Ion exchangers in radioactive waste management. Part XI. Removal of barium and strontium ions from aqueous solutions by hydrous ferric oxide.

The uptake of Ba(II) and Sr(II) by hydrous ferric oxide (HFO) was studied as a function of contact time, concentration, temperature and pH of the respective adsorptive solutions employing the 'radiotracer technique'. The uptake of both the ions was found to increase with the increase in concentration, temperature and pH of the adsorptive solutions. Concentration dependence data fitted well to the Freundlich adsorption isotherm over the entire range of concentration (10(-2)-10(-7) M) and the uptake process followed first-order rate kinetics. The desorption experiments demonstrate the irreversible nature of the uptake process, however, in the presence of H+ ions, i.e. on acidification, an appreciable amount of metal ions were removed in the bulk solution. The radiation stability of hydrous ferric oxide towards the uptake of Ba(II) and Sr(II) was also examined by using samples of hydrous ferric oxide irradiated by neutrons and gamma-rays prior to be employing as sorbents. The presence of some mono- and divalent co-ions along with the studied ions suppressed their removal appreciably.