Amphoteric charged nanofiltration membrane and preparation method thereof

The invention discloses an amphoteric charged nanofiltration membrane and a preparation method thereof. The amphoteric charged nanofiltration membrane is prepared by the steps of firstly grafting one negative charge monomer on the surface of an ultrafiltration membrane and then grafting one positive charge monomer by using the irradiation step grafting method. The prepared nanofiltration membrane has high trapping rate and permeation flux to salt solutions (such as Na2SO4, MgCl2 and the like) containing high valence cations or high valence anions. The invention has the characteristics of easy implementation, controlled reaction and the like, and the separating property of the membrane can be adjusted within a large range.