You are here:
DEVELOPMENT OF SULFATE RADICAL-BASED CHEMICAL OXIDATION PROCESSES FOR TREATMENT OF PCBS
Citation:
RASTOGI, A., S. R. AL-ABED, AND D. D. DIONYSIOU. DEVELOPMENT OF SULFATE RADICAL-BASED CHEMICAL OXIDATION PROCESSES FOR TREATMENT OF PCBS. Presented at The 13th International Conference of Advanced Oxidation Technologies for Treatment of Water Air and Soil, Niagara Falls, NY, September 24 - 27, 2007.
Impact/Purpose:
to present information
Description:
This study investigates transition metal based activation of peroxymonosulfate for generation of highly reactive sulfate radicals to degrade Polychlorinated Biphenyls (PCBs) in contaminated aqueous and sediment systems. Environmental friendly transition metal iron (Fe (II), Fe (III), ZVI) have been evaluated as a potential activator of a common stable oxidant, peroxymonosulfate. In homogeneous system both Fe (II) and Fe (III) were found effective in activating the oxidant. Elevated concentrations of Fe (II) were observed to produce an adverse effect on the degradation efficiency. Fe (II) acts as a sulfate radical scavenger at high concentrations indicating that there is an optimum concentration of Fe (II) for effective degradation of target contaminant. Though Fe (II) based systems showed faster kinetics, Fe (III) based system were less prone to radical quenching as observed in the Fe (II)-PMS system at higher Fe (II) concentration. At high pH, precipitation of iron from the solution was observed to be the main cause of the decrease in the degradation efficiency. For this reason, a low molecular weight multidentate metal chelating agent, sodium citrate was used to control the quantity of iron (Fe (II), Fe (III)) in the solution for effective activation of the oxidant. In presence of sodium citrate, improved degradation efficiency was observed up to metal: ligand ratio 1 :2, after which the increase in citrate concentration led to decrease in removal efficiency. In heterogeneous system both zero valent iron (ZVI) and iron oxide (Fe304) were found effective in activating peroxymonosulfate. The effect of catalyst concentration and pH on PCB degradation efficiency will be discussed.