Enhancing adsorptive removal of sulfate by metal layered double hydroxide functionalized Quartz-Albitophire iron ore waste: preparation, characterization and properties

Abstract

In this study, the seemingly worthless Quartz-Albitophire iron ore mineral waste has been modified with metal double hydroxides (Mg–Al, Ni–Fe, Ni–Al and Mg–Fe) and utilized as a sulfate adsorbent which is characterized by XRD, XRF, FTIR and SEM analysis. The optimum conditions were investigated by Response Surface Method (RSM) based on central composite design (CCD). The amount of adsorption in optimum conditions led to 46.74 and 33.73 mg g⁻¹ for Ni–Al and Ni–Fe Quartz-Albitophire, respectively. The equilibrium studies by two and three parameter models displayed that sulfate adsorption onto Ni–Al Quartz-Albitophire and Ni–Fe Quartz-Albitophire adsorption were homogenous with a uniform distribution of heat of adsorption. Kinetic studies have been performed by applying reaction based models (pseudo-first-order and pseudo-second-order) and diffusion-based models (Boyd, intraparticle diffusion and mass transfer models), which indicated the chemisorption interaction for all three adsorbents (raw and modified) by a controlling step of the macro-pore and micro-pore diffusion for sulfate adsorption process onto the Ni–Al Quartz-Albitophire and Ni–Fe Quartz-Albitophire respectively. Thermodynamic studies showed that the sulfate adsorption process onto Ni–Al and Ni–Fe Quartz-Albitophire were exothermic and spontaneous.