二氧化钍纳米球在碳酸铀酰铵溶液中对铀的吸附性能

doi:10.11944/j.issn.1000-0518.2017.10.170149

摘要/Abstract

摘要：

二氧化钍(ThO₂)是一种锕系金属氧化物,作为吸附剂是其重要的应用方向之一,但其应用范围还较为有限,有待进一步拓宽。我们研究了水热法合成的多晶ThO₂纳米球在碳酸铀酰铵((NH₄)₄[UO₂(CO₃)₃])溶液中对铀的吸附性能。结果表明,在含有2 mmol/L NH₄HCO₃和20 mmol/L三羟甲基氨基甲烷-HCl的(NH₄)₄[UO₂(CO₃)₃]溶液(pH=8.45)中,ThO₂纳米球对铀的吸附符合准二级动力学吸附模型,在初始铀浓度为20 mg/L时,ThO₂纳米球对铀的吸附容量可以达到6.52 mg/g;ThO₂纳米球对铀的等温吸附符合Freundlich模型。吸附铀后的ThO₂纳米球可通过低浓度的盐酸进行高效洗脱。机理研究表明,在此实验条件下,ThO₂纳米球带负电荷,通过阳离子吸附机理吸附UO22+,容易受到Ca²⁺、Cu²⁺和Ni²⁺等阳离子的竞争而出现吸附容量下降的情况。本文的研究工作对金属氧化物从弱碱性及中性放射性废液和海水中提取铀具有参考价值。

关键词: ThO₂, 铀, 吸附, 碳酸铀酰铵

Abstract:

Thorium dioxide(ThO₂), a kind of actinide metal oxides, has good performance as adsorbent, but it is necessary to extend their application scope. In the present work, we investigated the adsorption property of ThO₂ nanospheres prepared by hydrothermal method in the aqueous solution of ammonium uranyl tricarbonate. In the presence of 2 mmol/L NH₄HCO₃ and 20 mmol/L tris(hydroxymethyl)aminomethane)-HCl, ThO₂ nanospheres had an adsorption capacity of 6.52 mg/g when the initial concentration of uranium was 20 mg/L, which followed pseudo-second-order kinetic model well. In isothermal adsorption studies, Freundlich model was preferable. The desorption of ThO₂ nanospheres after adsorption was achieved easily by using dilute HCl solution. In the mechanism research, it was found that ThO₂ nanospheres have negative charges under the experiment conditions and adsorb UO22+ via cation adsorption mechanism. However, the uranium uptake was seriously affected by other cations, such as Ca²⁺, Cu²⁺ and Ni²⁺. This work will contribute to the recovery of uranium from seawater and alkaline/neutral radioactive waste by metal oxides.

Key words: thorium dioxide, uranium, adsorption, ammonium uranyl tricarbonate

刘小冬, 陈庆德, 沈兴海. 二氧化钍纳米球在碳酸铀酰铵溶液中对铀的吸附性能[J]. 应用化学, 2017, 34(10): 1177-1185.

LIU Xiaodong, CHEN Qingde, SHEN Xinghai. Adsorption Performance of Thorium Dioxide Nanospheres Towards Uranium in the Aqueous Solution of Ammonium Uranyl Tricarbonate[J]. Chinese Journal of Applied Chemistry, 2017, 34(10): 1177-1185.

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