▎ 摘　　要

NOVELTY - Preparation of ultra-thin nanofiltration membrane involves providing a polymer ultrafiltration membrane as a base film, covering with a porous substrate layer, treating the base film with e.g. polyanionic solution, and preparing nanofiltration membrane by filtering a graphene oxide solution using ion-treated base film, immersing obtained film in an organic phase solution, reacting, heat-treating, rinsing with distilled water, drying, coating a protective layer on the resultant product, treating with % aqueous solution of polyvinyl alcohol solution and drying. USE - Preparation of ultra-thin nanofiltration membrane (claimed). ADVANTAGE - The method enables preparation of ultra-thin nanofiltration membrane having excellent contamination resistance and high efficiency. DETAILED DESCRIPTION - Preparation of ultra-thin nanofiltration membrane involves providing a polymer ultrafiltration membrane as a base film, covering a porous substrate layer on surface of the base film, treating the base film with polyanionic solution by immersing the base film in 0.05-0.2 mol/L sodium polystyrene sulfonate solution for 25-30 minutes, controlling pH of the solution to 3-5, washing with pure water, and with polycation solution by immersing polyanion solution-treated base film in 0.05-0.2 mol/L polydiallyldimethylammonium chloride solution for 25-30 minutes, controlling pH to 4-6 and washing with pure water, and preparing nanofiltration membrane using ion-treated base film. The ultra-thin nanofiltration membrane is prepared by adding 98% concentrated sulfuric acid to expanded graphite raw materials in an ice water bath at 0 degrees C, slowly adding potassium permanganate, uniformly stirring, placing in a constant temperature water bath, heating to 45-50 degrees C for 0.5-2 hours, slowly dripping deionized water in the resultant product without bubbles, heating the resultant product to 95-100 degrees C in a constant temperature water bath, stirring for 25-30 minutes, naturally cooling, adding 25 %mass hydrogen peroxide solution to the resultant product to obtain a bright yellow suspension, filtering the resultant product, to obtain a brown colloid, pickling the resultant product, washing with deionized water to neutral, drying, ultrasonically dispersing, centrifuging in ultrapure water, placing obtained supernatant in a drying oven, drying, obtaining graphene oxide powder, dispersing the graphene oxide powder in a polar solvent for 1-5 hours, centrifuging to obtain a graphene oxide solution, filtering the graphene oxide solution using the ion-treated base film, maintaining at a pressure of 0.05-0.5 MPa to promote oxidation of graphene solution, immersing obtained film in an organic phase solution containing acid chloride monomers, reacting for 0.5-2 minutes, performing interface polymerization, forming a polyamide functional layer containing a zwitterionic group on the surface of the nanofiltration membrane, heat-treating the nanofiltration membrane at 40-65 degrees C for 45-60 minutes, rinsing with distilled water, drying in a vacuum oven, coating outer layer of the resultant product with a protective layer, treating protective layer with 11-15% aqueous solution of polyvinyl alcohol and drying in a vacuum oven to obtain ultra-thin nanofiltration membrane. The polymer ultrafiltration membrane material comprises 1.33-2.45 %mass polyethersulfone, 2.13-3.15 %mass polycaprolactam, 0.56-0.87 %mass polypropylene, 0.41-0.66 %mass polyethylene, 3.73-4.15 %mass polyvinylidene fluoride, 2.45-3.11 %mass cellulose acetate, 1.73-2.33 %mass cellulose diacetate, 1.33-1.56 %mass cellulose triacetate, 0.35-0.47 %mass cellulose propionate, 2.36-3.67 %mass cellulose butyrate, 1.55-1.86 %mass cellulose acetate propionate, 0.21-0.32 %mass cellulose dibutyrate, 1.13-1.48 %mass cellulose tributyrate, 0.82-1.26 %mass polyurethane, 0.53-0.75 %mass polyvinyl chloride, 1.42-1.66 %mass sulfonated polyimide, 1.47-1.65 %mass sulfonated polyethersulfone and 0.23-0.34 %mass polybenzimidazole, and remainder of polyacrylonitrile.