Liu Yueyu, Li Tingting, Guo Qing, Gao Lili, Yin Shaohua, Li Shiwei
Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China.
ACS Omega. 2024 Feb 27;9(10):12219-12227. doi: 10.1021/acsomega.4c00246. eCollection 2024 Mar 12.
A mass transfer model to predict the transport processes of magnesium and lithium ions through porous media in salt lakes has been proposed, which is a combination of the extended Nernst-Planck equation and Donnan effect, accounting for ion diffusion, electromigration, and convection within membrane pores. First, the morphological structure, thickness, surface roughness, and hydrophilicity of the membrane were characterized as fixed parameters, indicating that the surface of the nanofiltration membrane is smooth with low roughness and strong hydrophilicity, resulting in a lower desalination rate but higher water flux. Subsequently, numerical calculations based on the model were conducted to establish a reasonable transport equation for predicting the concentration and retention rate of the main magnesium and lithium ions. When compared with the experimental results, a deviation of less than 5.5% is obtained, confirming the accuracy of the model in describing ion mass transfer. Finally, computational fluid dynamics techniques were employed to simulate the model equations in both the feed and permeate subdomains, demonstrating that the flow characteristics align with reality. Thus, the established transport model exhibits higher predictive accuracy for NF ion separation than one-dimensional models.
提出了一种预测盐湖中镁离子和锂离子通过多孔介质传输过程的传质模型，该模型结合了扩展能斯特-普朗克方程和唐南效应，考虑了膜孔内的离子扩散、电迁移和对流。首先，将膜的形态结构、厚度、表面粗糙度和亲水性表征为固定参数，表明纳滤膜表面光滑，粗糙度低，亲水性强，导致脱盐率较低但水通量较高。随后，基于该模型进行了数值计算，建立了合理的传输方程，用于预测主要镁离子和锂离子的浓度和截留率。与实验结果相比，偏差小于5.5%，证实了该模型在描述离子传质方面的准确性。最后，采用计算流体动力学技术对进料和渗透子域中的模型方程进行了模拟，表明流动特性与实际情况相符。因此，所建立的传输模型在纳滤离子分离方面比一维模型具有更高的预测精度。
