Electrochemical methods are promising for treating high-salt wastewater. However, their reliance on expensive membranes increases operational costs and introduces membrane-related challenges. To address this, our laboratory has developed a preparative vertical free-flow electrophoresis (PVFE) technique using cost-effective quartz sands instead of expensive membranes. This innovative technique has effectively produced acids and bases from industrial high-salt wastewater. However, a comprehensive understanding of the underlying mechanisms and mass transfer is essential to enhancing the design and performance of the developed PVFE. Herein, the effects of voltage, flow rate, and feed concentration on ion migration in PVFE were systematically examined, providing detailed insights into its driving mechanisms. Results revealed that quartz sand packing effectively suppresses ion diffusion while ensuring a proper ion orientation during electromigration and convection. Additionally, both simulation and empirical models validate the mass-transfer mechanisms and quantify the effect of key operational parameters on the ion transfer capacity. Economic analysis further highlights that PVFE operates within the limiting current, achieving ∼100% current efficiency at low operating costs (5.94 yuan/kg for base and 6.87 yuan/kg for acid). This study provides a comprehensive understanding of mass-transfer mechanisms in PVFE and offers valuable guidance for optimizing its practical application in high-salt wastewater recycling.

中文翻译：

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石英砂介导的离子定向电迁移在制备型垂直自由流动电泳中用于高盐废水回收

电化学方法在处理高盐废水方面很有前途。然而，他们对昂贵膜的依赖增加了运营成本，并带来了与膜相关的挑战。为了解决这个问题，我们的实验室开发了一种制备型垂直自由流动电泳 （PVFE） 技术，使用具有成本效益的石英砂代替昂贵的膜。这种创新技术有效地从工业高盐废水中生产酸和碱。然而，全面了解潜在机制和传质对于增强所开发的 PVFE 的设计和性能至关重要。本文系统地研究了电压、流速和进料浓度对 PVFE 中离子迁移的影响，从而详细介绍了其驱动机制。结果表明，石英砂堆积有效抑制了离子扩散，同时确保了电迁移和对流过程中正确的离子取向。此外，仿真和经验模型都验证了传质机制，并量化了关键作参数对离子转移能力的影响。经济分析进一步强调，PVFE 在极限电流内运行，以较低的运营成本（碱 5.94 元/公斤，酸 6.87 元/公斤）实现 ∼100% 的电流效率。本研究全面了解了 PVFE 中的传质机制，为优化其在高盐废水回收中的实际应用提供了有价值的指导。