ABSTRACT. The present work investigated the kinetic and thermodynamic study of adsorbents to remove copper ions from aqueous solutions and compared the efficiency between the natural microalgae bio-adsorbent chlorella species (sp.) and synthetic magnetic nanoparticles. All materials synthesized and characterized by Fourier transform infrared (FT-IR), scanning electron microscope (SEM), energy dispersive X-ray (EDX). The highest Cu+2 ion adsorption for the copper solution at 100 mg/L was 57.2%, while at pH 8 it was 59.7%. The more efficient adsorbent for Cu+2 acquired by chlorella was 0.24 mg/g. The second-order kinetic model is fitted, the activation energy (Ea) for the three adsorbents; Chlorella, Fe3O4, (Fe3O4 coated with SiO2) were 95.24, 40.69, 20.39 kJ/mol, respectively indicating the adsorption process is slower than the magnetic nanoparticles. Enthalpy activation changes (ΔH#) were endothermic and showed that the adsorption of the Cu+2 on the chlorella was chemisorption and on the magnetic nanoparticles was physisorption. Entropy change of activation (ΔS#), and activation Gibbs free energy change (ΔG#) showed that adsorption process of Cu+2 on the three adsorbents was feasible and spontaneous in temperature range 293-313 K. The novelty of this work is to determine the type and efficiency of adsorption of algae and nanoparticles.
KEY WORDS: Adsorption, Kinetic models, Thermodynamic studies, Chlorella species, Magnetic nanoparticle, Efficiency percent
Bull. Chem. Soc. Ethiop. 2023, 37(1), 183-196.
DOI: https://dx.doi.org/10.4314/bcse.v37i1.15