| 不同物相TiO2对H2O2/O3氧化效能的影响 |
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| 引用本文： | 倪金雷,彭若帆,童少平,马淳安.不同物相TiO2对H2O2/O3氧化效能的影响[J].化工学报,2015,66(10):3950-3956. |
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| 作者姓名： | 倪金雷 彭若帆 童少平 马淳安 |
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| 作者单位： | 浙江工业大学化学工程学院, 绿色化学合成技术国家重点实验室培育基地, 浙江 杭州 310032 |
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| 基金项目： | 国家自然科学基金项目(21176225);浙江省重点科技专项(2013C03019)。 |
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| 摘 要： | 研究了不同物相TiO2对H2O2/O3氧化效能的影响,目标有机物为羟基自由基探针化合物乙酸。结果表明,在初始pH为7.0和10.0时,加入TiO2反而降低了H2O2/O3的氧化效率,其中锐钛矿TiO2比金红石TiO2的减弱作用更为明显。当初始pH为3.0时,金红石TiO2能显著提高H2O2/O3的氧化效率,但锐钛矿TiO2影响不明显。机理分析表明,H2O2浓度及其衰减速率与乙酸的去除效率有很大的相关性。在pH为7.0和10.0时,两种物相TiO2均能加快H2O2的分解,其中锐钛矿TiO2作用更为显著。此条件下HO2-能有效引发臭氧分解产生羟基自由基,故H2O2过快分解反而降低了乙酸的去除效果。在pH为3.0时,H2O2去质子化反应困难,故O3/H2O2氧化效率极低,H2O2浓度也几乎不变。加入TiO2能明显提高H2O2的分解速率,相比金红石TiO2,锐钛矿TiO2使H2O2在5 min内基本分解完毕,但其对H2O2/O3氧化效率几乎没有影响。饱和臭氧水分解速度的批处理实验也有相似的结果。由此可见,合适引发剂浓度可能是保证臭氧类高级氧化技术较高效率的关键,否则只会导致氧化剂的无效过快分解。利用氯化硝基四氮唑蓝法对比分析了酸性条件下H2O2/O3、锐钛矿TiO2/H2O2/O3和金红石TiO2/H2O2/O3体系产生超氧自由基(·O2-)的量,其大小顺序为:H2O2/O3< 金红石TiO2/H2O2/O3< 锐钛矿TiO2/H2O2/O3,这与前面结果吻合很好。
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| 关 键 词： | 臭氧 双氧水 氧化 催化剂 二氧化钛 物相 自由基 |
| 收稿时间： | 2014-12-16 |
Effect of TiO2 crystal phase on oxidation efficiency of H2O2/O3 |
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| NI Jinlei,PENG Ruofan,TONG Shaoping,MA Chun'an.Effect of TiO2 crystal phase on oxidation efficiency of H2O2/O3[J].Journal of Chemical Industry and Engineering(China),2015,66(10):3950-3956. |
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| Authors: | NI Jinlei PENG Ruofan TONG Shaoping MA Chun'an |
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| Affiliation: | State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, Zhejiang, China |
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| Abstract: | The oxidation efficiency of H2O2/O3 catalyzed by titanium dioxide (TiO2) for acetic acid (HAc) degradation, a probe compound for hydroxyl radical in ozonation, was investigated, with a focus on the effect of TiO2 crystal phase. The results indicated that the addition of TiO2 showed negative effect on the oxidation efficiency when the initial pH was at 7.0 and 10.0, and among all crystal phases of TiO2 anatase had the biggest negative effect. However, when the initial pH was at 3.0, rutile could significantly improve the oxidation efficiency of the H2O2/O3 system, and anatase had negligible effect. The mechanism study showed that there existed a good correlation between degradation rate of HAc and concentration of H2O2 (or its decomposition rate). Both anatase and rutile could accelerate decomposition of H2O2 at initial pH of 7.0 and 10.0, and faster was for the former than the latter. Too high decomposition rate of H2O2 could reduce removal rate of HAc at the two pH, because the conjugate base HO2- of H2O2 generated could react with ozone to effectively produce hydroxyl radicals (·OH). At initial pH 3.0, the oxidation efficiency of H2O2/O3 system was very low due to the difficulty of H2O2 deprotonation, so the concentration of H2O2 had almost no change. Addition of TiO2 could markedly accelerate the decomposition rate of H2O2, including deprotonation step, and anatase made H2O2 decomposition finish in 5 min and too fast, leading to have no effect on the oxidation efficiency. However, rutile had no such high decomposition rate for H2O2 and could generate HO2- -similar species which could react with ozone to produce hydroxyl radicals (·OH) to degrade acetic acid. The batch test carried out also gave a similar result. Therefore, it can be concluded that suitable initiator and its concentration may play an important role in ozone-based advanced oxidation process, and that too high concentration of initiator might lead to rapid consumption of oxidants. The amounts of superoxide ion radical (·O2-) in H2O2/O3, anatase TiO2/H2O2/O3 and rutile TiO2/H2O2/O3 systems were determined by capturing method of Nitro Blue Tetrazolium Chloride (NBT), the order was as follows: H2O2/O3< rutile TiO2/H2O2/O3< anatase TiO2/H2O2/O3, which was in accord with the results of the results of HAc degradation. |
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| Keywords: | ozone hydrogen peroxide oxidation catalyst titanium dioxide crystal phase radical |
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