The bimetal system has been proved as the efficient material to dechlorinate many chlorinated organic pollutants.  It is also known that addition of nickel ions to polyethylene-coated zerovalent silicon (SiPEG) can effectively dechlorinate tetrachloroethylene. However, the electrochemical reduction of Ni(II) to Ni(0) would increase produce SiO2 on the surface of Si, leading to the decrease in reactivity of SiPEG.  In this study, the Ni(0) was physically mixed with SiPEG to dechlorinate trichloroethylene (TCE) and found that the dechlorination efficiency and rate  of TCE by Ni(0)/SiPEG can be significantly enhanced. The XPS and EPMA analysis showed that the enhanced reactivity of SiPEG is mainly due to the less formation of silica on active surface of silicon.  The pseudo-first-order rate constant for TCE dechlorination by 0.05 g SiPEG and 0.01 g Ni(0) is 0.68 h-1 while no obvious degradation of TEC was found when only Si(0)/Ni(0) system was applied.  Ethane was found as the only end product during the dechlorination process.  Moreover, the TCE dechlorination behavior by SiPEG with various addition of Ni(0) from 0.1 to 0.01 g was examined.   The results clearly indicate that the dechlorination rate increased from 0.076 to 0.68 h-1 when Ni(0) loading decreased from 0.1 to 0.01 g.  Results obtained in this study provide another alternative by using SiPEG as the promising materials to further dechlorinate the chlorinated pollutants in the environment.

Enhanced dechlorination of trichloroethylene by PEG coated silicon and zerovalent nickel metal

247th National Meeting (2014)

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