Constructing Scalable Superhydrophobic Membranes for Ultrafast Water-Oil Separation

Superhydrophobic membranes are desirable for separation of water-in-oil emulsions, membrane distillation, and membrane condensation. However, the lack of large-scale manufacture methods of superhydrophobic membranes hampers their widespread applications. Here, a facile method of coaxial electrospinning is provided to manufacture superhydrophobic membranes for the ultrafast separation of water-in-oil emulsions. Under the high-voltage electric field, the polydimethylsiloxane (PDMS)-coated polyvinylidene fluoride (PVDF) nanofibers and PDMS microspheres with PVDF nanobulges were integrated together during the electrospinning process. Moreover, asymmetric composite membranes with selective layers are designed to reduce the resistance of the mass transfer. Consequently, the as-prepared asymmetric composite membrane exhibits an ultrafast permeance and excellent separation efficiency of about 99.6%, outperforming most of the state-of-the-art membranes reported previously. Most importantly, the membrane could be as large as 770 cm(2), could be manufactured continuously, and could be easily enlarged further via tailoring the roller receptor, showing strong promise in the separation of water-in-oil emulsions.

Automated summary

A simple method of coaxial electrospinning was proposed to manufacture superhydrophobic membranes for ultrafast separation of water-in-oil emulsions. By designing asymmetric composite membranes with selective layers, the mass transfer resistance was reduced, resulting in high separation efficiency and permeance. The manufactured membrane showed strong promise in separation of water-in-oil emulsions, with a large size, continuous production, and potential for further enlargement.