Advanced oxidation processes of decomposing dichloroacetic acid and trichloroacetic acid in water     

WANG Kun-ping  GUO Jin-song  YANG Min  JUNJI Hirotsuji  DENG Rong-sen  LIU Wei 《重庆大学学报(英文版)》2008,7(3):171-178

We studied the decomposition of two haloacetic acids （HAAs）, dichloroacetic acid （DCAA） and trichloroacetic acid （TCAA）, in water by single oxidants ozone （O3） and ultraviolet radiation （UV） and the advanced oxidation processes （AOPs） constituted by the combinations of O3/UV, H2O2/UV, O3/H2O2, and O3/H2O2/UV. The concentrations of HAAs were analyzed at specified time intervals to track their decomposition. Except for O3 and UV, the four combined oxidation processes remarkably enhance the decomposition of DCAA and TCAA owing to the generated very reactive hydroxyl radicals. The fastest decomposition process is O3/H2O2/UV, closely followed by O3/UV. DCAA is much easier to decompose than＇ TCAA. The kinetics of HAA decomposition by O3/UV can be described well by a pseudo first-order reaction model under a constant initial dissolved O3 concentration and fixed UV radiation. Humic acids and HCO3 in the reaction system both decrease the decomposition rate constants for DCAA and TCAA. The amount of H2O2 accumulates in the presence of humic acids in the O3/UV process.  相似文献