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首页> 外文期刊>Journal of Microencapsulation: Microcapsules Liposomes Nanoparticles Microcells Microspheres >Synthesis and characterization of new biopolymeric microcapsules containing DEHPA-TOPG extractants for separation of uranium from phosphoric acid solutions
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Synthesis and characterization of new biopolymeric microcapsules containing DEHPA-TOPG extractants for separation of uranium from phosphoric acid solutions

机译：含有DEHPA-TOPG萃取剂的新型生物聚合物微胶囊的合成与表征，用于从磷酸溶液中分离铀

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摘要

A novel microcapsule adsorbent for separation of uranium from phosphoric acid solutions was developed by immobilizing the di(2-ethylhexyl) phosphoric acid-trioctyl phosphine oxide extractants in the polymeric matrix of calcium alginate. Physical characterization of the microcapsules was accomplished by scanning electron microscopy and thermogravimetric techniques. Equilibrium experiments revealed that both ion exchange and solvent extraction mechanisms were involved in the adsorption of UO_2~(2+) ions, but the latter prevailed in a wider range of acid concentration. According to the results of kinetics study, at low acidity level, the rate controlling step was slow chemical reaction of UO_2~(2+) ions with the microdroplets of extractant, whereas it changed to intraparticle diffusion at higher acid concentration. The study also attempted identification of the diffusion paths of the ions within the microcapsules, and the mechanism of change of mass transfer rate during the uptake process. The prepared microcapsules preserved their entire capacity after three cycles of adsorption, and their breakthrough behaviour was well fitted by a new formula derived from shrinking core model.
机译：通过将二（2-乙基己基）磷酸-三辛基氧化膦萃取剂固定在藻酸钙的聚合物基体中，开发了一种用于从磷酸溶液中分离铀的新型微胶囊吸附剂。通过扫描电子显微镜和热重技术完成了微囊的物理表征。平衡实验表明，离子交换和溶剂萃取机理均参与了UO_2〜（2+）离子的吸附，但后者在较宽的酸浓度范围内占优势。根据动力学研究的结果，在低酸度条件下，速率控制步骤是UO_2〜（2+）离子与萃取剂微滴的化学反应缓慢，而在较高酸浓度下变为颗粒内扩散。该研究还试图确定微胶囊中离子的扩散路径，以及吸收过程中传质速率变化的机制。制备的微胶囊经过三个吸附周期后仍能保持其全部容量，并且其突破性行为通过收缩核心模型得出的新公式得到了很好的拟合。

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