Efficient removal of heavy metals from aqueous solutions using ion flotation technique

Abstract

In this study, the removal of cadmium, copper, and chromium via ion flotation technique from aqueous solutions was investigated with the addition of Sodium Dodecyl Sulfate (SDS) as a collector. The critical micelle concentration of SDS was initially determined. Ion flotation tests were conducted on both mono-metal solutions, each containing a single metal, and a multi-metal solution with a mixture of the three metals. The results demonstrated a more effective recovery in mono-metal solutions, achieving over 95 % removal for cadmium, 93 % for copper, and only 55 % for chromium. In contrast, the multi-metal solution showed reduced efficiency, with 80 % removal for cadmium, 78 % for copper, and 40 % for chromium. To better understand the interactions involved, Isothermal Titration Calorimetry measurements on the Metal-SDS complexes were performed, highlighting the lower removal rate of chromium. Additionally, SEM/EDS analyses were conducted to further elucidate these interactions. Furthermore, an NMR study focusing on the 113Cd isotope was carried out, potentially for the first time, to provide additional insights into the molecular dynamics associated with the ion flotation process. Therefore, SDS stands out as an effective agent for the removal of copper and cadmium from aqueous solutions, but it may not be the ideal choice for chromium abatement.