Grafite: estratégias de modificação superficial e potencial em aplicações como suporte para catalisadores

Abstract

Catalysts play a central role in the chemical industry by reducing the activation energy of reactions, making processes faster, more efficient and energetically viable. Among the various classes of catalysts, nanostructured materials stand out due to their extensive application in industrial processes, because of their stability and recyclability. In these materials, at least one of their dimensions is within the nanometric scale (<100 nm which imparts a high surface area and enhanced reactivity compared to conventional materials. In general, these materials consist of an active phase dispersed on a support, which promotes better dispersion of the former. Graphite, a carbon allotrope, exhibits properties such as thermal resistance and electrical conductivity, making it a promising material for use as a catalytic support. Thus, this study investigates the potential of graphite as a support in the development of catalysts, evaluating its structural and chemical properties through characterization analyses, as well as its performance as a catalyst in the oxidation of organic contaminants. Due to its inert character, graphite was subjected to surface modification processes to enhance its interaction with the active phase. In the first study, graphite was oxidized following the modified Hummers method and subsequently used as a support for the immobilization of magnetite particles, being applied in the removal of paracetamol and sulfamethoxazole, both individually and in mixture. The results demonstrated high catalytic activity of the composite, as well as a promoting effect of paracetamol, which modulated the activity of the supported material. In the second study, graphite was functionalized with boron via microwave radiation to act as a support for the anchoring of copper and iron nanoparticles. Characterization results indicated the incorporation of boron into the support material, suggesting the creation of anchoring sites. Imaging analyses confirmed the presence and dispersion of the nanoparticles, with average diameters of 11.05 nm for Fe and 24.24 nm for Cu. The nanostructured materials exhibited catalytic activity in a Fenton-type reaction for the removal of the Remazol Black dye, with emphasis on the promoting effect of boron in accelerating the iron redox cycle. Therefore, the materials presented in this study demonstrate potential for the removal of organic contaminants and may contribute to wastewater treatment applications.