Effects of Spinning Temperature on the Morphology and Performance of Poly(ether sulfone) Gas Separation Hollow Fiber Membranes

In this study, we demonstrated that poly(ether sulfone) (PES) hollow fiber membranes with almost defect-free surfaces could be prepared at low PES concentrations if the hollow fibers were spun at low temperatures by dry-jet wet spinning. A series of hollow fiber membranes were spun at different coagulation batch temperatures ( T c ) and dope solution temperatures ( T d ). Effects of T c and T d on the membranes’ morphologies and gas separation performances were investigated. Membrane morphologies characterized by using a scanning electron microscope (SEM) showed that the skin layer thicknesses increased with the decreases in T c and T d . Moreover, mean surface pore sizes of the membranes, which were evaluated by using the gas permeation method, significantly decreased as T c or T d decreased. PES hollow fiber membranes spun at the lowest temperatures ( T c = 7 °C, T d = 3 °C) showed O 2 and CO 2 permeances of 18.9 and 53.5 GPU, respectively. And selectivities of O 2 /N 2, CO 2 /N 2, and CO 2 /CH 4 gas pairs were 1.15, 3.26, and 1.24, respectively. After silicone coating, the selectivities increased to 7.24, 47.7, and 39.4, respectively, but O 2 and CO 2 permeances decreased to 4.85 and 31.9 GPU, respectively. To our best knowledge, the gas separation performance was the test among all PES hollow fiber membranes.