A large-scale reverse electrodialysis (RED) system consists of several hundred cell pairs, resulting in a stack voltage of tens of volts at the ends of the electrodes. Under this high voltage condition, water reduction/oxidation inevitably occurs despite the presence of redox couples, which means that a continuous supply of redox couples is required for long-term operation due to their instability under sudden changes in pH around the electrodes. On the other hand, water electrolysis can be used as an electrode reaction in natural seawater, without chemical reagents. However, inorganic precipitation by hydroxide ions produced in the water reduction reaction is a persistent problem that hampers cathode operation in seawater, because the deposits decrease the electrochemically active surface area of the cathode and hinder ionic flow across the ion exchange membranes. It has recently been demonstrated that seawater acidifies to pH 3 via a cooperative effect between proton flux from a bipolar membrane and inorganic precipitation at the cathode interface. In this study, seawater acidification was applied to the RED system to completely suppress dispersed inorganic deposits, enabling the stable operation of large-scale RED stacks without clogging problems. This result opens the possibility of developing an environmentally friendly RED system that does not use any chemical reagents.

中文翻译：

---

通过海水酸化完全抑制反向电渗析中分散的无机沉淀物

大型反向电渗析 (RED) 系统由数百对电池组成，在电极末端产生数十伏的电池堆电压。在这种高压条件下，尽管存在氧化还原电对，但不可避免地会发生水的还原/氧化，这意味着由于电极周围 pH 值突然变化下的不稳定，氧化还原电对需要持续供应才能长期运行。另一方面，水电解可作为天然海水中的电极反应，无需化学试剂。然而，水还原反应中产生的氢氧根离子引起的无机沉淀是阻碍阴极在海水中运行的一个长期问题，因为沉积物减少了阴极的电化学活性表面积并阻碍了离子流过离子交换膜。最近已经证明，通过双极膜的质子通量和阴极界面处的无机沉淀之间的协同作用，海水酸化至 pH 值 3。在这项研究中，将海水酸化应用于 RED 系统，以完全抑制分散的无机沉积物，使大型 RED 烟囱稳定运行而不会出现堵塞问题。这一结果开启了开发不使用任何化学试剂的环保 RED 系统的可能性。最近已经证明，通过双极膜的质子通量和阴极界面处的无机沉淀之间的协同作用，海水酸化至 pH 值 3。在这项研究中，将海水酸化应用于 RED 系统，以完全抑制分散的无机沉积物，使大型 RED 烟囱稳定运行而不会出现堵塞问题。这一结果开启了开发不使用任何化学试剂的环保 RED 系统的可能性。最近已经证明，通过双极膜的质子通量和阴极界面处的无机沉淀之间的协同作用，海水酸化至 pH 值 3。在这项研究中，将海水酸化应用于 RED 系统，以完全抑制分散的无机沉积物，使大型 RED 烟囱稳定运行而不会出现堵塞问题。这一结果开启了开发不使用任何化学试剂的环保 RED 系统的可能性。