Decomposition of aqueous tetrachloroethylene by Fenton oxidation treatment

Flask-scale experiments were performed to elucidate the reaction mechanism in which tetrachloroethylene (PCE) in water is decomposed by Fenton oxidati on treatment. Concentrations of Cl-, total inorganic carbon, and PCE were m easured during a 24-h reaction period in which there occurred a pseudo firs t-order reaction (k=0.17 h(-1)) and >95% dechlorination and mineralization. Results indicate that: (i) PCE decomposition due to Fenton oxidation is co mpensated throughout the experiment by increasing Cl- and CO2, and (ii) min eralization rates derived from the increase in CO2 are nearly the same as d echlorination Fates due to the increase in Cl-. GC/MS and GC/ECD analyses o f reaction intermediates confirmed the presence of trichloroacetic acid (TC AA) only. That is, organic compounds such as dichloroacetic acid (DCAA), mo nochloroacetic acid, acetic acid, and formic acid were not detected, having been decomposed by Fenton oxidation although no degradation of TCAA occurr ed and detected TCAA only explained 1% of decomposed PCE. These findings in dicate that dechlorination and mineralization proceed almost simultaneously during PCE decomposition by Fenton oxidation treatment, and not via interm ediates such as acetic acid and DCAA.