The sodium hydroxide solution used in the treatment of bovine leather in the production of gelatin has the function of dissolving undesirable organic substances, such as proteins and fats. To avoid the discard of this solution as an effluent to the environment, the intention of this project was to develop a process of sodium hydroxide purification, avoiding the waste of the solution and making it appropriate to be re-utilised in the process. Ultrafiltration experiments were carried out in a micro/ultrafiltration unit, Koch Membrane System, model Protosep, modified IV, with transmembrane pressures of 2.5; 3.5 and 4.5 kgf/cm² and temperatures of 25 and 50 °C. The membranes used were tubular ceramic (material: TiO2/alpha - Al2O3) with an average diameter of 0.01, 0.05 and 0.10 µm. The study was divided in two steps: in the first, the best pressure for each membrane was selected, and in the second, a pressure of 3.5 kgf/cm² was adopted and two different forms of feeding were used to define the membrane. The best operational conditions were determined in terms of permeate flow and product quality. With the results, the following operational conditions were selected: pressure of 3.5 kgf/cm², temperature of 25 °C and membrane with average pore diameter of 0.01 µm.
gelatin production; sodium hydroxide solution; ceramic membrane
