The use of aqueous thiocyanate solutions in liquid-liquid extraction and reversed-phase extraction chromatography. I

Abstract

Ten ions have been chromatographed on thin layers of cellulose impregnated with Aliquat 336, Alamine 336 S, Amberlite LA-1 or Primene JM-T, and on non-impregnated cellulose. Solutions of 0.3–7 M thiocyanate acidified with 0.01–1.0 N hydrochloric acid are used as eluents. R F spectra and a number of separations are reported. Percentage extraction versus NCS − molarity data and results of maximum-loading and spectroscopic measurements for the systems liquid anion exchangerCo(II)NCS − and liquid anion exchangerNi(II)NCS − are also reported. The sorption strength/extraction efficiency of the exchangers increases in the order Primene < Amberlite < Alamine < Aliquat. Increasing the acidity of the aqueous phase generally decreases the sorption/extraction of the complex metal—thiocyanato anions to a considerable extent. Sorption proceeds through anion exchange for all ions investigated. The Co(II)-containing species extracted into the organic phase is (R 3R′NH +) 2Co(NCS) 4 2− (R, alkyl; R′, alkyl or H). Nickel is present in the organic phase predominantly as Ni(NCS) 6 4−; however, depending upon the diluent used, Ni(NCS) 4 2− may also be present.