Formulation engineering of soybean-based green solvent enables highly efficient CO2 capture performance

Abstract

The soybean-based (SBB) solvent, derived from renewable feedstocks, exhibits significant potential for CO₂ chemisorption due to its sustainability, non-toxicity, biodegradability, and low regeneration energy consumption. However, the practical application of unrefined SBB at high concentrations is limited by its high content of low-reactive components (e.g., acidic and low-solubility amino acids). To address this limitation, we developed an isoelectric precipitation-based formulation engineering strategy to enhance the CO₂ capture performance of this absorbent. By selectively removing amino acids through pH-controlled precipitation, the concentration of active amino acids in the optimized solvent (SBB-M) increased by over 60 %, enabling its use at a refined and relatively high concentration (∼3 M). And the absorption capacity of the SBB-M solution has significantly increased by 16.6 times compared with that of the SBB solvent. Kinetic analysis revealed a reaction order of 1.68–1.8 and average activation energy of 24.7 kJ·mol⁻¹ for the CO₂ absorption into SBB-M aqueous solution, indicating efficient chemisorption ability. Remarkably, the regeneration energy of 3 M SBB-M was only 1.98 GJ·ton⁻¹ CO₂, approximately 48 % of that required for 5 M monoethanolamine (MEA), underscoring its energy-saving superiority. This formulation engineering of SBB represents a breakthrough in developing sustainable amino acid solvents for cost-effective and scalable carbon capture.