Uranium biosorption by Lemna sp. and Pistia stratiotes.

Biosorption-based technologies have been proposed for the removal of radionuclides from radioactive liquid waste containing organic compounds. Nevertheless, pytoremediation potential of uranium (U) by nonliving aquatic macrophytes Lemna sp. and Pistia stratiotes has not been previously addressed. In this study, uranium biosorption capacity by Pistia stratiotes and Lemna sp. was evaluated by equilibrium and kinetics experiments. The biomasses were added to synthetic and real waste solutions. The assays were tested in polypropylene vials containing 10 mL of uranium nitrate solution and 0.20 g of biomass. Solutions ranging from 0.25 to 84.03 mmol l-1 were employed for the assessment of uranium concentration in each macrophyte. The equilibrium time was 1 h for both macrophytes. Lemna sp. achieved the highest sorption capacity with the use of the synthetic solution, which was 0.68 mmol g-1 for the macrophyte. Since Lemna sp. exhibit a much higher adsorption capacity, only this biomass was exposed to the actual waste solution, being able to adsorb 9.24 × 10-3 mmol g-1 U (total). The results show that these materials are potentially applicable to the treatment of liquid radioactive waste.