Photocatalytic degradation of methylene blue dye by fluorite type FeZr-WO system under visible light irradiation.

Nano-sized FeZrWO system was prepared using the Pacini method where x = 0, 0.05, 0.1 and 0.15. All the samples were characterized using chemical analysis, X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), transmission electron microscopy (TEM), UV-vis diffuse reflectance measurements (DRS) and surface area measurements. The undoped FeZrO was crystallised in the cubic fluorite phase as a major phase in addition to rhombohedral phase of FeO and monoclinic phase of ZrO as the minor phases. Meanwhile, single cubic fluorite phase was defined for FeZrWO sample. The last has the lowest band gap (1.69 eV) and the highest surface area (106 m/g). From TEM, the average particle size of the prepared samples was in the range of (3-7 nm). The photocatalytic efficiency of the prepared FeZrWO system was manifested by the degradation of methylene blue and real textile wastewater of blue colour. Ascending degradation efficiency was exhibited with increasing tungsten concentration which is in accordance with their band gap as well as their surface area values. The degradation rate using FeZrWO sample obeys the pseudo-first order kinetic at the optimum degradation conditions (1.5 g/L catalyst and pH11). FeZrWO showed promising photocatalytic activity for real textile wastewater where the 69% COD removal was obtained under the same conditions used for methylene blue degradation.