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首页> 外文期刊>Environmental Science & Technology >Mechanisms of Photocatalytical Degradation of Monomethylarsonic and Dimethylarsinic Acids Using Nanociystalline Titanium Dioxide
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Mechanisms of Photocatalytical Degradation of Monomethylarsonic and Dimethylarsinic Acids Using Nanociystalline Titanium Dioxide

机译：纳米壳聚糖二氧化钛光催化降解单甲基ar酸和二甲基ar酸的机理

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摘要

Photodegradation mechanisms of monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) with nanocrystalline titanium dioxide under UV irradiation were investigated. In the presence of UV irradiation and 0.02 g/L TiO_2, 93% MMA (initial concentration is 10 mg-As/L) was transformed into inorganic arsenate, [As(V)], after 72 h of a batch reaction. The mineralization of DMA to As(V) occurred in two steps with MMA as an intermediate product. The photodegradation rate of MMA and DMA could be described using first-order kinetics, where the apparent rate constant is 0.033/h and 0.013/h for MMA and DMA, respectively. Radical scavengers, including superoxide dimutase (SOD), sodium bicarbonate, tert-butanol, and sodium azide, were used to study the photodegradation mechanisms of MMA and DMA. The results showed that hydroxyl radicals (HO~·) was the primary reactive oxygen species for the photodegradation of MMA and DMA. The methyl groups in MMAand DMA were transformed into organic carbon, including formic acid and possibly methanol, also through photochemical reactions. The results showed that nanocrystalline TiO_2 can be used for the photocatalytical degradation of MMA and DMA and subsequent removal of the converted As(V), since the high adsorption capacity of the material for inorganic arsenic species has been demonstrated in previous studies.
机译：研究了纳米甲基二氧化钛在紫外线辐射下光降解单甲基ar酸（MMA）和二甲基ar酸（DMA）的机理。在分批反应72小时后，在存在紫外线照射和0.02 g / L TiO_2的情况下，将93％MMA（初始浓度为10 mg-As / L）转化为无机砷酸盐[As（V）]。以MMA为中间产物，将DMA矿化为As（V）分两步进行。可以使用一级动力学描述MMA和DMA的光降解速率，其中MMA和DMA的表观速率常数分别为0.033 / h和0.013 / h。自由基清除剂，包括超氧化物歧化酶（SOD），碳酸氢钠，叔丁醇和叠氮化钠，用于研究MMA和DMA的光降解机理。结果表明，羟基自由基（HO〜·）是MMA和DMA光降解的主要活性氧。 MMA和DMA中的甲基也通过光化学反应转化为有机碳，包括甲酸和可能的甲醇。结果表明，由于在先前的研究中已经证明了该材料对无机砷物种的高吸附能力，因此可以将纳米晶TiO_2用于MMA和DMA的光催化降解以及随后去除转化的As（V）。

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