Bipolar membrane electrodialysis (BMED) is considered a state-of-the-art technology for the conversion of salts into acids and bases. However, the low concentration of base generated from a traditional BMED process may limit the viability of this technology for a large-scale application. Herein, we report an especially designed multistage-batch (two/three-stage-batch) BMED process to increase the base concentration by adjusting different volume ratios in the acid (V_acid), base (V_base), and salt compartments (V_salt). The findings indicated that performance of the two-stage-batch with a volume ratio of V_acid: V_base: V_salt = 1:1:5 was superior in comparison to the three-stage-batch with a volume ratio of V_acid: V_base: V_salt = 1:1:2. Besides, the base concentration could be further increased by exchanging the acid produced in the acid compartment with fresh water in the second stage-batch process. With the two-stage-batch BMED, the maximum concentration of the base can be obtained up to 3.40 mol · L⁻¹, which was higher than the most reported base production by BMED. The low energy consumption and high current efficiency further authenticate that the designed process is reliable, cost-effective, and more productive to convert saline water into valuable industrial commodities.

双极膜电渗析 (BMED) 被认为是将盐转化为酸和碱的最先进技术。然而，传统 BMED 工艺产生的低浓度碱可能会限制该技术在大规模应用中的可行性。在此，我们报告了一种特别设计的多阶段批次（两阶段/三阶段批次）BMED 工艺，通过调整酸（V_酸）、碱（V_碱）和盐室（V）中的不同体积比来增加碱浓度_盐）。结果表明，体积比为V_酸：V_碱：V的两阶段批次的性能与体积比为V_酸：V_碱：V_盐= 1:1:2的三阶段批次相比，_盐= 1:1:5 更好。此外，可以通过在第二阶段间歇过程中用新鲜水交换酸室中产生的酸来进一步提高碱浓度。使用两段式 BMED，碱的最大浓度可达 3.40 mol · L ^-1，高于 BMED 报道的最多的碱产量。低能耗和高电流效率进一步证明了设计的过程可靠、具有成本效益，并且在将盐水转化为有价值的工业商品方面效率更高。