Síntese e caracterização de nanocristais de BiVO 4 ancorados em diatomita: estudo da atividade fotocatolítica na degradação do corante azul de metileno e de resíduo de curtume

Abstract

The present work concerns the synthesis and characterization of diatomite-anchored BiVO4 nanocrystals and, additionally, on the investigation of its photocatalytic activity in the degradation of methylene blue dye and tannery residue, under solar irradiation, aiming to produce a photocatalyst as efficient as possible for the degradation of these organic pollutants. From the results of the structural characterization of samples, it was possible to extract relevant information, such as: crystallization temperature of BiVO4 nanocrystals and BiVO4@diatomite composites; crystallite size, which was around 32 ± 4 nm for BiVO4 nanocrystals and 23 ± 2 nm for SiO2, responsible for composing the porous matrix of diatomite, and quantitative determination of the crystalline phase using Rietveld method. Regarding the optical characterization, the results showed that the band gap of BiVO4 varies with the concentration of diatomite, ranging from 2.26 eV ≤ Eg ≤ 2.39 eV. The tests of solar photocatalysis in the degradation of methylene blue dye, the composite BVO_DE02 showed the best results, degrading 97% of the dye solution in just 120 min, having a reaction rate constant k = 1.32x10-3 min-1 , which was about 30% faster than pure BiVO4. The solar photocatalysis tests on the tannery residue indicate that the process with the BVO and BVO_DE02 samples causes a change in the coordination of hexaaquachrome(III) ions to pentaaquahydroxochrome(III) ions.