Preparation and characterization of metal organic framework-derived nanoporous carbons for highly efficient removal of vanadium from aqueous solution

The highly nanoporous carbon (NPC) materials were synthesized by carbonizing highly crystalline MOF-199 with addition carbon precursors and without any carbon precursors. In addition, a novel NPC@CNT was fabricated by the use of multi-walled carbon nanotubes (CNT) as carbon precursors and MOF-199 as the template. The morphology, structure, and surface properties of the synthesized NPC samples were characterized in detail. The NPC materials were employed as adsorbents for the removal of vanadium (V) from aqueous media by batch process. The effects of principal operational parameters on the adsorption of V ions are investigated, and the reaction mechanism for this treatment technology is also proposed. In order to determine the controlling mechanism of the adsorption process, the adsorption isotherms, kinetics and thermodynamics parameters were examined. The V adsorption onto NPC adsorbents can be best described with Langmuir isotherm points out the homogeneous surface sites of NPCs and also the monolayer formation of V ions on the adsorbent outer surface. The kinetic batch experiments revealed that more than the V ions were absorbed onto the synthesized NPCs within 15 min, and the pseudosecond-order kinetic model could explain the adsorption process. The thermodynamic study indicated that the adsorption process was exothermic and spontaneous and the system disorder increased during the adsorption process. The adsorbents showed preferential V ions adsorption with the existence of coexisting cation (Ni2+) and anions (SO42- and NO3-). The V adsorbed NPCs were regenerated with an efficiency of greater than 95% using 0.5 M sodium hydroxide. (C) 2019 Elsevier B.V. All rights reserved.