Explication of Water Splitting Mechanism and Fundamental Research of Materials and Systems Designs in Bipolar Membranes

双极膜是一层状结构，包括一个阳离子选择膜连接到一个阴离子选择膜。水的分裂必须伴随着在阴离子层和正离子层的交界面引起的水解离成氢离子和氢氧根离子，以及离子通过带电层的连续扩散。研究一种新的酸和碱的商业化生产方法具有实际意义。在恒定直流偏置电压下对双极膜的阻抗进行了测量，结果表明，反偏置电压下双极膜的电导率和电容量表现出与其他电压和膜条件下完全不同的特性。用等效电路分析的阻抗结果暗示了中间层的比电导率和介电常数的降低。测定了双极膜/LiCl +醇体系的电流电压特性，并与LiCl +水体系进行了比较。本研究考察了甲醇、乙醇、1-丙醇、乙二醇和丙二醇，并以氯化锂为电解质。电流-电压曲线表明，甲醇体系在阴离子交换层和阳离子交换层之间的界面上也发生了阳离子和阴离子的解离。在LiCl +甲醇体系中对阴离子交换层侧的产物进行了分析，证明了甲醇锂的生成。此外，还讨论了其他LiCl +醇体系与LiCl +甲醇体系的电流-电压特性的差异以及水作为杂质的影响。

The bipolar membrane is a layered structure involving a cation selective membrane joined to an anion selective one. Water splitting has to be accompanied with water dissociation into hydrogen and hydroxide ions caused in the boundary surface between anion and cation layers and successive ion diffusion through charged layers. It is of practical interest in a new process for the commercial production of acid and base. As a result of the impedance measurements of the bipolar membranes under the constant d.c. biased voltages, it was observed that the electric conductivity and the electric capacity under reverse-biased voltage showed quite different behavior from all the other applied voltage and membrane conditions. The reduction in both the specific electric conductivity and the dielectric constant of the intermediate layer was implied by the impedance results that were analyzed using equivalent circuits.The current-voltage characteristics of bipolar membrane/LiCl + alcohol systems were measured and compared with those of the LiCl + water system. In this study, methanol, ethanol, 1-propanol, ethylene glycol and propylene glycol were examined and lithium chloride was employed as an electrolyte. The current-voltage curves suggested that the dissociation into the cation and the anion had occurred also in the methanol system in the interface between the anion exchange and cation exchange layers. The product in the anion exchange layer side was analyzed in the LiCl + methanol system to prove the generation of lithium methoxide. In addition, the difference in the current-voltage characteristics in the other LiCl + alcohol systems to be compared with the LiCl + methanol system and the effect of water as an impurity were discussed.