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

Based on a few studies on the effect of different chelators on the Fenton system in a solution containing sur-factants, 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 center dot). Probe, scavenging, and EPR experiments demonstrated that SPC/chelated-Fe(II) systems produced more HO center dot. 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.

Automated summary

Based on a comparative study, it was found that citric acid (CA), oxalic acid (OA), and glutamic acid (GA) chelating agents could relieve the inhibition of sodium dodecyl sulfate (SDS) on trichloroethylene (TCE) removal in the Fe(II) catalyzed sodium percarbonate (SPC) system. GA, in particular, had the most significant promoting effect on TCE degradation due to the presence of SDS. The combination of GA and SDS could maintain the highest Fe(II) content and accelerate the formation of hydroxyl radical (HO center dot), leading to increased TCE removal.