Self-enhanced ozonation of benzoic acid at acidic pHs
| Autor: | Bihuang Xie, Huang Xianfeng, Xuchun Li, Bingcai Pan, Yanyang Zhang, Hongchao Li |
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| Rok vydání: | 2014 |
| Předmět: |
Reaction mechanism
Environmental Engineering Ozone Hydroxyl Radical Ecological Modeling Radical Advanced oxidation process Kinetics Electron Spin Resonance Spectroscopy Benzoic Acid Hydrogen-Ion Concentration Photochemistry Pollution Decomposition Waste Disposal Fluid Water Purification chemistry.chemical_compound chemistry Degradation (geology) Waste Management and Disposal Water Pollutants Chemical Water Science and Technology Civil and Structural Engineering Benzoic acid |
| Zdroj: | Water research. 73 |
| ISSN: | 1879-2448 |
| Popis: | Ozonation of recalcitrant contaminants under acidic conditions is inefficient due to the lack of initiator (e.g., OH−) for ozone to produce hydroxyl radicals (HO ). In this study, we reported that benzoic acid (BA), which is inert to ozone attack, underwent efficient degradation by ozone at acidic pH (2.3). The kinetics of BA degradation and ozone decomposition were both enhanced by increasing BA concentrations. Essentially, it is a HO -mediated reaction. Based on the exclusion of possible contributions of H2O2 and phenol-like intermediates for HO production, the reaction mechanism involved the formation of ozone ion ( O 3 · − ), which is an effective precursor of HO , was thus proposed. The hydroxycyclohexadienyl-type radicals generated during the attack of BA by HO may lead to the formation of O 3 · − . Meanwhile, O 3 · − could also be possibly formed from the reaction between ozone and organic (e.g., ROO∙) or inorganic peroxyl radicals (e.g., HO2 ). In addition, the hydroxylated products like phenol-like intermediates also played a positive role in HO production. Consequently, HO was produced efficiently under acidic conditions, resulting in rapid degradation of BA. This study provides a new approach for ozone activation even at acidic pHs, and broadens the knowledge of ozonation in removal of micropollutants from water. |
| Databáze: | OpenAIRE |
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