Sulfated Chitosan (SCS)/Polysulfone (PS) Composite Nanofiltration Membrane Surface Cross-linked by Epichlorohydrin

A series of composite nanofiltration membranes were prepared via a method of coating and cross-linking from sulfated chitosan (SCS) as the material of the active layer, Polysulfone (PS) UF membrane as the base membrane, and epichlorohydrin (ECH) as the cross-linker. Attenuated total reflection infrared spectroscopy (ATR-IR), scanning electron microscopy (SEM), and atomic force microscopy (AFM), were employed to characterize the resultant composite membrane. The effects of the operating conditions on the rejection performance of the composite membrane were investigated, respectively. The rejections of the resulting membrane to Na2SO4 and NaCI solutions (1000 mg.L-1) were 90.8 and 32.5% at 0.40 MPa and 15 degrees C, while the permeate fluxes were 22.9 and 58.4 kg.m(-2).h(-1) respectively. The rejections of this kind of membrane to the electrolyte solutions decreased in the order of Na2SO4, NaCl, MgSO4, and MgCl2. It suggested that the membrane active layer acquires a negative surface charge distribution by the adsorption of anions from the electrolyte solution, and this charge distribution mainly determined the membrane performance.