Synergistic effects and mechanism of biosurfactant and carbonic anhydrase on CO2 geosequestration in saline aquifer

： The excessive emission of carbon dioxide (CO 2 ) caused global warming and alarmed the world. Saline aquifers are widely considered as the most valuable storage sites for realizing globally significant levels of CO 2 capture and storage. Microbes will participate and promote CO 2 mineral trapping, as improve the stability and safety of CO 2 geological sequestration in the deep saline aquifers. In our study, Pseudomonas aeruginosa (Rha-T strain) was identified by 16S rDNA gene sequencing, which produced biosurfactant and effectively reduced the interfacial tension of bacterial liquid, and the hydrophobic group of biosurfactant was identified as palmitic acid. Various parameters (temperature, pH, salinity) were evaluated and affirmed that Rha-T strain and Bacillus licheniformis (a-CA strain) can maintain good activity under a wide range of conditions. The bicarbonate (HCO 3 - ) concentration in saline aquifers significantly increased comparing with other conditions when Rha-T and a-CA strain were mixed with a volume ratio of 100 mL: 200 mL. In saline aquifers system treated with Rha-T strain and a-CA strain, the pH values were stably maintained with pH 4.5 and 5.5-5.8 for 30 days, respectively, however, Ca 2+ and Mg 2+ concentration exhibited a downward trend with the extension of treatment time. Molecular dynamics simulations were used to authenticate that biosurfactant can effectively reduce the interfacial tension and alter the gas-liquid mass transfer coefficient and the two-phase interface area to effectively increase CO 2 dissolution. This study presents a comprehensive strategy to the synergy of microbial biosurfactant and microbial enzymes to improve CO 2 geological sequestration in saline aquifers, offering a sustainable and efficient approach for CO 2 capture and storage.