Potassium cobalt hexacyanoferrate (KCoFC) had high sorption capacity for Rb.
Rb was selectively sorbed by KCoFC in the presence of other alkali metals.
Langmuir sorption capacity was higher for Rb than Cs.
K release from KCoFC lattice was highest for Rb sorption among the alkali metals.
Intra-particle diffusion and lattice K release controlled Rb sorption kinetics.