The kinetic features of solvent and solid-phase extraction of yttrium and iron (III) from simulated and industrial phosphoric acid solutions are revealed. Di-2-ethylhexylphosphoric acid (D2EHPA) was used as a liquid extractant, and D2EHPA-containing Levextrel resin—a co-polymerization product of styrene and divinylbenzene in the presence of D2EHPA—was used as a solid-phase extraction agent. Significant dependence of yttrium extraction rate constant on the stirring rate was revealed using the formal first-order kinetic equation. The data obtained characterizes a diffusion-limited process with an activation energy of 16.2 ± 1.3 kJ/mol. Temperature increase during the iron (III) extraction process leads to a changeover of a rate-limiting stage from kinetic to diffusion, accompanied by drop of activation energy from 40.0 ± 1.4 to 11.4 ± 1.2 kJ/mol. Effective separation of elements at the extraction stage is possible at temperatures of 283–300 K under non-equilibrium conditions of the ferric ions transport from aqueous to organic phase. This condition ensures a high yttrium–iron separation coefficient of 23.2 in 1.5–2 min. Extraction kinetics by Levextrel resin are described by Fick’s second law equation, which establishes the laws of diffusion in the solid grain of the organic phase with an activation energy of 18.5 ± 2.0 kJ/mol.

中文翻译：

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二-2-乙基己基磷酸对溶剂的固相萃取动力学研究

揭示了溶剂和从模拟和工业磷酸溶液中固相萃取钇和铁（III）的动力学特征。将二-2-乙基己基磷酸（D2EHPA）用作液体萃取剂，并将包含D2EHPA的Levextrel树脂（在D2EHPA存在下，苯乙烯与二乙烯基苯的共聚产物）用作固相萃取剂。使用形式一阶动力学方程揭示了钇提取速率常数对搅拌速率的显着依赖性。获得的数据表征了具有16.2±1.3 kJ / mol的活化能的扩散受限过程。铁（III）萃取过程中的温度升高导致限速阶段从动力学转变为扩散，同时活化能从40.0±1.4降低至11.4±1.2 kJ / mol。在铁离子从水相到有机相的非平衡条件下，萃取阶段在283–300 K的温度下可以有效分离元素。这种情况可确保在1.5–2分钟内达到23.2的高的钇铁分离系数。Levextrel树脂的萃取动力学由Fick的第二定律方程描述，该方程建立了活化能为18.5±2.0 kJ / mol的有机相固体颗粒中的扩散定律。