change processes would be of great utility in many biotech-The thermodynamics and energetics of the ion exchange of bonology applications. In particular, such knowledge would vine serum albumin (BSA) at a cellulosic ion exchanger (Whatimprove the ability to predict and control the performance man QA52) have been studied. Equilibrium isotherm analysis alfor protein ion-exchange processes. lowed the determination of the thermodynamic equilibrium con-Ion exchange is a reversible interchange of ions between stants (K) for a range of pH. The heats of exchange of the BSA a liquid and solid, in which there are no permanent changes at Whatman QA52 were obtained by high-sensitivity titration miin the structure of the solid. However, phenomena associated crocalorimetry. A thermodynamic analysis procedure was develwith ion exchange involve mechanisms other than the ionic oped allowing calculation of the standard free energy, the standard exchange of ions. Since the transfer of ions between phases enthalpy, and the standard entropy of exchange. The results show that the relative contributions of the enthalpy and entropy change occurs at a solid phase, ion exchange can be considered as radically depend on the solution conditions. The knowledge of a sorption process and has many similarities with adsorption. these thermodynamic properties provided useful insights into the Protein ion exchange is an intricate process. It is the outcome relative importance of the factors contributing to the overall ionof the interplay of various forces mutually acting between exchange process. This assessment hence provides a basis for the sorbent surface, the protein molecules, the solvent moleguidelines for more effective separation and for establishing a more cules, low-molecular-weight ions, and any other solute in practical model for theoretical prediction of ion-exchange perforthe system (1). Electrostatic interactions are important in mance. แญง 1997 Academic Press aqueous systems, as many protein residues are ionized at