EFFECTS OF pH VALUE ON THE REDUCTIVE DEGRADATION OF NITROBENZENE IN SIMULATED GROUNDWATER BY ZERO-VALENT IRON

Batch experiments were conducted to investigate the effects of different pH values on the reduction of nitrobenzene (ArNO2) in simulated groundwater by zero-valent iron (ZVI).Experimental results showed that nitrobenzene in simulated groundwater could be reductively degraded effectively by zero-valent iron. The optimum pH for the reduction was found to be 3.0 within the tested pH ranges of 3.0 to 12.0. The pH value tended to increase gradually with the progress of reduction reaction. At various pH values, the reduction of nitrobenzene by ZVI seemed to follow pseudo-first-order kinetics, and the observed kinetic constant kobs increased with decreasing pH. Both the reduction rate of nitrobenzene and the formation of aniline decreased with increasing pH. UV spectral and GC-MS analyses indicated that aniline was the final reaction product of ArNO2 when reduced by zero-valent iron.