The Extraction of Divalent Manganese, Cobalt, Copper, Zinc, and Cadmium from Hydrochloric Acid Solutions by Tri-n-octylamine

The distribution of divalent manganese, cobalt, copper, zinc, and cadmium between hydrochloric acid solutions and solutions of tri-n-octylamine (TOA, R3N) in benzene has been investigated under different conditions. It is found that the extraction of these divalent metals by TOA proceeds as MCl2(aq) + 2R3NHCl(org) ⇄ (R3NH)2MCl4(org). The electronic, electron spin resonance, and infrared spectral results indicate that all the complexes formed in the organic phases are in a tetrahedral arrangement. Further, the stability constants of the aqueous chloro complexes of divalent manganese, cobalt, copper, and zinc are determined on the basis of the equilibrium equation.