Synergistic Assembly of Charged Oligomers and Amino Acids at the Air-Water Interface: An Avenue toward Surface-Directed CO2 Capture

Interfaces are considered a major bottleneck in the capture of CO2 from air. Efforts to design surfaces to enhance CO2 capture probabilities are challenging due to the remarkably poor understanding of chemistry and self-assembly taking place at these interfaces. Here, we leverage surface-specific vibrational spectroscopy, Langmuir trough techniques, and simulations to mechanistically elucidate how cationic oligomers can drive surface localization of amino acids (AAs) that serve as CO2 capture agents speeding up the apparent rate of absorption. We demonstrate how tuning these interfaces provides a means to facilitate CO2 capture chemistry to occur at the interface, while lowering surface tension and improving transport/reaction probabilities. We show that in the presence of interfacial AA-rich aggregates, one can improve capture probabilities vs that of a bare interface, which holds promise in addressing climate change through the removal of CO2 via tailored interfaces and associated chemistries.

Silicone polyether surfactant enhances bacterial cellulose synthesis and water holding capacity

The versatility and unique properties of bacterial cellulose (BC) motivate research into enhancing its synthesis. Here a silicone polyether surfactant (SPS) was synthesized and tested as a non-nutritional additive to the cultivation media of Komagataeibacter xylinus. The addition of SPS to the Hestrin-Schramm (HS) medium resulted in a concentration-dependent decrease in surface tension from 59.57 ± 0.37 mN/m to 30.05 ± 0.41 mN/m (for 0.1% addition) that was correlated with an increased yield of BC, up to 37% wet mass for surfactant concentration close to its critical micelle concentration (0.008%). Physicochemical characterization of bacterial cellulose obtained in presence of SPS, showed that surfactant is not incorporated into BC structure and has a moderate effect on its crystallinity, thermal stability. Moreover, the water holding capacity was enhanced by over 40%. Importantly, obtained BC did not affect L929 murine fibroblast cell viability. We conclude that SPS provides an eco-friendly approach to increasing BC yield in static culture, enabling more widespread industrial and biomedical applications.

Enhanced bioconversion of hydrogen and carbon dioxide to methane using a micro-nano sparger system: mass balance and energy consumption

Simultaneous CO₂ removal with renewable biofuel production can be achieved by methanogens through conversion of CO₂ and H₂ into CH₄. However, the low gas–liquid mass transfer (k_La) of H₂ limits the commercial application of this bioconversion. This study tested and compared the gas–liquid mass transfer of H₂ by using two stirred tank reactors (STRs) equipped with a micro-nano sparger (MNS) and common micro sparger (CMS), respectively. MNS was found to display superiority to CMS in methane production with the maximum methane evolution rate (MER) of 171.40 mmol/L_R/d and 136.10 mmol/L_R/d, along with a specific biomass growth rate of 0.15 d⁻¹ and 0.09 d⁻¹, respectively. Energy analysis indicated that the energy-productivity ratio for MNS was higher than that for CMS. This work suggests that MNS can be used as an applicable resolution to the limited k_La of H₂ and thus enhance the bioconversion of H₂ and CO₂ to CH₄.

Simultaneous CO₂ removal with renewable biofuel production can be achieved by methanogens through conversion of CO₂ and H₂ into CH₄. However, the low gas–liquid mass transfer (k_La) of H₂ limits the commercial application of this bioconversion.