REDUCTIVE DECHLORINATION OF TETRACHLOROETHYLENE BY GRS WITH PLATINUM

摘要

Green rust (GR), a layered Fe(II)-Fe(III) hydroxide solid phase with an anion in the interlayer, has been discovered as an intermediate corrosion product of iron under natural and alkaline conditions in suboxic soil and sediments. GRs have been named based on the anion content in their interlayers. Many studies already used GRs in reductive dechlorination of chlorinated compounds. It has been reported that carbon tetrachloride(CT), tetrachloroethylene (PCE), trichloroethylene (TCE), cis-dicloroethylene (cis-DCE) and vinyl chloride (VC) were successfully degraded by GR-SO4 . GR-Cl has been also used to reduce CT, TCE and PCE. Recently, it has been reported that the reactivity of GRs in reductive dechlorination could be improved by the addition of trace metals such as Cu, Ag, Au and Hg. The reaction rate by GR-SO4 with trace metals was enhanced up to three orders-of-magnitude compared to that of GR-SO4 alone. In this research, Pt was selected as a trace metal to improve the reactivity of GRs since Pt has also appeared to have the capability of improving the dechlorination rate by zero-valent iron (ZVI). We synthesized four different types of GRs (GR-Cl, GR-SO4, GR-CO3 and GR-F), modified them with Pt and used them in reductive dechlorination of PCE. PCE was selected as the target compound since it was one of the major contaminants observed in the superfund and national priority list (NPL) sites.