Bacterial cellulose-based submicrobundle framework-induced hyperporous cellulose microspheres functionalized by ionic liquids for anion exchange chromatography

Abstract

Ovalbumin (OVA) is widely used in food and pharmaceutical industries and can be separated using ion exchange chromatography. However, both rapid adsorption kinetics and great adsorption capacity are impeded by the nanoscale porous structures of chromatography media. Here, hyperporous cellulose microspheres (BCMs) with well-controllable micron-sized macropores are fabricated by a facile one-step pre-crosslinking strategy. Bacterial cellulose nanofibers and dissolved cellulose chains are pre-crosslinked by epichlorohydrin to form submicrobundles and generate an interconnected gel network. The preliminary gelation blocks induce a hyperporous framework during the recrystallization and assembly of regenerated cellulose. BCMs have demonstrated decreased mass transfer resistance and increased accessible active sites due to the micron-sized convective macropores (2.04 μm) and high specific surface area (194.25 m2 g−1). Cationic imidazolium ILs (AMIBr) functionalized BCMs (IL-BCMs) are prepared as anion exchangers. IL-BCMs exhibit rapid adsorption kinetics for OVA, reaching 85% of the equilibrium adsorption amount within 30 min. Additionally, IL-BCMs demonstrate endothermic chemosorption, high adsorption capacity (150.30 mg g−1, 25 °C), reusability (>85% removal efficiency after seven cycles), and selectivity towards OVA at pH 6.0. Continuous fixed-bed adsorption further suggests the practicality of IL-BCMs in ion exchange chromatography, indicating that IL-BCMs are appealing media for protein separation and purification.