Post-treatment effect on morphology and performance of polyurethane-based hollow fiber membranes through melt-spinning method

Polyurethane-based (PU-based) hollow fiber membranes were fabricated by melt-spinning method. The influence of hot-air treatment conditions including theoretical draw ratio, temperature and time on morphology and performance of membranes were investigated. The results showed that the maximum mean pore size and pure water flux were obtained as the theoretical draw ratio and treatment temperature reached to 2 and 70 °C, respectively. The deformation-recovery was mainly governed by the treatment temperature in comparison with theoretical draw ratio when the membrane was treated in hot air. The least treatment time that obtained the best pure water flux was 30 min. However, when the membrane treated in stress free conditions, the pore sizes on membrane outer surface were shrunk and the pure water flux decreased with the increment of heat treatment temperature. Moreover, a dense and smooth outer surface with thick skin layer formed as treatment temperature reached at 150 °C. The PU-based hollow fiber membranes which treated at the optimum treatment conditions were used to the microfiltration test of the Direct Sky Blue 5B dye wastewater and the removal rate of Direct Sky Blue 5B particles was higher than 94.57%.