCB77初始浓度为5mg/L,纳米材料投加量为5g/L,溶液pH4.5条件下,纳米Fe0体系对PCB77降解效果最为显著,64h时PCB77残留率仅为19.83%,氯离子浓度为50.3μmol/L,反应体系pH值从4.5升至5.26.纳米双元体系Fe0和Si0、Fe3O4和Si0对PCB77降解过程也符合准一级反应动力学,反应速率常数Kobs分别为0.0114,0.004h-1,其中纳米Fe0和Si0体系降解效果优于纳米Fe3O4和Si0体系.PCB77残留率分别为34.91%和66.62%,氯离子浓度分别为40.07,20.47μmol/L,反应体系pH值变化不明显.随着溶液初始pH值增加,纳米Fe0、纳米Fe3O4降解PCB77效果明显降低,但溶液pH值升高有利于纳米Si0对PCB77的降解.两组纳米双元体系对PCB77的降解效果受pH值影响小.

Dechlorinstive degradation of 3,3',4,4'-tetrachlorobiphenyl by nanometer-sized Fe and Si

The degradation kinetics of 3,3′,4,4′-tetrachlorobiphenyl (PCB77) by nanometer-sized iron and silicon were studied. PCB77 could be dechlorinated by nanometer-sized Fe0, Fe3O4 and Si0, which followed with the pseudo first-order reaction kinetics, and the reaction rates (Kobs) were 0.0177h-1, 0.0038 h-1 and 0.0045h-1, respectively. When the initial concentration of PCB77 was 5 mg/L, the amount of nanomaterials was 5 g/L and pH was at 4.5, the degradation efficiencies of nanometer-sized Fe0 to PCB77 was the highest,and the residual rate of PCB77 was 19.83% after 64 h and the concentration of chlorion was 50.3 μmol/L with significant change of pH from 4.5 to 5.26. Similarly, the degradation of PCB77 by nanometer-sized Fe0 and Si0, Fe3O4 and Si0 composition followed the pseudo first-order reaction kinetics, and the reaction rates (Kobs) were 0.0114 h-1 and 0.004 h-1 respectively. The degradation efficiencies of nanometer-sized Fe0 and Si0 composition were better than nanometer-sized Fe3O4 and Si0 combination, the residual rates of PCB77 were 34.91% and 66.62%, and the concentrations of chlorion were 40.07 μmol/L and 20.47 μmol/L without the change of pH. The degradation efficiencies of nanometer-sized Fe0 and Fe3O4 to PCB77 decreased with increasing of initial pH, while the degradation efficiencies of nanometer-sized Si0 to PCB77 increased with increasing of initial pH. The degradation efficiencies of nanometer-sized Fe0 and Si0, Fe3O4 and Si0 composition were not almost influenced by pH.