Fast and high removal of acid red 97 dye from aqueous solution by adsorption onto a synthetic hydrocalumite: Structural characterization and retention mechanisms

Owing to their structure and exceptional physical and chemical properties, layered double hydroxides (LDH) are highly recommended for many applications, such as catalysis, medicine, additives in polymers, and environ-mental treatments. In this framework, hydrocalumite (Ca-Al-Cl) type LDH was prepared via a co-precipitation procedure at constant pH to remove the acid red 97 dye (AR97). The hydrocalumite (HC) material formed was characterized by FTIR spectroscopy, X-ray powder diffraction, scanning electron microscopy (SEM), energy -dispersive X-ray spectroscopy (EDS), BET-BJH, and inductively coupled plasma atomic emission spectroscopy (ICP-OES). The adsorption capacity of the prepared HC material was investigated under different experimental conditions using AR97 as an anionic dye. This material has shown good performance and exceptional efficiency for AR97 dye adsorption. The pseudo-second order model is more effective in explaining the adsorption kinetics of AR97 dye/HC; the equilibrium has been achieved after 20 min of contact. Isothermal studies confirmed that the adsorption data follows the Langmuir model with a maximum monolayer coverage of Qmax = 1126.62 mg. g- 1. The adsorption process was physisorption, spontaneous and exothermic. Based on these promising results, it can be considered that hydrocalumite material has great efficiency in removing anionic dyes from wastewater.