负载型纳米Pd/Fe对挥发性氯代烃的去除

Removal of Volatile Chlorinated Hydrocarbons in Water by Supported Nanoscale Pd/Fe Particles

氯代烃的污染治理已成为当今世界最热门的研究领域之一。以水体中最常见的氯代烃污染物1,1-二氯乙烯(1,1-DCE)、林丹(γ-HCH)为主要目标污染物,探讨了不同条件下负载型纳米Pd/Fe对氯代烃的去除效果。负载型纳米Pd/Fe采用浸渍→液相还原→还原沉淀的方法制备,透射电镜显示采用该方法制备的负载型金属钯和铁的平均粒径均在纳米级范围内。负载型纳米Pd/Fe具有较高的表面反应活性,当负载型纳米Pd/Fe用量为40 g/L、反应时间达2 h时,1,1-二氯乙烯和林丹的去除率分别达到85%和100%。脱氯率与Pd/Fe投加量、钯含量、初始pH值、反应温度等因素有关,与溶液的初始浓度关系不大。负载型纳米Pd/Fe对1,1-DCE和γ-HCH去除均符合一级反应动力学方程,速率常数分别为0.528 3 h-1及2.012 9 h-1,反应的半衰期t1/2分别为1.31 h和0.34 h。推断在反应过程中,Fe腐蚀产生的H2为主要还原剂,Pd是良好的加氢催化剂,在金属颗粒表面形成高浓度反应相,使反应短时间内完成。

Control of chlorinated hydrocarbons pollution has gradually become the top research field in modern world.In order to investigate the removal ability of chlorinated hydrocarbons,the most widely existent pollutants,dichloroethylene（1,1-DCE） and Lidane（γ-HCH）were chosen as the aim pollutants,and the synthetical supported nanoscale Pd/Fe were chosen as the reaction medium.The supported Pd/ Fe bimetallic catalysts were made by the procedures of impregnation,liquid reduction,and reductive precipitation.The grain size of palladium and iron are at the nanoscale by the transmission electron microscope.The Fe/ Pd systems proved to be very effective,and the removal rate of 1,1-DCE and γ-HCH in 2 hours respectively reached about 85% and 100%.The removal of 1,1-DCE and γ-HCH in water by the supported Pd/Fe bimetallic catalysts follows the pseudo-frist order kinetics with the half-life t1/2 of 1.31 h and 0.34 h.The amount of Pd/ Fe,Pd/ Fe ratio,pH and reaction temperatures are the most important factors that affect the removal efficiency and there is little relationship with the initial concentration.During the reactions,H2,coming from eroded Fe,may be the main reducer.Pd is a good hydrogenation catalyst and it formed a high concentration reaction phase in the surface of Pd/Fe-Al2O3 particles which accelerated the reaction rate.