Enhanced dechlorination of trichloroethene by sulfidated microscale zero-valent iron under low-frequency AC...

In this study an electromagnetic heating strategy is proposed for remediation of trichloroethene (TCE) by ball milled, sulfidated microscale zero valent iron (S-mZVI^bm) particles. S-mZVI^bm is ferromagnetic, which generates heat under the application of a low-frequency alternating current electromagnetic field (AC EMF). We found that the temperature reached up to ~120 ℃ during 30-min electromagnetic induction heating of 10 g/L S-mZVI^bm (with S/Fe molar ratio of 0.1), compared with ~55 ℃ and ~80 ℃ for ZVI and ball milled mZVI^bm, respectively. The application of AC EMF accelerated the TCE degradation rate (k_TCE = 5.5 × 10^-1 h^-1) by up to 4-fold without compromising or even enhancing electron efficiency of S-mZVI^bm compared to no-heating. Furthermore, this process halved the generation of chlorinated intermediate, cis-DCE. In contrast, water-bath heating only increased the dechlorination rate 2-fold with unchanged cis-DCE generation and lowered electron efficiency. This is attributed to both rising temperature by induction heating and accelerated ZVI corrosion and surface Fe⁰ exposure caused by AC EMF. In real groundwater, the AC EMF maintained the same promoting effects for TCE dechlorination by S-mZVI^bm. This study shows that combination of filed-scale available AC EMF with S-mZVI^bm provides a promising approach for remediation of chlorinated hydrocarbons in contaminated groundwater.