Preparation of dual-layer acetylated methyl cellulose hollow fiber membranes via co-extrusion using thermally induced phase separation and non-solvent induced phase separation methods

Dual-layer acetylated methyl cellulose (AMC) hollow fiber membranes were prepared by coupling the thermally induced phase separation (TIPS) and non-solvent induced phase separation (NIPS) methods through a co-extrusion process. The TIPS layer was optimized by investigating the effects of coagulant composition on morphology and tensile strength. The solvent in the aqueous coagulation bath caused both delayed liquid-liquid demixing and decreased polymer concentration at the membrane surface, leading to porous structure. The addition of an additive (triethylene glycol, (TEG)) to the NIPS solution resolved the adhesion instability problem of the TIPS and NIPS layers, which occurred due to the different phase separation rates. The dual-layer AMC membrane showed good mechanical strength and performance. Comparison of the fouling resistance of the AMC membranes with dual-layer polyvinylidene fluoride (PVDF) hollow fiber membranes fabricated with the same method revealed less fouling of the AMC than the PVDF hollow fiber membrane. This study demonstrated that a dual-layer AMC membrane with good mechanical strength, performance, and fouling resistance can be successfully fabricated by a one-step process of TIPS and NIPS.close0