Comparative study on trichloroethylene degradation enhanced by three organic acid chelating agents in sodium percarbonate/Fe(II) system in the presence of surfactant

Abstract

Based on a few studies on the effect of different chelators on the Fenton system in a solution containing surfactants, sodium dodecyl sulfate (SDS) was selected as an exemplary surfactant to conduct a comparative study on trichloroethylene (TCE) degradation of Fe(II) catalyzed sodium percarbonate (SPC) system by citric acid (CA), oxalic acid (OA), and glutamic acid (GA) chelating agents, respectively. All these three chelators could relieve the inhibition of SDS on TCE removal. Due to the existence of SDS, GA had the most significant promoting effect on TCE degradation. According to Fe(II) concentration and the decomposition of chelators, it was proved that GA system combined with SDS could maintain the highest Fe(II) content and accelerate the formation of hydroxyl radical (HO•). Probe, scavenging, and EPR experiments demonstrated that SPC/chelated-Fe(II) systems produced more HO•. The hysteresis of the dechlorination process was found in the chloride ion release test, certifying that the degradation process of TCE in chelating systems was complicated. Through solution matrixes and actual groundwater experiments, the chelating systems could broaden the scope of pH application, reduce the influence of inorganic ions, and have a good practical application prospect.