Nuclear Engineering Program, Department of Civil and Environmental Engineering, University of Utah, 110 Central Campus Dr. Rm 2000, Salt Lake City, UT 84112, United States.
Nuclear Engineering Program, Department of Civil and Environmental Engineering, University of Utah, 110 Central Campus Dr. Rm 2000, Salt Lake City, UT 84112, United States; Department of Mechanical Engineering, University of Nevada Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154, United States.
J Chromatogr A. 2024 Sep 13;1732:465211. doi: 10.1016/j.chroma.2024.465211. Epub 2024 Jul 25.
Two commercially available extraction chromatography (EXC) resins containing N,N,N',N'-tetra-n-octyldiglycolamide (DGA Resin, Normal, 50 - 100 μm) and Bis(2-ethylhexyl) phosphate (LN Resin, 100 - 150 μm) were used as adsorbents to study fundamental adsorption properties such as thermodynamic values, equilibrium isotherms, and kinetic uptake models for terbium(III) adsorption. Weight distribution ratios (D) for terbium on DGA and LN resins were measured using a [Tb]Tbradiometric tracer in nitric acid as a function of acidity, temperature, initial analyte concentration, and equilibrium time. The D values showed increasing binding affinity for DGA resin at high nitric acid concentrations and decreasing binding affinity for LN resins. Thermodynamic studies for DGA and LN resins revealed that the Gibbs free energy (ΔG) increased consistently with temperature. To model equilibrium data, increasingly higher parameter equilibrium isotherm models (Henry (1) < Langmuir, Freundlich (2) < Redlich-Peterson (3) < Fritz-Schluender (4)) were compared on their root mean squared errors (RMSE) and adjusted determination coefficients to determine the most applicable model. In all cases, the empirical four-parameter Fritz-Schluender isotherm demonstrated a superior fit. Similar comparisons for reaction-based kinetic models (Pseudo-first-order < Pseudo-second-order < Pseudo-n-order) revealed that the higher-order PNO model yielded a superior fit of kinetic data for both resins. However, in some cases, adsorption isotherms and kinetic models could also be modeled by a lower-order model with minimal change in error parameters. Weber-Morris plots revealed that two linear sections are observed for each resin, where the first linear segment is attributed to fast (film diffusion) adsorption of terbium, followed by slower intraparticle diffusion of terbium through the pores as the rate-limiting step. Based on the Weber-Morris plot, both film and intraparticle diffusion are involved in controlling the kinetic rate of adsorption for DGA and LN resins.
两种市售的萃取色谱（EXC）树脂，一种含有 N,N,N',N'-四正辛基二甘酰胺（DGA 树脂，粒径 50-100μm），另一种含有双（2-乙基己基）磷酸（LN 树脂，粒径 100-150μm），被用作吸附剂，以研究铽（III）吸附的基本吸附特性，如热力学值、平衡等温线和动力学吸附模型。在硝酸中，使用[Tb]Tbradiometric 示踪剂作为函数，测量了 DGA 和 LN 树脂对铽的重量分布比（D），其取决于酸度、温度、初始分析物浓度和平衡时间。D 值表明，在高硝酸浓度下，DGA 树脂的结合亲和力增加，而 LN 树脂的结合亲和力降低。DGA 和 LN 树脂的热力学研究表明，吉布斯自由能（ΔG）随着温度的升高而持续增加。为了对平衡数据进行建模，越来越多的参数平衡等温线模型（亨利（1）<朗缪尔，弗伦德利希（2）<雷德利希-彼得森（3）<弗里茨-施伦德（4））在其均方根误差（RMSE）和调整后的决定系数方面进行了比较，以确定最适用的模型。在所有情况下，经验的四参数弗里茨-施伦德等温线都表现出更好的拟合。对基于反应的动力学模型（伪一级<伪二级<伪 n 级）的类似比较表明，对于两种树脂，较高阶的 PNO 模型对动力学数据的拟合更好。然而，在某些情况下，吸附等温线和动力学模型也可以通过误差参数变化最小的低阶模型进行建模。Weber-Morris 图显示，对于每种树脂，都观察到两个线性段，其中第一个线性段归因于铽的快速（膜扩散）吸附，然后是铽通过孔的较慢的内扩散，作为速率限制步骤。基于 Weber-Morris 图，DGA 和 LN 树脂的吸附动力学速率受到膜扩散和内扩散的共同控制。
