Preparation of Fe(III)-immobilized collagen fiber for lysozyme adsorption

A novel adsorbent was prepared by immobilizing Fe(III) onto collagen fiber matrix, and its adsorption to lysozyme was studied. Fe(III) was uniformly dispersed in collagen fibers mainly through chemical reaction and could endure the extraction of water. It was found that the Fe(III)-immobilized collagen fiber (FICF) exhibited high adsorption capacity to lysozyme. The adsorption capacity was 395 mg/g at 303 K when initial concentration of lysozyme was 2.5 mg/mL. The adsorption capacity was significantly influenced by pH, and it reached a maximum value around pH 8.0. The adsorption capacity increased with the increase of temperature. The adsorption capacity of lysozyme remarkably decreased when the concentration of NaCl was increased from 0 to 0.25 mol/L. However, the adsorption capacity increased slightly as the concentration of NaCl was further increased. The adsorption isotherms can be described by the Langmuir equation. Further analysis indicated that the adsorption kinetic data can be well fitted by the pseudo-second-order rate model, and the adsorption capacities calculated by the model were consistent with those of the actual measurements. In addition, Fe(III)-immobilized collagen fiber presented excellent column adsorption kinetic properties and high binding capacity. The adsorption behavior of the column was almost unchanged in adsorption–desorption cycles. The purification of lysozyme from chicken egg white powder by using FICF was investigated. The purity of lysozyme obtained was 100%, and recovery extent of lysozyme was 70.5%.