▎ 摘　　要

NOVELTY - Method for preparing nano-composite material involves (i) dispersing graphene in water to form a uniform dispersion (A), (ii) adding branched polyethyleneimine to dispersion (A) to form a uniform mixture (B), (iii) dispersing bentonite in water to form dispersion (C), and (iv) mixing uniform mixture (B) and dispersion (C), vibrating and mixing thoroughly at room temperature to form self-assembled nanocomposite material form graphene and bentonite, filtering, drying and grinding to obtain the product. USE - The method is useful for preparing nano-composite material for wastewater treatment, and flocculation and precipitation in paint spraying circulating wastewater (all claimed). ADVANTAGE - Th method solves the existing problem that simple and cheap methods cannot be used to treat spray paint wastewater, mixes graphite oxide and branched polyethyleneimine to improve the dispersibility of graphene and make the surface of graphene punctual, and uses branched polyimide to improve the adsorption capacity of bentonite layers. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a nano-composite material for water treatment prepared by the above method; and (2) a use of nano-composite material for flocculation and precipitation in paint spraying circulating wastewater, involving adding nano-composite material to paint spraying circulating wastewater to adjust pH of mixed system to 7.