Um estudo teórico e prático de adsorção para desagregação de negro de fumo aplicada à limpeza de dutos de exaustão

Abstract

Carbon black (CB) is a carbon-based material with high thermal stability and wide availability, showing potential as an adsorbent and in environmental remediation processes. Thus, according to its importance, this work aimed to structurally, chemically, and morphologically characterize CB, as well as to evaluate its adsorption capacity toward organic substances, seeking to understand the surface behavior of the material. For this purpose, CB was analyzed regarding the point of zero charge (pHPZC), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDX). The pHPZC was approximately 5.5, indicating that the material presents a positive value in acidic media and tends to be neutral or slightly negative at higher pH values. FTIR analyses revealed the presence of hydroxyl, methyl, and methylene functional groups, associated with a graphitic structure containing surface oxygenated groups, while TGA demonstrated high thermal stability, with mass loss lower than 10% up to 1000 °C. SEM showed that CB has nanometric spheroidal and agglomerated particles, with a fractal structure and high surface area, and these characteristics favor the adsorptive potential of the material. Adsorption tests with erythrosine indicated a high affinity of CB for negatively charged molecules, with rapid saturation kinetics, in about 20 minutes. Our results demonstrate that CB has a predominantly cationic surface under the conditions of this study, being effective in the adsorption of anionic organic compounds; however, requiring prior activation treatments to increase its adsorption capacity for metal ions. Thus, our results highlight a promising potential as an adsorbent in aqueous systems, especially after surface modifications that optimize its interaction with different types of contaminants.