Liquid-Liquid Extraction Behavior of Inorganic and Organic Anions with Color-Changeable Neutral Extractants

Abstract

Color-changeable extractants for acids, acidophores, were synthesized and examined; they were 4-(N, N dimethylaminophenylazo)-pyridines and quinolines. The fundamental physicochemical constants for the acidophores and their ion associates were determined by spectrophotometry. The liquid-liquid distribution was carried out between an aqueous phase and a chloroform phase. A parameter of the extractability of the protonated cations of the acidophores and of several inorganic and organic anions as ion associates was determined on the basis of the assumption that the extraction constant of an ion association complex, log K_ex, is divided into a cationic and an anionic contributions, C and A, respectively. The order of the extractability of the anions was: Br^-<I^-<ClO₄^-<SCN^- <Pic^-<(Ethyl range)^-<C₁₂H₂₅-OSO₃^-. Anionic surfactants could be quantitatively extracted into chloroform with 4-(4-N, N-dimethylaminophenylazo)-2-methylquinoline: the molar absorptivity was 4.5×10⁴l mol^-1 cm^-1 at 560nm. The acidophores once used could be recycled and be used repeatedly.