Adsorption properties of Ni(II) ions from an aqueous solution onto activated carbon prepared from Posidonia oceanica seagrass

This study examined the adsorption ability of Ni(II) metal ions from aqueous solutions on a physically activated adsorbent of Posidonia oceanica seagrass (AC-PO), which is both economically and naturally available. The effects of pH, amount of adsorbent, concentration of nickel ions, temperature, and contact time, which are among the parameters affecting the adsorption of Ni(II) ions on AC-PO, were examined. The kinetic data fit well with the pseudo-second-order model. The adsorption of Ni(II) ions showed compliance with Langmuir, Freundlich, and D-R isotherms. The Langmuir model showed better representation of data (0.9993). The maximum adsorption capacity of AC-PO for nickel ions was 138.89 mg·g⁻¹.at 25 °C The thermodynamic parameters such as ∆G°, ∆H°, and ∆S° were calculated for the Ni(II) ion, and it was determined that the adsorption was spontaneous and endothermic. In qualitative chemical analysis by energy dispersive spectroscopy (EDS), it was found that there was ion exchange with adsorption of nickel ions on the AC-PO adsorbent. According to the results obtained from this study, it can be said that the adsorption ability of the AC-PO adsorbent is quite high in the removal of Ni(II) ions from aqueous solutions.