Algal Surface-Inspired Chitosan-Modified Monodisperse Porous Polystyrene Microspheres: Pore Size Regulation and Adsorption Mechanism for Biopharmaceutical Wastewater

Monodisperse porous polystyrene microspheres (PPS) and their derivatives were successfully fabricated via a two-step swelling polymerization approach combined with secondary cross-linking technology. Inspired by the surface morphology of algae, PPS and derivatives were subsequently modified using chitosan with different viscosities (CS-1 and CS-2), thereby constructing chitosan-functionalized PPS. By precisely adjusting the amounts of vinyl chloroacetate (VCA) and the cross-linker 1,4-bis(chloromethyl)benzene (XDC), the pore size of PPS and derivatives could be finely tuned within the range of 5-20 nm. The specific surface area of PPS after secondary cross-linking (HPPS) reached up to 380.79 m²/g, which is approximately 3-5 times higher than that of uncross-linked PPS. Surface modification with chitosan significantly enhanced the water dispersibility, suspension stability, and adsorption capacity of PPS and derivatives toward organic pollutants. The adsorption kinetics of the modified microspheres were better described by a pseudo-second-order model. Notably, PPS containing chlorinated groups and modified with CS-2 (PPS-Cl@CS-2) retained over 80% of their adsorption efficiency after five consecutive cycles. This study presents a viable strategy for constructing porous microspheres with tunable structures and synergistically optimized performance, offering a practical pathway for the regulation of pore size and functional surface modification in porous materials.