Study of Anion Exchange Extraction of Some Anionic Complexes of Iron (Iii) by Organic Solutions of Quarterly Ammonium Salts

Abstract

The anion-exchange extraction of salicylate, thiosulphate and thiocyanate iron (III) complexes by solutions of chlorides of quaternary ammonium salts (QAS) in organic solvents (toluene, carbon tetrachloride, ethyl acetate, isobutyl alcohol, nitrobenzene) was studied. The composition of the iron (III) anionic complexes was established by the analysis of the calibration curves E = f(pCFe (III)) constructed from iron (III) solutions against the background of various contents of thiocyanate, thiosulphate and salicylate ions and the steepness of the electrode function. As an indicator electrode the ion-selective electrode was used with a membrane, which based on a nitrobenzene solution of tetradecylammonium bromide. The solution containing of alkyldimethylbenzylammonium chloride and alkyldimethylethylbenzylammonium chloride and the corresponding organic solvent were mixed in a ratio of 1:1. An organic layer containing the QAS was selected. The anion-exchange extraction was provided in contact with aqueoses solutions of Fe(III) anionic complexes. The extraction process is estimated quantitatively using a distribution coefficient (D). The value of D is calculated taking into account the iron (III) concentration in the aqueous phase before and after extraction. The content of iron (III) in solutions is determined spectrophotometrically (λ = 440 nm). It is established that the value of the distribution coefficient depends on the permittivity (ε) of the organic solvent. In the row toluene - carbon tetrachloride - ethyl acetate - isobutyl alcohol - nitrobenzene, the permittivity increases. In the same sequence, D increases for all studied complex iron(III) ions. Moreover, a decrease in the concentration of the extracted particle leads to an insignificant decrease in the value of the distribution coefficient. The composition and stability of the complex iron (III) ion have a significant effect on the extraction activity.