Photocatalytic degradation of methylene blue dye by fluorite type Fe_2Zr_(2-x)W_xO_7 system under visible light irradiation

摘要

Nano-sized Fe2Zr2-xWxO7 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 Fe2Zr2O7 was crystallised in the cubic fluorite phase as a major phase in addition to rhombohedral phase of Fe2O3 and monoclinic phase of ZrO2 as the minor phases. Meanwhile, single cubic fluorite phase was defined for Fe2Zr0.85W0.15O7 sample. The last has the lowest band gap (1.69 eV) and the highest surface area (106 m(2)/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 Fe2Zr2-xWxO7 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 Fe2Zr0.85W0.15O7 sample obeys the pseudo-first order kinetic at the optimum degradation conditions (1.5 g/L catalyst and pH11). Fe2Zr0.85W0.15O7 showed promising photocatalytic activity for real textile wastewater where the 69% COD removal was obtained under the same conditions used for methylene blue degradation.