Separation of Lower Molecular Weight Iron (III) by an Extraction Method with 8-Quinolinol and the Form of Iron (III) Ions on the Hydrolysis Reaction

Abstract

An improved extraction method with 8-quinolinol has been studied on the determination of lower molecular weight iron(III) ions in aqueous solution in the presence of higher molecular weight iron(III) ions. The extractable iron(III) species were considered to be the monomerk species. The monomeric species {lower molecular weight iron(III) ions) were also confirmed by UV spectroscopy and ultrafiltration (Diafio Membrane UM). The rate of hydrolysis of iron(III) ions was measured by the improved extraction method. The reaction rate is of the second order, and the Arrhenius plots of the rate constants vs. temperature gave a straight line. The Arrhenius activation energy (ΔE≒), activation freeenergy (ΔG298°K≠) and activation entropy (ΔS≠) are 39.5 kcal/mol, 16.4kcal/mol and 73 e. u. ([Fe3+] : (1.4±0.1) × lO-4mol/i, pH : 3.40±0.05) respectively. © 1975, The Chemical Society of Japan. All rights reserved.