Defluoridation by calcined layered double hydroxides synthesized from seawater

This work used calcined layered double hydroxides synthesized from seawater (ldhsw) in order to take advantage of its adsorption properties,especially in trapping fluoride anions as we aim to remove them from polluted water. in order to determine the experimental conditions suitable for removing the fluoride anions the influences of many parameters on the adsorption process were examined such as calcination temperature,time of contact,ph of aqueous solution,the dosage of adsorbent,charge density as well as the competition between the sulphate,nitrate and chloride anions. the results show that the adsorption of the fluoride by calcined ldhsw was very fast,the removal of the fluoride was almost complete. for one hour of contact time and a ph between 6 and 7 at room temperature,the removal rate was 99.2 %. for the co-existing anions,it seems that the nitrate anions do not have a significant impact on the defluoridation. however,the defluoridation rate constant decreases in presence of the chloride and the sulphate anions.