Phosphoric acid (H3PO4), commonly derived from phosphate rock, is vital in industry as it could be employed in numerous processes. Several techniques were used to purify H3PO4. In the current work, natural and H2SO4-activated clays were used to reduce cadmium (Cd) and magnesium (Mg) ions from the H3PO4 solution through the adsorption method. The solid materials were characterized using several analytical methods including Elemental analysis, Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and Thermogravimetric analysis (TGA-DTA). The main constituents of the studied clays were SiO2 (43.64 - 51.24 %), and Al2O3 (19.92 – 31.24%). The specific surface area values of the studied clays ranged from 74.25.35 to 85.14 m2/g. The diffractograms showed the presence of kaolinite, quartz, goethite, and hematite. Clay micrographs were formed of agglomerates with irregular shapes and small sizes (1 - 3 µm). The cadmium and magnesium retention capacity in clays are higher than 50% and 36%, respectively. The adsorption process followed well pseudo-second kinetic order and Freundlich isotherm equations. The process is demonstrated to be chemical. Overall, the current study has confirmed the efficiency of using abundant natural clays and activated ones to reduce Cd and Mg ions in phosphoric acid solution.
