The triazine dye Cibacron Blue F3GA was covalently immobilized as an affinity ligand onto microporous poly(2-hydroxyethyl methacrylate) (pHEMA) membranes. Three different metal ions [i.e.. Fe(III), Zn(II), or Cu(II)] were then chelated with the immobilized Cibacron Blue F3GA molecules. Lysozyme adsorption onto these affinity adsorbents from aqueous solutions containing different amounts of lysozyme at different pH was investigated in a batch system. Lysozyme adsorption capacity of all of the metal-dye-immobilized membranes was greater than that of the dye-immobilized membranes. The nonspecific adsorption of the protein on the pHEMA membranes was negligible. The adsorption phenomena appeared to follow a typical Lang muir isotherm. The maximum capacity (q(m)) of the Fe(III)-Zn(II),-or Cu(II)-dye chelated membranes for lysozyme adsorption (384, 326, and 306 mug/cm(2)) was greater than that of the dye-immobilized membrane (224 mug lysozyme/cm(2)), respectively. The dissociation constant (k(d)) values were found to be 2.51 x 10(-7) M with dye-immobilized membrane, and 2.32 X 10(-7), 2.38 X 10(-7), and 2.40 x 10(-7) M with the Fe(III)-Zn(II),-and Cu(II)-dye-chelated membranes, respectively. More than 95% of the adsorbed lysozyme was desorbed in 60 min in the desorption medium containing 0.5 M KSCN at pH 8.0.