T267 Advances in Spectroscopy for Geological and Mineralogical Analysis

Wednesday, 7 November 2012
1:30 PM - 5:30 PM
208B

MULTI-STEP ION EXCHANGE OF RARE EARTH ELEMENTS INTO MICROPOROUS ZORITE

Paper number: T267-6
Program: Technical Sessions
Time: 2:45 PM – 3:00 PM

Authors

Abstract

The relatively rare, microporous hydrated titanosilicate mineral zorite has industrial applications as a highly selective ion exchanger, gas separator, and selective catalyst of organic compounds. We investigate the crystallographic and spectroscopic changes in zorite that occur during rare earth element ion exchange.

We used both static single crystal X-ray diffraction and time-resolved Raman spectroscopy to determine absolute structural geometry and transient structural/molecular conformational changes, respectively. Ion exchange studies were conducted from both the starting sodium form (zorite-Na) and the modified hydrogen form (zorite-H). Zorite was synthetically prepared in the lab and exhibits a structure similar to ETS-4 (Engelhard Titanium Silicate #4).

Results of time-resolved Raman spectroscopy indicate multiple ion exchange steps as yttrium, europium, gadolinium and terbium exchange into the porous framework. The overall exchange dynamics were significantly different for each REE cation tested. In addition, extent and rate of exchange also depended on the form of the starting material (zorite-Na vs. zorite-H).