Comparison of Photodegradation Performance of 1,1,1-Trichloroethane in Aqueous Solution with the Addition of H2O2 or S2O82鈥?/sup> Oxidants

详细信息    查看全文

• 作者：Xiaogang Gu ; Shuguang Lu ; Zhaofu Qiu ; Qian Sui ; Zhouwei Miao ; Kuangfei Lin ; Yongdi Liu ; Qishi Luo
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2012
• 出版时间：May 30, 2012
• 年：2012
• 卷：51
• 期：21
• 页码：7196-7204
• 全文大小：434K
• 年卷期：v.51,no.21(May 30, 2012)
• ISSN：1520-5045

文摘

The chemical oxidation of 1,1,1-trichloroethane (TCA), a widely detected groundwater pollutant, by UV/H₂O₂ and UV/S₂O₈^{2鈥?/sup> processes was investigated. The effects of various factors were evaluated, including peroxide/TCA molar ratio, solution pH, Cl鈥?/sup> and HCO₃鈥?/sup> anions, and humic acid (HA). The results showed that TCA oxidation fit to a pseudo-first-order kinetic model. The optimum H₂O₂/TCA molar ratio was 5:1, with TCA removal of 54.2% in 60 min. In the UV/S₂O₈2鈥?/sup> process, higher molar ratios (from 1/1 to 10/1) resulted in higher TCA oxidation rates, and TCA could be completely removed after 60 min with a S₂O₈2鈥?/sup>/TCA molar ratio of 3/1. In addition, acidic conditions were favorable for TCA removal in the UV/S₂O₈2鈥?/sup> process, while maximum TCA removal was observed at pH 6 in the UV/H₂O₂ process. Both Cl鈥?/sup> and HCO₃鈥?/sup> anions adversely affected TCA oxidation performance, and higher concentration of HA resulted in a lag phase for TCA oxidation in both processes. Several reaction intermediates, including 1,1,1,2-tetrachloroethane, carbon tetrachloride, chloroform, tetrachloroethylene, 1,1-dichloroethylene, and tri- and dichloroacetic acids, were first identified during TCA oxidation by S₂O₈2鈥?/sup> chemistry, while only monochloroacetic acid was detected in the UV/H₂O₂ process. The results indicated that the UV/S₂O₈2鈥?/sup> process was much more effective than the UV/H₂O₂ process, but the latter was more environmentally friendly because fewer toxic intermediates were produced.}