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Zinc oxide-hydroxyapatite nanocomposites were prepared from a natural phosphate ore via a solvent-free method and evaluated for the photodegradation of two antibiotics in solution. The in situ growth of ZnO followed by thermal treatment allowed for the formation of photocatalytic nanocrystals homogeneously dispersed in the apatite phase. Nanocomposites exhibited higher rates of sorption of ofloxacin and ciprofloxacin compared to the individual phases. At high ZnO loadings, photodegradation performances of the nanocomposites under UV irradiation were equivalent or greater than that of the photocatalytic particles alone, depending on the considered antibiotic. This dependency reflects distinct degradation pathways that were attributed to different affinities of the antibiotics for the nanocomposite particles. Because of its simplicity and versatility, the here-described approach appears very promising for the development of multifunctional platforms for water remediation.

Phenol is very abundant in the aquatic environment and therefore requires an effective treatment using porous and low-cost adsorbents. Alumina-hydroxyapatite composites were prepared from natural phosphate ore in the presence of Al 3+ ions via a wet-chemical method. Porous composites were characterized and the Al-surface modification was produced by facile and inexpensive route to uptake adjacent toxic species. Supplementary active sites on their surface may improve their phenol remediation. Nanocomposites exhibit higher phenol sorption rates than pure hydroxyapatite. It is concluded that the specific surface area, surface charge and Al content are suitable for phenol removal from aqueous solution using Alumina-hydroxyapatite composites. The results show that the retention power of these composites depends on a complex interaction between intermolecular and molecule-solid interactions. These findings are relevant to better understand the contribution of alumina content in Alumina-hydroxyapatite composites to the fate and uptake of phenol from aquatic environments.

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The photocatalytic efficiency of the metal oxide-hydroxyapatite photocatalysts prepared by soft chemistry using phosphate rock as calcium and phosphorus precursors has been investigated on the degradation kinetic of ciprofloxacin residues in water under UV-light (HPK125 W Lamp). The nature of metal oxide (TiO2, ZnO, Fe2O3), structure, surface area and pore-size distributions of the catalysts were analyzed by various techniques analyses. Association of nanoscale metal oxide with hydroxyapatite could enhance the sorption properties of the materials and confers them interesting photodegradation properties. The results of the kinetic study revealed that the activities of these photocatalysts were dependent on the oxide surface and the best activity was obtained with TiO2/hydroxyapatite catalyst, which had the largest surface area. The effects of various operational parameters were thoroughly considered in order to achieve highest photodegradation efficiency. A correlation between the nature of associated metal oxide, surface properties, the sorption behavior and the photodegradation capacity of these composites could be establishedd.

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