Synergistic bio-physicochemical enhancement of microalgal CO2 fixation via Fe2O3 nanoparticle-embedded nanofiber membranes

Developed Fe 2 O 3 NPs-embedded membranes to overcome gas–liquid mass transfer limits. • Fe 2 O 3 NPs raise surface area and add C O groups, thereby enhancing CO 2 adsorption. • Fe 2 O 3 NPs-nanofiber membranes enhance biomass, CO 2 fixation, and delay decline. • Fe 2 O 3 NPs promote stable biofilm formation, enhancing initial attachment and growth. • Fe 2 O 3 NPs enhance ATP, photosynthesis and XDLVO adhesion for CO 2 fixation performance. Algae-based carbon capture and utilization (CCU) technique offers a sustainable strategy for CO 2 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 (Fe 2 O 3 NPs)-incorporated electrospun nanofiber membrane to enhance CO 2 capture and microalgal fixation. Results revealed that the Fe 2 O 3 NPs was able to reduce fiber diameter, refine pore architecture, and increase specific surface area, thereby the improved CO 2 adsorption. In Chlorella cultivation, the final biomass concentration and CO 2 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 Fe 2 O 3 NPs 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 (U LW ) and Lewis acid-base (U AB ) interaction energies increased by approximately twofold and 2.74-fold, respectively. These changes synergistically enhanced initial algal adhesion and attachment stability, facilitating CO 2 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. Download: Download high-res image (191KB) Download: Download full-size image