Performance, isotherm, kinetics and mechanism of simultaneous removal of Cr(VI), Cu(II) and F ions by CeO₂-MgO binary oxide nanomaterials

This study focuses on the synthesis of a novel Cerium-Magnesium (CeO₂-MgO) binary oxide nanomaterials by a simple co-precipitation process and used to remove harmful pollutants such as Cr(VI), Cu(II), and F. The morphology, phase, crystallite size, thermal stability, functional groups, surface area, and porosity of the synthesized nanomaterial were determined by using XRD, SEM, FTIR, TGA/DTA, and BET studies. The prepared nanomaterials showed adsorption selectivity of Cu(II) ≈ F^-> Cr(VI) with a high adsorption capacity of 84.3 - 133.3 mg/g for Cu(II), Cr(VI), and F^-. The distribution coefficient (K_d) for F^- and Cu(II) was found to be in the range of 10⁴ mL/g which was adequate. The adsorption isotherms for Cr(VI), Cu(II), and F^- followed the Freundlich isotherm model and the pseudo-second-order kinetic model in linear and nonlinear forms, indicated multilayer adsorption. Maximum removal of Cr(VI), Cu(II), and F^- ions was found to be 92.84%, 98.88%, and 95%, respectively, for a high initial concentration of 50 mg/l by 2 g/l dosages of prepared CeO₂-MgO binary oxide nanomaterials employed as an adsorbent in this study. The results showed that novel CeO₂-MgO binary oxide nanomaterials are promising adsorbent for removing hazardous inorganic contaminants from the water due to their adsorption capability and chemical stability.