A Study On The Performance And Morphology Of Multicomponents Hollow Fiber Ultrafiltration Membrane

Abstract

Multicomponent (Polysulfone/poly(vinylpyrolidone)–K30/N,N-dimethylacetamide) hollow fiber ultrafiltration membrane was spun using dry-wet spinning method. The membrane was produced at different shear rate. Permeation properties and separation tests were examined using pure water flux and sodium chloride solution of concentration 1g/L respectively. Membrane morphology and molecular orientation were observed and directly measured using scanning electron microscopy (SEM) and plan polarized infrared spectroscopy. Positive infrared dichroism was detected only in samples of highest shear membranes. This suggests that the polymer molecules become aligned under high shear. Permeation test using pure water showed that increasing shear rate increases flux. On contrary, percentage rejection using sodium chloride solution showed a decreasing trend in rejection with the increased in shear rate. Increasing shear rate during dope extrusion through spinneret in the spinning of hollow fiber ultrafiltration membranes will apparently decrease the skin layer thickness and thus increasing the flux and also enhances the molecular orientation in the skin layer which causes high percentage rejection which was in the range of 21% to 33% for transmembrane pressure of 6 bar. The results indicate that there is a strong correlation between extrusion shear rate and the membrane morphology thus affecting the flux and rejection of hollow fiber ultrafiltration membranes.