Abstract
The combination of zerovalent silicon (Si(0)) with poly(ethylene glycol) (PEG) is a novel technique to enhance the dechlorination efficiency and rate of chlorinated hydrocarbons. In this study, the dechlorination of tetrachloroethylene (PCE) by Si(0) in the presence of various concentrations of PEG was investigated under anoxic conditions. Several surfactants including cetyltrimethylamonium bromide (CTAB), sodium dodecyl sulfate (SDS) and Tween 80 were also selected for comparison. Addition of SDS and Tween 80 had little effect on the enhancement of PCE dechlorination, while CTAB and PEG significantly enhanced the dechlorination efficiency and rate of PCE by Si(0) under anoxic conditions. CTAB could enhance the apparent water solubility of PCE in solution containing Si(0), while PEG prevented the formation of silicon dioxide, and subsequently significantly enhance the dechlorination efficiency and rate of PCE. In addition, the dechlorination rate increased upon increasing PEG concentration and then leveled off to a plateau at 0.2 mM. The k obs for PCE dechlorination by Si(0) in the presence of PEG was 106 times higher than that by Si(0) alone.