School of Life Science and Agricultural Engineering, Nanyang Normal University, No. 1638 Wolong Road, Nanyang 473061, Henan Province, China.
School of Life Science and Agricultural Engineering, Nanyang Normal University, No. 1638 Wolong Road, Nanyang 473061, Henan Province, China.
J Chromatogr A. 2021 Jul 5;1648:462211. doi: 10.1016/j.chroma.2021.462211. Epub 2021 May 1.
The adsorption separation of L-tryptophan (L-Trp) by the weakly polar hyper-cross-linked resin XDA-200 was studied. First, the adsorption equilibria of different species of L-Trp on the resin were compared. Then, the adsorption isotherms and adsorption kinetics of L-Trp were studied at different pH values. Finally, the dynamic adsorption and separation processes of L-Trp in a packed bed of the resin were studied. The distribution coefficient of L-Trp between the resin and an aqueous solution of L-Trp (55.69) was found to be markedly larger than that of L-Trp (27.53) and L-Trp (10.42). An adsorption isotherm model depending on pH was established to simulate the adsorption equilibrium data of L-Trp. The cooperative adsorption of sodium ion (Na) with L-Trp cannot be ignored when the solution pH is higher than 8.0. Thus, a modified surface diffusion model considering cooperative adsorption of Na with L-Trp was established. The model fitted the kinetic curves for L-Trp adsorption under different pH values satisfactorily. The surface diffusion coefficient of L-Trp first decreased and then increased as pH increased from 3 to 12. In this study, a modified film-surface diffusion model considering cooperative adsorption of Na with L-Trp is proposed. Further, we show that our proposed model can predict the chromatographic peaks of L-Trp, L-glutamic acid (L-Glu), and Na satisfactorily.
本文研究了弱极性高交联树脂 XDA-200 对 L-色氨酸（L-Trp）的吸附分离性能。首先，比较了不同物种的 L-Trp 在树脂上的吸附平衡。然后，在不同 pH 值下研究了 L-Trp 的吸附等温线和吸附动力学。最后，研究了树脂填充床中 L-Trp 的动态吸附和分离过程。发现 L-Trp 在树脂和 L-Trp 水溶液（55.69）之间的分配系数明显大于 L-Trp（27.53）和 L-Trp（10.42）。建立了一个依赖 pH 的吸附等温线模型来模拟 L-Trp 的吸附平衡数据。当溶液 pH 值高于 8.0 时，不能忽略钠离子（Na）与 L-Trp 的协同吸附。因此，建立了一个考虑 Na 与 L-Trp 协同吸附的修正表面扩散模型。该模型很好地拟合了不同 pH 值下 L-Trp 吸附的动力学曲线。随着 pH 值从 3 增加到 12，L-Trp 的表面扩散系数先降低后升高。在这项研究中，提出了一个考虑 Na 与 L-Trp 协同吸附的修正膜-表面扩散模型。此外，我们还表明，我们提出的模型可以很好地预测 L-Trp、L-谷氨酸（L-Glu）和 Na 的色谱峰。
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