Azolla Caroliniana AS URANIUM AND THORIUM BIOACCUMULATING MATERIAL

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-* M n+ (* M n+ = UO 2 2+ , Th 4+) system was studied versus contact time, pH and anion nature with no ionic competition. The effective UO + 2 2 and Th 4+ ions removal from low radioactive 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 o C and 2⋅10-3 M UO 2 (CH 3 COO) 2 solution as uranium source; as result, the maximum of K d 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 o C and 10-3 M Th(NO 3) 4 solution as thorium source; the maximum of K d is about 900 mL/g, for the same ratio V/M.