Ternary phosphates are found to vitrify within large domains of compositions inside the phase diagrams P 2 O 5 -WO 3 -A 2 O (A ‫؍‬ Li, Na). Structural approach of the highly modified glasses P 2 O 5 -A 2 MoO 4 -A 2 O (M ‫؍‬ Mo,W) was investigated using various spectroscopic techniques such as infrared, Raman, and electron spin resonance (ESR). These glasses were found to contain MO 6 octahedra, MO 4 tetrahedra, M 2 O 7 dimers, PO 4 tetrahedra, and also P 2 O 7 or metaphosphate chains, depending on the composition considered. As shown in earlier studies, the glass network is progressively depolymerized as the content of A 2 O increases. ESR experiments were conducted on both X-ray irradiated and unirradiated samples. Unirradiated glasses exhibit two ESR signals attributed to W 5؉ and Mo 5؉ centers that are octahedrally coordinated. Irradiation of these glasses induces new paramagnetic centers ascribed to the phosphorus-oxygen-hole-center and peroxy radicals. The M 5؉ concentration depends strongly on the sample composition and temperature. ESR parameters are determined using a computer simulation approach adapted for vitreous materials.

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This study investigated the power of hydroxyapatite adsorbent prepared by a combined precipitation-microwave method, for removing a cationic dye methylene blue in aqueous media. The used adsorbent was characterized by X-ray diffraction (XRD) and infrared spectroscopy (IR). The adsorption tests were conducted in batch mode. The effect of temperature, the pH of the solution and the mass of the adsorbent on the adsorption were determined. It is found that the adsorption was pH and temperature dependent. The kinetic study showed that the second-order model gives a better description of the kinetics of the adsorption reaction than the first-order model. Analysis of adsorption isotherms using different classical models showed that adsorption may be governed by the isotherms of Langmuir. The thermodynamic parameters were determined from the values of the maximum adsorption capacity and equilibrium constants.

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