Application of modified silicates with gold nanoparticles on environmental remediation: Study of non-linear kinetic adsorption models focused on heavy metals

Abstract

In this work, the ultrasound-assisted synthesis of the montmorillonite-Au (MMT-Au) composite is proposed. The morphological, chemical and structural characterization was carried out by high-resolution Scanning electron microscopy (HR-SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray diffraction (XRD). The composite obtained was evaluated in Cu2+ adsorption from aqueous solutions. The adsorption capacity of the MMT-Au composite was measured by atomic absorption spectroscopy (AAS). The Cu2+ adsorption capacity presented by the MMT and the MMT-Au composite was compared. An increment in the Cu2+ adsorption rate and quantity of Cu2+ adsorbed by the MMT-Au sample, concerning the MMT, were observed. The maximum Cu2+ adsorption percentage obtained was 95% in 540 min. The adsorption capacity of the composite was evaluated by AAS and studied by four kinetic adsorption models, Pseudo-first Order, Pseudo-second order, Elovich and intraparticle diffusion models. Complementarily, non-linear forms from Pseudo-first and Pseudo-second order were employed to describe with high precision de Cu2+ adsorption process carried out by the mineral.