Distribution of nitric acid between water and amberlite LA-1 liquid anion exchanger

Abstract

The solute-solvent interaction between Amberlite LA-1, a long-chain secondary amine extractant dissolved in carbon tetrachloride or benzene and aqueous nitric acid solution up to ∼ 16 M has been investigated by physical and chemical measurements. The first reaction is an acid-base equilibrium leading to the formation of amine nitrate. The quilibrium constants were evaluated as K 1 = 3·8 × 10 5 and 5·4 × 10 5 in carbon tetrachloride and benzene respectively. The second and third reactions postulated involve amine nitrate and associated nitric acid molecules, leading to the formation of a molecular addition compound identified as R 2HNHNO 3·HNO 3 and to the physical partition of associated nitric acid between the aqueous and organic phases. The equilibrium concentration product quotients have the values K 2 = 1·85 for carbon tetrachloride and K 2 = 2·24 for benzene, and the distribution constant has the value K d = 0·1±0·02 for 1 M amine solution in both diluents. The effects of the formation of the amine nitrate aggregates or of the extracted molecular addition compound, or both, are not taken into account. Evidence was obtained that the aggregation of the species in the organic phase is largely a post-equilibrium phenomenon.