The role of residual Na+ and Li+ on the thermal transformation of Ba-exchanged zeolite A

This work intends to critically review the data concerning the variations of reactivity of Ba-exchanged zeolite A precursor with Na+ and Li+ content originally present in the zeolite framework. The main results were the following: a) obtaining a fully monoclinic celsian from Ba-exchanged zeolite A bearing Na+ residual content ranging between 0.20 and 0.74 meq/g required a 5–22 h thermal treatment at 1300 °C; b) obtaining a fully monoclinic celsian from Ba-exchanged zeolite A bearing the not further reducible Na+ residual content (about 0.20 meq/g) and Li+ contents ranging from 0.11 to 0.37 meq/g required a 4–10 h thermal treatment at 1000–1100 °C. New insight into the mechanism through which Na+ and Li+ develop their mineralizing action on the thermal transformation of Ba-exchanged zeolite A was attained.

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