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

In this study an electromagnetic heating strategy is proposed for remediation of trichloroethene (TCE) by ball milled, sulfidated microscale zero valent iron (S-mZVI) particles. S-mZVI 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 (with S/Fe molar ratio of 0.1), compared with ~55 ℃ and ~80 ℃ for ZVI and ball milled mZVI, respectively. The application of AC EMF accelerated the TCE degradation rate (k = 5.5 × 10 h) by up to 4-fold without compromising or even enhancing electron efficiency of S-mZVI 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 Fe exposure caused by AC EMF. In real groundwater, the AC EMF maintained the same promoting effects for TCE dechlorination by S-mZVI. This study shows that combination of filed-scale available AC EMF with S-mZVI provides a promising approach for remediation of chlorinated hydrocarbons in contaminated groundwater.