**4.1 Characterization of adsorbents**

## *4.1.1 X-ray diffraction*

X-ray diffractograms of hydroxyapatite-Alg and hydroxyapatite-(λ-Carr) are presented in **Figures 2** and **3**. For all compounds, the hydroxyapatite phase is conserved according to 00-024-0033 reference from the ICDD-PDF2 2003 database. However, in the case of CaHAp1-(Alg)20% new peaks appear at 2θ = 26.60° and 30.14°. These peaks are characteristic of monetite phase (CaHPO4) according to 01-077-0128 reference from the ICDD-PDF22003 database. The increase of the amount of biopolymer induced the broadening of peaks, which proves their incorporation on the apatitic surface.
