Degradation of Para-nitrochlorobenzene by the Combination of Zero-valent Iron Reduction and Persulfate Oxidation in Soil

摘要

The oxidation of para-nitrochlorobenzene (pNCB) by persulfate (PS) activated with zero-valent iron (Fe-0) was investigated through a series of batch experiments. The pNCB reduction ratio increased with the decrease of the initial solution pH. It is found that temperature and Fe-0 dosage could also influence the pNCB removal. Under the conditions of initial Fe-0 dosage 0.8mmol/g, initial pH of 6.6, and 25 degrees C, 66.3% of pNCB was reduced in 6h. The pNCB was slightly degraded in the presence of PS alone. When PS was dosed after 2h of Fe-0 reduction, significantly higher pNCB removal (94.1%) and mineralization (36.4%) were obtained relative to the case of simultaneous dosing of Fe-0 and PS (85.3% removal, 22.6% mineralization). This indicates that the reduction product of pNCB was more easily oxidized by PS than pNCB, suggesting that converting the nitro groups of pNCB to amino groups prior to oxidation can enhance their oxidation. These results suggest that a sequential Fe-0 reduction-PS oxidation process may be an effective strategy to promote pNCB decomposition in contaminated soil.