Preparation of polyimide hollow fiber membrane

Abstract

Abstract The polyimide hollow fiber membrane has the characteristics of high packing density, large specific surface area, simple membrane module structure, and good separation performance for CO2/CH4. Therefore, it has become a hotspot in the field of gas separation, while its preparation process needs further exploration. This study is aimed to prepare polyimide P84 hollow fiber membranes by the dry–wet phase transformation method and investigate the main influencing factors, such as spinning solution concentration, external coagulation bath selection, bore fluid selection, and air gap, in the preparation process. The results showed that the pore size of the dense layer of the hollow fiber membrane decreased with the spinning solution concentration. As the height of the air gap increased, the dense layer thickness on the outer surface also gradually rose. The external coagulation bath affected the internal finger holes of the hollow fiber membrane. As the external coagulation bath changed continuously from water, ethanol, and isopropanol to acetone, the finger pore structure decreased in turn. A mixed solution of water/isopropanol, water/ethanol, and water/acetone was used as the bore fluid. In the case of pure water application, the density of finger pores inside the film was remarkably reduced.