Synthetic Inorganic Ion-exchange Materials. X. Preparation and Properties of So-called Antimonic(V) Acid

Abstract

The preparation of so-called antimonic acid under various experimental conditions has been investigated in order to establish its usefulness as a chemically-stable cation-exchange material. In this experiment, the antimonic acid was mainly obtained by the hydrolysis of antimony pentachloride, and was rarely obtained from metallic antimony or potassium pyroantimonate. The hydrolyzed precipitate was amorphous at first, but it was gradually transformed into crystalline powder by keeping it in the mother liquor for a long time. The crystallization of the amorphous precipitate was facilitated by raising the temperature within a range of 0–80°C, and by increasing the concentration of strong mineral acid on aging, regardless of the kinds of starting antimony substances. The water-content of the air-dried samples is decreased by increasing the period of aging; the composition of the sample approximates Sb2O5·4H2O. The crystal of the antimonic acid is cubic and belong to the space group Oh7(Fd3m), with a lattice constant of 10.382 Å. The measurement of solubilities for the air-dried antimonic acid showed that both the amorphous and the glassy acids are soluble forms and that the crystalline is an insoluble form. The uptakes of potassium ions on these antimonic acids were little changed on the kinds of form; the uptake of lithium ions on the crystalline acid was very small as compared those on the amorphous and the glassy acids. This behavior may be attributed to the existence of different types of so-called antimonic acid, with different selectivities of their lithium ion adsorption, rather than to any difference in the size of the particle.