Change in adsorption behavior of aquatic humic substances on microplastic through biotic and abiotic aging processes.

Autor: Zafar R; Department of Environment and Energy, Sejong University, Seoul 05006, Republic of Korea., Bang TH; Department of Environment and Energy, Sejong University, Seoul 05006, Republic of Korea., Lee YK; Department of Environment and Energy, Sejong University, Seoul 05006, Republic of Korea., Begum MS; Department of Environment and Energy, Sejong University, Seoul 05006, Republic of Korea., Rabani I; Interface Lab, Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Republic of Korea., Hong S; Department of Ocean Environmental Sciences, Chungnam National University, Daejeon 34134, Republic of Korea., Hur J; Department of Environment and Energy, Sejong University, Seoul 05006, Republic of Korea. Electronic address: jinhur@sejong.ac.kr.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2022 Oct 15; Vol. 843, pp. 157010. Date of Electronic Publication: 2022 Jun 27.
DOI: 10.1016/j.scitotenv.2022.157010
Abstrakt: Interactions between microplastics (MPs) and humic substances (HS) are inevitable in MP-contaminated aquatic environment because of the ubiquitous presence of HS. In this study, we explored the effects of abiotic and biotic aging processes on the adsorption behavior of aquatic HS on MPs. Aging experiments were conducted using polyethylene (PE) as a representative MP, in which UV irradiation and microbial incubation were applied for 15 to 18 days to mimic the natural abiotic and biotic aging processes. Surface modifications after the aging treatments were evidenced by the appearance of CO, CO, O-C=O, and -OH groups; the formation of grooves on UV-aged PE; and the formation of biofilms on the surface of bio-aged PE. The specific surface areas of both treated PE MPs increased with aging. Higher HS adsorption on PE surface was observed after the aging treatments, with a highest kinetic rate for UV-aged PE than that for bio-aged PE. The adsorption isotherm models revealed that the aging processes enhanced the HS adsorption tendency, as evidenced by the highest adsorption capacity for UV-aged PE (~187 μg C/m 2 ), followed by bio-aged PE (~157 μg C/m 2 ) and pristine PE (~87.5 μg C/m 2 ) for a comparable extended aging period (15-18 days). The difference was more pronounced at a lower pH. The enhanced HS adsorption was mainly attributed to the formation of hydrogen bonds, whereas HS adsorption on pristine PE was dominated by hydrophobic interactions and weak van der Waals interactions. Among the two identified fluorescent components (terrestrial humic-like C1 and protein-like C2), C1 exhibited a higher affinity for adsorption onto PE irrespective of aging. Our findings provide insights into the substantial changes that occur in the interactions between MPs and aquatic organic matter with aging processes, which may alter the fate and environmental impacts of MPs in many aquatic systems.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing interests or personal relationships that could have influenced the study reported in this paper.
(Copyright © 2022 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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