Hierarchically porous nitrogen-doped carbon materials as efficient adsorbents for removal of heavy metal ions

Abstract

Abstract A series of hierarchically porous nitrogen-doped carbon materials (HNC) were prepared by using chitosan as main carbon/nitrogen source through a feasible sol-gel route. A variety characterization results confirm that the resultant HNC materials possess three-dimension (3D) interconnected porous structure, high BET surface area (591–1027 m2/g) and abundant surface nitrogen-containing groups (ie., pyridine N, pyrrole N, quaternary N species, etc.). All the HNC materials exhibit strong adsorption capacity for heavy metal ions (Pb2+ and Cd2+) in wastewater at room temperature, while relatively high adsorption efficiency could be achieved over the optimized material named HNC-3. Furthermore, the HNC materials can even work well in a solution with relatively wide pH range (from 2 to 6) for removing heavy metal ions, and can be easily recycled for several times without obvious loss in adsorption capability. The adsorption behaviors of Pb2+ and Cd2+ ions on the HNC materials comply with the Langmuir model and pseudo-second-order model, revealing a chemisorption nature of the adsorption process. These hierarchically porous nitrogen-doped carbon materials may have great potential for the remediation of heavy metal-polluted aqueous environment.