Fabrication and characterization of polyethersulfone hollow fiber membranes

Membrane technology is employed in a variety of industries because of its versatility such as water treatment, petrochemical, medical, and biotechnological, beverages, food, and metallurgical separation processes. The current study aims to produce and characterize hollow fiber membranes from polyethersulfone (PES) and pore former polyvinylpyrrolidone (PVP) . To achieve these goals, a small-scale hollow fiber membrane production setup was designed. Box-Behnken design of experiment (DOE) was then used to understand the relationship between four independent input variables (polymer concentration, additive molecular weight, bore fluid composition, and the air gap) and the dependent output variables (morphology, membrane diameter, membrane thickness, pure water permeability, porosity, and pore size distributions). N, N-Dimethylformamide (DMF) was used as the solvent. Water and ethanol (96%) were used as bore fluids. It was revealed that the pure water permeability (PWP) of the membranes was reduced with increasing polymer concentration. The lowest permeability found was 24.8 L/m2.h.bar at 17% polymer concentration while the highest permeability value found was 452.2 L/m2.h.bar at 11% polymer concentration. SEM analysis of the fiber membranes revealed spongy morphologies for membranes containing K90 pore former additive. Water as a quenching medium produced intrusion cells while water and alcohol combinations produced spongy structures with varying degrees of pore sizes. The porosity results varied in the range of 46.6-72.2%. Increasing the polymer content results in a reduction of porosity while increasing the additive concentrations increases the porosity. The average pore sizes and their distribution showed a large operational range. The average pore sizes of the membrane with the highest PWP were 10 times larger than the membrane with the lowest PWP.