Effect of coagulation bath in phase inversion on microstructure of hollow fiber porous Al₂O₃ support

Al₂O₃ hollow fiber porous supports with asymmetric structures were prepared by phase inversion method. The effects of ethanol/water solution with different contents as internal and external coagulation baths on the microstructure and performance of as-synthesized hollow fiber supports were investigated. The results indicated that the finger-like voids on inner side of support extended outwards and the pore size increased as well with the increasing of ethanol content in external coagulation bath when using water as internal coagulation bath. The three-point bending strength of the support increased firstly and then decreased, meanwhile pure water flux and N₂ permeance decreased firstly and then increased. The internal coagulation also had an effect on the structure of hollow fiber porous supports. When using ethanol and water as internal and external coagulation baths, respectively, the as-synthesized hollow fiber supports possessed sponge-like layer on inner side and finger-like voids on outer side. The N₂ permeance and pure water flux were about 6.85×10^-5 mol/(s·m²·Pa) and 4.5 m³/(m²·h) for the hollow fiber supports.