Generation and intensity of active oxygen species in thermally activated persulfate systems for the degradation of trichloroethylene

Abstract

The degradation of trichloroethylene (TCE) was evaluated in a thermally activated persulfate system and the generation of active oxygen species investigated using various probe compounds. The experimental results showed that TCE was completely degraded in 9 min at 50 °C with an initial TCE concentration of 0.15 mM and a dose of 0.3 M persulfate. The influence of the solution matrix on the degradation of TCE was evaluated and it was shown that concentrations of 100 mM Cl⁻, 10 mM HCO₃⁻ and 100 mg L⁻¹ humic acid (HA) affect the degradation of TCE. In addition, tests investigating the effects of Cl⁻, HCO₃⁻ and HA on the generation and intensity of active oxygen species showed that HCO₃⁻ affected the degradation of TCE by decreasing the intensities of ˙SO₄⁻ and ˙OH, while increasing the intensity of ˙O₂⁻. In contrast, Cl⁻ and HA influenced the degradation of TCE by decreasing the intensities of ˙OH and ˙O₂⁻ while increasing the intensity of ˙SO₄⁻. The results from this study provide a key foundation for further studies of the remediation of groundwater contaminated by chlorinated solvents using the thermally activated persulfate process.