Confinement of butanol-affinity polysiloxane nanolayer membrane into fast-diffusion nanoflake arrays for high-efficiency biofuel production

Pervaporation membranes with high n-butanol production have potential applications for the recovery of renewable biofuels from diluted fermentation broth. Proper structuring of membranes is necessary for pursuing combined performance metrics of high liquid flux and separation factors but poses a challenge. In this study, a loosely packed hydrophilic layer composed of a vertical nanoflake array was used to create a low-friction and low-barrier passage for n-butanol (as a fast diffusion layer), which took advantage of its surface areal topography to lock a cross-linked polysiloxane nanolayer for n-butanol capture (as a butanol affinity layer). The fast diffusion-butanol affinity (FD-BA) membranes demonstrated exceptional pervaporation performances for a 1.0 wt% aqueous n-butanol solution, achieving a flux of 15.8 kg m⁻² h⁻¹ and a separation factor of 24. When we coupled a single-pass membrane pervaporation with a simple liquid‒liquid phase separation technique at room temperature, 83.3 wt% n-butanol can be obtained. This FD-BA membrane can be scaled to large-area plate and tubular membranes.