Optimizing separation performance and interfacial adhesion of PDMS/PVDF composite membranes for butanol recovery from aqueous solution

Bio-butanol is an important aspect for development of renewable energy. Currently, it remains challenging for developing highly permeable and selective composite membranes to efficiently recover butanol produced in biomass fermentation process. In this work, we fabricated polydimethylsiloxane (PDMS) into thin and defect-free composite membranes by using porous PVDF as the substrate. The formation of PDMS membrane layer was finely controlled by optimizing the substrate pore size and casting solution viscosity. In particular, the interfacial adhesion between PDMS active layer and PVDF substrate layer, which is critical for practical application of composite membrane, was probed by using in-situ nano-indentation/scratch technique for the first time. The transport properties of the prepared PDMS/PVDF composite membranes were studied by pervaporation recovery of n-butanol from aqueous solution with different feed concentrations or temperatures. The results indicated that the PDMS membrane layer with a carefully tuned thickness of ∼11 μm offered high total flux of 2210 g/m²h and excellent separation factor of 46 (1 wt% butanol/water at 70 °C), as well as strong interfacial adhesion for the PDMS/PVDF composite membrane. The separation performance is superior to the reported membranes, showing great potential for application in bio-butanol separation.