Flotation Method for Selective Separation of Silver, Cadmium, Chromium, Manganese, Thallium, and Zinc from Aragonite Before Atomic Absorption Spectrometric Determination

Abstract

Selective separation of impurities contained in aragonite (CaCO₃) before their determination by atomic absorption spectrometry (AAS) was performed by the method of flotation. At proper selected pH, Ag, Cd, Cr, Mn, Tl, and Zn present in an aqueous solution of aragonite, unless Ca, were incorporated in the mass of the collector mixture consisting of hydrated iron(III) oxide, Fe₂O₃·xH₂O, and iron(III) hexamethylenedithiocarbamate, Fe(HMDTC)₃. By addition of surfactant, the collector precipitate was separated from liquid phase by air bubbles. After dissolving, the analytes were tested by, atomic absorption spectrometry (AAS). To ascertain optimal concentration of aragonite solution suitable for flotation, preliminary tests were performed. Flotation suppression because of the reaction among calcium and surfactant ions was very possible, and therefore, the most appropriate foaming reagent was selected. The detection limit of AAS method following flotation was found to be 0.024 μg g⁻¹ for Ag, 0.019 μg g⁻¹ for Cd, 0.016 μg g⁻¹ for Cr, and 0.117 μg g⁻¹ for Tl, determined by electrothermal atomic absorption spectrometry (ETAAS), and 1.596 μg g⁻¹ for Mn and 0.792 μg g⁻¹ for Zn, determined by flame AAS.

Keywords:

• Aragonite
• Trace elements
• Silver
• Cadmium
• Chromium
• Manganese
• Thallium
• Zinc flotation
• Atomic absorption spectrometry

Acknowledgments