Photoaged polystyrene microplastics serve as photosensitizers that enhance cimetidine photolysis in an aqueous environment
Journal
Chemosphere
Journal Volume
290
Date Issued
2022
Author(s)
Abstract
Microplastics (MPs) have received much attention in recent years because of their continuous photoaging process in aquatic environments. However, little research has been conducted on the photochemistry of aged microplastics and the associated effects on coexisting pharmaceuticals. This study investigated the photodegradation of cimetidine via aged polystyrene microplastics (PS-MPs) with different aging times (0–7 d) under simulated sunlight irradiation (700 W/m2). PS-MPs with 5 d of aging time resulted in much faster cimetidine degradation (>99%) after 2 h of irradiation than pristine PS-MPs (<8%). The enhanced photodegradation of cimetidine by aged PS-MPs was related to the increase in chromophoric oxygenated groups (C[dbnd]O, C–O) followed by redshifted absorbance through the photoaging process, which induced the formation of the environmentally persistent free radicals (EPFRs) [rad]OH, 1O2 and 3PS*. However, only 1O2 and 3PS* contributed to enhanced cimetidine photodegradation, with 1O2 playing a more important role in our case. This work also demonstrated that other compounds that are susceptible to indirect photolysis, such as codeine and morphine, are likewise significantly degraded under irradiation in the presence of aged PS-MPs. Although previous studies have reported how MPs can increase the persistence of contaminants, this study demonstrates that MPs can serve as photosensitizers and alter the fate of coexisting pharmaceuticals in aquatic environments. ? 2021 Elsevier Ltd
Subjects
Environmentally persistent free radicals
Pharmaceuticals
Photodegradation
Polystyrene microplastics
Reactive species
Irradiation
Photolysis
Photosensitizers
Polystyrenes
Aging time
Aquatic environments
Aqueous environment
Environmentally persistent free radical
Microplastics
Photo degradation
Photo-aging
Photosensitiser
Polystyrene microplastic
Free radicals
absorbance
irradiation
photochemistry
photodegradation
photolysis
plastic waste
polymer
cimetidine
photosensitizing agent
plastic
polystyrene derivative
water pollutant
Cimetidine
Photosensitizing Agents
Plastics
Water Pollutants, Chemical
Type
journal article