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 degrees and hexane of 67 degrees. 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).