▎ 摘　　要

NOVELTY - Preparing three-dimensional (3D) printing reduced graphene oxide filter core comprises (i) preparing expanded graphite including adding solid ammonium nitrate and sodium acetate to concentrated sulfuric acid solution, slowly adding while stirring concentrated sulfuric acid, adding crystalline flake graphite to mixed solution, stirring to obtain mixed solution, where molar ratio of concentrated sulfuric acid, ammonium nitrate, sodium acetate and crystalline flake graphite in mixed solution is 0.182:0.599:0.311:1, placing mixed solution in hot water bath, stirring for 30-50 minutes, pouring mixed solution into deionized water, filtering to obtain solid product, drying solid product, reducing moisture content to below 0.5%, heating at 900-1050 degrees C and naturally cooling, and (ii) preparing graphene oxide dispersion liquid including adding solid potassium permanganate and phosphorus pentoxide to concentrated sulfuric acid solution and slowly adding while stirring concentrated sulfuric acid. USE - The core is useful for processing uranium-containing wastewater (claimed). ADVANTAGE - The core: has loose, porous, and large surface area; increases the number of amino functional groups; and greatly increases the amount of uranium adsorbed. DETAILED DESCRIPTION - Preparing three-dimensional (3D) printing reduced graphene oxide filter core comprises (i) preparing expanded graphite including adding solid ammonium nitrate and sodium acetate to concentrated sulfuric acid solution, slowly adding while stirring concentrated sulfuric acid, adding crystalline flake graphite to mixed solution, stirring to obtain mixed solution, where molar ratio of concentrated sulfuric acid, ammonium nitrate, sodium acetate and crystalline flake graphite in mixed solution is 0.182:0.599:0.311:1, placing mixed solution in hot water bath, stirring for 30-50 minutes, pouring mixed solution into deionized water, filtering to obtain solid product, drying solid product, reducing moisture content to below 0.5%, heating at 900-1050 degrees C and naturally cooling, (ii) preparing graphene oxide dispersion liquid including adding solid potassium permanganate and phosphorus pentoxide to concentrated sulfuric acid solution, slowly adding while stirring concentrated sulfuric acid, adding expanded graphite obtained to mixed solution, where molar ratio of concentrated sulfuric acid, potassium permanganate, phosphorus pentoxide and expanded graphite in the mixed solution is 9.081:0.304:0.225:1, placing mixed solution in water bath device, stirring at 45-55 degrees C for 5-6 hours, pouring mixed solution into deionized water, adding hydrogen peroxide solution, where the amount of hydrogen peroxide added is 2-4% of molar amount of expanded graphite, neutralizing for three times with hydrochloric acid solution, adding deionized water and centrifuging for three times, (iii) preparing graphene oxide (GO) ink including adding deionized water to high-concentration graphene oxide dispersion liquid, adjusting concentration to 820 mg/ml, adding 2-5 vol.% ethylenediamine solution, where the volume ratio of graphene dispersion liquid to ethylenediamine solution is 100:0.6-3, and thoroughly stirring to obtain GO ink for 3D printing, and (iv) preparing graphene filter core including adding GO ink into 3D printing device, setting container under printing gun, pouring n-hexane solution into container, printing filter core into n-hexane solution, taking out the filter element, soaking in 2-5 vol.% ethylenediamine solution, bathing in hot water at 25-100 degrees C for 12-36 hours, making graphene sheet in filter core hydrothermally in ethylenediamine environment, taking out filter core, placing in freezer for 12-36 hours to freeze reduced graphene oxide sheet to form specific porous structure along ice crystal structure, taking out filter core, and freeze-drying by using freeze-drying device.