Industrial & Engineering Chemistry Research, Vol.57, No.31, 10292-10302, 2018
The Anion Effect on Zeolite Linde Type A to Sodalite Phase Transformation
This study reports on the effect of three different salts (Na2CO3, NaCl, and Na2SO4 ) on desilication product (DSP) precipitation in synthetic Bayer liquor. Na2SO4 had a distinct effect compared with both Na2CO3 and NaCl as only nosean-sodalite formed. With the addition of Na2SO4, both the templating effect of SO42- and subunit condensation processes appear to be involved. Na2CO3 promoted the transformation of zeolite Linde Type A (LTA) to sodalite, while NaCl did not have a significant effect on phase transformation compared with the control test. The unit cell size of zeolite LTA did not change as a function of time and anions present. The unit cell size of sodalite did significantly change as a function of salts added as follows: NaCl < control < Na2CO3 < Na2SO4. UV-Raman spectra exhibited signature peaks for sodalite with Na2CO3 and Na2SO4 which is useful since the differences in the XRD patterns for the same materials are subtle.