Desenvolvimento e avaliação de oxo clusters de titânio modificados com cério para degradação de poluentes orgânicos

Abstract

Titanium Oxo Clusters (TOCs) are polynuclear molecular compounds, structural analogs of TiO2. Besides a diverse array of applications, they can serve as a base for metal-organic frameworks (MOFs), simulate conventional TiO2 structures, or are even used in direct applications. These materials can act as conventional semiconductors where given energy corresponding to the material’s Band Gap, photo-excited species are formed, constituting what is called the Electron-Hole Pair (e-; h+), promoting the existence of redox sites that allow these materials to be used to mediate advanced oxidative processes. Therefore, allowing those materials to be applied in the decomposition of persistent and toxic organic pollutants for marine life aiming the decontamination of polluted water bodies. Therefore, four new TOCs containing the ligands: ascorbic acid (TOC A), benzoic acid (TOC B), and terephthalic acid (TOC T and T2) were synthesized. The formed TOCs were characterized by FTIR, XRD, TGA, SEM, EDS, DRS, and subjected to adsorption and photocatalysis tests. The materials were synthesized in mixtures of DMF and water/methanol. FTIR analysis allowed to determine the presence of ligands in the materials' structure through the analysis of characteristic bands such as C=O, additionally, it was possible to determine the coordination mode of the ligands experimentally. XRD and TGA analyses were performed and confirmed that the materials in question are distinct from Cerium and Titanium oxides, and by EDS, the insertion of Cerium in the materials was confirmed semi-quantitatively. Through DRS, applying the Tauc method, it was possible to determine the Band Gap values: 1.63 (TOC A), 1.47 (TOC B), 1.72 (TOC T), and 1.57 (TOC T2). Finally, through photocatalytic tests evaluation the light-driven decomposition of methylene blue dye, it was possible to determine that all materials exhibit photocatalytic activity or adsorptive properties towards the evaluated dye, with TOC T and TOC T2 standing out with decomposition percentages of 44% and 35% respectively. In addition, TOC A stood out as the best adsorptive material with an adsorption percentage of 80%. In the light of the structural, morphological, optical, photocatalytical and adsorption results properties, it was possible to infer that the proposed TOCs are promising materials for the photocatalytical remotion of organic pollutants from water bodies.