Two-Step Cavitation-Enhanced Waterborne CO2 Management: Aqueous Capture via Electrospun Membranes and Controlled Hydrodynamic Release

The increase in carbon dioxide (CO2) emissions in recent years highlights the urgent need for advanced and effective CO2 capture and release technologies. This study presents a two-step system aimed at first capturing CO2 in water and subsequently releasing it using cavitation processes. Using multiple layers of horizontally oriented hydrophilic electrospun nanofibers sandwiched between layers of CO2-philic nanofibers, we demonstrate a straightforward, reliable, efficient, and effective approach for dissolving pressurized CO2-containing gas in water, followed by controlled release through cavitation mechanisms. These nanofibers are electrospun using poly(methyl methacrylate) (PMMA) and polyethylene glycol (PEG) polymers, and their physical and chemical properties and CO2 absorption performance are characterized using thermogravimetric analysis, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), Brunauer--Emmett--Teller (BET) surface area analysis, and water contact angle measurements. The concentration, CO2 absorption in water, cavitation-induced release, and the dynamic effect of bubbles were investigated by an in-situ adsorption setup. The nanofiber adsorbent was reported to have a specific surface area of 183 m2 g-1 and a carbon adsorption capacity of 4 mmol g-1. The cavitation process significantly enhanced CO2 release efficiency, with bubble size changes strongly correlated with both adsorption and desorption rates. The CO2-philic nanofibers effectively trap and release CO2 molecules underwater, demonstrating enhanced dissolution and controlled release performance. This two-step capture-release system offers promising potential for applications in wastewater treatment, where controlled CO2 release can be utilized for micropollutant removal, presenting a sustainable approach for both carbon management and water purification technologies.