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

Abstract

Abstract 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 μS cm −1 min −1 without gas flow to 0.552 μS 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 μS 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 H 2 O 2 , 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 H 2 O 2 alone, but is rapidly degraded by a combination of O 3 /H 2 O 2 in the suction-cavitation system. The degradation rate of zero-order kinetics increases from 2.604 to 4.788 μM min −1 as orifice diameter increases from 5 to 8 mm. Increasing O 3 gas flow and temperature favor SA degradation. Increasing H 2 O 2 concentration is more effective in producing OH radicals and promoting the oxidation of succinic acid than increasing O 3 input amount.