Enhancing Zn (II) recovery efficiency: Bi-divalent nickel-cobalt ferrite spinel Ni_XCo_1-xFe₂O₄ as a Game-changing...

This study presents a comprehensive investigation into Ni_XCo_1-xFe₂O₄ (x = 0.5) spinel nanoparticles synthesized through a one-pot hydrothermal method using Co(NO₃)₂.6H₂O and Ni(NO₃)₂.6H₂O salts. XRD, FTIR, FESEM, and VSM analyses confirmed a cubic structure of Ni_XCo_1-xFe₂O₄ (x = 0.5) nanoparticles without impurities. These nanoparticles exhibit efficient Zn (II) adsorption characteristics, following Langmuir isotherm and pseudo-second-order kinetics. The maximum adsorption capacity was measured to be 666.67 mg g^-1 at pH = 7, with mechanisms involving both electrostatic attraction and cation exchange. Desorption studies indicate more than 75% Zn (II) recovery in an acidic environment (pH = 2) after three cycles. Computational analysis was used to validate the experimental results through Molecular Dynamics simulations, initially focusing on Ni_XCo_1-xFe₂O₄ (x = 0.5). Further exploration involved variations in x at 0.25 and 0.75 to identify the optimal Ni and Co ratio in this bivalent cation spinel ferrite. Computational analyses reveal the superior performance of Ni_XCo_1-xFe₂O₄ (x = 0.75) in Zn (II) removal, supported by radial distribution analysis, VdW energy, Coulombic energy, mean square displacement (MSD), root mean square displacement (RMSD), and interaction energy. This comprehensive study provides valuable insights into the adsorption behavior and structural stability of Ni_XCo_1-xFe₂O₄ nanoparticles, showcasing potential applications in Zn (II) removal.