▎ 摘　　要

NOVELTY - Method for preparing nano-filtration membrane, involves (i) mixing graphene oxide with pure water to form a graphene oxide dispersion, (ii) adding hydrogen bromide to the graphene oxide dispersion and stirring for 10-15 hours; (iii) adding oxalic acid to the reaction system, stirring the reaction for 2-6 hours and taking out the reaction product, (iv) performing centrifugal purification on the reaction product to obtain carboxylated graphene oxide, and (v) preparing carboxylated graphene oxide as a carboxylated graphene oxide dispersion, and subjecting the carboxylated graphene dispersion to suction filtration on a polyvinylidene fluoride support membrane to obtain the product. USE - The method is useful for preparing nano-filtration membrane which is used in the treatment of organic wastewater (all claimed). ADVANTAGE - The method enables preparation of nano-filtration membrane with high efficiency, excellent organic wastewater treatment and anti-fouling capabilities, is simple, easy to operate and environmentally-friendly, does not add more chemical reagents, and saves cost.