Bentonite clay modified with Nb2O5: An efficient and reused photocatalyst for the degradation of reactive textile dye

Nowadays, textile industries represent a great environmental threat in terms of water pollution. Conventional treatments for textile effluents are not effective and new alternatives for their treatment are under development, with special emphasis on heterogeneous photocatalysis. In this work, the Nb2O5 semiconductor supported on bentonite clay was synthesized in the pellets form and immobilized on glass slides, and applied in the photo-catalytic degradation of reactive blue 19 dye. The materials were characterized by X ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Al-27 and Si-29 Nuclear Magnetic Resonance - magic angle (NMR), Scanning Electron Microscopy with Field Emission (SEM-FEG) and Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis-DRS). The results obtained indicate that the semiconductor was successfully immobilized on bentonite clay. The degradation studies using immobilized catalyst were developed in a discontinuous photo catalytic reactor refrigerated, in which the substrate was irradiated using a 125 W mercury vapor lamp (without the original glass bulb). These results show that Nb2O5 supported on bentonite clay in pellets form presented better results in the reactive blue 19 dye degradation, after 2 h a 98% decrease in the band referring to the chromophore group was observed, while the material immobilized on glass slides promoted a 78% decrease in 5 h of treatment. Tests performed in the absence of H2O2 showed a decrease of 90% in the band referring to the chromophore group in 2 h, indicating that the use of H2O2 is unnecessary.