Fotocatálise heterogênea do TiO2 com adição de cobre para a descoloração dos corantes RhB e AM

Abstract

Effluents are pollutants derived from the global increase in the production of various products for different uses. Industries are major contributors to water contami nation, as well as the use of materials in various applications. Synthetic organic dyes, such as Rhodamine B (RhB) and Methylene Blue (MB), commonly found in the food industry, paper production, fabric dyeing, cosmetics, and pesticides, are particularly noteworthy. In this study, we tested the discoloration of RhB and MB dyes through heterogeneous photocatalysis, using TiO2 semiconductors with varying concentrations of copper in the crystal lattice. The TiO2 was synthesized through the Solvothermal Assisted by Microwave Synthesis (SAM), introducing defects in the crystal structure through copper addition for comparative purposes. The powdered materials were analyzed using techniques such as X-Ray Diffraction to determine the crystalline phases and ceramic powder compositions; Scanning Electron Microscopy (SEM) to identify morphology; Raman Scattering Spectroscopy (RAMAN) to obtain vibrational modes; Fourier Transform Infrared Spectroscopy (FTIR) to indicate functional groups; Transmission Electron Microscopy (TEM) to identify particle sizes; Ultraviolet-Visible Spectroscopy (UV-Vis) for band gap measurements and absorbance to obtain discol oration data. It was observed that the addition of copper reduced the efficiency of dye discoloration. Most materials fully discolored the dye in 100% within 90 minutes for RhB and 60 minutes for MB. Evaluating holes, hydroxyl radicals, and electrons using the scavengers ethylenediaminetetraacetic acid (EDTA), isopropyl alcohol (IPA), and silver nitrate (AgNO3) in the process showed efficiency loss results, with improvement observed only in the case of silver nitrate, indicating the importance of holes and hydroxyl radicals in the catalytic photodegradation process.