Magnetic recoverable Ag3PO4/Fe3O4/γ-Fe2O3 nanocomposite

Abstract

The use of nanomaterials in water treatment is an alternative for the development of new materials that optimize the purification process. Heterogeneous photocatalysis is used for the treatment of wastewaters contaminated with recalcitrant pollutants that cannot be removed in conventionally. Ag3PO4 has been reported to use visible light. Another important challenge of heterogeneous photocatalysis is to find a proper support for the photocatalysts to reduce the expense associated with the separation and reuse of these materials. However, the immobilization of the catalyst leads to lower reaction rates because the surface area exposed decreases and the material used as support can also interfere. In the last years, the use of magnetic materials to support photocatalysts has attracted special attention because it allows high surface areas to be exposed. Only few authors have reported the use of Ag3PO4/magnetic nanocomposites for photocatalysis and these need to be continued to improve their efficiency. In this work we synthesized Ag3PO4 and supported it on Fe3O4. Fe3O4 was synthesis at pH 12 by the addition of FeCl3 and FeCl2. The magnetic material was washed with water and dried at 80ºC. Ag3PO4 was synthesised over Fe3O4 from the reaction between AgNO3 and Na2HPO4. The final material was washed, recovered magnetically and dried at 80ºC. For characterization, a SEM and XRD studies were carried out. Ag3PO4 was synthesised and satisfactorily supported over Fe3O4/γ-Fe2O3. The photodegradation of 10 mg·L-1 of methylene blue was achieved, although the apparent reaction rate constant was slightly lower for the magnetic composite than for the Ag3PO4 alone. This is explained because the composite contained 48% of the active Ag3PO4 material, as depicted form DRX studies.