Insights into the adsorption of ibuprofen onto polyethylene microplastics using molecular dynamic simulation

Abstract

Microplastics (MPs) and pharmaceutical pollutants are emerging contaminants in aquatic environments. While microplastics can adsorb pharmaceutical pollutants, the mechanisms governing their interactions and the factors influencing these processes are not well understood. Understanding these interactions is crucial for assessing the environmental impact of co-existing pollutants. This study investigates the interaction between polyethylene (PE) MPs and ibuprofen (IB) in aquatic environments using a combination of molecular dynamics simulation (MDS) and batch adsorption experiments. The isotherms and kinetic models were applied to analyze the adsorption data, while MDS provided insights into the molecular interactions occurring between IB and PE MPs in aqueous environments. The adsorption capacity of IB onto PE MPs reaches 0.4139 mg/g, and the adsorption process follows the Temkin (R² = 0.9671) and Elovich (R² = 0.9856) models, suggesting a complex adsorption mechanism involving multilayer adsorption on the non-uniform surface. MDS reveals that non-bond interactions, particularly van der Waals forces, dominate the interaction between IB and PE MPs. This study provides critical insights into how MPs and pharmaceutical pollutants interact in aqueous environments, offering a deeper understanding of the environmental behavior of these co-existing pollutants.