Effect and mechanism of removal of trace p-chloronitrobenzene in aqueous solution by ZnOOH/O₃

Zinc hydroxide prepared in laboratory was used as catalyst in catalytic ozonation of trace p-chloronitrobenzene (pCNB) in water. The catalytic mechanism was deduced through the effect of radical inhibitor t-BuOH on the reaction. Furthermore, affecting factors of catalytic activity were investigated. Results show that zinc hydroxide has excellent property of catalytic ozonation. Compared to ozonation alone, the catalytic removal rate of pCNB dissolved in distilled water increases by 51.3 percents at reacting time of 20 min. The catalysis, which is influenced by density of hydroxyl groups combined on the surface of hydroxide, follows a hydroxyl radical reaction pathway. The removal gets better with increasing dosage of catalyst. Zinc hydroxide was used for 3 times without obvious changes of p CNB removal rate. Bicarbonate in water and phosphate in buffer solution could greatly depress its catalytic activity. The optimal catalysis is achieved at solution pH = 7.