Aminated-polyacrylonitrile-Ni-imidazole composite for CO₂ Capture: Synthesis, application and mechanistic insights

With increasing CO₂ emissions driving accelerating climate change, effective CO₂ capture is crucial for mitigating environmental damage and advancing toward a low-carbon future. A novel polymer composite, composed of amine-terminated polyacrylonitrile (PAN-II) decorated with Ni-imidazole complex was developed as a solid adsorbent for efficient CO₂ trapping. Various analytical methods, including FTIR, TGA, SEM, XRD, and adsorption isotherm were utalized to assess the physicochemical properties and CO₂ adsorption efficiency. FTIR analysis confirmed that CO₂ capture is enhanced through dual mechanisms: chemisorption via carbamate formation, evidenced by amine group consumption, and physisorption driven by van der Waals interactions. High adsorption efficiency percentages for both initial and regenerated adsorbents demonstrated effective recyclability under mild regeneration conditions. The results showed that, a 20 % Ni-imidazole complex content in the PAN-II composite (PAN-II/Ni-complex) significantly improved CO₂ adsorption performance. The PAN-II/Ni-complex showed good reusability, highlighting its strong potential for capturing CO₂ from industrial emissions. The experimental capacity results improved from 4.50 to 28.11 mL/g, when the temperature was increased from 273 K to 293 K, respectively. In the selectivity studies, the PAN-II/Ni-complex shows enhanced CO₂ adsorption compared to the base PAN-II, making it more effective for CO₂ capture, particularly in mixed-gas systems.