In this research, the adsorption of divalent cobalt (Co(II)) ions from aqueous solutions were inves- tigated using nano magnesium oxide (MgO-NPs) and montmorillonite nanoparticles (Mont-NPs). Batch experiments were carried out to measure the optimum values of pH, adsorbent dosage, contact time, and temperature. Adsorbents were characterized by powder X-ray diffraction and a scanning electron microscope with energy-dispersive X-ray. Thermodynamic parameters were cal- culated, and the results showed an exothermic and endothermic pattern for the adsorbents. The maximum adsorption capacities of MgO-NPs and Mont-NPs were calculated as 440 and 2.53 mg/g, respectively. The pseudo-second-order model justified the experimental data of the adsorbents, while the pseudo-first-order model only fitted the MgO-NPs data. Desorption was carried out at the last point of the isotherm figure to verify the preservation capability of the adsorbed ions. Regarding the adsorbent dosage and the isotherm experiments, this study revealed that MgO-NPs have an excellent potency for Co(II) ion adsorption from the aqueous solutions compared to Mont-NPs. MgO-NPs and Mont-NPs are present in some rocks and soil textures; hence, the finding of this study could help chemists and environmentalists with the trace of pollutants and the removal of heavy metals in the soil-water medium.
