Cs and Sr exchange reactions for Na on sedimentary, hydrothermal and synthe
tic phillipsites are studied by determining their exchange isotherms at 25
degrees C and 0.1 total normality, and computing the related thermodynamic
quantities K-a, and Delta G degrees. Sedimentary and synthetic phillipsite,
characterized by a higher Si/Al ratio, display good selectivity for Cs and
moderate selectivity for Sr. The more aluminous hydrothermal phillipsite d
isplays a lower selectivity for Cs and a higher selectivity for Sr than sed
imentary and synthetic phillipsite do. These results, perfectly explainable
in terms of held strength of the anionic zeolite framework and of ion char
ge density, demonstrate that the joint removal of Cs and Sr from water by p
hillipsite would be possible, provided cheap widespread aluminous phillipsi
te-rich materials were available. (C) 1999 Elsevier Science B.V. All rights
reserved.