Isotopic exchange kinetics of zinc ions in Zn-A zeolite
- 1 January 1976
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 72, 1150-1156
- https://doi.org/10.1039/f19767201150
Abstract
The isotopic exchange kinetics of Zn2+ ions in hydrated Zn-A zeolite of composition Zn5·55Na0·90(AlO2)12(SiO2)12·aq, have been investigated by measuring the fractional attainment of isotopic equilibrium between a ZnCl2 solution and a 65Zn-labelled Zn-A zeolite (30 and 45 µm particle radii) as a function of time, in the temperature range 25–60°C. The exchange mechanism is a two-step process which has been resolved, using the Brown–Sherry–Krambeck model, into diffusion in the solid particles, with Zn2+ diffusivity of D= 10–3.97 ± 0.03 exp (–ED/RT)m2 s–1, ED= 67.1 ± 0.5 kJ mol–1, and an intracrystalline first-order exchange between bound and mobile Zn2+ ions in the network, with a rate constant of k2= 103.05 ± 0.25 exp(–Ek/RT)s–1, Ek= 56.5 ± 1.5 kJ mol–1.Keywords
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