▎ 摘　　要

NOVELTY - A film comprises graphene oxide and divalent metal ion or oxygen acid ions, where the film is produced by covering vacuum-filtration or microfiltration membrane on substrate, size of the graphene oxide is 500 nm-5 mu m and thickness of the film is 10 nm. USE - Film for separating gases of carbon dioxide-methane and carbon dioxide-nitrogen (claimed). ADVANTAGE - The film can be produced simply, and has high flux, carbon dioxide-methane selectivity of 75 and carbon dioxide-nitrogen selectivity of 58. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for producing a film, which involves dispersing graphene oxide in water ultrasonically for 2 hours by Hummer method, adding divalent metal ion or oxygen-containing sodium chloride salt to the dispersed solution, heating the mixture at 40 degrees C, stirring and cooling the mixture to room temperature, vacuum-filtering the mixture for 20 minutes, drying the mixture and cross-linking the mixture for 2-4 hours to obtain finished product.