NANOCOMPOSITES FOR SUSTAINABLE COBALT (II) ION REMOVAL: SOL-GEL SYNTHESIS AND EXCEPTIONAL PERFORMANCE

Abstract

The removal of Cobalt (II) ions from wastewater is of paramount im- portance due to its toxic effects on both the environment and human health. In this study, Fe3O4/MgO nanocomposites synthesized through the sol-gel method were em- ployed as an efficient adsorbent for the removal of Cobalt (II) ions from aqueous so- lutions. The synthesized nanocomposites were thoroughly characterized, and their ad- sorption performance was evaluated. The nanocomposites' structural evolution during Cobalt (II) ion adsorption was examined using scanning electron microscopy (SEM), revealing a transition from a rod-like structure to an irregular shape, indicative of suc- cessful adsorption due to robust surface-ion interactions. X-ray diffraction (XRD) analysis identified cubic MgO and cubic Fe3O4 phases in the nanocomposites. Fol- lowing Cobalt (II) ion adsorption, additional phases, such as hexagonal Mg(OH)2, hexagonal Co(OH)2, Rhombo H. axes CoCo3, and cubic Co3O4, were detected, signi- fying changes in the nanocomposite's crystal structure. Vibrating sample magnetom- etry (VSM) analysis showed a magnetization of 30.19 emu g-1, enabling convenient magnetic separation after treatment. Optimization parameters were established, in- cluding an adsorbent dosage of 0.03 g L-1, an initial Cobalt (II) ion concentration of 40 mg L-1, a contact time of 120 minutes, and a pH of 8. Under these conditions, the Fe3O4/MgO nanocomposites displayed a remarkable adsorption capacity of 1300.04 mg g-1 and an impressive removal efficiency of 97.5%. The kinetic data fitting closely followed the pseudo-second-order model (R2=0.996), indicating chemisorption and intra-particle diffusion during the initial stage. Isotherm data analysis aligned well with the Langmuir isotherm model (R2=0.995), validating monolayer adsorption with a maximum adsorption capacity of 1178.55 mg g-1. This study underscores the poten- tial of sol-gel-synthesized Fe3O4/MgO nanocomposites as a highly efficient adsorbent for Cobalt (II) ion removal from wastewater. The exceptional adsorption capacity and efficiency of these nanocomposites offer a promising solution for environmental re- mediation and water purification.