Li Sun, Cao Zhenzhou, Cui Jixian, Huang Liuyang, Qi Xiaonan, Wei Yanjie, Li Xianhui
Algae-based carbon capture and utilization (CCU) technique offers a sustainable strategy for CO2 mitigation, but its efficiency is often limited by poor gas-liquid mass transfer and unstable carbon availability. Here, this study developed an iron oxide nanoparticle (Fe2O3NPs)-incorporated electrospun nanofiber membrane to enhance CO2 capture and microalgal fixation. Results revealed that the Fe2O3NPs was able to reduce fiber diameter, refine pore architecture, and increase specific surface area, thereby the improved CO2 adsorption. In Chlorella cultivation, the final biomass concentration and CO2 biofixation rate of modified membrane increased by respective 11.6%±1.2% and 14.3% compared with that of pristine nanofibers. Furthermore, the modified membrane significantly promoted the early-stage biofilm formation, yielding biofilms that were 47.9% thicker, denser, and exhibited increased rougher surface. Nanoparticle-induced "microhooks", together with enhanced EPS secretion, strengthened algal attachment, increased cell density, and improved spatial homogeneity, thus creating a favorable microenvironment for rapid biofilm development. Cellular analyses demonstrated that membranes modified with Fe2O3NPs increased intracellular ATP by 45.6%, superoxide dismutase activity by 39.9%, and specific growth rate by 41.8% compared to the blank controls, indicating enhanced metabolic activity and stress resistance. Physicochemical characterization further showed that a reduction in electrostatic repulsion and an increase in hydrophobicity. Meanwhile, Lifshitz-van der Waals (ULW) and Lewis acid-base (UAB) interaction energies increased by approximately twofold and 2.74-fold, respectively. These changes synergistically enhanced initial algal adhesion and attachment stability, facilitating CO2 enrichment. In summary, this work elucidates the synergistic bio-physicochemical mechanisms underlying nanoparticle-modified membranes and specify their potential for advancing efficient microalgae-based CCUS technologies.