SrTiO3@Nb2O5 produzido por síntese solvotérmica assistida por micro-ondas para degradação de corantes têxteis

Abstract

The textile industry represents an important branch of the economy employing a large number of workers and producing important products to the society. In this sense, it’s evident that the high volume of production will bring profound impacts to the environment (it´s demanded 100 L of water to produce 1 kg of fabric). Although many techniques have been used to deactivate the chromophore groups present in the colorant carbonic chain the photocatalytic route highlights important features such as high yield on the electrolysis of the water molecules generating high oxidizing free radicals such as hydroxyl ions that are capable of breaking the molecular structure of dyes and remove its color. Since Fujishima and Honda publication when ceramic oxides have been successfully used in the process of converting lower energy of photons into electrolytic agents that the use of semiconductors is been studied as an important way to achieve efficient photocatalytic reactions. In this work the system SrTiO3@Nb2O5, a multilayered oxide made by the heterojunction of two important ceramic oxides that even coordinated individually in distinct crystallographic spatial groups can present at least 1 miller plane with compatible lattice paramenter. The Synthesis of ths system SrTiO3@Nb2O5 was performed using the microwaved assisted synthesis method, in which SrTiO3 nano-seeds have been put in solution with precursors to make Nb2O5 oxide. Tis solution was heated at a 5/min heat rate until the temperature of 130 C remaining for 30 minutes in this isotherm. The SEM image presented highy geometrical particulates compatible with the expected for the Nb2O5 single synthesis, the image also presented unique SrTiO3@Nb2O5 spherical nanoparticles decorating the Nb2O5 surface. The X-rays diffractometry for the system SrTiO3@Nb2O5 exposed three distinct phases for the heterojunction. Two of these were related to The Nb2O5 stoichiometry a nanocrystalline phase and a H-Nb2O5 monoclinic array. One important factor to point out is the fact that Nb2O5 monoclinic arrays are generally achieved after the process of the synthesis due to heat treatments over 1.100 C. The TEM image for the system also corroborated the information from the XRD analysis evidencing the high compatibility of both crystalline lattices. The photocatalytic benchmark for the system SrTiO3@Nb2O5 when compared to SrTiO3 single particles demonstrated a higher capability of degradation on the Rhodamine B dye. With these results it has been clear that the use of multilayered oxides in a core-shell like system can contribute to the performance of advanced oxidative processes into the electrolysis of the water.