▎ 摘　　要

NOVELTY - Preparation of self-supporting composite nanofiltration membrane involves (1) preparing aminated graphene quantum dots, (2) preparing porous graphene-based two-dimensional sheet material and (3) quantitatively and uniformly injecting a polyamine aqueous solution into the solution after the interfacial polymerization reaction in the step (2) with a syringe, performing interfacial polymerization reaction, encapsulating the porous graphene-based two-dimensional sheet material by polyamide to prepare a porous graphene/polyamide separation layer, after removing the aqueous phase solution and the organic phase solution, loading the porous graphene/polyamide separation layer to the supporting base membrane, and performing heat treatment. The volume ratio of the aqueous ammonia with respect to the graphene oxide dispersion liquid is (1-4):1. USE - Preparation method of self-supporting composite nano-filtration membrane used in industrial wastewater treatment, dye desalting and chemical separation. ADVANTAGE - The method provides self-supporting composite nano-filtration membrane with excellent permeability and high selectivity. DETAILED DESCRIPTION - Preparation of self-supporting composite nanofiltration membrane involves (1) preparing aminated graphene quantum dots by dispersing a certain amount of graphene oxide in distilled water by ultrasonic vibration to obtain 0.01-1 weight/volume% graphene oxide dispersion liquid, adding a certain amount of aqueous ammonia, and uniformly transferring the obtained mixture to a reactor, sealing and placing a reaction kettle in a muffle furnace to carry out a chemical cutting reaction, after completing the reaction, cooling, filtering, vacuum distillating, freeze-drying, secondary dissolution, filtering, and freeze-drying, (2) preparing porous graphene-based two-dimensional sheet material by rinsing a supporting base film with distilled water, placing at the bottom of the sand core funnel, adjusting the pH to 11-13, adding 1 weight/volume% polybasic acid chloride organic solution into the sand core funnel to carry out interfacial polymerization reaction, and (3) quantitatively and uniformly injecting a polyamine aqueous solution into the solution after the interfacial polymerization reaction in the step (2) with a syringe, performing interfacial polymerization reaction, encapsulating the porous graphene-based two-dimensional sheet material by polyamide to prepare a porous graphene/polyamide separation layer, after removing the aqueous phase solution and the organic phase solution, loading the porous graphene/polyamide separation layer to the supporting base membrane, and performing heat treatment. The volume ratio of the aqueous ammonia with respect to the graphene oxide dispersion liquid is (1-4):1. In the step (1), the temperature in the muffle furnace is 100-140℃, the treatment time is 4-6 hours. The aminated graphene quantum dots comprise 0.01-1 weight/volume% aqueous solution.