Ultrafiltration by a super-hydrophilic regenerated cellulose membrane

Ultrafiltration (UF) has received tremendous attention in concentration and purification of proteins in biotechnology, biomedicine and food production industries. Accordingly, in the present work innovated super-hydrophilic UF membranes were fabricated by the phase inversion technique, from a special casting solution formulation consisting of cellulose acetate in different solvents/additives, followed by complete deacetylation to form a regenerated cellulose membrane. Variables investigated included time of evaporation of as-cast membrane, temperature of coagulation water bath and post annealing of membrane. The membranes were used in ultrafiltrating yeast suspensions and examined by scanning electron microscopy (SEM), Fourier transform infrared, contact angle, porosity and pore size. The membrane performance was found to be strongly affected by each variable, and the best membrane gave a consistently high flux (27 kg/m²h) on prolonged operation, with almost zero salt rejection (%SR), when subjected to 5 bar operating pressure. The super-hydrophilic membrane morphologies indicated an asymmetric structure by SEM examination.