Cellulose hollow fibers membranes for ion-exchange chromatography

The development of an efficient and cost-effective purification process is the objective of protein separation. Usually, the most common procedure is chromatography, typically performed in a packed bed column; however, the cost is relatively high. Nowadays, one of the most interesting and promising method is the employment of particular membranes, the hollow fibers, in the standard chromatographic operations. Hollow fibers membranes were developed in the 1960s, specifically for reverse osmosis; nonetheless, they are now largely applied in both liquid and gaseous applications. In this project, the preparation of cellulose hollow fibers, exploited for ion-exchange chromatography, was studied during a five months internship at the King Abdullah University of Science and Technology (KAUST) in the group of Professor Suzana Nunes. The hollow fibers were prepared, dissolving cellulose in 1-Ethyl-3-methylimidazolium diethyl phosphate (EMIM DEP), an ionic liquid commonly used as green solvent for cellulose. After a first research, regarding the performance of flat sheet membrane obtained by phase inversion, in which permeance and rejection were investigated using bovine serum albumin (BSA), the second phase of the project was the optimization of cellulose hollow fibers. Steps of the procedure included: a prior functionalization and application in ion-exchange chromatography. Ion exchange hollow fibers were, indeed, prepared reacting the cellulose with 1,4-butane sultone, and checked for proper functionalization by FTIR. The ion-exchange fibers were primarily characterized in bind and elute mode using pure lysozyme solutions. The Tris buffer, chosen for equilibration and adsorption, was optimized in terms of molarity and pH. The values of static binding capacity resulted in promising and comparable to that of the commercial ion-exchange membrane.