Radiotracer technique in adsorption study—XIII. Adsorption of barium and strontium ions on chromium(IV) oxide powder

The applicability of chromium(IV) oxide for efficient removal of barium and strontium ions from aqueous solutions by adsorption has been investigated. Lower concentrations of Ba2+, Sr2+ solutions with higher pH and temperature were found to be favourable conditions for adsorption of Ba(II) and Sr(II) on chromium(IV) oxide. The kinetics of adsorption of Ba(II) and Sr(II) follows essentially a first-order rate law with bulk ion concentration and obeys the Freundlich isotherm in the entire range of metal ion concentration (10−2–10−7 M). The uptake process was found to be endothermic and irreversible in nature. Equilibrium adsorption values at different temperatures have been utilized to evaluate change in standard thermodynamic quantities (viz ΔH0, ΔG0 and ΔS0). The adsorption of Ba(II) and Sr(II) ions were not significantly affected by the exposure of chromium(IV) oxide adsorbent to neutrons and γ-radiations from a (Ra---Be) neutron source having an integral neutron flux of 3.85 × 106 neutron/cm2/s and associated with nominal γ-dose of ca 172 rad/h.