Ion exchange in the synthetic gismondine, zeolite MAP

Abstract

Ion exchange has been studied in zeolite MAP, a synthetic gismondine used as a commercial detergent builder. The zeolite was fully characterized and shown to be a stable phase throughout the three year period of study. The ions pairs examined were; Na ↔ Li,K,Rb,Cs and Na ↔ ½ Mg,Ca,Sr,Ba. All cation forms prepared were examined by powder X-ray diffraction (PXRD), magic-angle spinning (MAS) NMR and thermal analysis. When cation exchanges were shown to be reversible their isotherms were analysed to produce thermodynamic data. The values were then compared with literature values obtained for similar zeolite exchanges. Structural data (PXRD, MASNMR) showed that cation exchange often caused changes in unit cell symmetry as well as the creation of immiscible phases rich in the end-members when calcium and strontium were the in-going cations.