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Indexed by:期刊论文

Date of Publication:2018-09-15

Journal:JOURNAL OF HAZARDOUS MATERIALS

Included Journals:PubMed、SCIE

Volume:358

Page Number:216-221

ISSN No.:0304-3894

Key Words:Photodegradation; Coexisting contaminants; Fibrate drugs; Photochemically produced reactive intermediates; Excited states

Abstract:Pharmaceuticals are a group of ubiquitous emerging pollutants, many of which have been shown to undergo efficient photolysis in the environment. Photochemically produced reactive intermediates (PPRIs) sensitized by the pharmaceuticals in sunlit natural waters may induce photodegradation of coexisting compounds. In this study, the roles of coexisting contaminants on the phototransformation of pharmaceuticals were unveiled with the fibrate drugs gemfibrozil (GMF), fenofibrate (ENE), and fenofibric acid (FNFA) as model compounds. GMF undergoes initial concentration dependent photodegradation due to the involvement of singlet oxygen (102) initiated self-sensitized photolysis, and undergoes pH dependent photodegradation due to dissociation and hydroxyl radical (center dot OH) generation. The decarboxylated intermediates of GMF and coexisting FNFA significantly accelerated the photodegradation of GMF. The promotional effects of the decarboxylated intermediates are attributed to generation of PPRIs, e.g. O-1(2), superoxide (O-2 center dot(-)), that subsequently react with GMF. Besides, FNFA can also promote the photodegradation of GMF through the electron transfer reaction from ground state GMF to excited state FNFA, leading to the formation of decarboxylated intermediates. The formed intermediates can subsequently also facilitate GMF photodegradation. The results presented here provided valuable novel insights into the effects of coexisting contaminants on the photodegradation of pharmaceuticals in polluted waters.