Abstract
Tetrachloroethylene (PCE) and heavy metals are the most often found toxic chemicals in contaminated aquifers. Zero-valent silicon (ZVS) is a promising reductant to effectively reduce PCE. In addition, the reduction of metal ions by ZVS to their zero-valent forms could accelerate the dechlorination efficiency and rate of PCE. The objective of this study was to investigate the synergistic effect of ZVS and metal ions on the dechlorination of PCE. Addition of Ni(II) was found to have better dechlorination efficiency and rate of PCE than the other metal ions (Cu, Fe, Co). XPS results showed that Ni(II) can sorb onto the surface of ZVS, resulting in the formation of Ni(0). Ethane was the major degradation product in Ni-amended solution, depicting that elimination is the major pathway for PCE dechlorination. In addition, the dechlorination rate and mechanism for PCE dechlorination under various pH and ZVS/Ni(II) ratios were determined.