Preparation and characterization of polypiperazine amide/PPESK hollow fiber composite nanofiltration membrane

A modified interfacial polymerization procedure suitable for preparing hollow fiber composite membrane was developed. By this modified procedure, a new hollow fiber composite nanofiltration membrane with high permeability was prepared by interfacial polymerization of piperazine (PIP) aqueous solution and trimesoyl chloride (TMC) hexane solution. The selective layer was synthesized on the inner surface of poly(phthalazinone ether sulfone ketone) (PPESK) hollow fiber ultrafiltration membrane. The effects of preparation conditions (such as concentration of the monomers, residence time of monomer solutions, etc.) on the performance of the hollow fiber composite membranes were studied. When tested at 0.35 MPa, room temperature, the hollow fiber composite membrane had a Na2SO4 rejection of 99.0% and a flux of about 45 L/m2 h. The rejections for MgSO4, NaCl, MgCl2, glucose, sucrose and raffinose were 72.1%, 26.8%, 9.6%, 53.9%, 99.1% and 99.8%, respectively. The composite membrane showed good stability in the long-term running. The morphologies of the hollow fiber membranes were studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM).