Surface-Modified Zeolite-Filled Poly(Piperazine-Amide)/Polysulfone Composite Membrane for Potassium Extraction

Polysulfone (PS) hollow fiber microporous membrane was used as substrate, the micropores of which were filled with surface-modified zeolites suspension on the outer surface by vacuum method, and then zeolite-filled poly(piperazine-amide)/PS hollow fiber composite membrane was synthesized on the substrate by interfacial polymerization reaction with piperazine (PIP) aqueous solution and trimesoyl chloride (TMC) n-hexane solution. The substrate membrane and synthetic composite membrane were characterized by scanning electron microscopy (SEM). A thin poly(piperazine-amide) active skin layer was synthesized on the substrate and the surface-modified zeolite particles were successfully embedded in the surface micropores of the substrate. The separation factors of the sample to K+ are 4.25, 60.46 and 93.61 in the mixed K+-Na+, K+-Ca2+ and K+-Mg2+ solutions respectively, which indicates that the sample has preference selectivity to K+ and can be used as a potential ion-exchange membrane for potassium continuous extraction from seawater.