Concentration of Gelatin Solutions by Dynamic Ultrafiltration Membranes

A dual-layer dynamic membrane was successfully developed and employed in dewatering aqueous gelatin solutions. The membrane was formed by flowing suspended solutions of alumina sol and colloidal silica on a porous ceramic tube. The silica layer was treated with buffer solution of pH 2 to 3, and was fixed by flowing either hot water or gelatin solution. This membrane rejected more than 90 % of polyethylene glycol, the molecular weight of which was about 1500. The optimum gelatin concentrating conditions were found to be : pressure, 2-3 MPa; mean flow velocity, 0.6-1.0 m/s; temperature, 60°C. Under these conditions this membrane was able to reject 99.5% of the gelatin with high water flux. Low-molecular weight components including inorganic salts in the feed were partly removed from the gelatin solution in this operation.