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

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 degrees 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-)-S-center dot and (OH)-O-center dot, while increasing the intensity of O-center dot(2)-. In contrast, Cl and HA influenced the degradation of TCE by decreasing the intensities of (OH)-O-center dot and O-center dot(2) while increasing the intensity of (SO4-)-S-center dot. 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.