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Masahito Uchikoshi, Determination of the Distribution of Ferric Chloro Complexes in Hydrochloric Acid Solutions at 298 K, Bulletin of the Chemical Society of Japan, Volume 92, Issue 12, December 2019, Pages 1928–1934, https://doi.org/10.1246/bcsj.20190195
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Abstract
Understanding the intrinsic nature of materials requires ultrahigh-purity materials because impurities affect various properties. Ion-exchange separation is one of the most promising purification technologies; however, the thermodynamic details of the ion-exchange reaction have not been made clear. The condition of metal species in the solution phase is fundamental to investigating the ion-exchange reaction. In this paper, the distribution of ferric chloro complexes in hydrochloric acid solutions was investigated by factor analysis of UV-Vis absorption spectra, followed by fitting analysis of a theoretical model to individual molar attenuation coefficients obtained by mathematical decomposition of UV-Vis absorption spectra. Five ferric species were detected by principal component analysis using a novel index proposed in this paper. In the results of factor analysis followed by fitting analysis, [FeIII]3+, [FeIIICl]2+, [FeIIICl2]+, [FeIIICl3]0, and [FeIIICl4]− were identified. The activity coefficients of charged species in concentrated aqueous solutions were estimated by using a modified Debye-Hückel equation. The thermodynamic parameters of the four cumulative formation constants and a Setchénow coefficient for neutral species of [FeIIICl3]0 were determined. The adsorbability of ferric, cupric, and cobalt species to an anion exchanger from hydrochloric acid solutions was qualitatively discussed using the results obtained in this paper.
