Síntese, caracterização e aplicação de materiais à base de ferro em processos de adsorção e fotocatalíticos com o corante Amarelo Reactron

Abstract

The textile industry is responsible for generating a considerable amount of effluent, which contains a diverse number of contaminants. Its main characteristic is the presence of coloring, due to the incomplete fixation of dyes during the dyeing of fabrics, resulting in toxic effects on fauna and flora, and in the imbalance of aquatic environments. Therefore, many studies focus on developing new treatment techniques, or improving existing technologies, to deal with pollutants that are poorly or non-biodegradable and/or toxic, such as textile dyes. Therefore, the objective of this work consisted in the synthesis of iron-based materials using different methodologies, evaluating the possible use of these solids as adsorbents and/or photocatalysts in the removal of a textile dye. In this work, nine materials were synthesized, whose preparation was based on urea hydrolysis, hydrothermal and coprecipitation methods. These materials were submitted to X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Absorption Spectroscopy (FTIR), Thermogravimetry (TG) and X-Ray Fluorescence (XRF) analyses. As a result, it was found that a mixture of oxides was obtained, with a prevalence of oxide structures (hematite, magnetite and maghemite), oxyhydroxide (goethite) and iron carbonate (siderite), except for one of the materials, whose predominant structure was the zinc oxide. Owing to evaluate the performance of the synthesized solids in the removal of a textile dye, adsorption tests in the absence of radiation were carried out and also photocatalytic tests, under visible and ultraviolet radiation. Both tests were carried out under the same reaction conditions, using an aqueous dye solution of Reactron Yellow 4 GL. Through the techniques of UV-Vis Spectrophotometry and Total Organic Carbon (TOC) analysis, the percentages of discoloration and the organic carbon removal were determined, respectively, parameters used to estimate the efficiency of the materials. In general, in terms of adsorption, the materials promoted a significant removal of the Reactron Yellow dye. On the other hand, the photocatalytic effect, both in the UV and VIS ranges, did not significantly contribute to the increase in discoloration. Regarding the organic matter removal, in the adsorption tests, the synthesized solids reached expressive results, in general, while the photocatalytic effect was negligible compared to the adsorptive effect. Among the materials tested, Zn0.75Fe0.25 (PP), whose predominant structure was zinc oxide, showed the best performance in both parameters, reaching 100% of discoloration and about 68% on organic carbon removal.