Competence kinetic and thermodynamic studies between natural bio-adsorbent green microalgae and synthetic adsorbent magnetic nanoparticles for copper(II) ion in water

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 &nbsp