Aging dependent plastic bag derived-microplastics as a vector of metals in lake water

The adsorption of microplastics (MPs) for metals in aquatic environment remains poorly understood due to the use of either commercial MPs, which have different property from the MPs in environments, or artificial solutions, which have not only the significantly higher concentration of metals than natural aqueous environment but also the different natures. In this study, we elaborated the adsorption throughout the aging process of plastic bag derived-MPs (initially 1-2 mm) by potassium persulfate (K2S2O8) solution to metals in lake water. Comparatively, plastic bag derived-MPs had the highest adsorption capacity for Zn2+ followed by Fe3+, Pb2+, Mn2+, Cr6+, Ni2+, Cu2+ and Cd2+, which is not completely consistent with the literature. Both the adsorption capacity and distribution coefficients of Cu2+, Ni2+, Zn2+, Mn2+ and Pb2+ had significant linear correlation with carbonyl index (p < 0.05). Although the aging overall enhanced the adsorption, the adsorption capacities of MPs might fluctuate depending on metal.