包覆型纳米铁的制备及对三氯乙烯的降解研究  

Preparation of Coated Iron Nanoparticles for Reduction of Trichloroethylene

作　　者：刘炳晶[1] 金朝晖[1] 李铁龙[1,2] 安毅[1] 李淑静[1] 王薇[1] 

机构地区：[1]南开大学环境科学与工程学院,天津300071 [2]天津市城市生态环境修复与污染防治重点实验室,天津300071

出　　处：《环境科学》2009年第1期140-145,共6页Environmental Science

基　　金：国家自然科学基金项目(20477019)

摘　　要：采用微乳包覆法制备出粒径约为80 nm的纳米铁粒子.结果表明,包覆型纳米铁与普通液相法、微乳液法制备纳米铁相比,在空气中能稳定存在7 d,经过700 h后,其对初始浓度为10 mg.L-1三氯乙烯(TCE)的去除率可达90%;对反应动力学规律进行了探讨,认为纳米铁对TCE的还原过程为准一级反应,在无氧、室温、中性条件下,浓度为87.5、175、262.5、350 mg.L-1的包覆型纳米铁的表观速率常数kobs值分别为6.49×10-4、6.64×10-4、7.10×10-4、7.43×10-4min-1,证明kobs与纳米铁质量浓度成正比;纳米铁与TCE的反应过程,是纳米铁失电子,在纳米铁表面生成Fe3O4,在水和Fe3O4界面上生成Fe2O3,TCE得电子降解,主要生成乙烯、乙烷,同时也有少量的其他含氯产物.Nanoscale α-Fe particles with size of about 80nm were prepared with a microemulsion-coated method. The results demonstrated that this kind of iron particles could exist stably in the air for 7 d compared with nanoscale iron particles prepared by liquid-phase and microemulsion methods. The removal rate of trichloroethylene with an initial concentration of 10 mg· L^-1 can reach 90% in 700 b. The reduction kinetics was studied under room temperature, neutral, and anaerobic conditions. Experiments show that the reduction process of TCE by nanoscale iron particles conforms to pseudo first order reaction law. The apparent rate constant （kobs） is proportional to concentration of nanoseale iron particles. The kobs values 6.49 × 10^-4, 6.64 × 10^-4,7.10 × 10^-4 ,7.43 × 10^-4 min^-1 , are corresponding to concentrations of 87.5,175, 262.5,350 mg· L^-1 respectively. In the reaction, nanoscale iron particles provides electrons and forms an inner film of Fe3O4, on the surface of which an outer film of Fe2 O3 is formed together with water. TCE is degraded by electrons. The principal degradation products were ethene and ethane, and smaller amounts of other chlorinated degradation products were also founded.

关 键 词：稳定纳米铁 微乳包覆 三氯乙烯 反应动力学 反应机制 

分 类 号：X703.1[环境科学与工程—环境工程]