Synthesis Of Chromogen Films Of Metal Oxides Used As Semiconductors In Advanced Oxidative Processes

TiO2 is a semiconductor used commercially as a material to impart opacity to paints, cosmetics, plastics and papers. It has three allotropes, anatase, brookite and rutile. Doping of TiO2 with metals is an option to increase its ability to absorb radiation in the visible spectrum. In this work, metal oxide chromogen films were synthesized by spin-coating. For this, first TiO2 andTiO2 fibers containing H2WO4 or Na2WO4. 2H2O were obtained by electrospinning. These fibers were treated at temperatures ranging between 650 ºC and 800 ºC. The samples were characterized by X-ray diffraction (XRD) in order to determine the phases formed, the morphology was observed through a scanning electron microscope (SEM), the chromogenism of the films was observed through colorimetric tests, performed with the aid of a Konica-Minolta spectrophotometer. And the photoactivity was determined by means of degradation tests of 125 mL of a20 ppm solution of the orange methyl dye, using the chromogenic films as semiconductors in the presence of UV-vis radiation. The results showed that the chromogenic films containing TiO2/Na2WO4.2H2O present greater effectiveness in the degradation of the orange methyl dye, due to the increase in the calcination temperature, which caused a disorder in the electronic structure of the samples, while decreasing the band gap of these, favoring their optical and photocatalytic properties. The increase in thermal excitation promoted the electrons from the valence band to the conduction band, intensifying the light absorption and degradation capacity of the films.