Sodium, Rubidium and Cesium Ions Adsorption by Prussian Blue (PB)

摘要

The adsorption of alkali metal ions onto prepared Prussian blue (PB) was investigated in single-element solutions. The released quantities of K~+ constitutive of PB were measured in course of adsorption time. Acidification occurred in these solutions because of decrease in pH values after adsorption. The PB was examined by Energy dispersive spectroscopy (EDS) technique. The results showed that the equilibrium adsorption capacities was in the sequence Cs~+ > Rb~+ > Na~+. The mechanisms for the adsorption of Na~+, Rb~+ and Cs~+ onto PB were deduced comprehensively as ion exchange with K~+ and trapping through H~+. The selectivity sequence was Rb~+ > Cs~+ ≥ Na~+ for ion exchange with K~+ because of the ionic radius of Rb~+ similar to that of K~+. The adsorption mechanism was dependent of ion trapping through H~+ leading to the sequence of Cs~+ > Rb~+ > Na~+ owing to the size of their hydrated radius.