Synergistic flotation of U(VI)–alizarin complex with some diamines followed by spectrophotometric determination of U(VI) using 4,4′-diaminophenylmethane

In this work, synergistic flotation of U(VI)–alizarin complex at the presence of some diamine compounds was firstly investigated by the spectrophotometric method. The flotation process was carried out on aliquots of 100 ml of U(VI) solutions containing alizarin and the diamine at pH of 5.00 using n-heptane. The floated layer was then dissolved in acetonitrile and its absorbance was measured. Since the synergistic effect of 4,4′-diaminophenylmethane (dapm) was much more than the others, it was used for the determination of U(VI) by this method. Beer's law was obeyed ( λ max = 591 nm) in the range of 5 × 10 −7 to 1 × 10 −5 mol l −1 with the apparent molar absorptivity of 1.12 × 10 6 l mol −1 cm −1, and a correlation coefficient of 0.9991. The detection limit ( n = 7) was 1 × 10 −7 mol l −1, and the R.S.D. ( n = 7) obtained for 4 × 10 −6 mol l −1 of U(VI) was 2.23%. Except that only a few analogous cations, which could be masked by EDTA, no interference was observed at the presence of various conventional ions, even at high concentrations. The reliability and applicability of the method were confirmed using some geological standard reference materials and spiked synthetic water samples, respectively.