Phenolic-modified cationic polymers as coagulants for microplastic removal

Owing to the potential toxicological threat to the environment and human health associated with microplastics, researchers have increasingly focused on microplastic removal in wastewater treatment. Inspired by natural processes, metal–phenolic coordination bonds have been applied to microplastic coagulation using surface phenolic-modified beads. The scope of candidate materials for cationic polymer and phenolic molecules involved in the coagulation process was expanded for surface modification, yielding a high removal efficiency (>90%) of polystyrene beads. To reduce the complexity of the two-material treatment approach, tannic acid–chitosan conjugates were synthesized as a single coagulant – phenolic-modified cationic polymer. The polymers were effectively modified on the surface of the polystyrene beads, and they demonstrated dramatic coagulation behavior within 5 min following the introduction of FeCl3 additive. The removal efficiency of the beads exceeded 80% for all tested polymer types. The effects of purified and non-purified microplastic solutions were compared in cell studies, and the oxidative stress and inflammatory response in cells treated with purified solutions were reduced to levels similar to those observed without exposure to the bead solution.