Thermodynamic Study of Cadmium Ions Removal from Aqueous Solution using Spherical Alumina and Zeolite Alumina Nanocomposite

Abstract

Cd (II) is among the most hazardous transition metals for biological species Due to its cumulative toxicity and its effect on the kidneys and vital tissues. Consequently, it is imperative to develop effective strategies for the remediation of cadmium from water and soil. Spherical alumina and zeolite alumina nanocomposites have been investigated theoretically and empirically for their efficacy in removing Cd ions from their aqueous solution. Various advanced techniques, such as X-ray diffraction, scanning electron microscopy (SEM-EDS), Fourier Transform Infrared Spectroscopy (FT-IR), and (BET) surface area analysis, were utilized to examine the crystalline, morphological, chemical, and porosity properties of adsorbents. Optimal Cd(II) removal occurred at pH 6, and the efficiency was influenced by both the initial Cd(II) concentration and the alumina content in the adsorbents. The sorption of Cd ions on spherical alumina exhibited a higher removal efficiency due to their high surface area and active sites, that achieved a removal efficiency of 92.5%, compared to 90% of zeolite-alumina nanocomposite with multilayer adsorption capacities of 3.07 mg/g and 8.95 mg/g, respectively. The collected experimental adsorption data were analysed using five isotherm models. The Freundlich, Dubinin, and Temkin adsorption isotherm models yielded the most accurate fit for the Cd (II) ions adsorption data, indicating that the adsorption process is multilayered. The obtained thermodynamic values demonstrated that the adsorption process is spontaneous and exothermic on the zeolite-alumina nanocomposite with decreased randomness in contrast to spherical alumina at the solid adsorbents –ions adsorbate interface during the adsorption process.