The presence of heavy metals in the environment is a major issue for ecosystems and human health. Among possible remediation strategies, adsorption techniques appear as most promising. This PhD work was devoted to the preparation of novel materials based on hydroxyapatite in order to obtain improved metal immobilization properties. Two approaches have been explored. The first one relies on the formation of hydroxyapatite in the presence of carboxylic acids that exhibit affinity for both the calcium of the mineral phase and the metal ions to be trapped. This approach allows the preparation of porous organo-apatites. Based on extensive characterization, including XRD, solid state NMR, N2-sorption and electronic microscopy, we discuss the influence of carboxylic acids on the structure and surface chemistry of the materials. This discussion provides basis for the understanding of the sorption behavior of Pb2+ and Zn2+ ions on these materials. The second approach relies on the preparation of nanocomposites associating hydroxyapatite with zirconia. We describe a new sol-gel based synthetic route leading to homogeneous micro- and mesoporous materials. The association of the two phases allows the combination of affinity for both Cr(III) and Cr(VI) species within a single material.
