Carbon nanotubes and porous organic polymers for CO₂ capture

Emissions of carbon dioxide are considered to be the major factors leading to climate change. Reducing CO₂ influence on global warming requires its capture and utilization. Current technologies of CO₂ capture include chemical and physical absorption, membrane separation, and cryogenic distillation. Particularly, solid adsorbents demonstrate a high efficiency for CO₂ capture and storage tasks. Porous liquids, containing a solid adsorbent dispersed on a compatible liquid, represent another promising approach for CO₂ capture.

In this study, commercial and synthetic porous carbon nanomaterials and frameworks were obtained. Structure, amorphous domain, and thermal stability of samples were checked by Fourier-transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. Synthesized nanomaterials were dispersed in the water solutions of different surfactants and further compared on the efficiency of CO₂ uptake. The characterization of samples confirmed successful synthesis and modification of nanomaterials in different conditions and provided the necessary data for further optimization of synthesis parameters for targeted applications.

Synthetic porous carbon nanomaterials and frameworks were compared for their efficiency as porous fillers in the fluids. The efficiency of porous fluids was estimated and compared with blank measurements for water and water with surfactants. Adding surfactants enhanced the dissolution of CO₂, leading to a double increase in CO₂ uptake for the water–surfactant solution, compared with pure water. Dispersion with commercial materials as porous fillers demonstrated a slight enhancement in CO₂ uptake, compared with the water–surfactant solution. Synthesized carbon nanomaterials resulted in higher CO₂ adsorption, exhibiting two times higher CO₂ uptake in comparison with water–surfactant.

The modification of carbon nanomaterials led to an enhancement in CO₂ adsorption capacity. Porous liquids containing adsorbents with a greater number of polar groups demonstrated higher CO₂ uptake. Particularly, nitrogen-doped carbon nanomaterials were more efficient, while surface-modified materials without nitrogen in their composition demonstrated less CO₂ uptake.