Adsorption properties of polyethylene microplastics as a function of their shape

Microplastics (MPs) are a diverse group of pollutants with properties that depend on many variables such as the type of polymer, the type and amount of additives in the material, the size and the shape. In particular, the shape-dependent effects are rarely considered in environmental processes where the shape of MPs can influence the interactions. In our study, we investigated the rate and capacity of adsorption for polyethylene MPs. The MPs had comparable size (≈ 100 μm) and specific surface area, but differed in shape: spheres, fragments, and films. Methylene blue dye (MB) was selected as a model compound. The results showed that the adsorption of MB occurred at different rates. Adsorption was the fastest for the spheres, followed by the fragments and then the films. The maximum adsorption capacity of MB also differed between the shapes, with almost twice as much dye adsorbed on the films as on the spheres and fragments. This was unexpected as films and fragments had more comparable properties (irregular shape and comparable degree of crystallinity) compared to the spheres. This indicates that, in addition to other common parameters, the shape itself plays an important role in the adsorption process. Also see: https://micro2024.sciencesconf.org/556542/document