Actually I added nitric acid and sulfuric acid 1:3 proportion followed by potassium chlorate and 4 days of stirring but did not get typical brown colour of graphene oxide. I will appreciate any help in this regard. Thanks.
Do experiment according to bellow:
Natural graphite powder (with a particle size of 70 µm and a purity of 99.999%) was chemically oxidized to form graphite oxide (GO) at room temperature. The graphite (1 g) was continuously stirred in a mixed solution of sulfuric acid (20 mL), nitric acid (10 mL), and potassium chlorate (10 g) for approximately 100 h. The resulting GO was rinsed with 5 wt% HCl aqueous solution and then repeatedly washed with de-ionized water until the pH of the filtrate became neutral and then was dried in air. GO was then functionalized by acetate group. For this purpose, 1 g of graphene oxide was sonicated for 10 hours with excess of chloroacetic acid and then refluxed for 10 hours. The colloid was then diluted by D.I. water to balance pH. Colloid was then filtered through hydrophilic 0.2µ Millipore filter paper and washed 5 times with distilled water. Carboxylated graphene oxide was dried under vacuum at 50°C.The powder (graphene) was stored at room temperature.
Do experiment according to bellow:
Natural graphite powder (with a particle size of 70 µm and a purity of 99.999%) was chemically oxidized to form graphite oxide (GO) at room temperature. The graphite (1 g) was continuously stirred in a mixed solution of sulfuric acid (20 mL), nitric acid (10 mL), and potassium chlorate (10 g) for approximately 100 h. The resulting GO was rinsed with 5 wt% HCl aqueous solution and then repeatedly washed with de-ionized water until the pH of the filtrate became neutral and then was dried in air. GO was then functionalized by acetate group. For this purpose, 1 g of graphene oxide was sonicated for 10 hours with excess of chloroacetic acid and then refluxed for 10 hours. The colloid was then diluted by D.I. water to balance pH. Colloid was then filtered through hydrophilic 0.2µ Millipore filter paper and washed 5 times with distilled water. Carboxylated graphene oxide was dried under vacuum at 50°C.The powder (graphene) was stored at room temperature.
Just curious, have you tried hummer method? Is not as dangerous as staudenmaier, not uses clorates (explosion hazard, disposal problems) nor nitric acd ( highly corrosive)..nevertheless the staudenmaier prodecure has the advantage of no mn ions to remove.. . On yur question i also think is because your graphite concentration or particle size...Also, very nice explanation on go functinalzation Prof Faraj.
F. Caballero-Briones I haven't tried Hummers method as its widely used. I wanted to follow a less popular way to make graphene.
Other methods to oxidize graphite were suggested with answers to two other questions at this forum:
https://www.researchgate.net/post/Chemical_etchant_or_thermal_etching_condition_for_graphite
https://www.researchgate.net/post/How_can_I_remove_graphitic_carbon_form_a_flat_diamond_substrate
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