A novel positively charged composite nanofiltration membrane was prepared by coating the casting solution of 2-hydroxypropyltrimethyl ammonium chloride chitosan(HACC) on polysulfone ultrafiltration membrane and cross-linking with epichlorohydrin.The molecular weight cut-off of the representative nanofiltration membrane is 720.And this membrane has the composite structure.At 20 ℃
its pure water permeability is 12.6 L·h-1·m-2·MPa-1.The rejection for different salt solutions follows the decreasing order of MgCl2