Halonitromethanes (HNMs) and haloacetonitriles (HANs) are two groups of emerging disinfection by-products (DBPs) that are more toxic and recalcitrant to conventional treatments than the regulated DBPs. This study investigated the direct and hydrogen peroxide (H2O2)-assisted UV photolysis of HNMs and HANs including monobromonitromethane (MBNM), dibromonitromethane (DBNM), dichloronitromethane (DCNM), trichloronitromethane (TCNM), monochloroacetonitrile (MCAN), dibromoacetonitrile (DBAN), dichloroacetonitrile (DCAN), and trichloroacetonitrile (TCAN). HNMs and DBAN can be effectively degraded by direct UV photolysis, and degradation of chlorine-containing HANs requires H2O2-assisted UV photolysis. The rates of direct UV photolysis of HNMs and HANs were positively correlated with their molar absorptivities. The rates of MCAN, DCAN, and TCAN degradation in the UV-H2O2 system increased with increasing degree of halogenation and, in the cases of DCAN and TCAN degradation, with increasing pH and H2O2 concentrations as well. The pH and H2O2 concentration dependencies are primarily attributed to different rates of hydrolysis driven by different hydroperoxide (HO2-) concentrations in the solution.

Direct and hydrogen peroxide-assisted UV photolysis of halonitromethanes and haloacetonitriles

248th National Meeting (2014)

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