Ion flotation of copper(II)-, mercury(II)-, silver(I)-, zinc (II)-and cadmium(II)-thiosulfate complexes

Ion flotation of Cu(II), Hg(II), Ag(I), Zn(II) and Cd(II) in sodium thiosulfate solutions with cetylpyridinium chloride (CPC) was investigated. A 20 ml aliquot of (0.15.0)×10-2M sodium thiosulfate solution (pH 4.15.5) containing (3.854.22)×10-4M of an abovementioned metal ion and (1.673.34)×10-3M of CPC. was subjected to flotation in a 2.7 cm i.d.×20 cm cell for about 10 min with nitrogen bubbles. The metals were floated from the respective metal solutions in 96100% yield. Separation of Cu(II) from Co(II) and Ni(II) were achieved fairly well in 1.0×10-2M thiosulfate solutions with 2.5×10-3M CPC. The analysis of the relations between the mean number of the ligand S2O32- per each metal and the concentration of thiosulfate by means of the molar ratio method suggested the existence of species such as M(S2O3)22-, M(S2O3)34- and M(S2O3)46- for Cu(II) and Hg(II), MS2O3-, M(S2O3)23- and M(S2O3)25- for Ag(I) in (0.16.0) ×10-2 M thiosulfate solutions (pH 5.5). This flotation method was successfully applied during pretreatment to the determination of Ag(I) and Cd(II) in a photo-processing waste solution by using 100 ml of the solution diluted 12.5 times, and of Zn(II) in the guaranteed reagent of magnesium nitrate by using 500 ml of the solution containing 5 g of the sample, and 4.0×10-3 M of thiosulfate in a cell (6.6 cm i.d. ×40 cm), respectively.