Understanding the sorption behavior of Pu⁴⁺ on poly(amidoamine) dendrimer functionalized carbon nanotube. Sorption equilibrium, mechanism, kinetics, radiolytic stability, and back-extraction studies

Poly(amidoamine) dendrimer functionalized carbon nanotube was demonstrated as highly efficient sorbent of the Pu⁴⁺ from radioactive waste solution. The second generation dendrimer was found to have more efficiency as compared to the 1^st generation might be due to the availability of more functionality for coordinating to the Pu⁴⁺ ion. Analysis of different isotherm models revealed that, Langmuir isotherm was predominantly operating through chemi-sorption (with the sorption energy 10.07 and 16.95 kJ mol^-1 for 1^st and 2^nd generation dendrimer) with the sorption capacity 89.22 mg g^-1 and 92.48 mg g^-1 for 1^st and 2^nd generation dendrimer, respectively. Analysis of different sorption kinetics model revealed that the sorption proceeded via pseudo 2^nd order reaction. The 2^nd generation dendrimer was found to be radiolytically more stable while oxalic acid was found to be suitable for quantitative back extraction of Pu⁴⁺.