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 SO42−. HCO3− 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, NO3− increased the p-CNB reduction rate. The reduction rate by ClO4− decreased because the ClO4− competed with p-CNB for electrons. The p-CNB reduction was inhibited by PO43−, SiO32− and humic acid, in the order humic acid < PO43− < SiO32−, 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.
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; Effects of common dissolved anions on the reduction of para-chloronitrobenzene by zero-valent iron in groundwater. Water Sci Technol 1 April 2011; 63 (7): 1485–1490. doi: https://doi.org/10.2166/wst.2011.392
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