Photocatalytic activity of novel Y2InSbO7 and Y2GdSbO7 nanocatalysts for degradation of environmental pollutant rhodamine B under visible light irradiation

In order to remove the environmental pollutant rhodamine B from wastewater, the nanocatalysts Y2InSbO7 and Y2GdSbO7 were synthesized and utilized for the first time. The structural and photocatalytic properties of Y2InSbO7 and Y2GdSbO7 were investigated under visible light irradiation. The results displayed that Y2InSbO7 and Y2GdSbO7 crystallized with the pyrochlore-type structure, cubic crystal system and space group Fd3m. The lattice parameters of Y2InSbO7 and Y2GdSbO7 were 10.43213(2) and 10.50703(6) angstrom. The band gaps of Y2InSbO7 and Y2GdSbO7 were calculated to be 2.618 and 2.437 eV, respectively. The photocatalytic degradation of rhodamine B was carried out with Y2InSbO7 or Y2GdSbO7 as catalyst under visible light irradiation. The results showed that Y2InSbO7 and Y2GdSbO7 owned higher catalytic activity compared with P25 TiO2 or Bi2InTaO7 for the photocatalytic degradation of rhodamine B. Furthermore, Y2InSbO7 exhibited higher catalytic activity than Y2GdSbO7. The photocatalytic degradation of rhodamine B followed with the first-order reaction kinetics, as a result, the apparent first-order rate constant k was 0.023889, 0.017192, 0.006268 or 0.00329 min(-1) with Y2InSbO7. Y2GdSbO7, P25 TiO2 or Bi2InTaO7 as catalyst, respectively. Complete removal of rhodamine B was observed after visible light irradiation for 220 min or 235 min with Y2InSbO7 or Y2GdSbO7 as catalyst. The reduction of the total organic carbon and the evolution of CO2 were realized and these results indicated the continuous mineralization of rhodamine B during the photocatalytic process. The possible pathway of the photocatalytic degradation of RhB was proposed under visible light irradiation. Y2InSbO7 (or Y2GdSbO7)/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems. (C) 2010 Elsevier B.V. All rights reserved.