Polyethersulfone hollow fiber membranes: effect of the internal liquid and the addition of clay

ABSTRACT Polymer membranes have been widely used in the treatment of effluents worldwide, solving medical, social and environmental problems. Thus, hollow fiber membranes were produced from polyethersulfone (PES) with adding Cloisite Na -CLNa clay and also by inserting the N, N dimethylformamide (DMF) solvent, in order to modify the membrane morphology. Clay was characterized by X-ray fluorescence (FRX) and X-ray diffraction (XRD). By FRX, it was seen that the clay presented naturally sodium and with little accessory materials. The XRD showed that Cloisite Na has a characteristic of a montmorillonite clay containing Na+. The membranes were characterized by contact angle (flat membrane), scanning electron microscopy (SEM) and flow measurements. By means of the contact angle measurements it was seen that the presence of clay favored an increase the hydrophilicity of the membranes. At the hollow fiber membranes, it was observed by SEM that the presence of clay modified the membrane morphology, changing the uniformity of the “fingers” and the macropores and modifying the dense layer in the center of the porous support. The addition of the acid in the internal liquid modified even more the morphology, decreasing the dense layer at the center of the membrane porous support and also changing the “fingers” and the macropores, having a greater uniformity of the same with respect to the membrane without the presence of DMF in the internal liquid. From the flow measurements it was possible to observe that the membrane containing 5% CLNa with the presence of the solvent in the internal liquid obtained a greater flow over time, this occurred due to the presented more uniform morphology of the membrane.