Mechanism insight into the facet-dependent photoaging of polystyrene microplastics on hematite in freshwater

Autor: Jiehong He, Lanfang Han, Weiwei Ma, Chao Xu, Elvis Genbo Xu, Chuanxin Ma, Baoshan Xing, Zhifeng Yang
Jazyk: angličtina
Rok vydání: 2023
Předmět:
Zdroj: Water Research X, Vol 19, Iss , Pp 100185- (2023)
Druh dokumentu: article
ISSN: 2589-9147
DOI: 10.1016/j.wroa.2023.100185
Popis: Hematite, as an extensive natural mineral with multiple crystal facets, profoundly affects the migration and transformation of pollutants in the natural environment. However, little is known about the photochemical behavior of microplastics on different facets of hematite in the aquatic environment. In this work, the photoaging of polystyrene microplastics (PS-MPs) on different crystal planes ({001}, {100}, and {012} facets) and related mechanisms were studied. Two-dimensional correlation spectroscopy analysis illustrated that the reaction pathways of PS-MPs photoaging on hematite tended to preferential chemical oxidization. The stronger performance of PS-MPs photoaging, expressed by particle size reduction and surface oxidation, was observed on the {012} crystal facet. Under irradiation, {012} facet-dominated hematite with a narrower bandgap (1.93 eV) reinforced the photogenerated charge carrier separation, and the lower activation energy barrier (1.41 eV calculated from density functional theory) led to effective •OH formation from water oxidation. These findings elucidate the underlying photoaging mechanism of MPs on hematite with different mineralogical phases.
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