[Comparative study on O3/H2O2 and O3/Mn processes for removal of refractory organics in water].

A comparative study of O3/H2O2 and O3/Mn was made to evaluate their respective effectiveness and mechanism for removal of refractory organics from water with nitrobenzene as the model pollutant. It was found that both processes enhanced the degradation of nitrobenzene that can be hardly degraded by ozonation and had respective optimum dosage of H2O2 and Mn(II) under the experimental conditions. By comparing the mechanism of O3/H2O2 process and considering the chemical character of nitrobenzene and variation of residual aqueous ozone, it is speculated that the degradation of nitrobenzene by O3/Mn might follow a radical pathway. As shown by the experimental result, the addition of H2O2 and Mn(II) both improved the mass transfer efficiency of ozone and thus more ozone was consumed for degradation of nitrobenzene, which is also an indication of the radical type reaction mechanism. The characteristic of O3/H2O2 and O3/Mn processes and their application in the drinking water treatment were finally discussed.