Green thermally induced phase separation (TIPS) process for braided tube reinforced polyvinylidene fluoride (PVDF) hollow fiber composite membranes with favorable bonding layer

Currently, membrane separation technology was used in the fields of water treatment, gas separation and electrodialysis. Among them, water treatment was still the main field of application of membrane separation technology, for example, in the treatment of industrial wastewater, membrane separation technology does not destroy or change the composition of wastewater during the treatment process, and valuable products can be recovered and used commercially. The braided tube reinforced polyvinylidene fluoride (PVDF) hollow fiber composite membranes were successfully prepared by thermally induced phase separation (TIPS) method with no harmful diluent and additives (green preparation) based on concentric circle spinning process. The membrane morphology was characterized by scanning electron microscopy (SEM) and confocal scanning microscopy (CSM). The effects of polyethylene oxide (PEO) content on the performance of the prepared hollow fiber membranes were investigated in terms of mechanical strength, pure water flux and bovine serum protein (BSA) rejection. The results showed that the addition of PEO promoted the phase separation process and inhibited the growth of PVDF spherical crystals. When the PEO content was 15wt%, the membrane has high pure water flux and excellent BSA rejection. In addition, the tensile strength of the reinforced hollow fiber membranes exceeded 100 MPa and exhibited favorable interfacial bonding.