Facile Synthesis and Characterization of Novel CoFe2O4@MgO@(Mg0.23Co0.77)(Mg0.35Co1.65)O4@C and CoFe2O4@MgO@C Nanocomposites for Efficient Removal of Zn(II) Ions from Aqueous Media

Abstract

Excessive levels of Zn(II) ions in aquatic environments pose significant risks to both ecosystems and human health. In aquatic systems, Zn(II) ions disrupt metabolic functions in organisms, leading to toxicity and bioaccumulation. For humans, prolonged exposure can result in gastrointestinal distress, immune system dysfunction, and neurological complications, necessitating effective removal strategies. This study reports the synthesis and characterization of CoFe-MgO-C-M600 (CoFe2O4@MgO@(Mg0.23Co0.77)(Mg0.35Co1.65)O4@C) and CoFe-MgO-C-M800 (CoFe2O4@MgO@C) nanocomposites for the efficient removal of Zn(II) ions from aqueous media. The nanocomposites were synthesized using the Pechini sol-gel method and characterized through X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM). XRD analysis confirmed the crystalline structure of both nanocomposites, with CoFe-MgO-C-M600 exhibiting a smaller average crystallite size (38.67 nm) than CoFe-MgO-C-M800 (75.48 nm). EDX results verified the elemental composition of the nanocomposites, ensuring the successful incorporation of key elements. FE-SEM analysis revealed significant morphological differences, with CoFe-MgO-C-M600 displaying smaller and more uniform grains compared to CoFe-MgO-C-M800. The results show that CoFe-MgO-C-M600 possesses a highly porous and interconnected structure, enhancing its surface area and adsorption potential. In contrast, CoFe-MgO-C-M800 demonstrates larger and more compact grains, which may affect its adsorption performance. HR-TEM further confirmed these findings, demonstrating that CoFe-MgO-C-M600 had a smaller average particle diameter (35.45 nm) than CoFe-MgO-C-M800 (321.14 nm). Adsorption studies indicated that CoFe-MgO-C-M600 and CoFe-MgO-C-M800 achieved maximum adsorption capacities of 276.24 and 200.00 mg/g, respectively. The adsorption process was determined to be exothermic, spontaneous, and physical in nature, following the pseudo-second-order kinetic model and the Langmuir isotherm.