Sorption of caesium by complex hexacyanoferrates iv. ion exchange kinetics and mechanism of sorption by potassium copper ferrocyanide

The kinetics of caesium sorption by potassium copper ferrocyanide have been studied. Liquid film diffusion is rate controlling in very dilute solutions of caesium (3.8 × 10 −6 m). The average film diffusion coefficient was found to be 1.465 × 10 −9 m 2 s −1 at 20°C and the activation energy for the corresponding process was found to be 15.14 kJ mol −1 . Chemical reaction rate controls the caesium‐potassium ion exchange process at a higher caesium concentration of 3.8 × 10 −3 m. The shell progressive reaction model was found applicable to the sorption process. The activation energy for the caesium‐potassium ion exchange reaction was measured to be 74.85 kJ mol −1 . Finally, a comparison between the theoretical and the experimental sorption profile has been made to demonstrate the validity of the theory.