Coprecipitation of microamounts of radionuclides on chitosans of various molecular weights in solutions

• Published in: Radiochemistry (New York, N.Y.) Vol. 51; no. 5; pp. 484 - 489
• Main Authors: Veleshko, I. E., Veleshko, A. N., Kulyukhin, S. A., Kislova, I. A., Il’ina, A. V., Lopatin, S. A.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01.10.2009
• Subjects: Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Nuclear Chemistry; 81.20.Fw; 28.41.Kw
• ISSN: 1066-3622; 1608-3288
• DOI: 10.1134/S1066362209050087

Coprecipitation of 233 U, 239 Pu, 241 Am, 152 Eu, 90 Sr, 90 Y, and 60 Co on chitosans of various molecular weights (MW) was studied. Low-molecular-weight chitosan (LMWC) with MW of 5 kDa (5 × 10 3 g mol −1 ) proved to be a more effective coprecipitant than high-molecular-weight chitosan (HMWC) with MW of 700 kDa (7 × 10 5 g mol −1 ). With HMWC, the degree of coprecipitation (α) was 80% for 152 Eu and 90 Y, 99% for 233 U and 241 Am, and 85% for 239 Pu. For 60 Co, α monotonically increased with an increase in the chitosan concentration in solution and reached 40% at [HMWC] = 5 g l −1 . For 90 Sr, α did not exceed 3% in the entire examined range of chitosan concentrations. With LMWC, the α values for An, 152 Eu, and 90 Y differed insignificantly (92–99%). For 60 Co and 90 Sr, α increased to 40% in the range of chitosan concentrations from 0 to 1 g l −1 . The presence of inorganic salts in solution considerably decreases α of UO 2 2+ with chitosans but does not noticeably affect the behavior of Am, Pu, and Eu. The effect of salts on the efficiency of 233 UO 2/2+ coprecipitation on HMWC decreases in the order Na 2 SO 4 > NaCl > Na 2 CO 3 > NaNO 3 > Na 3 PO 4 . Based on the results obtained, a procedure suitable for expedition conditions was developed for preconcentration of Pu from seawater on chitosan, with simultaneous separation of Pu from U, for radioecological monitoring of natural waters. The specific activity of Pu in samples of near-bottom seawater of gulfs of the Novaya Zemlya archipelago was (150–170) ± 20 mBq m −3 . The results are well consistent with the published data.