Decomposition of chloroform and succinic acid by ozonation in a suction-cavitation system: Effects of gas flow

The conductivity of aqueous solutions containing 1 mM chloroform increases upon the chloroform decomposition that is induced by hydrodynamic cavitation in the suction-cavitation system. However, the rate of increase in conductivity (RIC) drops significantly, from 1.314 mu S cm(-1) min(-1) without gas flow to 0.552 mu S cm(-1) min(-1) with 25 mL min(-1) of air flow. The RIC decreases further with increasing air flow, until pseudo-zero growth is reached at 200 mL min(-1) air flow. Introducing O-3 at 33 mL min(-1) gas flow (effective cavitation) improves RIC, from 0.4193 to 0.5509 mu S cm(-1) min(-1), but the enhanced rate (31.4%) is lower than at 200 mL min(-1) of gas flow (little effective cavitation). The concentrations of dissolved O-2, O-3 and H2O2, that is formed on-site, increase with increasing gas flow and orifice plate hole diameter. Succinic acid (0.42 mM) is not oxidized by O-3 or H2O2 alone, but is rapidly degraded by a combination of O-3/H2O2 in the suction-cavitation system. The degradation rate of zero-order kinetics increases from 2.604 to 4.788 mu M min(-1) as orifice diameter increases from 5 to 8 mm. Increasing O-3 gas flow and temperature favor SA degradation. Increasing H2O2 concentration is more effective in producing OH radicals and promoting the oxidation of succinic acid than increasing O-3 input amount. (C) 2016 Elsevier B.V. All rights reserved.