The present invention discloses synergistic graphene sand nanocomposites of different metallic compounds for photo degradation of antibiotics in waste water e.g. Bi2WO6 and Fe3O4 Mn/Fe2O4 and Bi2O3/BiOCl at a very low concentration of just 0.05% (50 mg/100 ml). The novel nanocomposites are extremely economical and efficient in photodegradation of antibiotics in waste water. Compared to graphene sand composite alone, addition of metallic compounds gives synergistic effect, which results in much higher photodegradation than what can be achieved by individually by the components.
