Effects of biofilm on metal adsorption behavior and microbial community of microplastics

In this study, the adsorption behavior of Cu(II) and Pb(II) on the biofilm-developed polystyrene (PS) micro plastics (MPs) was compared with the virgin PS (V-PS) and UV-aged PS (UV-PS). The results demonstrated that the biofilm could enhance the adsorption abilities onto MPs more than UV radiation. The intra-particle diffusion model suggested that the adsorption on V-PS was dominated by intra-particle diffusion, while the adsorption rate was controlled by the binding diffusion on UV-PS and biofilm-developed PS (Bio-PS). Compared with the V-PS and UV-PS, the Bio-PS showed the largest adsorption capacity based on the Freundlich isotherm model, which indicated that the adsorption of heavy metals onto Bio-PS was multilayer and heterogeneous. The adsorption mechanism of Bio-PS contained physical adsorption, chemisorption, and biosorption. These Bio-PS adsorption types participated in both oxygen and nitrogen groups. Based on the 16S rRNA analysis, the diversity of the microbial community with biofilm changed to a certain extent after the adsorption of heavy metals. Furthermore, the stress of lead (Pb) adsorption had a higher impact on the microbial community distribution and the PS biofilm. This study illustrated how the formation of biofilms can highly affect the adsorption behavior of MPs as well as the microbial community of MPs.

Automated summary

This study found that biofilm can enhance the adsorption capacity of microplastics to copper and lead, while the influence of UV radiation is minimal. According to modeling analysis, adsorption on V-PS is dominated by intra-particle diffusion, while the adsorption rate on UV-PS and Bio-PS is mainly controlled by binding diffusion. Bio-PS has the strongest adsorption capacity and the adsorption mechanisms include physical adsorption, chemisorption, and biosorption.