Effect of pH on adsorption of cephalosporin C by a nonionic polymeric sorbent

Adsorption of cephalosporin C in a column charged with a nonionic polymeric sorbent, SP850, was studied at various pH values to assess the effect of pH on the dynamic behavior in column adsorbers. Since cephalosporin C is amphoteric, the fractions of each ionic form were calculated from the pK values at a given solution pH. Single-species isotherm parameters for each ionic form were simultaneously extracted from all sets of adsorption equilibrium data measured at several pH values. The mutual interaction between different ionic forms on SP850 was described by a competitive adsorption, namely the ideal adsorbed solution theory (IAST). This treatment made it possible to simulate the dynamic behavior of cephalosporin C at low pH values properly by a dynamic model which was incorporated with the mutual competitive adsorption.