Tuning of hollow fiber membrane properties using different bore fluids

Polymer solutions of a modified poly(ether ether ketone) and poly(vinyl pyrrolidone) in dimethylformamide were spun to prepare hollow fiber membranes by dry–wet spinning method. The influence of Rsingle bondOH bore fluids (BF), with Rdouble bond; length as m-dashH; CH3; C2H5; n-C3H7 or n-C4H9, on morphology and transport and mechanical properties was studied by electron scanning microscopy (SEM) and by measurements of water permeability (WP), dextrane rejection, tensile strength and elastic modulus. The results were discussed on the basis of ternary phase diagrams and Hildebrand solubility parameters, δ. The use of water as the bore fluid resulted in typical UF membranes with the lowest water permeability (158 l h−1 m−2 bar−1) and the highest dextrane rejection (99%). On the other hand, n-alkyl alcohols as the bore fluid produced MF membranes with a water permeability, increasing from about 600 to 1200 l h−1 m−2 bar−1 with increasing alkyl chain length, and with a low dextrane rejection.