A cost-effective synthesis of heteroatom-doped porous carbon by sulfur-containing waste liquid treatment: As a promising adsorbent for CO2 capture

Abstract Based on efficiency and environmental concerns, the development of porous carbon from waste and biomass materials has attracted extensive attention as a novel approach. In this study, poplar sawdust was an inexpensive carbon precursor, sulfur-containing waste liquid (SCWL) was used as a modifier to turn waste into treasure, and potassium oxalate (K2C2O4) was a mild activator, successfully prepared N, S, O co-doped new porous activated carbon with excellent CO2 capture performance. The heteroatom doping and pore structure can be controlled by using SCWL and K2C2O4, and adjusting the activation temperature. The best sample (PCSK-2-3-800) prepared with SCWL and K2C2O4 showed excellent CO2 adsorption performance, reaching 3.82 and 5.61 mmol/g under normal pressure at 25 and 0 °C, respectively. This is attributed to the synergy of porous structure and surface chemistry. The pore structure parameter results showed that K2C2O4 promotes the development of activated carbon pore structure. The specific surface area, micropore volume and narrow micropore volume of PCSK-2-3-800 are 1418 m2/g, 0.55 cm3/g and 0.43 mL/g, respectively. The characterization results of FTIR and XPS showed that the addition of SCWL can successfully introduce heteroatoms into the carbon skeleton, and form CO2-philic active sites on the surface of the porous carbon. Both aspects promoted the adsorption of CO2. In addition, the PCSK-2-3-800 sample has a moderate adsorption heat of 27.13 kJ/mmol, good adsorption selectivity of CO2 and N2 is 13, and excellent recyclability, which is very promising for CO2 separation or storage. This paper develops a sustainable scheme for the first-time using biomass and SCWL to develop a new solid carbon adsorbent, which provides useful information and inspiration for capturing CO2.