CO2 capture by modified porous carbon adsorbents: Effect of various activating agents

Abstract

Abstract Activated carbons with highly porous structure have been successfully synthesized via carbonization of the polyacrylonitrile followed by the chemical activation with various activating agents (NaNH2, NaOH, and K2CO3) and the different mass ratios (1–4). Total pore volume and surface area of the adsorbents lie in between the range of 0.14–0.64 cm3 g−1 and 263–1250 m2 g−1, respectively. XPS analysis confirms the presence of the various functional groups on the carbon surface which increases the total basicity of the adsorbents. Both of the properties of microporosity and functional groups explicate the high CO2 capture performance of the activated carbons under dynamic conditions. In particular, K2CO3 activated carbons exhibited maximum dynamic adsorption capacities (2.05–2.44 mmol g−1) in comparison to NaOH (1.90–2.20 mmol g−1) and NaNH2 (1.10–1.75 mmol g−1) activated carbons at 30 °C respectively. The synthesized carbons can be regenerate and reuse by multiple times without loss in the adsorption performance. Furthermore, the Temkin isotherm model shows the best description for the adsorption data at different temperatures, confirms the heterogeneous surface of the adsorbents.