Calcium phosphate tricalcic apatitic (CaPT-Ap) was synthesized by co-precipitation at low temperature and basic medium. The potential of CaPT-Ap as an adsorbent was investigated in a batch reactor under different experimental conditions for removing dye Eriochrome Black T (EBT) from aqueous solutions. The used adsorbent was characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and chemical analysis indicate that this calcium phosphate is a CaPT-Ap. The effect of particle sizes , mass of the adsorbent, contact time ,temperature and the concentration of the dye on the adsorption were determined. The kinetic study showed that the pseudo-second-order model gives a better description of the kinetics of the adsorption reaction than the pseudo-first-order model. Analysis of adsorption isotherms showed that adsorption governed by the isotherms of Freundlich. Thermodynamic parameters such as ΔG°, ΔS° and ΔH° were calculated. It was found that EBT dye adsorption was spontaneous and endothermic
