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首页> 外文期刊>Environmental Science & Technology >Photochemical Oxidation of Arsenic(Ⅲ) to Arsenic(Ⅴ) using Peroxydisulfate Ions as an Oxidizing Agent
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Photochemical Oxidation of Arsenic(Ⅲ) to Arsenic(Ⅴ) using Peroxydisulfate Ions as an Oxidizing Agent

机译：过二硫酸盐离子作为氧化剂将砷（Ⅲ）光化学氧化为砷（Ⅴ）

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摘要

The photochemical oxidation of arsenic, As(Ⅲ), to the less toxic As(V) using peroxydisulfate ions (S_2O_8~(2-)) as the oxidizing agent under UV light irradiation was investigated. The photochemical oxidation of As(Ⅲ) to As(Ⅴ) assisted using peroxydisulfate ions (KPS) proved to be a simple and efficient method, and the rate of oxidation for As(lll) was exceptionally high in accordance with the concentration of KPS. In this study, the UV light intensity was of primary importance for the dissociation of the KPS in generating sulfate anion radicals (SO_4~(-·)). Upon intense UV light irradiation, very efficient oxidation was achieved due to the complete decomposition of KPS into SO_4~(-·) radicals which favor a higher reaction rate. Subsequent pH variation from 3 to 9 was seen to have no influence on the photolytic cleavage of KPS, and hence, the reaction was unaltered. There was also no significant effect from the continuous purging of oxygen or dissolved oxygen before the reaction as the air-equilibrated condition was found to be sufficient for efficient oxidation. However, the continuous purging of nitrogen substantially reduced the reaction rate (20%), confirming that the dissolved oxygen plays a role in this reaction, although at high concentrations of KPS, this situation was overcome. Humic acid was also found to have no detrimental effect on the reaction rate, even at 20 ppm concentration. The resultant SO_4~(2-) obtained in this study was, thus, not considered a pollutant. Moreover, there was no need for a sensitizer or other metals with highly alkaline conditions that are normally used in conjunction with KPS. Natural solar light could also effectively oxidize As(Ⅲ) at room temperature. This simple technique was, thus, considered a cost-effective and safe method for the oxidation of As(Ⅲ) to As(Ⅴ).
机译：以过氧二硫酸根离子（S_2O_8〜（2-））为氧化剂，在紫外光照射下，研究了砷（As）（Ⅲ）的光化学氧化为毒性较小的As（V）。过氧二硫酸根离子（KPS）辅助将As（Ⅲ）光化学氧化为As（Ⅴ）是一种简单而有效的方法，并且根据KPS的浓度，As（III）的氧化速率极高。在这项研究中，紫外线强度对于KPS在产生硫酸根阴离子自由基（SO_4〜（-·））时的解离至关重要。在强烈的紫外线照射下，由于KPS完全分解成SO_4〜（-·）自由基而实现了非常有效的氧化，这有利于更高的反应速率。随后观察到从3到9的pH变化对KPS的光解裂解没有影响，因此反应没有改变。在反应之前连续吹扫氧气或溶解的氧气也没有显着影响，因为发现空气平衡条件足以进行有效的氧化。但是，连续吹扫氮气会大大降低反应速率（20％），这证实了溶解的氧气在该反应中发挥了作用，尽管在高浓度的KPS下，这种情况得以克服。还发现腐殖酸即使在浓度为20ppm时也对反应速率没有有害影响。因此，本研究中获得的SO_4〜（2-）未被认为是污染物。此外，不需要通常与KPS一起使用的具有高碱性条件的敏化剂或其他金属。天然太阳光还可以在室温下有效地氧化As（Ⅲ）。因此，该简单技术被认为是将As（Ⅲ）氧化为As（Ⅴ）的一种经济高效且安全的方法。

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