(668a) Enhanced Carbon Capture Using Amine-Modified Hollow Carbon Spheres Synthesized By Spray Drying

The increase in greenhouse gas emissions in recent decades raises concerns about global warming, and CO₂ is the primary greenhouse gas responsible for climate change. Until cleaner and sustainable energy sources become more efficient, improving carbon capture methods is crucial for reducing CO₂ emissions and mitigating climate change. Using amine-based media is industrialized in power plants for the chemical sorption of CO₂. This process has some drawbacks, like being costly, and these solvents are challenging to regenerate. So, finding a better adsorbent is still a challenge. Activated carbon is a solid adsorbent for CO₂ capture, and lignin is a good source for developing carbon-based adsorbents for CO₂ removal due to its highly aromatic structure. Also, hollow carbon spheres (HCSs) have recently gained significant attention for various applications due to their unique physicochemical properties and structural advantages.

In this study, amine-modified HCSs were synthesized through two steps: first, we employed the spray-drying method to synthesize HCSs using a lignin-KOH solution and then modified the surface of the adsorbent by physical impregnation of different amine solutions. For this purpose, we used four different amines: Ethylenediamine (ETA), Diethylenetriamine (DETA), (3-Aminopropyl) triethoxysilane (APTES), and Chitosan with different loadings amount from 10% to 70% by weight. We employed characterization techniques, including SEM, XRD, BET, and CHNS elemental analysis, to realize the structural and chemical changes induced by amine modification. The results for surface area, pore volume, and pore size distribution before and after modification showed that increasing the amine loading on the HCSs leads to a decrease in the surface area. For CO₂ capture, both the surface area and amine functional group loading are important, so our goal was to find the optimum loading amount that maximizes the CO₂ capture capacity for each amine solution. The adsorption capacity of the samples was investigated by using setups for both static and dynamic CO₂ adsorption experiments. We also fitted the experimental data with different isotherm and kinetic models, including the Pseudo-first-order, Pseudo-second-order, and Avrami model, to see which model best describes the nature of the CO₂ adsorption on our samples. This study showed us with this method, we can utilize low-cost precursor materials like lignin to synthesize effective CO₂ adsorbent.