ABSTRACT Fractionation and purification of complex protein mixture has becomes a great interest and has attracted a considerable amount of attention in recent years. This study aimed is to demonstrate the factors influencing the lysozyme separation through polyethersulfone ultrafiltration (UF) membrane. Asymmetric UF membrane with 15% polymer composition (UF15) was developed via phase inversion technique. Membrane was characterized in term of morphology, membrane surface charge and molecular weight cut-off to ensure its suitability for lysozyme separation. Effect of pH on the transmission of lysozyme through the UF15 membrane has been examined at different pH (5, 7, 9, 11 and 13) and ionic strength (0.1M, 0.2M and 0.3M). Results displayed that at optimum pressure 3 bars, permeation with pH 9 and 0.1M ionic strength of feed solution obtained the optimum flux and lysozyme transmission for about 36.6 x 10 -5 m 3 /m 2 and 92.9%, respectively. This study has proved that pH and ionic strength were found to be greatly affected the lysozyme transmission and promoted the lysozyme separation to a significant degree
