Effects of hydroxyl group content on adsorption and desorption of anthracene and anthrol by polyvinyl chloride microplastics

Pollutant-attached microplastics have received increasing attention in recent years. However, information regarding the influence of hydroxyl group content of pollutants on the adsorption and desorption behavior is unclear, which affects their fate and risks in the aquatic environment. In this study, we investigated the adsorption and desorption behavior of anthracene (ANT) and its hydroxy derivatives (OHAs), including 2hydroxyanthracene (MOHA), 2,6-dihydroxyanthracene (DOHA), and 1,8,9-trihydroxyanthracene (TOHA) on polyvinyl chloride (PVC) microplastics, and their interaction mechanism through the batch, characterization, and computational experiments. The results showed that the adsorption of ANT and OHAs on PVC microplastics conformed to the pseudo-second-order kinetic model and was exothermic spontaneously. The adsorption effi-ciency on PVC followed the order of ANT > MOHA > DOHA > TOHA, indicating that increase in hydroxyl group substitution degree will inhibit pollutant adsorption on PVC microplastics. Conversely, the release amounts of MOHA from PVC into simulated gastric fluids were higher than those of ANT. Experimental and computational results suggested that the affinity of ANT/OHAs to PVC microplastics was the most likely outcome in hydrophobic effect, electrostatic repulsion, and CH-pi interaction forces. These findings help elucidate the mechanisms of pollutant adsorption on microplastics and evaluate the risk of pollutant-attached microplastics in the aquatic environment. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the adsorption and desorption behavior of pollutants on PVC microplastics, with results showing that an increase in hydroxyl group substitution degree can inhibit the adsorption of pollutants. Conversely, the release amounts of pollutants from PVC were influenced by the hydroxyl group content. The affinity of pollutants to PVC microplastics is mainly influenced by hydrophobic effect, electrostatic repulsion, and CH-pi interaction forces.