Recent Progress in Chitosan-Based Microsphere Composites for Phosphorus Removal from Aqueous Environments

• • Chitosan microspheres exhibit high phosphorus adsorption capacity, with modified composites achieving capacities up to 150 mg P/g, enabling efficient removal from wastewater with phosphate concentrations as low as 0.02 mg/L, which is critical for preventing eutrophication. • • Modification strategies, such as metal loading (e.g., Fe, La, Zr), significantly enhance adsorption selectivity and capacity; for instance, Fe-loaded magnetic alginate-chitosan beads show stable performance across pH 3-9, addressing pH sensitivity in real effluents. • • Regeneration of spent microspheres using alkaline solutions (e.g., 0.1 M NaOH) achieves >90% desorption efficiency, allowing multiple cycles and reducing operational costs by up to 40% compared to single-use adsorbents. • • The adsorption mechanism involves electrostatic interactions and ligand exchange, with kinetic data fitting pseudo-second-order models (R² > 0.99), indicating chemisorption as the rate-limiting step, which is essential for designing scalable column systems.