Multiple transformation pathways of p-arsanilic acid to inorganic arsenic species in water during UV disinfection
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- 作者：Suqi Li1 ; Jing Xu1 ; Wei Chen1 ; Yingtan Yu1 ; Zizheng Liu2 ; lzz@hust.edu.cn" class="auth_mail" title="E-mail the corresponding author ; Jinjun Li1 ; ljj0410@163.com" class="auth_mail" title="E-mail the corresponding author ; Feng Wu1
- 关键词：p-Arsanilic acid ; Phototransformation ; Inorganic arsenic species ; Kinetics ; Mechanism
- 刊名：Journal of Environmental Sciences
- 出版年：2016
- 出版时间：September 2016
- 年：2016
- 卷：47
- 期：Complete
- 页码：39-48
- 全文大小：1378 K
文摘
p-Arsanilic acid (p-ASA) is widely used in China as livestock and poultry feed additive for promoting animal growth. The use of organoarsenics poses a potential threat to the environment because it is mostly excreted by animals in its original form and can be transformed by UV–Vis light excitation. This work examined the initial rate and efficiency of p-ASA phototransformation under UV-C disinfection lamp. Several factors influencing p-ASA phototransformation, namely, pH, initial concentration, temperature, as well as the presence of NaCl, NH4+, and humic acid, were investigated. Quenching experiments and LC–MS were performed to investigate the mechanism of p-ASA phototransformation. Results show that p-ASA was decomposed to inorganic arsenic (including As(III) and As(V)) and aromatic products by UV-C light through direct photolysis and indirect oxidation. The oxidation efficency of p-ASA by direct photosis was about 32%, and those by HO
and 1O2 were 19% and 49%, respectively. Cleavage of the arsenic–benzene bond through direct photolysis, HO oxidation or 1O2 oxidation results in simultaneous formation of inorganic As(III), As(IV), and As(V). Inorganic As(III) is oxidized to As(IV) and then to As(V) by 1O2 or HO. As(IV) can undergo dismutation or simply react with oxygen to produce As(V) as well. Reactions of the organic moieties of p-ASA produce aniline, aminophenol and azobenzene derivatives as main products. The photoconvertible property of p-ASA implies that UV disinfection of wastewaters from poultry and swine farms containing p-ASA poses a potential threat to the ecosystem, especially agricultural environments.
and 1O2 were 19% and 49%, respectively. Cleavage of the arsenic–benzene bond through direct photolysis, HO oxidation or 1O2 oxidation results in simultaneous formation of inorganic As(III), As(IV), and As(V). Inorganic As(III) is oxidized to As(IV) and then to As(V) by 1O2 or HO. As(IV) can undergo dismutation or simply react with oxygen to produce As(V) as well. Reactions of the organic moieties of p-ASA produce aniline, aminophenol and azobenzene derivatives as main products. The photoconvertible property of p-ASA implies that UV disinfection of wastewaters from poultry and swine farms containing p-ASA poses a potential threat to the ecosystem, especially agricultural environments.