View in EDS

Degradation of propranolol by UV-activated persulfate oxidation: Reaction kinetics, mechanisms, reactive sites, transformation pathways and Gaussian calculation.

Saved in:
Bibliographic Details
Title: Degradation of propranolol by UV-activated persulfate oxidation: Reaction kinetics, mechanisms, reactive sites, transformation pathways and Gaussian calculation.
Authors: Chen, Tiansheng1 (AUTHOR), Ma, Jingshuai1 (AUTHOR), Zhang, Qianxin1 (AUTHOR), Xie, Zhijie1 (AUTHOR), Zeng, Yongqin1 (AUTHOR), Li, Ruobai1 (AUTHOR), Liu, Haijin1 (AUTHOR), Liu, Yang1 (AUTHOR), Lv, Wenying1 (AUTHOR) lvwy612@163.com, Liu, Guoguang1 (AUTHOR) liugg615@163.com
Source: Science of the Total Environment. Nov2019, Vol. 690, p878-890. 13p.
Abstract: Contamination with β-blockers such as propranolol (PRO) poses a potential threat to human health and ecological system. The present study investigated the kinetics and mechanisms of PRO degradation by UV-activated persulfate (UV/PS) oxidation. Here, the experimental results showed that the degradation of PRO followed pseudo-first-order reaction kinetics, the degradation rate constant (k obs) was increased dramatically with increasing PS dosage or decreasing initial PRO concentration. And increasing the initial solution pH could also enhance the degradation efficiency of PRO. Radical scavenging experiments demonstrated that the main radical species was sulfate radicals (SO 4 •−), with hydroxyl radicals (HO·) playing a less important role. Meanwhile, the second-order rate constants of PRO degradation with SO 4 •− and HO· were determined to be 1.94 × 1010 M−1 s−1 and 6.77 × 109 M−1 s−1, respectively. In addition, the presence of natural organic matter (NOM) and nitrate anion (NO 3 −) showed inhibitory effect on PRO degradation, whereas bicarbonate anion (HCO 3 −) and chlorine anion (Cl−) greatly enhanced the degradation of PRO. Moreover, the transformation products of PRO were identified by applying ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) technique. Molecular orbital calculations were used to estimate the reaction site of PRO with radicals, simultaneously. Hence, the transformation pathways including hydroxylation, dehydration, naphthalene ring opening, and the cleavage of aldehyde groups were proposed. This work enriches the mechanism of PRO degradation under UV/PS system on the basis of results obtained by experimental characterization and Gaussian theoretical calculation. Unlabelled Image • Efficient oxidation of propranolol could be achieved by UV-activated persulfate. • UV/PS process was much more effective than the UV/H 2 O 2 process in degrading propranolol. • Sulfate radical was identified as the primary oxidizing species. • Gaussian calculations were applied to the intermediate product path speculation and the mechanism was further analyzed. • Studies on the transformation mechanisms revealed three different reaction pathways. [ABSTRACT FROM AUTHOR]
Copyright of Science of the Total Environment is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
Description
Abstract:Contamination with β-blockers such as propranolol (PRO) poses a potential threat to human health and ecological system. The present study investigated the kinetics and mechanisms of PRO degradation by UV-activated persulfate (UV/PS) oxidation. Here, the experimental results showed that the degradation of PRO followed pseudo-first-order reaction kinetics, the degradation rate constant (k obs) was increased dramatically with increasing PS dosage or decreasing initial PRO concentration. And increasing the initial solution pH could also enhance the degradation efficiency of PRO. Radical scavenging experiments demonstrated that the main radical species was sulfate radicals (SO 4 •−), with hydroxyl radicals (HO·) playing a less important role. Meanwhile, the second-order rate constants of PRO degradation with SO 4 •− and HO· were determined to be 1.94 × 1010 M−1 s−1 and 6.77 × 109 M−1 s−1, respectively. In addition, the presence of natural organic matter (NOM) and nitrate anion (NO 3 −) showed inhibitory effect on PRO degradation, whereas bicarbonate anion (HCO 3 −) and chlorine anion (Cl−) greatly enhanced the degradation of PRO. Moreover, the transformation products of PRO were identified by applying ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) technique. Molecular orbital calculations were used to estimate the reaction site of PRO with radicals, simultaneously. Hence, the transformation pathways including hydroxylation, dehydration, naphthalene ring opening, and the cleavage of aldehyde groups were proposed. This work enriches the mechanism of PRO degradation under UV/PS system on the basis of results obtained by experimental characterization and Gaussian theoretical calculation. Unlabelled Image • Efficient oxidation of propranolol could be achieved by UV-activated persulfate. • UV/PS process was much more effective than the UV/H 2 O 2 process in degrading propranolol. • Sulfate radical was identified as the primary oxidizing species. • Gaussian calculations were applied to the intermediate product path speculation and the mechanism was further analyzed. • Studies on the transformation mechanisms revealed three different reaction pathways. [ABSTRACT FROM AUTHOR]
ISSN:00489697
DOI:10.1016/j.scitotenv.2019.07.034