Hydrothermal preparation of Zn2SnO4 nanocrystals and photocatalytic degradation of a leather dye

Zinc stannate (Zn₂SnO₄) powder was prepared by a hydrothermal process at 200 °C for 12 h. The material was characterized by X-ray-diffraction (XRD) and N₂ adsorption–desorption isotherms. The synthesized sample presented a pure phase, an average nanocrystal size of about 19 nm, a surface area (BET) of about 41.8 m² g^?1 and total pore volume of about 0.19 cm³ g^?1. Its photocatalytic activity was tested by the degradation of the leather azo-dye, Direct Black 38, in aqueous solution under UV irradiation. Adsorption kinetic data showed that the pseudo-second-order model was the most appropriate for the dye studied. Adsorption onto the Zn₂SnO₄ surface followed the Langmuir isotherm. The catalyst showed highly photocatalytic activity towards degradation of the dye, almost equal to that of the TiO₂-P25 Degussa photocatalyst. The results indicate that Zn₂SnO₄ could be employed for the removal of dyes from wastewaters.