Integration of biofuel extraction and biorefinery <scp>carbon dioxide</scp> capture for closed‐loop salt recycling to reduce carbon emission

Abstract Combining CO 2 capture with sustainable salt recovery in biofuel production is a promising strategy to address environmental and economic challenges in biorefinery. This study demonstrates a closed‐loop system that utilizes K 2 CO 3 as a bifunctional agent for both separation and purification of acetone–1‐butanol–ethanol (ABE) solution and CO 2 capture from biofuel fermentation. Salt reuse and CO 2 sequestration were achieved by reacting CO 2 with salted K 2 CO 3 ‐rich aqueous phase to form KHCO 3 . The experimental results showed that K 2 CO 3 could achieve efficient ABE separation (>99% recovery of 1‐butanol at 500 g/kg) and CO 2 utilization reached 88% under optimal conditions (stirring rate of 1100 r/min, gas flow rate of 40 mL/min). Salt recovery stabilized at 84%, which was limited by KHCO 3 solubility and ionic strength. This research provides a scalable blueprint for sustainable biofuel production by addressing the twin challenges of resource waste and carbon emissions.