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

Abstract

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 (<i>T</i><sub>c</sub>) and dope solution temperatures (<i>T</i><sub>d</sub>). Effects of <i>T</i><sub>c</sub> and <i>T</i><sub>d</sub> 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 <i>T</i><sub>c</sub> and <i>T</i><sub>d</sub>. Moreover, mean surface pore sizes of the membranes, which were evaluated by using the gas permeation method, significantly decreased as <i>T</i><sub>c</sub> or <i>T</i><sub>d</sub> decreased. PES hollow fiber membranes spun at the lowest temperatures (<i>T</i><sub>c</sub> = 7 °C, <i>T</i><sub>d</sub> = 3 °C) showed O<sub>2</sub> and CO<sub>2</sub> permeances of 18.9 and 53.5 GPU, respectively. And selectivities of O<sub>2</sub>/N<sub>2</sub>, CO<sub>2</sub>/N<sub>2</sub>, and CO<sub>2</sub>/CH<sub>4</sub> 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<sub>2</sub> and CO<sub>2</sub> 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

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