Polydopamine-modified sodium alginate hydrogel for microplastics removal: Adsorption performance, characteristics, and kinetics

The potential health hazards of micro/nanoplastics in food have become a significant concern. This study developed a Polydopamine-modified sodium alginate hydrogel (PMSAH) for removing microplastics in daily drinking water. The hydrogel's performance, characteristics, and kinetics for microplastic removal were systematically evaluated. Results demonstrated that the incorporation of polydopamine reduced the hydrogel's surface zeta potential and increased its adsorption capacity for microplastics. PMSAH5 exhibited the highest removal efficiency, reaching approximately 99.6 %. Additionally, polydopamine-modified sodium alginate hydrogel exhibited higher elasticity and thermal stability. The hydrogel successfully adsorbed microplastics, regardless of their size and surface charge. This adsorption was driven by the combined action of multiple forces, resulting in multilayer adsorption. The unique advantages of polydopamine-mediated multi-molecular interactions present a promising and environmentally friendly approach for effective removal of microplastics in daily drinking water.