Sorption isotherms for the ternary system Cs-Sr-Co using 'Nonscents,'
a zeolitized volcanic tuff material from southeast Arizona, as sorbent
were measured with a columnar flow technique. The isotherms were corr
elated with an ion-exchange phase-equilibrium model, and the triangle
rule of ion exchange has been validated. Sorbent-phase selectivity for
the ternary system has been successfully predicted from a knowledge o
f the selectivity of constituent binary pairs. The study helps in the
understanding of multisolute sorption behavior during host rock-ground
water interactions relevant to a high-level nuclear waste repository.