Synthesis of calcium tungstate nanoparticles from phosphogypsum waste

The current study focused on the preparation of calcium tungstate nanoparticles (CaWO₄NPs), also known as scheelite, using an innovative room temperature co-precipitation method. This involved mixing Moroccan phosphogypsum (PG), an industrial waste product, with Na₂WO₄.2H₂O as a tungstate precursor in the presence of sodium hydroxide. The synthesized nanoparticles (CaWO₄) underwent comprehensive analysis, including X-ray diffraction (XRD) for crystal structure examination and Fourier transform infrared spectroscopy (FT-IR) for investigating chemical composition and molecular-level binding. Additionally, scanning electron microscopy (SEM) was employed to observe surface morphology, while ultraviolet-visible (UV-Vis) spectroscopy was utilized to determine optical properties. The results confirm the synthesis of highly pure calcium tungstate, with a particle size of 13 nm and an optical band gap of 4.3 eV. Using phosphogypsum as a raw material encourages the development of environmentally friendly materials and provides an economically viable alternative to conventional sources.