Structural and morphological investigations of nanolayered double hydroxides as effective adsorbents of methyl orange

This study aims to synthesize a new series of nanolayered double hydroxides (LDHs) containing zinc, cobalt, aluminum, and iron and study the influence of divalent cations (Zn 2+ , Co 2+ ) in the composition on LDHs structure. The LDHs samples were prepared by coprecipitation by controlling the pH of the solution. Various analytical techniques have been used to investigate the structural and morphological characteristics of LDHs (including X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analyses, scanning electron microscopy, and energy-dispersive X-ray) and showed a detailed description of the influence of the composition on the structural organization of the LDHs. The obtained results showed a strong relationship between the composition of the LDHs phases and their structural properties. The LDHs materials were used to remove methyl orange (MO) dye from an aqueous solution. The influence of various parameters such as solution pH, initial dye concentration, and contact time on the adsorption process was studied. The pH influenced the sorption behavior of dye onto LDHs, with the best removal efficiency being observed in the pH range of 3–5. The adsorption capacity was increased with the increase of initial dye concentration. The adsorption kinetics of MO onto the LDHs were considerably rapid within the first 60 min, and it reached equilibrium at 240 min. Experimental results were fitted with the Langmuir models, with a high adsorption capacity of 1141.58, 936.75, 800.6, 733.17, and 623.07 mg g −1 for Zn–AlFe–CO 3 , Zn 0.75 Co 0.25 –AlFe–CO 3 , Zn 0.5 Co 0.5 –AlFe–CO 3 , Zn 0.25 Co 0.75 –AlFe–CO 3 , and Co–AlFe–CO 3 , respectively.