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论文类型：期刊论文

发表时间：2018-01-01

发表刊物：CHEMOSPHERE

收录刊物：SCIE、EI、PubMed

卷号：191

期号：1

页面范围：1021-1027

ISSN号：0045-6535

关键字：Photodegradation; Sulfapyridine; Water treatment; Photophysical and photochemical processes

摘要：For organic pollutants, photodegradation, as a major abiotic elimination process and of great importance to the environmental fate and risk, involves rather complicated physical and chemical processes of excited molecules. Herein, we systematically studied the photophysical and photochemical processes of a widely used antibiotic, namely sulfapyridine. By means of density functional theory (NT) computations, we examined the rate constants and the competition of both photophysical and photochemical processes, elucidated the photochemical reaction mechanism, calculated reaction quantum yield (Phi) based on both photophysical and photochemical processes, and subsequently estimated the photodegradation rate constant. We further conducted photolysis experiments to measure the photodegradation rate constant of sulfapyridine. Our computations showed that sulfapyridine at the lowest excited singlet state (Si) mainly undergoes internal conversion to its ground state, and is difficult to transfer to the lowest excited triplet states (T-1) via intersystem crossing (ISC) and emit fluorescence. In T-1 state, compared with phosphorescence emission and ISC, chemical reaction is much easier to initiate. Encouragingly, the theoretically predicted photodegradation rate constant is close to the experimentally observed value, indicating that quantum chemistry computation is powerful enough to study photodegradation involving ultra-fast photophysical and photochemical processes. (C) 2017 Elsevier Ltd. All rights reserved.