Removal of Methylene Blue from Water Using Hydroxyapatite Submitted to Microwave Irradiation

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.