Efficient degradation of trichloroethene with the existence of surfactants by peroxymonosulfate activated by nano-zero-valent iron: performance and mechanism investigation.

Abstract

In this study, the degradation of trichloroethylene (TCE) with the existence of tween-80 (TW-80) or sodium dodecyl sulfate (SDS) using peroxymonosulfate (PMS) activated by nano-zero-valent iron (nZVI) was investigated. Over 87.6% TCE (with 1.3 g L-1 TW-80 presence) was degraded by 0.9 mM PMS and 0.12 g L-1 nZVI, while 89.7% TCE (with 2.3 g L-1 SDS presence) was degraded by 1.2 mM PMS and 0.20 g L-1 nZVI, in which more than 71.9% TCE with TW-80 existence and 87.5% TCE with SDS existence were dechlorinated. Besides, the effects of some factors (i.e., PMS and nZVI dosages, initial solution pH, and inorganic anions) on TCE removal were evaluated. The degradation of TCE was restrained continuously with increasing surfactant concentration, and TW-80 was more easily decomposed than SDS in PMS/nZVI system. Furthermore, sulfate radical (SO4-•) and hydroxyl radical (HO•) were demonstrated the main reactive oxygen species (ROS) contributing to TCE degradation and SO4-• played a dominant role through EPR tests and ROS scavenging experiments. Finally, the results of TCE degradation in actual groundwater confirmed that PMS/nZVI process has great advantages and potential in remediation of actual TCE-contaminated groundwater with TW-80 or SDS existence.