STUDY ON UNUSUALSORPTION OF URANIUM ONTO BIOTITE

• Project/Area Number: 10680491
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Nuclear engineering
• Research Institution: KYUSHU UNIVERSITY
• Principal Investigator: IDEMITSU Kazuya KYUSHU UNIVERSITY, Graduated School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (10221079)
• Co-Investigator(Kenkyū-buntansha): 出光 一哉 九州大学, 大学院・工学研究科, 助教授 (10221079)
• Project Period (FY): 1998 – 1999
• Project Status: Completed (Fiscal Year 1999)
• Budget Amount: ¥3,700,000 (Direct Cost: ¥3,700,000); Fiscal Year 1999: ¥1,400,000 (Direct Cost: ¥1,400,000); Fiscal Year 1998: ¥2,300,000 (Direct Cost: ¥2,300,000)
• Keywords: Uranium / Biotite / Unusual Sorption / Acidity Constant / pH dependence / Desorption / Specific Area / PZC / PH依存性 / ウラン化学種

Research Abstract

Experiments on the sorption of U(VI) on a biotite were carried out in the atmospheres of air and 1 atm of COィイD22ィエD2 over a wide range of pH to understand the fundamental controls on uranium sorption on biotite minerals. Biotite powder (mesh 32 - 60) were washed with 1N HCl for a week and were rinsed twice with deionized water for a week. This HCl treatment was necessary to avoid the effects by other minerals. The uranium solutions were prepared from ィイD2233ィエD2UOィイD22ィエD2 regent by dissolving into nitric acid and then adjusted at a pH of interest with the initial concentration of 4.8 x 10ィイD1-6ィエD1 M. The concentration of uranium and pH in each solution were measured at regular time intervals before and after adding some biotite powder. The peak Kd values in air and COィイD22ィエD2 were higher than 100 ml/g around pH 6 and approximately 2 ml/g around pH 5, respectively. A comparison of aqueous uranium speciations and sorption results indicates that neutral uranyl hydroxide could be an important species sorbed on the biotite in both atmospheres. Sequential desorption experiments with KCl and nitric acid solutions were also carried out after sorption experiments to investigate sorption forms of uranium. Several percent of uranium in solution was sorbed on the biotite as an exchangeable ion with potassium. The fraction of exchangeable uranium had a little dependence on pH. Approximately 50% of uranium sorbed on the biotite was extracted by 1N of nitric acid. The other uranium could not be extracted even by 1N HNOィイD23ィエD2 solution. It is possible that most of the uranium could be reduced from U(VI) to U(IV) via Fe(II) on the biotite surface after sorption.

Research Products

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