Integration of hydroxyapatite from fish scales and polyethersulfone membrane for protease separation from Bacillus subtilis

In the present study, an ion exchange membrane for thermostable alkaline protease separation from Bacillus subtilis was prepared via integration of hydroxyapatite from fish scales (FSHAp) and polyether sulfone membrane. The prepared membranes were characterized in terms of morphology, surface chemistry, ion exchange capacity, water uptake and fouling analysis. The performance of ion exchange membranes were evaluated by protease separation at different pH (3, 5, 7, 9, and 11) and ionic strength (0.05, 0.1, 0.15, 0.2, and 0.25 M). Characterization study revealed that PES/FSHAp-1000 membrane promoted the highest performance with a high permeability coefficient of about 64.0 L/m(2).h.bar and membrane porosity around 90.1%. It also had a high ion exchange capacity of around 7.09 meq/g and water uptake for about 97.08%. This membrane's hydrophilicity was also improved by 53%, and its flux recovery ratio (FRR) was about 97.79%. Fourier transform infra-red Spectroscopy (FTIR) and X-ray- diffractometer (XRD) ascertained the successful integration of FSHAp onto the membrane's surface. Optimum recovery of protease (92.30%) obtained when the elution process performed using a glycine-NaOH buffer at pH 11 and 2.0 M ionic strength.