Preparation and characterization of alumina hollow fiber membranes

Abstract

With the rapid development of membrane technology in water treatment, there is a growing demand for membrane products with high performance. The inorganic hollow fiber membranes are of great interest due to their high resistance to abrasion, chemical/thermal degradation, and higher surface area/volume ratio therefore they can be utilized in the fields of water treatment. In this study, the alumina (Al2O3) hollow fiber membranes were prepared by a combined phase-inversion and sintering method. The organic binder solution (dope) containing suspended Al2O3 powders was spun to a hollow fiber precursor, which was then sintered at elevated temperatures in order to obtain the Al2O3 hollow fiber membrane. The dope solution consisted of polyethersulfone (PES), Nmethyl-2-pyrrolidone (NMP) and polyvinylpyrrolidone (PVP), which were used as polymer binder, solvent and additive, respectively. The prepared Al2O3 hollow fiber membranes were characterized by a scanning electron microscope (SEM) and thermal gravimetric analysis (TG). The effects of the sintering temperature and Al2O3/PES ratios on the morphological structure, pure water flux, pore size and porosity of the membranes were also investigated extensively. The results showed that the pure water flux, maximum pore size and porosity of the prepared membranes decreased with the increase in Al2O3/PES ratios and sintering temperature. When the Al2O3/PES ratio reached 9, the pure water flux and maximum pore size were at 2547 L/m2·h and 1.4 μm, respectively. Under 1600dgC of sintering temperature, the pure water flux and maximum pore size reached 2398 L/(m2·h) and 2.3 μm, respectively. The results showed that the alumina hollow fiber membranes we prepared were suitable for the microfiltration process. The morphology investigation also revealed that the prepared Al2O3 hollow fiber membrane retained its’asymmetric structure even after the sintering process.