Enhancement of Pb(II) Adsorption by Aged Microplastics in the Presence of Microalgae: Kinetic and Mechanistic

This study investigated the effects of different aging treatments (UV light, potassium permanganate, and sodium hydroxide treatments) on the adsorption of lead (Pb(II)) by PET microplastics, as well as the impact of Microcystis aeruginosa on lead adsorption by PET microplastics. The results indicated that different aging treatments significantly affected the adsorption capacity of microplastics, which could be attributed to the increased functional groups and surface porosity during the aging process. Kinetic analysis revealed that the adsorption of Pb(II) follows a pseudo-second-order model, suggested that the adsorption process is mainly controlled by chemical adsorption. Intraparticle diffusion analysis further elucidated the migration mechanism of Pb(II) within the microplastics. On the other hand, the presence of Microcystis aeruginosa significantly enhanced the adsorption capacity of microplastics. As the concentration of microalgae increases, the promoting effect of microalgae on Pb(II) adsorption by microplastics gradually strengthens, with extracellular polymeric substances (EPS) secreted by microalgae playing a key role in facilitating Pb(II) adsorption. These findings suggested that microalgae could strengthen the role of microplastics as carriers of heavy metal lead and aggravate the risk of lead pollution diffusion in aquatic ecological environment.