Preparation of PVDF Hollow Fiber Membranes Using SiO2 Particles: The Effect of Acid and Alkali Treatment on the Membrane Performances

This work presents the preparation of PVDF hollow fiber membranes using SiO2 particles as an additive via a conventional immersion precipitation method. The asymmetric membrane formed consists of a uniform distribution of finger-like structure near the inner layer with sponge-like structure near the outer layer. SiO2 particles were removed from the spun membranes by a treatment using either sodium hydroxide (NaOH) solution or hydrofluoric (HF) acid. Both the NaOH solution and HF acid treatments have resulted in PVDF hollow fiber membranes with enhanced water permeability of up to 748.4 L/m(2) . h and 690.7 L/m(2) . h, respectively. HF acid was found to be more efficient in dissolving SiO2 and subsequently washing the particles out of the membrane for only 10 min compared to the treatment with NaOH solution, which took almost I h for complete removal. Mechanical properties of hollow filer membrane treated with HF acid was found to be almost unaffected and showed a much better ductile behavior compared to the original one; while the one treated with NaOH solution possessed poor mechanical properties.