Binder-free production of 3D N-doped porous carbon cubes for efficient Pb2+ removal through batch and fixed bed adsorption

• Published in: Journal of cleaner production 2017-12, Vol.168, p.290-301
• Main Authors: Sawant, Sandesh Y., Pawar, Radheshyam R., Lee, Seung-Mok, Cho, Moo Hwan
• Format: Article
• Language: English
• Subjects: 3D adsorbent; Carbon cubes; N-doped carbon; Pb2+ adsorption; Water treatment
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2017.08.229

N-doped carbon cubes (NCCs) with varying nitrogen contents and different densities were fabricated using a simple and binder-free method that involved the curing of resorcinol-formaldehyde (RF) gel with different RF contents in the framework of a melamine sponge. In addition to the robust structure and nitrogen doping, the porosity of the NCCs could be tailored easily within the mesopores and ultra-micropores with a unique combination of macro, meso, and micropores. The prepared NCCs exhibited excellent uptake capacity, ranging from 32.1 to 39.3 mg/g Pb2+ ions, owing to their high surface area (up to 675 m2/g) and nitrogen doping (max. 4.9 wt. %). The Pb2+ adsorption property of NCC-10 was also compared with that of widely used commercial 3D carbon adsorbents. The weight and surface area-normalized Pb2+ adsorption capacity of NCC-10 was found to be 3.7 and 6.6 times higher, respectively than the commercial activated carbon granules. The continuous mode model data fitted with experimental fixed-bed results well, and showed 8.95 mg/g loading capacity, proving that NCC-10 is an effective 3D adsorbent. The prepared NCCs could be used as a practical adsorbent for the removal of Pb2+ ions because of their high adsorption capacity, easy regeneration, and exceptional stability maintained after longer reuse. [Display omitted] •Binder-free method for the synthesis of 3D N-doped carbon cubes (NCCs) is reported.•NCCs possess high porosity with unique combination of macro, meso, and micropores.•N-doping and porosity can be tailored by varying resorcinol-formaldehyde content.•NCCs showed higher Pb2+ adsorption capacity than commercial 3D carbon adsorbents.•A long-term and continuous Pb2+ removal can be achieved with fixed bed adsorption.