▎ 摘　　要

NOVELTY - Preparing graphene oxide by using waste graphene film leftover material, involves collecting leftover material of waste graphite film, and soaking in liquid nitrogen to obtain film-made graphite with a mesh size of 50-200. The obtained film-made graphite is mixed with conventional graphite to obtain recycled graphite, in which the film-made graphite accounts for 100-0 wt.%. The recovered graphite and concentrated sulfuric acid are mixed in a mass ratio of 1:5-1:30 into a container to make pre-intercalated graphite, put the container under ultrasonic treatment and stirred. The concentrated sulfuric acid is added to the container, the quality of the added concentrated sulfuric acid is 20-40 times of the recovered graphite mass, after mixing, stirred uniformly at 10℃, and then slowly added potassium permanganate into the container. USE - Method for preparing graphene oxide by using waste graphene film leftover material. ADVANTAGE - The method realizes waste resource waste into valuable recycling, which is capable of reducing graphene heat conducting film industry chain cost. DETAILED DESCRIPTION - Preparing graphene oxide by using waste graphene film leftover material, involves collecting leftover material of waste graphite film, and soaking in liquid nitrogen to obtain film-made graphite with a mesh size of 50-200. The obtained film-made graphite is mixed with conventional graphite to obtain recycled graphite, in which the film-made graphite accounts for 100-0 wt.%. The recovered graphite and concentrated sulfuric acid are mixed in a mass ratio of 1:5-1:30 into a container to make pre-intercalated graphite, put the container under ultrasonic treatment and stirred. The concentrated sulfuric acid is added to the container, the quality of the added concentrated sulfuric acid is 20-40 times of the recovered graphite mass, after mixing, stirred uniformly at 10℃, then slowly added potassium permanganate into the container, where the mass ratio of the added potassium permanganate to the recovered graphite is (2.5-3.5): 1, when potassium manganate is used, the system temperature is controlled below 12℃ throughout the process, after the potassium permanganate is added, the temperature of the system in the container is raised to 30-40℃ for 90-180 minutes. The deionized water is added to the container, the mass ratio of deionized water to concentrated sulfuric acid is (0.5-2.0): 1, when adding water, the system heats up, and the temperature is controlled at 70-90℃, where the mass of concentrated sulfuric acid is the sum of the mass of the concentrated sulfuric acid added twice. The system is kept at 70-90℃ for 0-2 hours, after the heat preservation is over, to prepare the graphene oxide stock solution, and transferred it into a suction filter bottle for suction filtration to form the initial graphene oxide filter cake. The initial graphene oxide filter cake is washed with deionized water and dilute hydrochloric acid solution for 2-5 times to obtain graphene oxide filter cake after suction filtration.