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 medi a. 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 Ag2CrO4 or Ag2Cr2O7 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 mos t 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 s urfactant and analyte concentrations, foreign ions and temperature have bee n examined. The application of these procedures to recover the analytes add ed 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 sugges ted as a useful tool for speciation studies. Moreover, the flotation mechan ism is proposed.