Synthesis and characterization of cadmium chlorapatite Cd₅(PO₄)₃Cl

One of the most effective methods for the immobilization of toxic metals involves the use of minerals from the apatite supergroup. The formation of cadmium chlorapatite may lead to successful entrapping of cadmium; thus, it is important to examine the solubility constant to determine the stability of cadmium in the the apatite structure. Cadmium chlorapatite was synthetized and characterized by X-ray diffraction, infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy. The solubility constant (log) K_sp of cadmium chlorapatite was -65.58. The Gibbs free energy of formation of cadmium chlorapatite reached -3950.48 kJ mol⁻¹. The solubility constant turned out to be low but was enough for cadmium chlorapatiteto be considered a very stable compound..