Study on Adsorption of Heavy Metals Cu and Zn by Microplastics Under Different Aged Factors

Abstract

Microplastics are widely distributed in a variety of environments, absorbing heavy metals in the environment while aging due to various environmental factors. In this paper, the effects of different aging factors (pH, DOM, and H2O2) on the adsorption capacity of heavy metals Cu and Zn on polyethylene microplastics (PE-MPs) were investigated, and the changes in physical and chemical properties of PE microplastics were analyzed. The results demonstrate that H2O2 aging bears the greatest effect on the adsorption effect of PE microplastics, dissolved organic matter (DOM) aging has the least effect on the adsorption effect of PE microplastics, and the adsorption effect of microplastics aged with pH=9 is stronger than that aged with pH=4; the adsorption kinetics model of microplastics fitted to the pseudo-second-order kinetic model, and the thermodynamic model fitted to Langmuir model; aging mainly changed the surface structure of microplastics, increased the Zeta potential of microplastics, introduced more oxygen-containing functional groups, and finally affected the ability of microplastics to adsorb heavy metals. The research provides data reference for understanding the influence of different aging on the adsorption capacity of heavy metals in microplastics.