Preliminary Study On Enhanced Reactivity And Mechanisms Of Mesoporous Carbon Supported Zero-valent Iron Composite For Trichloroethylene Dechlorination

Carbon materials have the advantages of good stability,strong adsorption capability,and excellent conductivity.These characteristics could improve the reactivity and mobility of nanoscale zero-valent iron(nZVI)particles.Iron-carbon composites are considered as a promising method for remediation of organochlorine compounds(OCs)contamination.Ordered mesoporous carbon(CMK-3)supported nZVI composites were synthesized and used for the removal of trichloroethylene(TCE).TCE degradation performance by nZVI/CMK-3 composites were studied.The mechanism of CMK-3 action in TCE dechlorination was also explored.This study attempts to provide guidance for the development of new effective iron-carbon composites.The main conclusions are as follows:(1)CMK-3 inhibited the agglomeration of nZVI particles and enhanced the dechlorination of TCE.The hydraulic diameter of nZVI/CMK-3 composites was reduced from 3672.60?m of nZVI to 1454.30?2007.08?m.The TCE removal efficiency of nZVI/CMK-3 was 2.5 times that of nZVI within 5 days.Dechlorination dominated the process of TCE removal(75.3?79.4%),whereas adsorption accounted for 20.6?24.7%.The dechlorination enhancement by CMK-3 was favored with the increase of CMK-3 content(0?75%)in nZVI/CMK-3.(2)The conductivity and hydrogen adsorption capacity of CMK-3 are essential to the TCE degradation enhancement.These two properties played roles in the direct and indirect electron transfer pathways,respectively.The total corrosion current density of nZVI/CMK-3 composite was 10.69?A/cm~2,which was 17.5 times that of nZVI.The direct electron transfer was significantly enhanced.The great hydrogen adsorption capacity of CMK-3 made a local accumulation of the atomic hydrogen and accelerated TCE reduction.