LIQUID-LIQUID-EXTRACTION OF ZIRCONIUM FROM HAFNIUM AND OTHER ELEMENTS WITH DICYCLOHEXYL-18-CROWN-6

Zirconium was quantitatively extracted with 2.5 x 10(-2) M dicyclohexyl-18-crown-6 in dichloromethane from 8.5 M hydrochloric acid. It was stripped with 0.5 M hydrochloric acid and was determined spectrophotometrically as its complex with Arsenazo III. Hafnium was not extracted under these conditions, but from the residual aqueous phase it was extracted with 7.0 x 10(-2) M dicyclohexyl-18-crown-6 in dichloromethane from 9.0 M hydrochloric acid. It was stripped with 0.1 M perchloric acid and determined spectrophotometrically at 540 nm as its complex with xylenol orange. The separation of zirconium and hafnium from other metals is also described

SEPARATION OF NIOBIUM FROM CHLORIDE MEDIA BY SOLVENT-EXTRACTION WITH DICYCLOHEXYL-18-CROWN-6

Niobium was quantitatively extracted from 7-10 mol dm-3 hydrochloric acid with 2.0 x 10(-2) mol dm-3 dicyclohexyl-18-crown-6 in dichloromethane. The metal was stripped from the organic phase with 0.1 mol dm-3 sulphuric acid and determined spectrophotometrically at 540 nm as its complex with 4-(2-thiazolylazo)resorcinol. This method permits the sequential separation of niobium from vanadium, tantalum, zirconium, hafnium and iron

SEPARATION OF SCANDIUM USING LIQUID-LIQUID-EXTRACTION WITH MACROCYCLIC POLYETHER(S) FROM PICRATE MEDIA

Scandium was quantitatively extracted at pH 2.5-4.5 with 4.0x10(-2) mol dm-3 18-crown-6 in dichloromethane from 4.0x10(-2) mol dm-3 solution of picric acid. It was stripped with 0.1 mol dm-3 nitric acid and determined spectrophotometrically at 650 nm as its complex with Arsenazo-III. It was separated from yttrium, lanthanides, zirconium, hafnium, vanadium, niobium, and uranium in multicomponent mixtures. Scandium from rock sample was also analysed

SOLVENT-EXTRACTION SEPARATION OF COBALT(II) FROM NICKEL AND OTHER METALS WITH CYANEX-272

Cobalt(II) was quantitatively extracted at pH 8.0 with 5 x 10(-3)M Cyanex 272 [Bis(2,4,4 trimethyl pentyl) phosphoric acid] in chloroform. Cobalt(II) was stripped with 0.5M nitric acid and was determined by atomic absorption spectrometry as well as by spectrophotometry of the complex with nitroso R salt. Cobalt(II) was separated from vanadium, chromium, nickel, manganese, iron and zinc. Mixtures having different ratios of iron, cobalt and nickel were separated by proposed method