▎ 摘　　要

NOVELTY - Nitrogen-doped magnetic graphene oxide confined iron-cobalt bimetallic single-atom material is claimed. The material uses graphene oxide as a matrix, and the matrix is loaded with magnetic nanoparticle, nitrogen-containing group and two metal mono atom. USE - The material is useful for removing tetracycline in the wastewater, preferably the tetracycline concentration is 40 mg/l (claimed). ADVANTAGE - The method: adopts the introduction of nitrogen-containing groups to greatly increase the anchoring sites of monoatomic iron and cobalt on graphene oxide; uses molten salt to assist high-temperature pyrolysis, which reduces the agglomeration of metal atoms, easily wash and recycle the salt phase and is environmentally friendly and non-toxic. The material: greatly increases the loading of monoatomic iron and cobalt on graphene oxide; has strong stability; is easily separated from the solution; can be recycled; reduces the preparation cost; is economical and efficient and has good degradation effect on tetracycline in wastewater. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing nitrogen-doped magnetic graphene oxide confined iron-cobalt double metal single-atom material comprising (1) using Hummers method for preparing graphene oxide aqueous suspension: adding 6 g graphite powder, 5 g potassium persulfate and 5 g phosphorus pentoxide, adding into 24 ml of sulfuric acid (98%), using triangular cone bottle to place into the water bath pot to stir, oxidizing for 4.5 hours at 80℃, cooling to room temperature, adding 1 l ultra-pure water to dilute, placing for overnight 12 hours to obtain mixture A, filtering the mixture A and washing the residual acid with deionized water to neutral, obtaining pre-oxidized graphite at 60℃ oven dry, adding the pre-oxidized graphite into the 240 ml sulfuric acid (98%) solution, stirring while adding 5 g sodium nitrate and 30 g Potassium permanganate for 4 hours at 0℃ or less, raising the temperature to 35℃, reacting for 2 hours, adding 500 ml ultra-pure water to react for 1 hours at 98℃, continuously adding 1 l ultra-pure water and 40 ml Hydrogen peroxide (30%) at room temperature, continuously reacting for two hours to obtain the mixture B, washing the obtained mixture B with 10% Hydrochloric acid, using a lot of water to wash to neutral, adding water to constant volume, ultrasonically dispersing for 2 hours at 50℃ to obtain oxidized graphene aqueous suspension, (2) loading the magnetic nano-particles on the graphene oxide by coprecipitation method: taking 1 g oxidized graphene, heating and stirring in the water bath at 85℃, taking 0.01 mol ferric chloride and 0.005 mol ferrous sulfate to respectively in 100 ml water to obtain the mixed solution, adding the obtained mixed solution into the oxidized graphene, stirring for 2 minutes, adding aqueous ammonia, adjusting the pH value to 10, stirring for 45 minutes, magnetically separating, washing, drying and grinding to obtain the magnetic graphene oxide and (3) using molten salt auxiliary high temperature cracking method to obtain the final material: weighing 0.02 g ferric nitrate, 0.02 g cobalt nitrate and 1 g melamine and 100 ml ultra-pure water, fully mixing for 2 hours in the ultrasonic cleaning machine, adding 4 g sodium chloride and 4 g potassium chloride, stirring for half an hour under the cantilever type electric stirrer, mixing the obtained solution uniformly, continuously adding 1 g cyanuric acid and 0.4 g magnetic graphene oxide, stirring for 2 hours until mixing uniformly to obtain mixture C, freezing the dry mixture C under the protection of nitrogen for heat treatment, raising the temperature to 800℃ in a tubular furnace of 5℃/minute for calcining for 2 hours, repeatedly centrifuging and washing with a large amount of ultra-pure water, so as to remove the soluble salt, freeze-drying, grinding and sieving to obtain the nitrogen-doped magnetic graphene oxide confined iron-cobalt double metal single-atom material.