Acid/Base Production via Bipolar Membrane Electrodialysis: Brine Feed Streams to Reduce Fresh Water Consumption

Abstract

The increasing demand for environmentally friendly production of alkaline and acidic materials has boosted the advancement of electrodialysis with bipolar membranes (EDBM) as an efficient and sustainable technology. In this context, this study aims to optimize the EDBM system performance and minimize its environmental impact. Specifically, this work focuses on the use of concentrated brines in alkaline or acid channels as innovative EDBM schemes to reduce freshwater consumption. Two different commercial monopolar and bipolar membrane sets were tested (Fumatech and SUEZ) showing a difference in productivity ratios, between them, ranging from 9% to 40%. The use of brine in the compartments leads to a reduction in the water footprint and highlights potential pathways to enhance the overall EDBM system sustainability. Remarkably, introducing a brine in the alkaline channels does not affect energy performance while achieving 50% reduction in freshwater consumption. In contrast, feeding brine into acid channels leads to a performance decline. This research provides a holistic perspective on the interplay between technical and environmental performance of EDBM process, providing a valuable guide for future research and paving the way for novel membranes, long-term stability, and strategies to minimize energy consumption and environmental impact, toward sustainable industrial practices.

Electrochemical Coproduction of Hydrogen, Oxygen, Sodium Hydroxide, and Hydrochloric Acid from Brines via Direct Electrosynthesis with Chlorine Suppression

“…These performances of Pt are competitive with those reported in recent studies of BMED systems. However, the relatively higher energy consumption of HCl (6.1–35.9 kWh/kg HCl ) compared to reported studies may be attributed to the back diffusion of protons, resulting in lower yields of HCl. , With the MnMo/Ti anode, the DE system demonstrates the lowest normalized energy consumption of 3.6 kWh/kg NaOH compared to the CEM (4.2 kWh/kg NaOH ) and AEM (5.3 kWh/kg NaOH ) systems. These results highlight the importance of developing novel anode materials with energy consumption considerations for application in a DE system.…”

“…The influence of Pt and MnMo/Ti anode electrodes on brine electrolysis was investigated in all systems. Compared to the BMED system, which utilized multiple membranes, including one or more bipolar membranes that prevent the formation of chlorine gas in the anode, the DE system uses only cation and anion exchange membranes, resulting in a more simplified configuration that avoids the use of bipolar membrane(s) (Figure a). , However, DE systems usually generate Cl 2 gas along with O 2 gas at the anode (reaction ). The corrosivity and toxicity of Cl 2 gas make it challenging to develop and scale up DE systems.…”