School of Biotechnology and Health Science, Wuyi University, Jiangmen 529020, China.
Department of Cardiovascular Medicine, Guangdong Hospital of Traditional Chinese Medicine, Guangzhou 510120, China.
Environ Sci Technol. 2021 Feb 2;55(3):2037-2047. doi: 10.1021/acs.est.0c05084. Epub 2021 Jan 12.
Roxarsone (ROX) has been widely used as an organoarsenic additive in animal feeding operations and poses a risk to the environment. Here, we first report the efficient degradation of ROX by UV/chlorine, where the kinetics, removal of total arsenic (As), and cytotoxicity were investigated. The kinetics study presented that reactive chlorine species (RCS) and HO were the dominant species to react with ROX. Furthermore, the degradation rate of ROX can reach the maximum value at pH 7.5 due to the formation of more RCS. The degradation of ROX was affected by the amount of chlorine, pH, and water matrix. Through product analysis and Gauss theoretical calculation, two possible ROX degradation pathways were proposed. The free radicals attacked the As-C bond of ROX and resulted in releasing arsenate (As(V)). It was the reason that for an enhancement of the removal of total As by ferrous appeared after UV/chlorine, and over 98% of the total As was removed. In addition, cytotoxicity studies indicated that the cytotoxicity significantly enhanced during the degradation of ROX by UV/chlorine. However, by combination of UV/chlorine and adsorption, cytotoxicity can be greatly eliminated, probably due to the removal of As(V) and chlorinated products. These results further demonstrated that UV/chlorine treatment could be an effective method for the control of the potential environmental risks posed by organoarsenic.
罗沙砷（ROX）已被广泛用作动物饲养操作中的有机砷添加剂，对环境构成风险。在这里，我们首次报道了 UV/氯体系高效降解 ROX，研究了动力学、总砷（As）去除率和细胞毒性。动力学研究表明，活性氯物种（RCS）和 HO 是与 ROX 反应的主要物种。此外，由于更多 RCS 的形成，ROX 的降解速率在 pH 7.5 时达到最大值。ROX 的降解受氯的量、pH 和水基质的影响。通过产物分析和高斯理论计算，提出了两种可能的 ROX 降解途径。自由基攻击 ROX 的 As-C 键，导致释放出砷酸盐（As(V)）。这就是为什么在 UV/氯处理后，亚铁的出现会增强总 As 的去除率，超过 98%的总 As 被去除。此外，细胞毒性研究表明，在 ROX 被 UV/氯降解过程中，细胞毒性显著增强。然而，通过 UV/氯和吸附的结合，可以大大消除细胞毒性，这可能是由于 As(V)和氯化产物的去除。这些结果进一步表明，UV/氯处理可能是控制有机砷带来的潜在环境风险的有效方法。
