Procion Brown MX-5BR attached and Lewis metals ion-immobilized poly(hydroxyethyl methacrylate)/chitosan IPNs membranes: Their lysozyme adsorption equilibria and kinetics characterization

Interpenetration networks (IPNs) in membrane form were synthesized from 2-hydroxyethyl methacrylate (HEMA) and chitosan (pHEMA/chitosan) via UV-initiated photo-polymerization in the presence of an initiator alpha, alpha'-azoisobutyronitrile. Procion Brown MX-5BR (PB MX-5BR) was covalently attached onto IPNs membrane as a metal chelating dye-ligand. Two different Lewis metal ions (Fe(III) or Cu(II)) were immobilized onto the dye-ligand for utilization in the immobilized metal affinity chromatography (IMAC). The binding characteristics of a model protein (lysozyme) to IMAC adsorbents and selectivity of immobilized metal ions (Fe(III) and Cu(II)) to the lysozyme have been investigated from aqueous solution using the dye-ligand-attached IPNs membrane as a control system. The experimental data was analysed using the two adsorption kinetic models the pseudo-first-order and pseudo-second order to determine the best-fit equation for the adsorption of lysozyme onto dye-ligand and IMAC adsorbents. The second-order equation for the adsorption of lysozyme on the dye-ligand, dye-ligand-Fe(III) and dye-ligand-Cu(II) membrane systems is the most appropriate equation to predict the adsorption capacity for all the tested adsorbents. The reversible lysozyme adsorption on the dye-ligand and IMAC adsorbents obeyed the Temkin isotherm. The lysozyme adsorption capacities of the dye-ligand, dye-ligand-Fe(III) and dye-ligand-Cu(II) immobilized IPNs membranes were 79.1, 147.4, and 128.2 mg ml(-1), respectively. The adsorption of the lysozyme on the pHEMA/chitosan membrane plain was about 8.3 mg ml(-1). (C) 2002 Elsevier Science Ltd. All rights reserved.