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Indexed by:期刊论文

Date of Publication:2016-10-01

Journal:ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH

Included Journals:SCIE、PubMed、Scopus

Volume:23

Issue:19

Page Number:19921-19930

ISSN No.:0944-1344

Key Words:Sulfameter; Photodegradation mechanism; Metal ions; DOM; DFT

Abstract:Sulfonamide antibiotics (SAs) have been observed to undergo direct and indirect photodegradation in natural water environments. In this study, the density functional theory (DFT) method was employed for the study of direct and indirect photodegradation mechanisms of sulfameter (SME) with excited triplet states of dissolved organic matter ((DOM*)-D-3) and metal ions. SME was adopted as a representative of SAs, and SO2 extrusion product was obtained with different energy paths in the triplet-sensitized photodegradation of the neutral (SME0) and the anionic (SME-) form of SME. The selected divalent metal ions (Ca2+, Mg2+, and Zn2+) promoted the triplet-sensitized photodegradation of SME0 but showed an inhibitory effect in triplet-sensitized photodegradation of SME-. The triplet-sensitized indirect photodegradation mechanism of SME was investigated with the three DOM analogues, i.e., 2-acetonaphthone (2-AN), fluorenone (FN), and thioxanthone (TN). Results indicated that the selected DOM analogues are highly responsible for the photodegradation via attacking on amine moiety of SME. According to the natural bond orbital (NBO) analysis, the triplet-sensitized photodegradation mechanism of SME0 with 2-AN, FN, and TN was H-transfer, and the SME- was proton plus electron transfer with these DOM analogues.