Ion-Exchange Properties of the Natural Zeolite Amicite

Abstract

Crystals of the natural zeolite amicite, ideally Kx4Nax4(Alx8Six8Ox32)·10Hx2O, were ion-exchanged in the reactions with 0.1 N aqueous solutions of AgNOx3, RbNOx3, CsNOx3 and Pb(NOx3)x2 at 363 K for 24 h. Under these conditions, Csx+ substitutes Kx+ whereas the most part of Nax+ remains unexchanged; Rbx+ partly substitutes both Nax+ and Kx+; Pbx2+ and Agx+ completely substitute Nax+ and Kx+. All the compounds are monoclinic. The Cs- and Rb-substituted samples have unit-cell parameters close to those of initial amici-te. The exchange of Nax+ and Kx+ for Agx+ is accompanied by a significant decrease of the unit-cell volume. The unit-cell parameter c of Pb-amicite is nearly threefold larger than the c parameter of initial amicite. Infrared spectra show that framework topology is preserved during the ion exchange. The crystal struc-tures of initial and Cs-exchanged amicites have been solved by direct methods.