Extraction and separation of cadmium and zinc with a mixture of di-(2-ethylhexyl)-dithiophosphoric acid and trioctyl amine

The extraction of cadmium and zinc with di-(2-ethylhexyl)-dithiophosphoric acid(D(2)EHDTPA)-toluene and D(2)EHDTPA-trioctyl amine(TOA)-toluene has been investigated. Infrared spectrum analysis, the nuclear magnetic resonance spectrum(NMR) analysis and conductivity measurements confirm that the probable structures of the extracted complexes are CdA(2) and ZnA(2). Cadmium can be extracted by D(2)EHDTPA. very easily. Almost all the cadmium can be extracted, but stripping of cadmium from the organic phase is very difficult. When a mixture of D(2)EWDTPA and TOA is used, selective extraction of cadmium from zinc sulfate solution can be achieved. Cadmium can be easily stripped from the organic phase.