▎ 摘　　要

NOVELTY - Preparing magnesium hydroxide/reduced graphene oxide composite material, comprises (i) adding natural graphite, concentrated sulfuric acid and potassium permanganate into a reactor in batches, reacting under rapid stirring, heating, reacting, cooling the reaction mixture to room temperature, pouring into aqueous solution of hydrogen peroxide, cooling with ice water, washing the reaction product with diluted hydrochloric acid, washing with ethanol and deionized water, respectively, centrifuging the number of reaction, to obtain graphene oxide and directly dispersing the graphene oxide in water; and (ii) pouring graphene oxide suspension into molten lactam, subjecting to ultrasonic dispersion, adding magnesium salt, magnetic stirring during dispersion, drying, distilling to dehydrate, cooling, slowly adding alkaline substance, reacting, reducing the graphene oxide to graphene oxide, separating lactam by centrifugation, obtaining precipitate, washing with deionized water and drying. USE - The composite material is useful in removing organic pollutants, preferably organic pollutants are methylene blue, methyl orange, direct blue 86 or reactive azo dyes in printing and dyeing wastewater (all claimed). ADVANTAGE - The composite material has strong photocatalytic degradation effect under multiple cycles, where due to high density of magnesium hydroxide the composite materials are easily separated from sewage and easily recycles catalysts. DETAILED DESCRIPTION - Preparing magnesium hydroxide/reduced graphene oxide composite material, comprises (i) adding 1-3 pts. wt. natural graphite, 50-150 ml concentrated sulfuric acid (98%) and 7-21 pts. wt. potassium permanganate into a reactor in batches, maintaining reaction temperature at 0 degrees C, reacting under rapid stirring for 2 hours, heating to 50 degrees C, reacting for 10-12 hours, cooling the reaction mixture to room temperature, pouring into 30 wt.% aqueous solution of hydrogen peroxide, cooling with ice water, washing the reaction product with 30% diluted hydrochloric acid, washing with ethanol and deionized water, respectively, centrifuging the number of reaction, to obtain graphene oxide and directly dispersing the graphene oxide in water to obtain a suspension of graphene oxide, where the concentration range of the graphene oxide is controlled at 0.006-0.009 g/ml; and (ii) pouring graphene oxide suspension into molten lactam, subjecting to ultrasonic dispersion at 70 degrees C for 30-60 minutes, adding magnesium salt, magnetic stirring during dispersion for 30-120 minutes, drying under reduced pressure at 140-180 degrees C, distilling to dehydrate, cooling to 100 degrees C, slowly adding alkaline substance, reacting at 100 degrees C for 1.5-3 hours, reducing the graphene oxide to graphene oxide, reacting, separating lactam by centrifugation at 70 degrees C, obtaining precipitate, washing with deionized water and drying to obtain the final product, where the mass ratio of magnesium hydroxide and reduced graphene oxide in the composite material is (10-100):100. An INDEPENDENT CLAIM is also included for use method of composite material in removing organic pollutants in printing and dyeing wastewater, comprising adsorbing organic pollutants using the composite material, irradiating the composite material using UV light, degrading the organic pollutants by photocatalytic reaction, washing the composite material and repeatedly adsorbing and degrading the organic pollutants.