Insights into the release of triclosan from microplastics in aquatic environment assessed with diffusive gradient in thin-films

Si-Si Liu; Yu-Wei Jia; Xiao-Yuan Guo; Jian-Liang Zhao; Yue Gao; Andy J Sweetman; Guang-Guo Ying; Li Xu; Chen Tu; Chang-Er Chen

doi:10.1016/j.scitotenv.2023.163601

Insights into the release of triclosan from microplastics in aquatic environment assessed with diffusive gradient in thin-films

Sci Total Environ. 2023 Jul 15:882:163601. doi: 10.1016/j.scitotenv.2023.163601. Epub 2023 Apr 20.

Authors

Si-Si Liu¹, Yu-Wei Jia², Xiao-Yuan Guo³, Jian-Liang Zhao¹, Yue Gao⁴, Andy J Sweetman⁵, Guang-Guo Ying¹, Li Xu⁶, Chen Tu⁷, Chang-Er Chen⁸

Affiliations

¹ Environmental Research Institute, School of Environment, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety, MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, PR China.
² Environmental Research Institute, School of Environment, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety, MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, PR China; Analytical, Environmental and Geochemistry (AMGC), Vrije Universiteit Brussel (VUB), Brussel, Belgium.
³ Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, 999078, Macau.
⁴ Analytical, Environmental and Geochemistry (AMGC), Vrije Universiteit Brussel (VUB), Brussel, Belgium.
⁵ Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
⁶ Institute of Quality Standard and Testing Technology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
⁷ CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
⁸ Environmental Research Institute, School of Environment, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety, MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, PR China. Electronic address: changer.chen@m.scnu.edu.cn.

PMID: 37087021
DOI: 10.1016/j.scitotenv.2023.163601

Abstract

Organic chemicals associated with microplastics (MPs) can be released and thus pose potential risks during weathering processes. However, the thermodynamics and kinetics of their release processes still need to be better understood. Herein, the adsorption and desorption kinetics of triclosan on polystyrene (PS) and polyvinyl chloride (PVC) were investigated by using both batch experiments and diffusive gradients in thin-films (DGT) technique. The pseudo-second-order model fitted the data best, implying that both intraparticle diffusion and external liquid film diffusion influence the adsorption and desorption processes. DGT continuously accumulated triclosan from MP suspensions but slower than theoretical values, indicating some restrictions to desorption. The DGT-induced fluxes in Soils/Sediment (DIFS) model, employed to interpret DGT data, gave distribution coefficients for labile species (K_dl) of 5000 mL g^-1 (PS) and 1000 mL g^-1 (PVC) and the corresponding response times (T_c) were 10 s and 1000 s, respectively. Higher K_dl but smaller T_c for PS than PVC showed that more triclosan adsorbed on PS could be rapidly released, while there were some kinetic limitations for triclosan on PVC. A novel finding was that pH and ionic strength individually and interactively affected the supply of triclosan to DGT. This is the first study to quantify interactions of organics with MPs by using DGT, aiding our understanding of MPs' adsorption/desorption behavior in the aquatic environment.

Keywords: Diffusive gradients in thin-films; Microplastics; Organic pollutants; Sorption; Waters.