THIN FILM COMPOSITE NANOFILTRATION HOLLOW FIBER MEMBRANES

摘要

THIN FILM COMPOSITE NANOFILTRATION HOLLOW FIBER MEMBRANESABSTRACTThe present invention relates to a thin-film composite nanofiltration (NF) membrane that is fabricated by interfacial polymerization of hyperbranchedpolyethyleneimine (HPEI) and isophthaloyl chloride (IPC). The substrate possesses a unique cross-section structure comprising a layer full of macrovoid located in the middle and sandwiched by two thin spongy-like layers. Such a sandwich-like sublayer structure provides minimal transport resistance and sufficient mechanical strength for water permeation under high pressures. Afterinterfacial polymerization, the NF membrane possesses a negatively charged substrate and a positively charged selective layer with a mean effective pore radius of 0.36 nm, molecular weight cut off of 489 Da, and pure water permeability of 4.85 Im[err]bar[err]h[err]. Due to this double-repulsion effect, together with the steric hindrance and the solute electro-neutrality effects, the newly developed NFmembrane shows superior rejections (over 99%) for both positively and negatively charged dye molecules. By adjusting the pH of cephalexin aqueous solution to modify the ionization states of this zwitterionic molecule, the NF membrane shows high rejections over a wide pH range.[FIG. 2]