Preparation and characterization of thermally stable poly(piperazine amide)/PPBES composite nanofiltration membrane

Copoly(phthalazinone biphenyl ether sulfone) (PPBES) with excellent performance is utilized to fabricate the substrate membrane of the composite nanofiltration (NF) membrane and the functional layer of the NF membrane is prepared by the interfacial polymerization from piperazine (PIP) and trimesoyl chloride (TMC). The performances of the substrate ultrafiltration (UF) membrane such as molecular weight cut-off (MWCO) and hydrophilicity are also studied to improve the composite membrane performance. When the composite membrane is prepared under optimized conditions and tested at 1.0 MPa and 20 °C, the flux of the composite NF membrane is about 77 L/m2 h and the Na2SO4 rejection of it is about 97.5%. The surface morphologies of the composite membrane and substrate membrane are observed by scanning electron microscopy (SEM). The flux is increased from 61 to 290 L/m2 h with the rejection of the membrane decreases 3.8% when the operation temperature increases from 18 °C to 85 °C at 1.0 MPa.