Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16801, United States.
Water Desalination and Reuse Center, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia.
Environ Sci Technol. 2024 Jun 25;58(25):10969-10978. doi: 10.1021/acs.est.4c02397. Epub 2024 Jun 11.
Affordable thin-film composite (TFC) membranes are a potential alternative to more expensive ion exchange membranes in saltwater electrolyzers used for hydrogen gas production. We used a solution-friction transport model to study how the induced potential gradient controls ion transport across the polyamide (PA) active layer and support layers of TFC membranes during electrolysis. The set of parameters was simplified by assigning the same size-related partition and friction coefficients for all salt ions through the membrane active layer. The model was fit to experimental ion transport data from saltwater electrolysis with 600 mM electrolytes at a current density of 10 mA cm. When the electrolyte concentration and current density were increased, the transport of major charge carriers was successfully predicted by the model. Ion transport calculated using the model only minimally changed when the negative active layer charge density was varied from 0 to 600 mM, indicating active layer charge was not largely responsible for controlling ion crossover during electrolysis. Based on model simulations, a sharp pH gradient was predicted to occur within the supporting layer of the membrane. These results can help guide membrane design and operation conditions in water electrolyzers using TFC membranes.
经济实惠的薄膜复合（TFC）膜是一种有潜力的替代品，可以替代用于氢气生产的咸水电解器中更昂贵的离子交换膜。我们使用溶液摩擦输运模型来研究感应电势梯度如何在电解析过程中控制穿过 TFC 膜的聚酰胺（PA）活性层和支撑层的离子传输。通过在膜活性层中为所有盐离子分配相同的与尺寸相关的分配和摩擦系数，简化了参数集。该模型拟合了在电流密度为 10 mA cm 的条件下，使用 600 mM 电解质进行咸水电解的实验离子传输数据。当电解质浓度和电流密度增加时，该模型成功预测了主要载流子的传输。当负活性层电荷密度从 0 变化到 600 mM 时，使用该模型计算的离子传输仅略有变化，这表明活性层电荷在电解析过程中对控制离子穿越的作用不大。基于模型模拟，预计在膜的支撑层内会出现尖锐的 pH 梯度。这些结果可以帮助指导使用 TFC 膜的水电解器中的膜设计和操作条件。
