Abstract: Although thermo-responsive polyacrylamide gels possess excellent CO2 capture and release capabilities at temperatures below 100 °C, their industrial application is hindered by the difficulties associated with the separation and purification of emulsion-type gels. In this work, the influence of nanosized silica particles introduced into the polymerization system on the adsorption performance of organic–inorganic composite polyacrylamide gels was systematically investigated. Large-sized solid amine gel particles with improved separability and purification characteristics were successfully synthesized. The prepared adsorbent exhibited a maximum CO2 adsorption capacity of 2.4 mmol·g-1 toward low-concentration CO2 and could be effectively regenerated at 80 °C. No noticeable decline in adsorption performance was observed after ten adsorption–desorption cycles. The adsorbent also showed strong resistance to NO gas. Although SO2 significantly suppressed CO2 adsorption, its adsorption performance could be restored by alkaline washing. Mechanistic analysis indicated that CO2 was predominantly captured in the form of bicarbonate (HCO3-) species within the polyacrylamide gel matrix.

Key words: Polyacrylamide gel, Silica, Carbon capture, Thermo-responsiveness