▎ 摘　　要

NOVELTY - Preparing graphene-titanium dioxide composite photocatalyst involves preparing graphene oxide by mixing 300-500 mg graphite powder and 1.8-2.0 gm sodium nitrate and adding 18-20 ml of concentrated sulfuric acid having mass concentration of 98%. The reaction mixture is stirred at a temperature less than or equal to 5 degrees C for 1-1.5 hours. The mixture is slowly added with 2.0-3.0 gm of potassium permanganate powder and the mixture is reacted for 1.5-2.0 hours in the temperature range of less than or equal to 5 degrees C. The reaction mixture is kept for heat preservation at 35-40 degrees C for 1-1.5 hours. USE - Method for preparing graphene-titanium dioxide composite photocatalyst (claimed). ADVANTAGE - The method enables to prepare graphene-titanium dioxide composite photocatalyst in simple, convenient, low cost and eco-friendly manner and the composite has good photocatalytic performance, is capable of degrading organic pollutants more than the similar photocatalysts and reusable. DETAILED DESCRIPTION - Preparing graphene-titanium dioxide composite photocatalyst involves preparing graphene oxide by mixing 300-500 mg graphite powder and 1.8-2.0 gm sodium nitrate and adding 18-20 ml of concentrated sulfuric acid having mass concentration of 98%. The reaction mixture is stirred at a temperature less than or equal to 5 degrees C for 1-1.5 hours. The mixture is slowly added with 2.0-3.0 gm of potassium permanganate powder and the mixture is reacted for 1.5-2.0 hours in the temperature range of less than or equal to 5 degrees C. The reaction mixture is kept for heat preservation at 35-40 degrees C for 1-1.5 hours. The reaction mixture is then added with 40-50 ml of deionized water and the temperature of the reaction system is raised to 90-100 degrees C for 10-5 minutes. The reaction product is then cooled to room temperature, diluted with 70-100 ml of deionized water and added with 10-15 ml of hydrogen peroxide solution having mass concentration of 35 wt.%. The reaction product is then filtered to obtain filter cake. The filter cake is first washed with 300-400 ml of 5% hydrochloric acid and then with deionized water three times. The filter cake is then carried for dialysis treatment for two days and then the obtained product is dried at 60 degrees C under vacuum drying conditions for 24 hours. The dried product is ground to obtain graphene oxide. The obtained graphene oxide is added to deionized water and the solution is subjected to ultrasonic treatment for 20-60 minutes by ultrasonic cleaner to obtain 1 mg/ml oxidized graphene dispersion. The cetyltrimethylammonium bromide in 5.8-6 gm is dissolved in 10 ml of n-pentanol and 60 ml of n-hexane to obtain a suspension of cetyltrimethylammonium bromide. The oxidized graphene dispersion in 10-20 ml is slowly added to the suspension of cetyltrimethylammonium bromide with stirring for half an hour. The mixture is then added with 0.6-6 ml of 28% titanium oxide solution and the mixture is stirred for half an hour. The mixture is then placed in a high-pressure reactor and the components of the mixture are allowed to react at 180-200 degrees C for 3-12 hours. The reaction product is then placed in a rotatory evaporator and after that the mixture is added with n-pentanol and n-hexane solvent. The obtained product is then washed with water and alcohol for 2-3 times and the product is dried at 80 degrees C for 1-2 hours to obtain graphene-titanium dioxide composite photocatalyst.