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• Moroccan phosphogypsum and aluminum wastes are transformed into hydrocalumite. • Characterization techniques confirmed the formation of hydrocalumite. • Sustainable synthesis approach reduces waste generation, promotes circular economy. • Synthesis process shows potential for commercialization of waste-based products. Each year, the phosphate industries in Morocco discard over 20 million tons of phosphogypsum into the Atlantic Ocean, posing a significant threat to aquatic life and causing potential long-term damage to ecosystems due to the accumulation of harmful substances. Hence, developing eco-friendly and cost-effective strategies to valorize phosphogypsum is vital to protect ecosystems and human health. This study aims to provide a concrete and efficient strategy for exploiting phosphogypsum and aluminum wastes in the preparation of hydrocalumite using the co-precipitation method. The synthesis strategy's effectiveness was assessed through a comprehensive analysis of the phosphogypsum-based hydrocalumite using various techniques, including FT-IR spectroscopy, X-ray powder diffraction, scanning electron microscopy (SEM), Energy-Dispersive X-Ray (EDX) analysis, X-ray fluorescence (XRF), and inductively coupled plasma optical emission spectrometry (ICP-OES). In addition, the structure was refined to discuss the arrangement of the polyhedrons occupied by the different ions in the hydrocalumite framework. It was found that the phosphogypsum-based hydrocalumite exhibited chemical and structural properties comparable to those of conventionally synthesized hydrocalumite, suggesting its potential applicability in diverse fields, including catalysis, cement and concrete production, polymer additives, medicine, and environmental remediation. Overall, in this work, the Moroccan phosphogypsum and aluminum wastes proved to be effective precursors of hydrocalumite, with structural and chemical properties presumably close to the conventional hydrocalumite. [ABSTRACT FROM AUTHOR]

CaAl-Layered double hydroxide (LDH) of hydrocalumite-type with nitrate anions in the inter-lamellar region was synthesized via the co-precipitation method at fixed pH and with a selected Ca/Al molar ratio of the starting salts equal to two. The obtained CaAl–NO3 compound was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). In this context, this material has been employed as an adsorbent for the retention of the reactive azo dye, alizarin yellow R (AYR), from an aqueous solution. To further investigate the practical potential of CaAl–NO3 for AYR dye adsorption, the effects of various parameters such as temperature, the concentration of dye, pH, adsorbent dose, and contact time on adsorption capacity were separately exanimated. The findings results suggest that a pH of 9 is more suitable for the AYR dye adsorption process. The adsorption kinetics was better explained by the pseudo-first-order model, and equilibrium was achieved after 30 min of contact. The equilibrium adsorption data of AYR dye on the prepared CaAl–NO3 was well fitted to the Langmuir model, and it was characterized by an excellent adsorption capacity of 2107 mg/g at 293 K. Thus, due to the 2D structure and its positively charged layers, CaAl–NO3 material exhibits an exceptional ability to remove alizarin yellow R dye from aqueous solutions. [ABSTRACT FROM AUTHOR]

CaAl-Layered double hydroxide (LDH) of hydrocalumite-type with nitrate anions in the inter-lamellar region was synthesized via the co-precipitation method at fixed pH and with a selected Ca/Al molar ratio of the starting salts equal to two. The obtained CaAl–NO3 compound was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). In this context, this material has been employed as an adsorbent for the retention of the reactive azo dye, alizarin yellow R (AYR), from an aqueous solution. To further investigate the practical potential of CaAl–NO3 for AYR dye adsorption, the effects of various parameters such as temperature, the concentration of dye, pH, adsorbent dose, and contact time on adsorption capacity were separately exanimated. The findings results suggest that a pH of 9 is more suitable for the AYR dye adsorption process. The adsorption kinetics was better explained by the pseudo-first-order model, and equilibrium was achieved after 30 min of contact. The equilibrium adsorption data of AYR dye on the prepared CaAl–NO3 was well fitted to the Langmuir model, and it was characterized by an excellent adsorption capacity of 2107 mg/g at 293 K. Thus, due to the 2D structure and its positively charged layers, CaAl–NO3 material exhibits an exceptional ability to remove alizarin yellow R dye from aqueous solutions. [ABSTRACT FROM AUTHOR]