摘要
The feasibility of using zerovalent silicon (Si <sup>0</sup> ) as a novel reductant to remove chlorinated compounds and heavy metals in contaminated sites was investigated. The kinetics and degradation mechanism of carbon tetrachloride (CT) by Si <sup>0</sup> were also examined. Results showed that zerovalent silicon could effectively dechlorinate the chlorinated compounds. A nearly complete dechlorination of CT by Si <sup>0</sup> was obtained within 14 h. The produced concentrations of chloroform (CF) accounted for 71-88% loss of CT, showing that reductive dechlorination is the major degradation pathway for the degradation of chlorinated hydrocarbons by Si <sup>0</sup> . The degradation followed pseudo first-order kinetics and the normalized surface reaction rate constant (k <sub>sa</sub> ) for CT dechlorination ranged between 0.0342 and 0.0454 L m <sup>-2</sup> h <sup>-1</sup> when CT concentrations were in the range of 3-20 μM. A linear relationship between the k <sub>sa</sub> and pH value was also established. In addidon, zerovalent silicon has a high capability in the removal of heavy metals. 83% of Cr(VI) was removed by 0.5g Si <sup>0</sup> within 5 h, which is higher than that by Fe <sup>0</sup> . The removal efficiency of divalent metal ions by Si <sup>0</sup> followed the order of Cu(II) > Pb(II) > Ni(II). This indicates that zerovalent silicon is an alternative reductant and can undergo coupled reduction of heavy metals and chlorinated hydrocarbons in contaminated groundwater. © IWA Publishing 2004.