Evaluation of phosphate removal from water by calcined-LDH synthesized from the dolomite

In the present study, the characteristics of the adsorption of phosphate on calcined layered double hydroxides (LDHs) from aqueous solution were evaluated under laboratory conditions. The anionic clays were Mg₃pH₁₀-LDH synthesized by co-precipitation and D ₁pH₁₀-LDH synthesized from the dolomite. The equilibrium isotherm showed that the uptake of phosphate ion by Mg₃pH₁₀(500)-LDH was in agreement with the Langmuir and Freundlich equations; the Langmuir model gave a better fit to the experimental data than the Freundlich one. The equilibrium isotherm showed, however, that the adsorption of the phosphate on D₁pH₁₀(500)-LDH was accompanied with precipitation reac tion of the phosphate salts. A mechanism proposed for the removal of phosphate ion has been confirmed by X-ray diffraction and FT-IR spectroscopy.