Production of sulfate radical and hydroxyl radical by reaction of ozone with peroxymonosulfate: a novel advanced oxidation process.
Production of sulfate radical and hydroxyl radical by reaction of ozone with peroxymonosulfate: a novel advanced oxidation process.
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DOI：
10.1021/es506362e
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发表时间：
2015-06
影响因子：
11.4
通讯作者：
Yi Yang;Jin Jiang;Xinglin Lu;Jun Ma;Yongze Liu
中科院分区：
文献类型：
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作者：
Yi Yang;Jin Jiang;Xinglin Lu;Jun Ma;Yongze Liu
在这项工作中，提出并通过实验验证了臭氧（O3）与过一硫酸盐（PMS；HSO5−）反应同时产生羟基自由基（·OH）和硫酸根（SO4−−）。我们证明，PMS 阴离子（即 SO52−）和 O3 之间的反应主要负责驱动 O3 消耗，测量的二阶速率常数为 (2.12 ± 0.03) × 10(4) M(-1) s(-1)。 SO52− 和 O3 之间的反应形成了•OH 和SO4•−，这已通过化学探针得到证实（即，硝基苯生成•OH，莠去津生成•OH 和SO4•−）。每消耗 mol O3，•OH 和 SO4•− 的产量分别确定为 0.43 ± 0.1 和 0.45 ± 0.1。假设第一步是加合物−O3SOO− + O3 → −O3SO5−，该加合物进一步分解为SO5•− 和O3•−。随后 SO5•− 与 O3 反应生成 SO4•−，而 O3•− 则转化为•OH。采用R(ct,•OH) 和R(ct,SO4•−) 的定义（即•OH 和SO4•− 暴露量与O3 暴露量的各自比率）来量化•OH 和SO4•− 的相对贡献。增加 pH 值会导致 R(ct,•OH) 和 R(ct,SO4•−) 值增加，但不会显着影响 R(ct,SO4••) 与 R(ct,•OH) 的比率（即 R(ct,SO4•••)/R(ct,•OH)），该比率表示 SO4••• 与•OH 的相对形成。碳酸氢盐的存在明显抑制了探针的降解，并相当程度地降低了·OH对其降解的相对贡献，这可能归因于·OH和SO4·−都转化为更具选择性的碳酸盐自由基(CO3·−)。腐殖酸促进O3消耗以生成·OH，从而导致探针中的R(ct,·OH)值增加。 O3/PMS过程，而腐植酸对R(ct,SO4•−)值的影响可以忽略不计。这种差异可以通过腐植酸对 SO4•− 形成的影响可以忽略不计以及腐植酸与 SO4•− 反应的速率常数低于与•OH 反应的速率常数来合理解释。此外，O3/PMS工艺在真实水中的功效也得到了证实。
In this work, simultaneous generation of hydroxyl radical (•OH) and sulfate radical (SO4•−) by the reaction of ozone (O3) with peroxymonosulfate (PMS; HSO5−) has been proposed and experimentally verified. We demonstrate that the reaction between the anion of PMS (i.e.,SO52−) and O3 is primarily responsible for driving O3 consumption with a measured second order rate constant of (2.12 ± 0.03) × 10(4) M(-1) s(-1). The formation of both •OH and SO4•− from the reaction between SO52− and O3 is confirmed by chemical probes (i.e., nitrobenzene for •OH and atrazine forb oth •OH and SO4•−). The yields of •OH and SO4•− are determined to be 0.43 ± 0.1 and 0.45 ± 0.1 per mol of O3 consumption, respectively. An adduct,−O3SOO− + O3 → −O3SO5−, is assumed as the first step, which further decomposes into SO5•− and O3•−. The subsequent reaction of SO5•− with O3is proposed to generate SO4•−, while O3•− converts to •OH. A definition of R(ct,•OH) and R(ct,SO4•−) (i.e., respective ratios of •OH and SO4•− exposures to O3 exposure) is adopted to quantify relative contributions of •OH and SO4•−. Increasing pH leads to increases in both values of R(ct,•OH) and R(ct,SO4•−) but does not significantly affect the ratio of R(ct,SO4•−) to R(ct,•OH) (i.e., R(ct,SO4•−)/R(ct,•OH)), which represents the relative formation of SO4•− to •OH. The presence of bicarbonate appreciably inhibits the degradation of probes and fairly decreases the relative contribution of •OH for their degradation, which may be attributed to the conversion of both •OH and SO4•− to the more selective carbonate radical (CO3•−).Humic acid promotes O3 consumption to generate •OH and thus leads to an increase in the R(ct,•OH) value in the O3/PMS process,w hile humic acid has negligible influence on the R(ct,SO4•−) value. This discrepancy is reasonably explained by the negligible effect of humic acid on SO4•− formation and a lower rate constant for the reaction of humic acid with SO4•− than with •OH. In addition, the efficacy of the O3/PMS process in real water is also confirmed.