Study on liquid-solid flotation separation of lead (II) by sodium nitrate-ammonium thiocyanate-rhodamine 6G system

The liquid-solid flotation separation behaviour of Pb2+ in sodium nitrate-ammonium thiocyanate-rhodamine 6G (Rh6G) system and the conditions for the separation of Pb2+ were studied. The results showed that with the amount of 0.5 mL of the solution of 0.1 mol/L NH4SCN and 1.0 mL of the solution of 1.0 × 10-3 mol/L Rh6G, the ternary association complex of NH4SCN-Rh6G-Pb floated above the salt-water and formed liquid-solid phase with clear interface in presence of 1.0 g NaNO3. In this condition, Zn2+, Mn2+, Co2+, Ni2+, Al3+, Fe2+ could not be floated and Pb2+ could be floated quantitatively. This method has been used for the flotation separation of trace Pb2+ in synthetic water samples, and the flotation yield of lead is 93.6%-108.7%.