Dual adsorption behaviour of fluoride from drinking water on Ca-Zn(OH)2CO3 adsorbent

Fluoride is a toxic environmental contaminant. Long-term exposure to fluorine poses serious health hazards, therefore, its removal is an imperative and urgent need. The development of efficient adsorbents together with their adsorption mechanisms are of prime importance nowadays. Herein, we report an adsorbent, basic calcium zinc carbonate (BCZC), with high surface area (423 m2/g) and abundant hydroxyl and carbonate groups that demonstrated high potential for fluoride. The results indicated the maximum adsorption capacity of BCZC as 210 mg/g at pH 7. Particularly, the presence of other co-existing anions, for instance, Cl−, NO3−, SO42- and PO43- except CO32− negligibly affected the adsorption efficacy of adsorbent. Zeta potential studies described the existence of electrostatic interactions between BCZC surface charge and fluoride. Furthermore, both X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) observations confirmed the involvement of both hydroxyl and carbonate groups in fluoride adsorption. Thus BCZC adsorbent is reasonably priced and can be considered for practical water treatment applications.