Flotation-separation of the pollutant species of chromium, cadmium and lead from aqueous solutions and natural waters

Simple, rapid and accurate procedures have been presented for removing the pollutant species of chromium, cadmium and lead from different aqueous media. To achieve this goal, precipitate flotation was the method of choice for this investigation using oleic acid (HOL) as a surfactant. Cr(III) as its hydroxide and Cr(VI) as Ag sub 2 CrO sub 4 or Ag sub 2 Cr sub 2 O sub 7 are removed in the pH ranges 6.2-6.8 and 6.0-7.5, respectively. 2,4,6-Tri(2-pyridyl)-1,3,5-triazine (TPTA), in the presence of KI, and chloranilic acid (CAA) are found to be the most effective complexing agents for the flotation of trace amounts of Cd(II) and Pb(II) over the pH ranges 6-7.5 and 4-7, respectively. The effects of surfactant and analyte concentrations, foreign ions and temperature have been examined. The application of these procedures to recover the analytes added to natural water samples has been investigated. Since the system Cr(VI)/Cr(III) is toxic, it occurs in industrial effluents and some natural waters, a procedure for the selective separation of Cr(VI) from Cr(III) is suggested as a useful tool for speciation studies. Moreover, the flotation mechanism is proposed.