• 其他栏目

    谢晴

    • 高级工程师    
    • 主要任职:无
    • 性别:女
    • 毕业院校:大连理工大学
    • 学位:博士
    • 在职信息:在职
    • 所在单位:环境学院
    • 学科:环境工程
    • 办公地点:环境楼A315
    • 电子邮箱:

    访问量:

    开通时间 :..

    最后更新时间:..

    Unveiling self-sensitized photodegradation pathways by DPT calculations: A case of sunscreen p-aminobenzoic acid

    点击量:

    论文类型:期刊论文

    第一作者:Zhang, Siyu

    通讯作者:Chen, JW (reprint author), Dalian Univ Technol, Sch Environm Sci & Technol, Key Lab Ind Ecol & Environm Engn MOE, Linggong Rd 2, Dalian 116024, Peoples R China.

    合写作者:Chen, Jingwen,Zhao, Qing,Xie, Qing,Wei, Xiaoxuan

    发表时间:2016-11-01

    发表刊物:CHEMOSPHERE

    收录刊物:EI、SCIE、PubMed、Scopus

    卷号:163

    页面范围:227-233

    ISSN号:0045-6535

    关键字:Self-sensitized photodegradation mechanism; Singlet state oxygen; p-aminobenzoic acid; Density functional theory

    摘要:Self-sensitized photodegradation has been observed for diverse aquatic organic pollutants. However, photodegradation pathways have not been clarified in, previous experimental studies. Here, we attempted to probe self-sensitized photodegradation pathways of organic pollutants employing both photolytic experiments and density functional theory calculations. By performing photolytic experiments, we found that singlet state oxygen (O-1(2)) play an essential role in photodegradation of a sunscreen p-aminobenzoic acid (PABA). PABA can photogenerate O-1(2) and react fast with O-1(2). We hypothesized that PABA underwent O-1(2) induced self-sensitized photodegradation. By calculating transition states, intermediates and reaction barriers, we found that O-1(2) can oxidize PABA through electrophilic attacks on the benzene ring to abstract one H atom of the amino group following a 1,3-addition mechanism or to induce decarboxylation. Either pathway produces a hydroperoxide. O-O bond cleavage of the hydro peroxides occurring at ground states or the lowest triplet excited states can produce phenoxyl radical precursors of 4-amino-3-hydroxybenzoic acid and 4-aminophenol, which are photodegradation products detected in experiments. Thus, a viable O-1(2) self-sensitized photodegradation mechanism was unveiled for PABA. (C) 2016 Elsevier Ltd. All rights reserved.