Electron induced efficient dechlorination of trichlorethylene with S doped FeB: The enhancement mechanism of S.

In this work, S doped FeB (FeB-S) was synthesized by sintering method and applied for the enhanced dechlorination of trichlorethylene (TCE). The degradation ratio (D) of TCE was 99.8% with reaction rate constant (k) of 0.956 h by 10.0at% S doped FeB (corresponding to FeB-S), compared to D and k values 37.3% and 0.067 h by FeB, respectively. The major dechlorination products of acetylene, ethene, ethane and C-C hydrocarbon compounds were observed from a reductive β-elimination pathway. S doped and undoped FeB could form the first-level in-situ galvanic cell, and the returned S provided a second-level galvanic cell to further enhance electron transfer. The doped S worked as electron donor to increase the density of localized unpaired electrons, and the electron enriched Fe atoms leading to stronger reducibility were verified by the density functional theory (DFT) calculation. This work provides a complete insight into the enhancement mechanism of S doped FeB and guides the potential design of zero-valent iron (ZVI) with properties tailored for chlorinated hydrocarbons dechlorination.