Biosorptive behavior of mango (Mangifera indica) and neem (Azadirachta indica) barks for 134Cs from aqueous solutions. A radiotracer study

The role of dead biomasses viz., mango (Mangifera indica) and neem (Azadirachta indica) bark samples are assessed in the removal behavior of, one of important fission fragments, Cs(I) from aqueous solutions employing a radiotracer technique. The batch type studies were carried out to obtain various physico-chemical data. It is to be noted that the increase in sorptive concentration (from 1.0 x 10-8 to 1.0 x 10-2 mol x dm-3), temperature (from 298 to 328 K) and pH (2.6 to 10.3) apparently favor the uptake of Cs(I) by these two bark samples. The concentration dependence data obeyed Freundlich adsorption isotherm and the uptake follows first order rate law. Thermodynamic data evaluation and desorption experiments reveal the adsorption to be irreversible and endothermic in nature proceeding through ion-exchange and surface complexation for both dead biomasses. Both bark samples showed a fairly good radiation stability in respect of adsorption uptake of Cs(I) when irradiated with a 300 mCi (Ra- Be) neutron source having an integral neutron flux of ∼ 3.85 x 106 n x cm-2 x s-1 and associated with a nominal γ-dose of ∼ 1.72 Gy x h-1. (author)