Sorption removal of anions and cations in single batch systems by uncalcined and calcined Mg-Al-CO3 hydrotalcite

In this study, the sorption removal of two anions (phosphates, thiocyanates) and three cations (cadmium, lead, nickel), in single batch systems, was investigated from aqueous solutions. The process involves the sorption of the ions by hydrotalcite, which is a double-layered mixed-metal hydroxide and belongs to the family of anionic clays. The sorbent used was Mg-Al-CO3 hydrotalcite in two forms: uncalcined and calcined at 500degreesC. The calcined material showed the higher sorption capacity, for all the ions, than the uncalcined. The approximate sorption capacity of calcined material was: phosphates 250 mg g(-1), thiocyanates 80 mg g(-1), nickel/lead 100 mg g(-1) and cadmium 70 mg g(-1). The kinetic results of the anions were fitted satisfactory with the Lagergren equation. Since the sorption capacity is relatively high, hydrotalcite can be considered as a potential material for sorption of both anions and cations in wastewater treatment systems.