Phosphate and fluoride removal using calcined anionic clays: a simple and efficient water treatment process

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Alexandra Jakob*, Guillaume Darracq, Christel Carême, Anastasiya Silina, Arthur Perraud

The removal of toxic anions is of paramount importance to ensure the provision of high quality drinking water. Electrostatic adsorption mechanisms pose a challenge as most of the negatively-charged natural clays show limited affinity for anions. In order to address this issue, the feasibility of  positively-charged clays as adsorbents for phosphate and fluoride in water treatment applications was tested. A comparison of  the adsorption performances of synthetic calcined layered double hydroxides (LDHs) is presented in this study. The minerals were at first characterized by XRD in order to highlight their mineralogical purity. Subsequently, the adsorption kinetics and isotherm experiments were carried out to evaluate both phosphate and fluoride adsorption performances. It has been found out that the removal of phosphate was very efficient with calcined ZnAlCO3 LDH, with an adsorption capacity up to 860 mg/g. A discussion on the adsorption mechanisms is presented and an outlook on the selection of adsorbent for industrial applications is shown, underlining the practical relevance of the findings in the context of water treatment.

Keywords: layered double hydroxide, water treatment, phosphate removal, fluoride removal

Proscience vol. 9

Pp 19-24

DOI: 10.14644/EC2023.004