Thin-film composite nanofiltration membranes were prepared by a simple dipping and crosslinking process.A polysulfone (PSF) ultrafiltration membrane was used a s the support and a crosslinked hyperbranched polyester (HPE) as the active sepa ration layer.The separation layer was immobilized onto the support via the aldol condensation of HPE with glutaraldehyde (GA).The prepared membranes were charac terized by attenuated total reflection Fourier transform infrared spectroscopy ( ATR-FTIR)

water contact angle measurements and scanning electron microscopy (SE M).The results of FTIR examination confirmed the existence of crosslinked HPE la yer on membrane surface.The results of SEM observation indicated that a thin den se layer of crosslinked HPE was deposited on the support membrane.Water contact angle measurements showed that the membrane hydrophilicity was significantly imp roved.The effects of HPE concentration and GA concentration during membrane prep aration on the separation and permeation properties were investigated.The optimi zed HPE and GA concentrations were 9.8 g/L and 7.4 g/L

respectively

and t he water flux for the resultant membrane reached 69.6 L/(m2#12539;h)

and the Na2 SO4 rejection ratio was 93.2%.The sequence of rejection ratio to various sal ts was Na2SO4＞NaCl＞MgSO4＞MgCl2

which was characteristic of electron egative nanofiltration membranes.These results showed that a high performance na nofiltration membrane with low operation pressure

high permeability and high rejection could be obtained by the present process.