| The paper was aimed to prepare high performance nanofiltration hollow fiber composite membrane. Polysulfone was chosen as the material for making the porous substrate because of its excellence in compress-to-denseness resistance, its cheap price and its great availability. By fabricating an ultra thin functional layer on the polysulfone substrate through interfacial polymerization taking piperazine as the monomer in aqueous phase, trimesoyl chloride as the monomer in organic phase and triethylamine as the proton acceptor, high performance nanofiltration composite membranes were prepared. Using 0.1% MgSO4 aqueous solution as the feed, the hollow fiber composite membrane show a salt rejection of 99% and a permeating flux of 30 L.m-2/h under an operation pressure of 0.4MPa.The study conducted research on the following four fields:â… . On the basis of previous work, we improved the synthesis process of trimesoyl chloride (TMC) by lengthening the refluxing time and pumping time. The product is of high quality TMC, the experiment is practical and the process is stable.â…¡. PSF hollow fiber substrates with different morphology were spun using C shaped spinneret by regulating the composition of the dope, spinning temperature, air gap and the take-up velocity. According to measurements, two kind substrates were subjected to coating, one with a molecular weight cut-off (MWCO) of 6,000 and the other, 20,000.â…¢. The performance of the composite membrane prepared on the substrate with MWCO of 20,000 is much better than that on the one with MWCO of 6,000. by adding in triethylamine during interfacial polymerization, the performance of the composite membrane was greatly enhanced. A good condition is under a concentration of piperazine in aqueous phase being 2%, a concentration of trimesoyl in hexane being 0.5% containing 1% triethylamine, a treating time in water being 4 minutes, and a polymerization time being 30 seconds.â…£. The structure of the hollow fiber membrane was investigated by means of scanning electron microscopy, optical microscopy, atomic force microscopy and attenuated total reflection-Fourier transform infrared spectroscopy. The results showed that the thicker the functional layer of the composite membrane, the higher the salt rejection, but the lower the permeating flux. The morphology of the functional layer was full of grains, bumps and holes, which enlarged theexposed area to the solution and strengthen its chargeability. As a result both the salt rejection and the permeating flux of the composite membrane were improved.V. Two kinds of thin film composites (TFC), hollow fiber and plate TFC, are prepared. Their separation performances were investigated. The results show that the performances of these two kinds of membranes exhibit evident difference, though the polymerization conditions are the same and the substrates used show similar performances. By analyzing the deformation of the TFCs under certain pressure, it can be concluded that the differences between the two TFC is attributed to the stresses in a plate being different from those in a hollow fiber.
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