利用扫描电镜技术研究纳米Ni-Fe颗粒对四氯化碳快速脱氯的机理  

Kinetics and Mechanism of Carbon Tetrachloride Rapid Reduction by Nanoscale Ni-Fe Particles Using Scanning Electron Microscope

作　　者：黄园英[1] 王倩[2] 韩子金 刘菲[2] 

机构地区：[1]国家地质实验测试中心,北京100037 [2]中国地质大学(北京)水资源与环境学院,北京100083

出　　处：《岩矿测试》2015年第3期346-352,共7页Rock and Mineral Analysis

基　　金：国土资源部公益性行业专项(201411089)

摘　　要：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%CH2Cl2。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 CH2Cl2（ ~ 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 byproduct. 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 laboratorysynthesized 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.

关 键 词：扫描电镜 纳米Ni-Fe颗粒 四氯化碳 脱氯机理 

分 类 号：P575.2[天文地球—矿物学] TB383[天文地球—地质学]