Use of Natural Phosphate as Alternative Adsorbent for Water Depollution

Abstract

Heavy metals are found in the effluents of many industrial units. The applicability of Moroccan natural phosphate from Benguerir (NPB) and Khouribga (NPK) regions can remove some heavy metals from water. This approach is considered benefic, inexpensive, and very effective for the treatment of contaminated waters. The raw samples of NPB and NPK are mainly composed of carbonated fluorapatite (FAP) associated with some impurities such as SiO 2 and CaF 2 . The heat treatment of these materials at 600 °C, 800 °C, and 1000 °C results in a single crystalline phase of phosphosilicate apatite. First, the adsorption efficiency of the dried phosphates depends on their mineralogy on the nature of the metal (Pb 2+ , Cd 2+ , Zn 2+ , and Cr 3+ ) in the order Pb 2+ > Cr 3+ > Cd 2+ > Zn 2+ . After treatment at 600 °C and 800 °C, the adsorption efficiency of the selected NPB sample was tested against Cr 3+ and Cd 2+ ions and it was slightly better compared to the raw sample. Therefore, NPB heat-treated at 600 °C can be considered a stable adsor-bent and depollution agent for wastewaters.