Preparation And Characterization Of PVDF/PAN/nano-Clay Hybrid Hollow Fiber UF Membrane

Poly(vinylidene fluoride) (PVDF) is a kind of membrane material with excellent properties. Poly(vinylidene fluoride)/Polyacrylonitrile(PAN) blend hollow fiber UF membranes were prepared by L-S phase inversion and dry-wet spinning method. The effect of preparation parameters on the structures and properties of PVDF/PAN blend hollow fiber membranes was studied. PVDF/PAN/nano-Clay hybrid hollow fiber UF membranes were prepared by adding nano-clay to dope solutions. Different membranes with different content of nano-clay and different kinds of additives were prepared. The effect of nano-clay addition and different kinds of additives on the structures and properties of hybrid membranes was aslo studied.The effect of dope solution composition and spinning process on the structure and performance of PVDF blend hollow fiber membranes was studied. It is found that the sponge-like structure at the cross section of the membrane is inhibited with the increase of polymer concentration in dope solutions. The hydrophilicity of PVDF membranes improves by blending with PAN. Addition of small amount of LiCl is conducive to inhibit the formation of large pore structure, but higher content of LiCl will encourage the growth of finger-like structure.The finger-like structure grows in lenghth and width, meanwhile the number of macrovoids and the pore size on the inner surface increase with the coagulation bath temperature increasing. Lower coagulant bath temperature is conducive to the formation of finger-like structure. In addition, the sponge-like structure at the cross section of the membrane increases meanwhile the pure water flux and BSA rejection decrease when DMAc is added into bore fluid (internal coagulant). With the increase of air gap, the finger-like structure becomes wider with the trend of formation of larger cavities, and the surface of the hollow fiber membrane becomes smoother. The pure water flux increases while the rejection decreases. The membrane has the best tensile properties when the air gap is 1cm.PVDF/PAN/nano-Clay hybrid hollow fiber membranes were prepared by L-S phase inversion and dry-wet spinning method. The effect of nano-clay content, kinds of additives and preparation conditions on the structure and performance of hybrid membranes was investigated. It is shown that under the same conditions, the order of pure water flux of hybrid membranes prepared with different kinds of additives is: Without additive