Kinetics of sequential and parallel sorption of zinc and albumin on hydroxyapatite

The sorption kinetics of zinc ions and bovine serum albumin (BSA) on the surface of suspended hydroxyapatite (HAP) was studied. The sorption kinetics of zinc ions and BSA is described by the pseudo-second-order Lagergren equation. The maximum amounts of both components adsorbed in the course of the sequential and parallel sorption of BSA and zinc ions on HAP are lower than those found for sorption of the individual components on HAP. The interaction of zinc ions with BSA in a solution results in the formation of particles composed of complexes, the average size of which increases with increasing concentration of metal ions until some particles reach the size needed for the isolation of a separate solid phase.