Azolla caroliniana as uranium and thorium bioaccumulating material

Rodica Calmoi1, Marian Raileanu1, Ioan Caraus2, Alexandru Cecal1, Karin Popa1

1 Al. I. Cuza University, Department of Inorganic Chemistry, 11 Carol I Bd., 700506 Iasi, Romania
2 University of Bacau, Department of Biology, 157 Calea Marasesti, 600115 Bacau, Romania

Abstract


The possibility of bioaccumulation of uranium and thorium species in the blue-green algae Azolla caroliniana Willd. was investigated. The behavior of the Azolla caroliniana *Mn+ (*Mn+ = UO22+, Th4+) system was studied versus contact time, pH and anion 2+nature with no ionic competition. The effective UO and Th4+ ions removal from low 2radioactive waste waters was demonstrated. The analysis of the data revealed the following optimum working conditions: for uranium: contact time 20 hours, pH = 6.0, t = 28 oC and 2 10-3M UO2(CH3COO)2 solution as uranium source; as result, the maximum of Kd is obtained for a value of nearly 600 mL/g, and a ratio V/M=100 mL/g; for thorium: contact time 30 hours, pH = 5.5, t = 26 oC and 10-3M Th(NO3)4 solution as thorium source; the maximum of Kd is about 900 mL/g, for the same ratio V/M.

Keywords


Azolla caroliniana Willd.; bioaccumulation; thorium; uranium

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