A facile strategy towards developing amphiphobic polysulfone membrane with double Re-entrant structure for membrane distillation

Membrane surface wetting and fouling are still crucial issues in many separation processes such as membrane distillation (MD), especially when oil-contained feed solution was treated. To solve that problem, a facile synthesis strategy for amphiphobic polymeric membrane was successfully proposed in the current work. Via traditional non-solvent induced phase separation (NIPS) and subsequent sol-gel process, double re-entrant structure was ingeniously constructed; that is, the first level re-entrant structure was supplied by the bicontinuous inter-connected porous structure obtained through optimized phase separation parameters and the second level re-entrant structure was offered by the spherical and dimensionally different silicon dioxide (SiO2) nanoparticles which were spontaneously generated during sol-gel process. After cooperating with the fluorine-contained chemical coating, the resultant polysulfone (PSf) membrane with double re-entrant structure exhibited excellent and stable repellency performance to both water and organic liquid, even showing high hexadecane contact angle of 121° and hexane of 67°. Compared with solely hydrophobic membrane, the as-fabricated amphiphobic PSf membrane achieved long-term stable vapor flux and salt rejection in MD process even with the presence of surfactant sodium dodecyl sulfonate (SDS).