▎ 摘　　要

NOVELTY - A seawater desalination nanofiltration membrane comprises 50-80 pts. wt. polyvinylidene fluoride, 5-15 pts. wt. graphene chitosan composite nanoparticles, 3-10 pts. wt. piperazine, and 3-10 pts. wt. trimesoyl chloride. The graphene chitosan composite nanoparticles are prepared by (1) dissolving chitosan in deionized water, adding EDTA, heating and stirring to dissolve, gradually adding ethanol under the condition of stirring until the transparent solution becomes turbid, adding curing agent glutaraldehyde, leaving still at room temperature, centrifuging and separating, and freeze-drying to obtain chitosan nanoparticles, and (2) ultrasonically dispersing the chitosan nanoparticles prepared in step (1) in absolute ethyl alcohol uniformly, adding graphene oxide, stirring uniformly, centrifuging and separating, and drying to obtain composite nanoparticles. USE - Seawater desalination nanofiltration membrane. ADVANTAGE - The base film overcomes the problem of poor hydrophilicity of polyvinylidene fluoride, and the obtained base film can make the piperazine solution and trimesoyl chloride solution disperse more evenly, thus greatly reducing the occurrence of agglomeration, and through the reaction of the amino group of piperazine and the chloride group of trimesoyl chloride to generate N-C=O bond, a highly crosslinked polyamide network is formed on the surface of the base membrane, so that the polyvinylidene fluoride membrane with hydrophilic groups exhibits excellent antifouling performance and has improved water flux and salt rejection rate. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a preparation method of the seawater desalination nanofiltration membrane, which involves (a1) stirring and mixing polyvinylidene fluoride and 1-methyl-2-pyrrolidone uniformly to obtain solution (A), uniformly ultrasonically dispersing the graphene chitosan composite nanoparticles in 1-methyl-2-pyrrolidone to obtain solution (B), pouring the solution (B) into the solution (A), stirring and degassing to obtain mixed solution, casting the mixed solution on a nonwoven fabric, after evaporating the solvent, rinsing and soaking to obtain a base film, (a2) placing the base film prepared in the step (a1) in a frame of customized design, adding the piperazine solution into the frame, after 3-4 minutes, removing the excess piperazine solution, adding trimesoyl chloride solution, taking out the base film, washing after 1-2 minutes, and drying to obtain the final product.