Robust superhydrophobic PVDF membrane constructed by template-assisted strategy via thermally induced phase separation for rapid water-in-oil emulsions separation

The bottlenecks of low separation efficiency and unsatisfactory structural stability restrain the advancement of superhydrophobic membranes in water-in-oil emulsions separation. In this work, a facile template-assisted strategy was proposed to construct the robust membranes by casting the polyvinylidene fluoride (PVDF) solution onto the hot stainless plate with the silicon dioxide (SiO2) suspension sprayed as the template in advance. The underlying merits of SiO2 incorporated for the construction of hierarchical structure characteristics and meanwhile served as the reaction sites for the follow-up fluorinated modification were demonstrated, in terms of developing highly-permeable membrane with super hydrophobicity. Correspondingly, the best performing membrane of M−300F shows the fluxes of 2351 ± 225 L·m−2·h−1 and 2752 ± 210 L·m−2·h−1 in the separation of simulated water-in-toluene and water-in-hexane emulsions, and meanwhile exhibits the water rejection of 98.9 ± 0.6 % and 99.1 ± 0.3 % respectively. Results reported in this work might demonstrate a new insight in constructing superhydrophobic membranes for practical water-in-oil emulsions separation.