▎ 摘　　要

NOVELTY - Nanofiltration composite film comprises substrate support layer (1), middle porous layer (2) and ultra-thin separating layer (3) arranged from bottom to top. The ultrathin separating layer is set with graphene oxide (4) and added to polyamide by in-situ interfacial polymerization reaction. USE - Nanofiltration composite film used for selective ion separation (claimed). ADVANTAGE - The film simultaneously increases water flux and ion selectivity of nanofiltration membrane. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of the selective ion separation nanofiltration composite membrane comprising dissolving polysulfone polymer material in N-methyl pyrrolidone solvent to prepare polysulfone solution, coating polysulfone solution uniformly on woven fabric surface using automatic coating machine, soaking in deionized water after solidifying and forming until coating thickness is 50-100 mu m, and drying at 60-80 degrees C for 10-30 minutes; crushing graphene oxide solution with cell crushing instrument, and controlling ultrasonic graphite oxide layer size at 20-500 nm; dissolving piperazine, camphor sulfonic acid and triethylamine in deionized water to prepare piperazine water phase solution; ultrasonically dispersing graphene oxide into piperazine aqueous solution, and controlling content of graphene oxide at 10-500 ppm; dissolving trimesoyl chloride in petroleum hydrocarbon solvent to prepare trimesoyl chloride oil phase solution; and putting coated base film of non-woven fabric with polysulfone material tiled on plate, pouring piperazine and graphene oxide water phase solution, keeping for 1-3 minutes, removing surface residual solution by roller, pouring into trimesoyl chloride oil phase solution for 10-30 seconds, and drying at 60-80 degrees C for 1-5 minutes. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of nanofiltration composite film. Substrate support layer (1) Middle porous layer (2) Ultra-thin separating layer (3) Graphene oxide (4)