Characterization and evaluation of the novel agarose-nickel composite matrix for possible use in expanded bed adsorption of bio-products

Agarose-nickel (Ag-Ni) composite matrix was evaluated for its use in expanded bed adsorption (EBA). Bovine serum albumin (BSA) and lysozyme were used as model proteins in batch and column adsorption studies. Accordingly, Reactive Green 19 (RG19) dye-ligand was covalently immobilized onto the support matrix to prepare affinity adsorbent for protein adsorption. Results were then compared with data obtained from Streamline commercial matrix. In batch experiments RG19 derivatives of Ag-Ni (RG19-Ag-Ni) exhibited high adsorption rate; and also a higher binding capacity of BSA (31.4 mg/ml adsorbent) was observed for Ag-Ni compared to the commercial adsorbent. More than 70% of the adsorption capacity was achieved within 30 min which is a reasonable contact time for EBA operations. The equilibrium adsorption data well agreed with Langmuir isotherm model. The expanded bed adsorption studies showed a reasonable breakthrough behavior at high flow rates and a higher dynamic binding capacity (DBC) was obtained for novel matrix in compare to streamline at the same fluid velocity. DBC at 10% breakthrough reached 66% of the saturated adsorption capacity at the high flow velocity of 450 cm/h which indicates the favorable column efficiency. Additionally, two different Ag-Ni size fractions (75-150 and 150-300 μm) were examined to investigate the expanded bed performance dependency on the adsorbent particle size with respect to the hydrodynamic stability and adsorption properties using lysozyme as model protein. Interestingly, the small ones showed less axial dispersion coefficient (<1.0 × 10−5 m2/s) which resulted in higher bed stability in high fluid viscosities. Overall, the adsorption experiments results demonstrated that small size fraction of Ag-Ni matrices acts more effectively for expanded bed adsorption of bio-molecules.