▎ 摘　　要

NOVELTY - A composite material includes a hollow three-dimensional phosphorylated biomass carbon whose pore diameter is 10-50 mu m, hierarchical structure titanium dioxide, and reduced graphene oxide. The hierarchical structure titanium dioxide is composed of titanium dioxide nanosheets with a length of 500 nm to 1 mu m interlaced with each other. USE - Composite material. ADVANTAGE - The composite material: can efficiently and quickly remove ammoniacal nitrogen by combining high specific surface area of hollow phosphorylated biomass carbon and reduced graphene oxide with photocatalytic performance of titanium dioxide; and can be prepared by a controllable and simple method, which is suitable for large-scale industrial production. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of the composite material, which involves: (1) preparing biomass charcoal by cutting biomass into small blocks, and calcining at 400-600 degrees C for 2-4 hours under the protection of nitrogen; (2) preparing phosphorylated biomass charcoal by immersing the biomass charcoal in a phosphoric acid solution to phosphorylate the biomass charcoal, stirring, reacting at room temperature for 5-30 minutes, heating at 140-160 degrees C, and evaporating water; (3) preparing hollow three-dimensional phosphorylated biomass carbon/reduced graphene oxide composite material by adding reduced graphene oxide and the phosphorylated biomass carbon to water, evenly stirring to form a suspension, then evaporating water in the suspension, and calcining the remaining material after evaporation in a tubular furnace at 500-700 degrees C for 3-5 hours under the protection of nitrogen; and (4) adding 100 mg composite material, 5-15 ml surfactant and 5-15 ml polar aprotic organic solvent to 50-200 ml glacial acetic acid in a reactor, evenly stirring to obtain a suspension, slowly dripping titanium source into the suspension, and hydrothermally reacting at 100-200 degrees C for 8-20 hours.