Effects of common dissolved anions on the reduction of para-chloronitrobenzene by zero-valent iron in groundwater.

C Le, J H Wu, S B Deng, P Li, X D Wang, N W Zhu, P X Wu

Index: Water Sci. Technol. 63(7) , 1485-90, (2011)

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Abstract

Batch tests were conducted to evaluate the influences of several common dissolved anions in groundwater on the reduction of para-chloronitrobenzene (p-CNB) by zero-valent iron (ZVI). The results showed that p-CNB reduction was enhanced by both Cl(-) and SO(4)(2-). HCO(3)(-) could either improve or inhibit p-CNB reduction, depending on whether the mixing speed was intense enough to rapidly eliminate Fe-carbonate complex deposited on ZVI surface. Above a concentration of 100 mg L(-1), NO(3)(-) increased the p-CNB reduction rate. The reduction rate by ClO(4)(-) decreased because the ClO(4)(-) competed with p-CNB for electrons. The p-CNB reduction was inhibited by PO(4)(3-), SiO(3)(2-) and humic acid, in the order humic acid < PO(4)(3-) < SiO(3)(2-), since these ions could form inner-sphere complexes on iron surface. The reaction even ceased when the ion concentrations were greater than 4, 0.5, and 30 mg L(-1), respectively. The results indicated that common dissolved anions in groundwater should be taken into account when ZVI is applied for contaminated groundwater remediation.