Desenvolvimento de redes metalorgânicas (MOFs) com arquitetura de poros otimizada para remoção de contaminantes orgânicos em meios aquosos

Abstract

Metal Organic Frameworks (MOFs) are a class of materials belonging to the group of coordinating polymers. They are characterized by having a high specific surface area and microporous structure that can be controlled based on the careful choice of its components: metallic nodes (clusters) and organic ligands that make the connection of these nodes. Such structures also offer the possibility of several network configurations, which allows their modification to better meet the requirements of a specific application. Such characteristics are especially interesting in the fields of adsorption and catalysis. In both cases, the large specific surface area and high density of active sites are capable of providing high efficiency in such processes. However, few studies have broadly evaluated the defect influence in such structures on practical processes. In this way, the current work aims to investigate the synthesis of materials with tailored porosity, combining the intrinsic microporosity of the tetravalent metal MOFs (Ti)MIL 125 (Material from Institute Lavoisier) and (Zr)UiO-66 (University of Oslo) with the creation of defects, by controlling the rate of crystallization and growth of the crystals thus produced. These materials were chosen because they have interesting characteristics such as high stability and photoactivity, in addition to representing a relatively recent class of MOFs, those of tetravalent metals (UiO-Zr4+ and MIL-Ti4+). The expansion of the microporous network and generation of mesopores, which can be obtained from the insertion of defects in the crystalline structure, significantly increased the mass transfer and access to active sites, enabling an increase in scale in the aforementioned processes. In adsorption, the different MOFs obtained were tested with organic contaminants of different natures in order to have a better understanding of the main interaction mechanisms on the different structures. In photocatalysis, the synthesized MOFs, as well as composites formed from the combination of these networks with another semiconductor typically used in photocatalytic processes, TiO2 (anatase), were evaluated for the photodegradation of a high photostable dye. Finally, the metal-organic frameworks were tested regarding their stability, both in purely adsorptive and photocatalytic processes