Comparisons of azo dye adsorptions onto activated carbon and silicon carbide nanoparticles loaded on activated carbon

This paper presents a comparative study of the surface chemistry, texture, and adsorption properties of activated carbon and silicon carbide nanoparticles loaded on activated carbon. Activated carbon has been prepared from the pulp of oak cups using a chemical activation method, with silicon carbide nanoparticles used to modify the surface of activated carbon. Scanning electron microscopy, Fourier transform infrared spectroscopy, N₂ adsorption–desorption isotherms, and points of zero charge determination are the methods that have been employed to determine the physicochemical properties of raw material, activated carbon, and silicon carbide nanoparticles loaded on activated carbon, respectively. Results demonstrated that the activated carbon is composed mainly of micropores, with a Brunauer–Emmett–Teller surface area of 1253.92 (m²/g), and that the attachment of silicon carbide nanoparticles changed the surface properties of activated carbon. The adsorption equilibrium of two azo dyes on activated carbon and silicon carbide nanoparticles loaded on activated carbon was investigated using the Langmuir, Freundlich, and Temkin isotherms. Experimental data were fitted to conventional kinetic models, including the pseudo-first-order, second-order, Elovich, and intraparticle diffusion models. For all adsorbents, the removal process follows the pseudo-second-order kinetic model. Equilibrium adsorption parameters reveal that a higher adsorption capacity was found for silicon carbide nanoparticles loaded on activated carbon. These features indicate that silicon carbide nanoparticle-activated carbon is a promising and new adsorbent for the removal of acidic dyes during wastewater treatment.z

Keywords
Activation; Congo red; Isotherm; Methyl orange; Modification; Points of zero charge; Surface area