Concentration and Desalination of Protein Solutions with Superabsorbent Hydrogels.

We quantitatively investigated a process for concentrating and desalinating bovine serum albumin (BSA) in potassium chloride solution by multi-stage operation with superabsorbent-crosslinked hydrogels. The process employs swelling of gel particles by the absorption of water and electrolyte with exclusion of protein molecules. In the two-stage operation, the concentrated solution was diluted with water, and then other gels were added to the diluted solution in order to further concentrate the protein. As a result, the solution was effectively concentrated and desalinated with the superabsorbent hydrogels, and the characteristics of concentration and desalination of a protein solution by multi-stage operations are well expressed by the swelling behavior of superabsorbent hydrogels for a variety of electrolyte concentrations. Furthermore, the optimum dosage of gel particles in each stage was also determined.