▎ 摘　　要

NOVELTY - Highly active visible light catalyst is supported by fly ash float bead. The inner core is a fly ash float with a diameter of 0.075-0.85 mm, and the outer shell is a visible light catalyst active component with a thickness of 100-500 nanometer. USE - Highly active visible light catalyst used for wastewater treatment (claimed). ADVANTAGE - The highly active visible light catalyst has synergistic effect on the degradation of the organic pollutant. DETAILED DESCRIPTION - Highly active visible light catalyst is supported by fly ash float bead. The inner core is fly ash float with diameter of 0.075-0.85 mm, and the outer shell is visible light catalyst active component with thickness of 100-500 nm. The visible light catalyst comprises 1-5 wt.% nano titanium dioxide, 2-10 wt.% nano bismuth oxide, 5-15 wt.% graphene-doped nano-silicon dioxide, 75-87 wt.% fly ash floating bead. The specific gravity is 0.45-0.95 g/cm3, and specific surface area is 10-50 m2/g. The gel film is formed by drying visible light catalyst precursor hydrosol coated on fly ash floating bead, and sintering at 500-700degrees Celsius to obtain gel film. The fly ash float bead comprises 50-65 wt.% silicon dioxide, 25-35 wt.% aluminum oxide, 4-9 wt.% iron oxide, 2.5-15 wt.% alkali metal and alkaline earth metal oxide, the particle size is 20-200 mesh, specific surface area is 0.3-1 m2/g, and specific gravity is 0.25-0.45 g/cm3. The visible light catalyst active component includes bismuth-doped nano-titanium dioxide and composite of nano-bismuth titanate and graphene-doped nano-silicon dioxide. INDEPENDENT CLAIMS are included for: (1)a method for preparing highly active visible light catalyst for wastewater treatment, which involves: (a) dissolving titanyl sulfate and bismuth nitrate raw material in deionized water, neutralizing to pH=9-11 with aqueous ammonia to obtain coprecipitation of Ti(OH)4-Bi(OH)3, controlling molar ratio of raw material to be titanium:bismuth=1:0.1-1, filtering, separating Ti(OH)4-Bi(OH)3 co-precipitation;(b)washing with deionized water until there is no sulfate ion in co-precipitated washing water, dispersing Ti(OH)4-Bi(OH)3 co-precipitation in polybasic carboxylic acid aqueous solution, where control feed molar ratio is (titanium+bismuth):polycarboxylic acid=1:1-2.5, peptizing at 60-80degrees Celsius for 0.5-2h;(c)diluting with deionized water to obtain (titanium dioxide+bismuth oxide) with a mass fraction of 1-3 wt.% nano-Ti(OH)4-Bi(OH)3 hydrosol, where polycarboxylic acid includes oxalic acid, lactic acid, tartaric acid, citric acid or mixture;(d)dispersing ultrasonically aqueous dispersion of ethyl orthosilicate and graphene oxide in aqueous ethanol solution containing phosphoric acid, controlling mass fraction of the raw material as ethyl orthosilicate:graphene oxide: ethanol:water:phosphoric acid=1:0.001-0.003:2-5:2-5:0.02-0.05;(e)performing hydrolysis reaction at room temperature for 24-48 hours, diluting with deionized water to obtain nano-graphene oxide-silicon dioxide hydrosol with 3-5 wt.% silicon dioxide, where graphene oxide includes graphene oxide, graphene or its mixture;(f)immersing fly ash float bead with 40-85 wt.% phosphoric acid aqueous solution for 4-12 hours, etching, roughening surface, drying at 120-160degrees Celsius, the surface of the fly ash floating beads forms silicon phosphate, aluminum phosphate and iron phosphate precipitation, in order to increase the specific surface area of fly ash float bead and increase adhesion to visible light catalyst active component;(g)mixing nano-Ti(OH)4-Bi(OH)3 hydrosol and nano-GO (graphene oxide)-SiO2 (silicon dioxide) hydrosol, controlling the feeding molar ratio as:(titanium+bismuth):silicon=1:2-5;(h)diluting with deionized water to obtain a Ti(OH)4-Bi(OH)3+GO+SiO2 mixed hydrosol with a nanometer (titanium dioxide+bismuth oxide+GO+SiO2) mass fraction of 2-5 wt.%, spraying mixed hydrosol covered on fly ash float bead, stirring uniformly to coat mixed hydrosol;(i)volatilizing ethanol solvent, drying at 100-150degrees Celsius, putting into high temperature furnace of 500-700degrees Celsius, and sintering for 0.5-3 hours to obtain visible light catalyst with core-shell structure; and (2)a method for evaluating the application performance of highly active visible light catalyst for wastewater treatment, which involves: (a) taking cylindrical wastewater air aeration treatment test device with diameter of 300 mm and height of 1000 mm, adding 10 L phenolic wastewater, introducing compressed air into room at flow rate of 0.5-2 m3/h under natural light, aerating phenolic wastewater for 10 hours, adding chemical oxidant, adding amount of active oxygen to the wastewater by chemical oxidant is controlled to be 80-120 mg, sampling to determine the changes of chemical oxygen demand (COD) and ammonia nitrogen content in phenolic wastewater before and after treatment, where COD removal rate is 44-48%, and ammonia nitrogen removal rate is 42-44%, where chemical oxidant includes ozone, hydrogen peroxide aqueous solution or ammonium persulfate aqueous solution, preparing phenolic waste water by neutralizing the waste liquid of industrial pharmaceutical intermediate p-hydroxybenzohydantoin to pH=6-8;(b)diluting with tap water, where COD is 800-1200 mg/L, and ammonia nitrogen content is 200-300 mg/L, discharging treated phenolic wastewater from bottom of cylindrical pool of test device, adding again 10 L phenolic wastewater, adding high-activity visible light catalyst with specific volume of phenolic wastewater at a ratio of 3-10 g/L, performing under illumination of indoor natural light, aerating wastewater for 10 h by introducing compressed air;(c)taking sample to determine changes of COD and ammonia nitrogen content in phenolic wastewater before and after treatment, where COD removal rate is 57-60%, and ammonia nitrogen removal rate is 53-55%, discharging treated phenolic wastewater from bottom of the cylindrical pool of test device, adding again 10 L phenolic wastewater, adding high-activity visible light catalyst at ratio of 3-10 g/L, starting 100 watt energy-saving lamp located 1 m at top of water surface, irradiating visible light catalyst floating on surface of phenolic wastewater with light intensity of 1000 watt/m2, introducing compressed air at flow rate of 0.5-2 m3/h to aerate wastewater for 10 hours;(d) taking sample to measure changes in COD and ammonia nitrogen content in phenolic wastewater before and after treatment, where COD removal rate is 75-80%, and ammonia nitrogen removal rate is 70-75%.