Highly selective adsorption of Hg (Ⅱ) from aqueous solution by three-dimensional porous N-doped starch-based carbon

Abstract

Herein, a new 3D porous layered skeleton of N-doped starch-based carbon (3D-NC) was fabricated by one-step co-pyrolysis of natural corn starch and melamine using metal catalyst (Ni (Ⅱ) and Mn (Ⅱ)) and applied in effective removal of mercury (Ⅱ) (Hg (Ⅱ)). The 3D-NC possessed a heterogeneously meso-macroporous surface with a hierarchical connected sheet structure insider. Batch adsorption experiments suggested that Hg (Ⅱ) adsorption by the 3D-NC could be completed within 90 min and had maximum adsorption capacities as high as 403.24 mg/g at 293 K, pH = 5. The adsorption mechanism for Hg (Ⅱ) was carefully evaluated and followed the physical adsorption, electrostatic attraction, covalent coordination and chelation. Besides, thermodynamic study demonstrated that the Hg (Ⅱ) adsorption procedure was spontaneous, endothermic, and randomness. More importantly, the 3D-NC could be regenerated and recovered well after adsorption-desorption cycles, showing a promising prospect in the remediation of Hg (Ⅱ)-contaminated wastewater.