Pore Regulation of Cellulose Acetate Microspheres by Solvent Evaporation-Induced Phase Separation and Immobilization by Ionic Liquids for Congo Red Adsorption

The development of polymeric microspheres with tunable porous structures is crucial yet challenging for separation applications. Herein, cellulose acetate (CA) microspheres with adjustable porosity are synthesized via a solvent evaporation-induced phase separation technique using dichloromethane (DCM) as a porogen. Temperature-induced phase separation between CA and DCM enables structural control, yielding non-porous, porous, macroporous, or large-hole configurations by varying DCM concentration (10–40% w/v). Porosity increases from 0% to 30.5%, with pore sizes ranging up to 0∼30 μm. Methylimidazolium ionic-liquid-functionalized CA microspheres (CA-IL) exhibit rapid Congo red adsorption (equilibrium in 30 min), high capacity (90.08 mg/g), and 85% efficiency retention over seven cycles. Fixed-bed experiments confirm CA-IL’s practicality for ion-exchange chromatography. This work provides a scalable strategy to design porous polymers with tailored structures and functionalities, addressing challenges in separation science. The tunable architecture, recyclability, and adsorption performance of CA microspheres highlight their potential in wastewater treatment and chromatographic processes.