PHASE INVERSION PREPARATION AND MORPHOLOGICAL STUDY OF POLYVINYLIDENE FLUORIDE ULTRAFILTRATION MEMBRANE MODIFIED BY NANO-SIZED ALUMINA

In this study, polyvinylidene fluoride (PVDF) membranes with various structures ranging from dense to highly asymmetric morphologies were obtained by changing the effective parameters in the phase inversion process. The effect of some important processing parameters such as solution concentration, harshness of the precipitation bath, exposure time before immersion in coagulation bath and bath temperature was studied and the mentioned parameters were optimized. The membranes were then modified with nano-sized alumina powder in order to improve the hydrophilicity of the PVDF membranes. The surface morphology, surface and cross-sectional structures of the membranes were examined by scanning electron microscope (SEM) and atomic force microscope (AFM). The specific surface area of the membranes was determined using the Brunauer-Emmett-Teller (BET) method. The contact angles between water and the membranes' surfaces were measured in order to study the hydrophilicity changes of the membrane surface. The results indicated that the addition of nano-sized alumina to the casting dope increased the hydrophilicity of the PVDF membrane surface.