Preparation of Pyroaurite-Like Compounds with Ion-Memory Effect for Nitrate Ion

Abstract

Pyroaurite-like compounds in the systems of Mg, Fe-NO₃ and Mg, Fe-SO₄ have been prepared under the hydrothermal condition and their Cl-derivatives have been also obtained by the ion exchange of these pyroaurite-like compounds with Cl- ion in saturated NaCl solution. The ion exchange characteristics of these Cl-derivatives for NO₃^- or SO₄^2- ion which was included in the interlayer space of the original pyroaurite-like compounds are compared with those of a pyroaurite-like compound in the system of Mg, Fe-Cl. The ion exchange reactions with NO₃^-are exothermic and the reaction heat for the Cl-derivative of NO₃^--form is larger than that for the Cl-form. The Cl-derivative of NO₃^--form has exhibited high selectivity for NO₃- ion and is possessed of the ion memory effect. On the other hand, the ion exchange reactions with SO₄^2- are endothermic and the exchaved ratios are rather low.