Novel copper-aluminum oxide nanocomposite based on natural diatomite for efficient Cr⁶⁺ removal

Removing hexavalent chromium (Cr⁶⁺) from wastewater is of great significance for ecological environment, human health, and sustainable industrial development. In this work, Cu-Al2O3 nano powders and Cu-Al2O3@AD nanocomposite were prepared by coprecipitation method, which were used to adsorb Cr⁶⁺. The materials Cu-Al2O3@AD have ordered structures, and rich functional groups as verified by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), energy spectrum analysis (EDS), and field emission scanning electron microscope (FESEM). Then, Cu-Al2O3@AD was used as adsorbents for fast and efficient removal of Cr⁶⁺ from aqueous solution by batch equilibrium experiments. The experimental results demonstrate that when the adsorbent dosage was10 g/L, the pH value was 3, the initial concentration of Cr6+ was 2 μ g/mL, and the reaction temperature was 30℃, the adsorption performance of Cu-Al2O3@AD is the best, with a removal rate of up to 90%. The adsorption kinetic and isotherm data follow the pseudo-first-order equation and the Langmuir model, respectively. The adsorption mechanisms of Cr⁶⁺ are ascribed to the monolayer adsorption.