Biosorptive behaviour of rice hulls for Cs-134 from aqueous solutions: a radiotracer study

Removal behaviour of rice hulls was assessed for the removal of Cs-134 from aqueous solutions. Results obtained from batch-type experiments revealed that relatively low uptake of Cs(I) was favoured with increasing the sorptive concentration (from 1 x 10(-8) to 1 x 10(-2) molL(-1)), temperature (298-328), and pH (2.40-10.20). The concentration dependence data fitted well for Freundlich adsorption isotherm. Thermodynamic parameters revealed that the uptake process was endothermic and proceeded via 'ion exchange' along with 'surface complexation'. Moreover, the adsorbed species were not to be desorbed into the bulk concentration even at elevated temperatures, i.e., up to 328 K hence forming a stable adsorption phase. Further, the radiation stability of the rice hulls samples was also assessed by exposing it towards 300 mCi neutron source having the neutron flux of ca. 3.85 x 10(6) ncm(-2)s(-1) associated with nominal gamma-dose of ca. 1.72 Gyh(-1) and indeed it was observed that the rice hulls samples were found to be stable at least for the removal of Cs-134.