The Resource Utilization of Poplar Leaves for CO₂ Adsorption

Every late autumn, fluttering poplar leaves scatter throughout the campus and city streets. In this work, poplar leaves were used as the raw material, while H₃PO₄ and KOH were used as activators and urea was used as the nitrogen source to prepare biomass based-activated carbons (ACs) to capture CO₂. The pore structures, functional groups and morphology, and desorption performance of the prepared ACs were characterized; the CO₂ adsorption, regeneration, and kinetics were also evaluated. The results showed that H₃PO₄ and urea obviously promoted the development of pore structures and pyrrole nitrogen (N-5), while KOH and urea were more conductive to the formation of hydroxyl (-OH) and ether (C-O) functional groups. At optimal operating conditions, the CO₂ adsorption capacity of H₃PO₄- and KOH-activated poplar leaves after urea treatment reached 4.07 and 3.85 mmol/g, respectively, at room temperature; both showed stable regenerative behaviour after ten adsorption-desorption cycles.