纳米镍/铁和铜/铁双金属对四氯乙烯脱氯研究

以实验室合成的纳米双金属颗粒(Ni/Fe和Cu/Fe)为反应材料,对四氯乙烯(PCE)进行脱氯试验研究.纳米金属颗粒(直径范围在1～100nm)比表面积比微米级铁颗粒高数十倍.结果表明,纳米Ni/Fe和Cu/Fe对四氯乙烯有明显的脱氯作用,且脱氯反应符合准一级反应动力学方程;在作为还原剂的铁表面镀上一薄层起催化作用的金属Ni或Cu,催化剂的存在大大降低脱氯反应活化能,提高了脱氯速率,并减少氯代副产物的产量.与零价铁及微米级双金属系统(Ni/Fe,Cu/Fe)相比,纳米颗粒对PCE的脱氯速率有明显提高,尤其是纳米Ni/Fe,标准化反应速率常数KSA为4.283 mL·m-2·h-1,分别比零价铁和微米级Ni/Fe系统快33.23倍和11.59倍.纳米Cu/Fe标准化反应速率常数KSA为1.194 mL·m-2·h-1,分别比零价铁和微米级Cu/Fe双金属系统快9.26倍和5.24倍.在相同条件下,纳米Ni/Fe脱氯速率常数KSA是纳米Cu/Fe的3.59倍.

Dechlorination of tetrachloroethene with nanoscale Ni/Fe and Cu/Fe bimetallic particles

Nanoscale bimetallic particales( Ni/Fe and Cu/Fe) have been synthesized in the laboratory for the treatment of tetrachloroethene (PCE). Specific surface areas of the nanoscale particles are tens of times larger than those of microscale metal particles. Experiment results show that bimetal systems are effective to the dechlorination of PCE and the reactions fit first order reaction kinetic equation. A bimetallic structure is adopted in which a thin layer of catalyst(e.g., Ni, Cu) is deposited on the surface of a reductant (e.g., Fe).The catalyst reduces activation energy and increases the rate of dechlorination reactions. More importantly, production of chlorinated byproducts is less than 10% that is reported in studies with iron particles. The reaction rate constant (KSA) is 4.283 mL·m-2·h-1for nanoscale Ni/Fe. It is about 33.23, 11.59 times higher than that of microscale iron and Ni/Fe, respectively. KSA is 1.194 mL·m-2·h-1 for nanoscale Cu/Fe. It is about 9.26, 5.24 times higher than microscale iron and Cu/Fe, respectively. KSA of nanoscale Ni/Fe is 3.59 times than that of nanoscale Cu/Fe under the same condition.