▎ 摘　　要

NOVELTY - A nanofiltration membrane preparation method involves adding metal salt and amino-functionalized ligands to solvent, followed by dissolving under ultrasonic conditions, forming precursor solution referred to as H2N-metal organic framework (MOF), obtaining surface-modified amino functional MOF/graphene oxide (GO) composites which is referred to as H2N-MOF/GO, adding dopamine hydrochloride buffer solution to ultrafiltration membrane and removing the membrane. The membrane is immersed in buffer solution, followed by stirring and removing the membrane. The membrane is rinsed. USE - Method for preparing nanofiltration membrane (claimed). ADVANTAGE - The method enables preparing nanofiltration membrane with industrialization effect, large scale productivity, better retention effect and milder preparation condition in a simple and cost-effective manner. DETAILED DESCRIPTION - A nanofiltration membrane preparation method involves adding metal salt and amino-functionalized ligands to solvent, followed by dissolving under ultrasonic conditions, forming precursor solution referred to as H2N- MOF. The precursor solution is added with GO. The solution is dissolved under ultrasonic conditions, obtaining mixed solution. The solution is mixed under thermal conditions in presence of solvent at 80-280 degrees C for 6-74 hours and followed by performing centrifugation. The obtained product is initially washed with solvent for several times, followed by washing using low boiling solvent for several times, drying in vacuum oven at 40-140 degrees C for 0.5-30 hours, obtaining surface-modified amino functional MOF/GO composites which is referred to as H2N-MOF/GO, adding dopamine hydrochloride buffer solution having pH 7-12 to molecular weight cut-off (MWCO) of 15-400 kDa ultrafiltration membrane, stirring at 10-80 degrees C for 1-48 hours and removing the membrane. The membrane is rinsed with deionized water. The membrane is dried to remove deionized water from its surface. The membrane is immersed in buffer solution having pH of 7-12, followed by adding H2N-MOF/GO, stirring at 10-80 degrees C for 1-48 hours and removing the membrane. The membrane is rinsed with deionized water, obtaining surface-modified amino functional MOF/ GO composites positively charged nanofiltration membrane, where the metal salt is transition metal salt or lanthanide metal salt or their mixtures, the ligand is aromatic amino acid or amino nitrogen-containing heterocyclic compounds or their mixtures and molar ratio of metal salt and ligand is 1:16-16:1. An INDEPENDENT CLAIM is also included for a nanofiltration membrane, which is prepared by the above method.