[Study on removal of nitrobenzene in water by O3/H2O2]

Comparative experiments of ozonation and O3/H2O2 processes were conducted with nitrobenzene as the model organic pollutant. It was found that O3/H2O2 greatly increased the removal efficiency of nitrobenzene compared with that achieved by ozonation alone. It was believed that both in ozonation and O3/H2O2 processes nitrobenzene was primarily oxidized by OH.. Several factors that are likely to influence O3/H2O2 process in practical application were investigated. Experimental results demonstrated that with the same dosage of applied ozone and hydrogen peroxide, the multiple steps addition of ozone and hydrogen peroxide showed a much higher removal efficiency than that obtained by adding hydrogen peroxide within one step before the start of the experiment. Under the conditions of this experiment, the optimum molar ratios of hydrogen peroxide to ozone for the removal of nitrobenzene in distilled water and tap water were proved to be both 0.5, no significant negative effect was observed when the alkalinity levels (as CaCO3) were less than 100 mg/L.