Desenvolvimento e aplicação de sistema híbrido de adsorção e oxidação avançada para remoção de corante azoico em meio aquoso

Abstract

The intensification of challenges associated with the degradation of complex organic compounds in effluents, particularly azo dyes, whose stable N=N bonds and resistant aromatic rings hinder their removal, have highlighted the limitations of conventional treatment processes, driving the search for more effective alternatives. In this context, systems integrating adsorptive and nanotechnological materials emerge as promising strategies by combining adsorption capacity with the activation of reactive species. This study proposes the development and application of a hybrid adsorption advanced oxidation system incorporating zero-valent iron nanoparticles (nZVI) and adsorbent materials (sodium alginate and activated carbon), aiming to evaluate the potential of coupling adsorption and advanced oxidation mechanisms for the remediation of water contaminated with an azo dye. The synthesis of the ferrous precursor (FeSO ) from steelmaking residues, iron scale and ferrous slag, showed high efficiency in recovering ferrous ions, ensuring their availability for catalyst production. This approach not only adds value to widely generated industrial residues but also reinforces the sustainability of the process by converting environmental liabilities into useful inputs. Characterization of the catalysts confirmed the successful incorporation of nZVI into their respective matrices. Treatability assays demonstrated that the AC/nZVI catalyst achieved superior performance, attributed to its enhanced adsorptive properties and the structural protection provided to the nanoparticles, which maintained their availability and reactivity during the Fenton-based advanced oxidation process. Optimal operational conditions for dye degradation were achieved at pH 5, with 3 hours of reaction and gradual addition of 0.4 mL of H O , resulting in approximately 99.8% decolorization, 99.9% TOC reduction, removal of 88.8% of Folin Ciocalteu reactive species, and a final ferrous residual of 0.03 mg L ¹, demonstrating the high efficiency of the process in degrading azo dyes.