A sustainable bipolar membrane electrodialysis process for effective conversion of CO2 and NaCl brine into NaHCO3.

Abstract

Climate change demands innovative carbon capture and utilization (CCU) strategies, yet converting captured CO₂ into high-value products while managing industrial waste remains elusive. Here, we demonstrate a single-step, energy-efficient bipolar membrane electrodialysis (BMED) system integrated with CCU, enabling the simultaneous conversion of NaCl brine and CO₂ into high-purity sodium bicarbonate (NaHCO₃) with unprecedented efficiency, but without requiring external alkali sources or energy-intensive thermal regeneration steps. By optimizing key parameters - such as current density and CO₂ aeration rate, and gas-liquid flow ratios - we achieved a bicarbonate concentration of 1.186 mol/L in the alkaline chamber, coupled with 57.65% carbon sequestration efficiency and an energy consumption as low as 3.1 kW·h/m³ CO₂ (or 716.9 kW·h/t NaHCO₃). This approach not only recovers valuable sodium resources from brine but also enhances CO₂ absorption through electrochemical mechanisms, potentially reducing global carbon emissions by up to 20% in brine-intensive industries. Our work paves the way for scalable, sustainable CCUS technologies, transforming waste streams into economic assets and advancing the fight against climate change.