纳米Fe_3O_4协同微生物对除草剂2,4-D的降解

Degradation of 2,4-D by Combined Use of Nanoscale Fe_3O_4 and Microorganism

【目的】采用纳米Fe3O4协同微生物降解水溶液中2,4-D,提高2,4-D的降解效率,为有机氯农药污染环境的生物修复提供理论基础。【方法】利用纳米Fe3O4的还原作用脱去2,4-D环上的氯原子,使其毒性降低或消除;再利用微生物的共代谢作用,引入降解菌,协同降解2,4-D。通过分析纳米Fe3O4与微生物之间的相互关系,揭示纳米Fe3O4与微生物降解的协同作用机理。【结果】纳米Fe3O4对2,4-D有还原降解作用,投加纳米Fe3O4体系中2,4-D浓度降低、氯离子浓度升高,纳米Fe3O4对2,4-D的降解是一个还原脱氯过程;微生物能以2,4-D为C源,投加降解菌体系中2,4-D浓度降低、微生物生长的OD600值增大,2,4-D为微生物生长提供营养;纳米Fe3O4/微生物联合体系能明显加快2,4-D的降解,7 d时2,4-D的残留率降至35.7%,远低于纳米Fe3O4或微生物单独降解体系中2,4-D的残留率。采用微生物对中间产物2,4-DCP进行降解,反应5 d时,2,4-DCP的残留率为50.1%,相应地,降解菌生长的OD600值为3.29。【结论】纳米Fe3O4/微生物联合体系对2,4-D的降解效率显著高于单一纳米Fe3O4或微生物体系;纳米Fe3O4能够刺激微生物的生长,2,4-D还原降解的中间产物2,4-DCP比2,4-D更易于被微生物降解。

【Objective】 The degradation of 2,4-D with a combination of nanoscale Fe3O4 and microorganism in solution was studied.The research will provide a basis for remediation of pesticide pollution.【Method】 Nanoscale Fe3O4 would eliminate the toxicity by reductively transform the electron-withdrawing chlorine groups to chloride,then the bacteria was employed to combine with nanoscale Fe3O4 to degrade 2,4-D.The combination mechanism was revealed by analysis of the relationship between bacteria and nanoscale Fe3O4.【Result】 The results showed that the residual rates of 2,4-D decreased from 100% to 52.0% in 48 h in the presence of 300 mg？L-1 Fe3O4 nanoparticles.Meanwhile,the concentration of chloride ion was increased to 85 μmol？L-1,and the degradation of 2,4-D was a preliminary reductive dechlorination process.2,4-D could provide carbon sources for promoting microbial growth,and the residual rates of 2,4-D was 57.0% in 5 days by the microorganism treatments.The combination of nanoscale Fe3O4 with microorganism had significantly increased degradation of 2,4-D,and the residual rates of 2,4-D decreased to 35.7% in 7 days,which was much lower than the single treatment of nanoscale Fe3O4 or microorganism.Additionally,microorganisms was also used to degrade 2,4-DCP which was the reductive degradation products of 2,4-D,the residual rates of 2,4-DCP was 50.1% in 5 days,accordingly,the growth OD600 value of microorganisms was 3.29.【Conclusion】 The degradation rate of 2,4-D by combination treatment was much higher than that separate nanoscale Fe3O4 or microorganism.Nanoscale Fe3O4 could stimulate the growth of microorganisms and reductive degradation product 2,4-DCP was more apt to degradation than 2,4-D.