OH-initiated transformation and hydrolysis of aspirin in AOPs system: DFT and experimental studies

Advanced oxidation processes (AOPs) are widely used in wastewater treatment of pharmaceutical and personal care products (PPCPs). In this work, the OH-initiated transformation as well as the hydrolysis of a typical PPCPs, aspirin, was investigated using density functional theory (DFT) calculations a...

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Bibliographic Details
Published in:The Science of the total environment 2017-08, Vol.592, p.33-40
Main Authors: He, Lin, Sun, Xiaomin, Zhu, Fanping, Ren, Shaojie, Wang, Shuguang
Format: Article
Language:English
Subjects:
Advanced oxidation processes
Aspirin
Aspirin - chemistry
DFT
Hydrogen Peroxide
Hydrolysis
Hydroxyl Radical
Kinetics
Oxidation-Reduction
Transformation mechanism
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Summary:Advanced oxidation processes (AOPs) are widely used in wastewater treatment of pharmaceutical and personal care products (PPCPs). In this work, the OH-initiated transformation as well as the hydrolysis of a typical PPCPs, aspirin, was investigated using density functional theory (DFT) calculations and laboratory experiments. For DFT calculations, the frontier electron densities and bond dissociation energies were analyzed. Profiles of the potential energy surface were constructed, and all the possible pathways were discussed. Additionally, rate constants for each pathway were calculated with transition state theory (TST) method. UV/H2O2 experiments of aspirin were performed and degradation intermediates were identified by UPLC-MS-MS analysis. Different findings from previous experimental works were reported that the H-abstraction pathways at methyl position were dominated and OH-addition pathways on benzene ring were also favored. Meantime, hydroxyl ASA was confirmed as the main stable intermediate. Moreover, it was the first time to use DFT method to investigate the hydrolysis mechanisms of organic ester compound. [Display omitted] •OH-initiated transformation of aspirin in aqueous environments was investigated.•H-abstraction pathways at methyl position OH-addition pathways were dominated rather than hydrolysis reactions in AOPs.•Hydrolysis mechanisms of organic ester compound were investigated by DFT methods for the first time.•UV/H2O2 experiments were performed to confirm calculation findings.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2017.03.041