Methods of forming graphene may include reacting a dispersed mixture, comprising fly ash, a charged heteroaromatic compound, particularly a pyridinium compound, such as a 1-(4-pyridyl)-pyridinium salt, and a solvent, particularly an alcohol, such as ethanol, with a polymeric oxidizing agent, preferably polymer-supported pyridinium chlorochromate, to form a second mixture; and contacting the second mixture at a temperature of 120 to 180° C. with a gas stream comprising at least 0.1 vol. % CH4 and at least 10 vol. % H2 to form graphene on the fly ash. Methods of managing waste may comprise using fly ash waste to produce graphene. Devices for implementing such methods may involve steel cylindrical reaction vessels including a cover through which a valve-stoppable pipe is fed, which reaction vessel is at least partially surrounded by a heating device, and suitable for handling solvent and fly ash, as well as for receiving gas inflow through the pipe.