Outstanding electrical, optical and mechanical properties of graphene make it a very desirable material, not only in the application of electrochemical energy storage, flexible electronics, medicine, but also in photocatalysis for wastewater treatment. The task of this work was to obtain graphene by ultrasonic exfoliation of expanded persulfate-intercalated graphite in water, and to characterize the obtained product with the intent to use the material in environmental photocatalysis. Intercalation was performed in concentrated sulfuric acid with ammonium persulfate to obtain intercalated graphite (GIC). GIC was then subjected to thermal shock at high temperature in order to obtain expanded GIC (EGIC). Exfoliation of the EGIC was further conducted in an aqueous medium with sodium lauryl sulfate as the surfactant, in order to stabilize the resulting graphene particles. Graphene was removed from the suspension by centrifugation. The possibility of heat treatment of the extracted graphene for the purpose of purification was investigated. The obtained samples were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Electron microscopy showed that the thermal shock to which GIC was subjected resulted in significant expansion of the individual layers, thus opening the possibility of obtaining a monolayer of graphene by ultrasonic exfoliation. Thermogravimetric analysis and FT-IR analysis showed that the obtained sample was chemically heterogeneous and probably contaminated up to a considerable extent. In further research it is necessary to improve the process of ultrasonic exfoliation and purification in order to obtain graphene of the desired properties.