纳米铁具有高的比表面积和高反应活性，能快速将氯代烯烃还原成无毒氯离子、乙烯和乙烷，但对于氯代烷烃的脱氯仍能产生大量的氯代中间或最终产物，可以通过合成制得纳米双金属提高脱氯速率和减少氯代中间产物。本文利用扫描电镜测得实验室制备的纳米 Ni －Fe（2％，质量分数）颗粒直径为20～60 nm，通过批实验方式对纳米 Ni －Fe 降解四氯化碳的反应动力学性质、产物、持久性能和反应机理进行了探讨。结果表明，纳米 Ni －Fe 体系主要最终产物为42％ CH4和17％ CH2 Cl2。与铸铁屑和纳米铁相比，纳米Ni －Fe由于催化脱氯加氢，显著提高了氯代烃脱氯速率，同时降低了有毒氯代产物的产量，且 Ni 作为催化剂不会进入水体引起二次污染。纳米 Ni －Fe 颗粒在空气中具有很好的稳定性，虽然降解四氯化碳的最终产物CH4与纳米 Pd －Fe 相比少13％，但由于价格便宜，有望在工程上应用于氯代有机化合物水土污染治理。%The nanoscale iron particles have high specific surface area and high reactivity,can be used to rapidly reduce chlorinated alkene to the non-toxic chloride ions,chlorine-free end products ethene and ethane.But nanoscale iron particle degrades chlorinated alkanes with much toxic intermediate or end products.A small amount of a second metal deposited on the iron surface has proved to enhance the reactivity of metal particles.In this paper,laboratory-synthesized nanoscale Ni-Fe (2% by weight)particles have diameters on the order of 20 -60 nm using Scanning Electron Microscope.In batch experiments,the kinetics,products,stability of performance,and mechanism of carbon tetrachloride (CT)by Ni-Fe nanoparticles were investigated.CH4 (~42%)and CH2 Cl2 (~17%)in nanoscale Ni-Fe system were the major end products.Compared to nanoscale iron and the cast iron scarp,a major benefit of the nanoscale Ni-Fe particles for treatment of CT is the low yield of chlorinated by-product.Due to the presence of catalyst (Ni)on the surface,dechlorination rate was significantly increased and production of chlorinated byproducts was notably reduced.Catalytic metal Ni from the nanoscale Ni-Fe particles would not dissolve into water so that it would not form a secondary contamination of water body.The laboratory-synthesized nanoscale particles are quite stable under ambient conditions.For nano-scale Ni-Fe particles system, the end-product CH4 were reduced by 13% compared with nanoscale Pd-Fe particles.Although tnano-scale Pd-Fe particles are effective in dechlorination of chlorinated organic compounds,nano-scale Ni-Fe particles are more economically viable which made it possible for the large scale remediation of water and soil contaminated by chlorinated organic compounds.
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