O3/H2O2去除水中硝基苯效果与机理

以硝基苯为目标反应物,对O₃/H₂O₂体系氧化去除水中硝基苯的效果和机理进行了研究,考察了pH值、H₂O₂剂量、自由基抑制剂或促进剂对硝基苯的去除效果的影响.研究发现,在pH≤7时,H₂O₂促进臭氧化去除硝基苯的效果较为明显,当H₂O₂投加量从1.0 mg/L增加到4.0 mg/L时,在氧化5 min内,硝基苯

Effect and Mechanism of Degradation of Nitrobenzene in Aqueous Solution by O3/H2O2

Nitrobenzene(NB) was selected as the model pollutant in water and the efficiency and mechanism of degradation of NB in aqueous solution by O₃/H₂O₂ were investigated.The effects of pH,H₂O₂ dose and the inhibitor or accelerant of ·OH on the removal rate of NB were studied.H₂O₂ could obviously improve the ozonation decay rate of NB when the pH value of the solution was below 7.The removal rate of NB was enhanced remarkably while H₂O₂ dose was increased from 1.0 mg/L to 4.0 mg/L.However,as H₂O₂ dose increased from 4.0 mg/L to 20 mg/L,the removal efficiency of NB decreased.Different quantities of H₂O₂ were yielded in different reaction phases of single ozonation system.Both systems of single ozonation and H₂O₂-catalysed ozonation could not reduce TOC observably.During the NB degradation process,organonitrogen was almost completely converted to nitrate and the pH value of the solution reduced significantly.Results of LC-MS and GC-MS analysis showed that the main intermediate products were phenolic compounds and carbonyl compounds.A possible reaction pathway of the catalytic ozonation of NB was also proposed.It was found that the catalytic ozonation of NB could be divided into two steps.First,hydroxyl radical attacked phenyl ring to form phenolic compounds,then the ring was opened,forming into various aliphatic compounds or being mineralized to inorganic compounds.