LIQUID-LIQUID-EXTRACTION OF TUNGSTEN BY DIISODODECYLAMINE

The liquid-liquid extraction of tungsten (VI) by diisododecylamine (DI DA) from sulfuric-acid solutions at pH 2 is studied by the equilibrium -shift, isomolar-series, saturation, and IR-spectroscopic methods. Tol uene and kerosine are used as the solvents of DIDA, DIDA extracts tung sten (VI) from sulfate media analogously to the well-known extractant tri-n-octylamine (TOA), by amine-exchange reaction with the formation of complex polyanions corresponding to a metal:DIDA ratio of 3:1 in th e organic phase. If the tungsten content in the initial solution is le ss than 0.05 M, a complex of 1:1 type is extracted. In comparison with TOA, DIDA is characterized by greater extraction of tungsten; the ext raction constant log K is 3.68 and 2.60 for DIDA and TOA, respectively , in comparable conditions. The effects observed are explained by ster ic factors and the weaker effect of the competing extraction of minera l acids in secondary amines than in tertiary amines.