Sorption of plutonium from low level liquid waste using nano MnO2

Nano-crystalline MnO2 has been synthesized by the method of alcoholic hydrolysis of KMnO4 and its potential as a sorbent for plutonium present in the low level liquid waste (LLW) solutions was investigated. The kinetic studies on the sorption of Pu by MnO2 reveal the attainment of equilibrium sorption in 15 h, however 90 % of sorption could be achieved within an hour. In the studies on optimization of the solution conditions for sorption, it was observed that the sorption increases with the pH of the aqueous solution, attains the maximum value of 100 % at pH = 3 and remains constant thereafter. The sorption was found to be nearly independent of the ionic strength (0.01-1.0 M) of the aqueous solutions maintained using NaClO4, indicating the inner sphere complexation between the Pu4+ ions and the surface sites on MnO2. Interference studies with different fission products, viz., Cs+, Sr2+ and Nd3+, revealed decrease in the percentage sorption with increasing pH of the suspension indicating the competition between the metal ions. However, at the metal ion concentrations prevalent in the low level liquid waste solutions, the decrease in the Pu sorption was only marginally decreased to 90 % at pH = 3, the decrease being more in the case of Nd3+ than that in the case of Cs+. This study, therefore, shows nano-crystalline MnO2 can be used as a sorbent for separation of Pu from LLW solutions.