Valorization of waste polyethylene terephthalate plastic into N-doped microporous carbon for CO₂ capture through a one-pot synthesis

Valorization of waste polyethylene terephthalate (PET) plastic into microporous carbon with N-doping treatment was successfully performed in a one-pot synthesis and the N-doped microporous carbon was used for CO₂ capture, which can mitigate plastic pollution and climate change simultaneously. The PET-derived microporous carbon developed by KOH activation and urea treatment in a one-pot synthesis at 700 °C exhibited the highest CO₂ adsorption uptake of 6.23 mmol g⁻¹ at 0 °C and 4.58 mmol g⁻¹ at 25 °C (1 atm). The Langmuir and pseudo second-order models displayed well-fitting relationships with equilibrium and kinetic experimental data obtained in this study. The N-doped microporous carbon showed high CO₂ selectivity over N₂, implying that it is feasible for treating flue gases (10% CO₂ and 90% N₂) at 50 °C. In addition, the CO₂ uptake was not only affected by micropores but also related with nitrogen and oxygen functional groups. Compared to the porous carbon prepared by two-pot synthesis where KOH activation and urea treatment were conducted separately, the porous carbon prepared by one-pot synthesis had higher oxygen contents and higher CO₂ adsorption uptake. All of findings implied that the N-doped microporous carbon was successfully developed from waste PET plastic for capturing CO₂ and can play a promising role in both sustainable waste management and environmental protection.