▎ 摘　　要

NOVELTY - A nanofiltration membrane contains functional layer containing set of 1st filter holes which run through functional layer and supporting layer containing set of 2nd filter holes which run through supporting layer in which supporting layer is connected to functional layer, diameter of 2nd filter hole is greater than diameter of 1st filter hole, and 2nd filter hole is connected to greater than or equal to 1 1st filter hole. USE - A nanofiltration membrane for preparing fluorescent graphene quantum dots (claimed). ADVANTAGE - Fluorescent graphene quantum dots has small and uniform size and high luminous efficiency and quantum yield. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) preparation of nanofiltration membrane which involves performing 1st anodic oxidation on aluminum plate to form 1st aluminum oxide layer on aluminum plate surface, placing in chromic acid, reacting at 60 degrees C for 2 hours to remove 1st aluminum oxide layer, performing 2nd anodic oxidation to form barrier layer and 2nd aluminum oxide layer containing set of holes, performing hole expansion process in phosphoric acid to form 1st filter holes on 2nd aluminum oxide layer which run through 2nd aluminum oxide layer, performing 3rd anodic oxidation to form 3rd aluminum oxide layer between 2nd aluminum oxide layer and barrier layer, and removing remaining aluminum plate and barrier layer in which 3rd aluminum oxide layer contains set of 2nd filter holes running through 3rd aluminum oxide layer; and (2) preparation of fluorescent graphene quantum dots which involves separating 1st graphene quantum dot solution using nanofiltration membrane to obtain 2nd graphene quantum dot solution containing graphene quantum dots with transverse size of less than or equal to 5 nm. DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart for the preparation of nanofiltration membrane. (Drawing includes non-English language text).