Insight into trichloroethene removal in alkaline condition with the presence of surfactant based on persulfate system

Abstract

Trichloroethene (TCE) degradation was investigated in Fe(II)/citric acid (CA) activated persulfate (PS) system containing surfactant sodium dodecyl sulfate (SDS). Only 37.7% removal of TCE was achieved at PS/Fe(II)/CA/TCE molar ratio of 40/20/20/1 in the presence of 2.3 g L−1 SDS with pH unadjusted (pH = 2.96). However, this result was significantly increased to 81% after adjusting the initial solution pH = 9.0. The presence of SDS inhibited TCE degradation and this inhibitory effect was initially increased and then declined with SDS concentration increase from 0 to 9.2 g L−1. Radical scavenger experiments revealed that the major reactive oxygen species (ROS) contributed to TCE degradation were HO• and SO4−•, while less contribution was owed to O2−•. The intermediates of SDS were identified with GC-MS and possible decomposition pathway of SDS was proposed. The performance of TCE degradation in other solution matrixes were investigated. Actual groundwater tests showed that PS/Fe(II)/CA system possessed huge potential in remediating groundwater contaminated by TCE with SDS presence. This research found that alkaline condition was more favorable for TCE degradation in PS/Fe(II)/CA system in the presence of SDS and the possible reasons for this phenomenon were explored from various aspects.