Adsorptive potential of sulfonated poly(glycidylmethacrylate)-grafted cellulose for separation of lysozyme from aqueous phase: Mass transfer analysis, kinetic and equilibrium profiles

Lysozyme (LYZ) adsorption onto poly(glycidylmethacrylate)-grafted cellulose having sulfonate functional group (PGMA-g-Cell-SO3H) was investigated. PGMA-g-Cell-SO3H was prepared by graft copolymerization of glycidylmethacrylate (GMA) onto cellulose in the presence of ethyleneglycoldimethacrylate as cross linker using α,α′-azobisisobutyronitrile as initiator followed by the introduction of sulfonic acid groups through ring opening reaction of epoxide group in grafted GMA with sodium sulfite–isopropanol–water mixture. The adsorbent was characterized by means of FTIR, SEM, XRD and BET analysis. The maximum value of LYZ adsorption was found to be 74.93 and 96.21 mg/g for an initial concentration of 150 and 200 mg/L, respectively, at pH 6.0. The batch adsorption process followed pseudo-second-order kinetics and the equilibrium was achieved within 3 h. The kinetic data were also analyzed using external and intraparticle diffusion models. The intraparticle mass transfer diffusion model gave a better fit to the experimental data. Equilibrium isotherm data were well fitted with the Langmuir isotherm with maximum adsorption capacity of 141.67 mg/g at 30 °C. Thermodynamic study revealed an endothermic adsorption process. All of the adsorbed LYZ was eluted completely by 0.2 M CH3COOH solution. Results obtained from repeated adsorption/desorption process showed that PGMA-g-Cell-SO3H can be used for the separation of LYZ from aqueous solutions.