Abiotic Degradation of Trichloroethylene by Iron Minerals

Trichloroethylene (TCE) is a dense liquid chemical often used as an industrial degreaser. TCE poses public health risks as a probable carcinogen, with growing evidence of negative effects to developmental, reproductive, and hepatic health. Traditional cleanup of aquifers contaminated with TCE is expensive, difficult, and inconsistent because TCE sinks to the bottom of an aquifer, making access and precise location challenging. Exploring the potential for iron minerals within an aquifer, such as magnetite, to break down TCE at the site of contamination opens the door to natural attenuation of TCE, reducing costs and carbon emissions related to cleanup. Though magnetite alone is not effective in breaking down TCE, magnetite in the presence of aqueous sulfide may form iron (II) sulfide (mackinawite), a mineral with proven success in reductive dechlorination of TCE. For this study, reactors were made at pH 6 and 7 with magnetite, sulfide, and TCE. There was no reduction of TCE in any of these reactors. However, in each of these reactors, the concentration of aqueous sulfide dropped dramatically, and one reactor showed evidence of the formation of greigite (Fe₃S₄). Further research should explore the reaction between magnetite, sulfide, and TCE at higher pHs, and more work is needed in characterizing solid products of the reaction between magnetite and sulfide.