Enhanced degradation of ortho -nitrochlorobenzene by the combined system of zero-valent iron reduction and persulfate oxidation in soils

ortho -Nitrochlorobenzene ( o -NCB) in soil poses significant health risks to human because of its persistence and high toxicity. The removal of o -NCB by both zero-valent iron (ZVI) and chemical oxidation (persulfate) was investigated by batch experiments. The o -NCB removal rate increases significantly from 15.1 to 97.3 % with an increase of iron dosage from 0.1 to 1.0 mmol g −1 . The o -NCB removal rate increases with the decrease of the initial solution pH, and a removal efficiency of 90.3 % is obtained at an initial pH value of 6.8 in this combined system. It is found that temperature and soil moisture could also increase the o -NCB removal rate. The o -NCB degradation rate increases from 83.9 to 96.2 % and from 41.5 to 82.4 % with an increase of temperature (15 to 35 °C) and soil moisture (0.25 to 1.50 mL g −1 ), respectively. Compared to the persulfate oxidation system and ZVI system, the persulfate–iron system shows high o -NCB removal capacity. o -NCB removal rates of 41.5 and 62.4 % are obtained in both the persulfate oxidation system and the ZVI system, while the removal rate of o -NCB is 90.3 % in the persulfate–iron system.