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

The present work investigated the more competent and challenging adsorbent to remove copper ions from aqueous solutions, comparing the efficiency between the natural microalgae bio-adsorbent chlorella species (that are present in Greater Zab River near Erbil city, which is known as hyper accumulate heavy metal ions) and synthetic magnetic nanoparticles coated with silica (SiO2) (that are gaining popularity for the treatment of heavy metals in water because of there smaller size, highly dispersible in different pH and magnetically resonant efficient). All the materials synthesized and characterized by Fourier transform infrared (FT-IR) analysis, the morphology observed by Scanning electron microscope (SEM), crystalline structure, and grain size provided by Energy Dispersive X-ray (EDX) and X-ray diffraction (XRD). The maximum Cu+ 2 ion adsorption was for 100mg/L for the copper solution was 57.2%, at pH8 was 59.7%, and at the temperature, 30°C was 80.2% are the optimum conditions obtained for each adsorbent. The more efficient adsorbent for copper ion acquired was low cost, and environmentally friendly natural bio-adsorbent chlorella spices (sp.) was 0.24mg/g, due to high surface functional group and has high selective as compared to magnetic nanoparticles that are coated with SiO2 are lower capacity for adsorption 0.16mg/g.

ABSTRACT. Magnetic nanoparticles (MNPs) are gaining popularity because of their small size allowing for research into the fundamentals of magnetism. In wastewater treatment, adsorption methods commonly remove heavy metals, but copper (Cu+2) ion removal using magnetic nanoparticles (NPs) has not been investigated. In this study two different modes were used to determine maximum adsorption capacity to remove copper(II). The nanoparticles containing the Fe3O4 with Chlorella, core-shell Fe3O4/SiO2 with Chlorella sp. synthesized and characterized by Fourier transform infrared (FT-IR) analysis, the morphology observed by scanning electron microscope (SEM), crystalline structure, and grain size provided by energy dispersive X-ray (EDX) and X-ray diffraction (XRD). Copper(II) ion removal showed in both modes. The maximum copper(II) ion reduction percent was obtained by nanoparticles containing core-shell Fe3O4/Chlorella 80.3%, Fe3O4/SiO2 with Chlorella sp. (86.9%) the result showed maximum removal using Fe3O4/SiO2 with Chlorella sp. due to increase of surface area. The results indicate that the adsorption using magnetic nanoparticles with Chlorella sp. enhances the cell surface and provides easy access to the separation for both preparation and recapture.   KEY WORDS: Copper(II) ion, Magnetic nanoparticles, Chlorella sp., SiO2 core-shell, Adsorption capacity percent Bull. Chem. Soc. Ethiop. 2022, 36(3), 585-596.                                                             DOI: https://dx.doi.org/10.4314/bcse.v36i3.8