Waste to wealth: Synthesis of hydrocalumite from Moroccan phosphogypsum and aluminum wastes

Abstract

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.