Magnetic nanoparticles-embedded nitrogen-doped carbon nanotube/porous carbon hybrid derived from a metal-organic framework as a highly efficient adsorbent for selective removal of Pb(II) ions from aqueous solution.

In this work, a magnetic nitrogen-doped carbon nanotube/porous carbon hybrid was prepared by the facile carbonization of zeolitic imidazolate frameworks (ZIF-8) impregnated with iron salt. The as-obtained hybrid (denoted as Fe 3 O 4 @ Z -NCNT/PC), with a high surface area (1358 m2 g−1), large pore volume (1.61 cm3 g−1), and considerable functional groups, was used as a recyclable adsorbent for the selective removal of Pb(II) ions from water solution. The factors influencing the adsorption performance of Fe 3 O 4 @ Z -NCNT/PC toward Pb(II) ions were studied using batch experiments. The adsorbent exhibited very fast adsorption kinetics for Pb(II) ions and could efficiently remove more than 99% of Pb(II) in 20 min. The maximum adsorption capacity of the hybrid was found to be 789.87 mg g−1 which was much higher than most of the previously reported adsorbents. Moreover, the adsorbent exhibited high removal selectivity of Pb(II) ions in the presence of other ions and could maintain a high removal performance even after 10 cycles. The extraordinary adsorption performance of the adsorbent toward Pb(II) ions was attributed to the synergistic contributions of the unique hybrid structure providing abundant routs for easy mass transfer of Pb(II) ions to access active sites as well as nitrogen-functionalities introduced into the framework providing basic active sites for Pb2+ adsorption. This study provides a simple strategy for the construction of MOF-based adsorbents and also offers possible applications in water treatment due to their outstanding adsorption properties. Unlabelled Image • Magnetic N-doped CNT/PC hybrid was prepared by pyrolysis of Fe2+ loaded ZIF-8. • Z-MNCNT/PC showed high removal selectivity for Pb2+ in the presence of other ions. • Adsorbent provided advantages of magnetic NPs and N-doped CNT/porous carbon hybrid. • Sorbent had high removal efficiency, high adsorption capacity, and good reusability. • Fast adsorption kinetics with high adsorption capacity of 789.87 mg g−1 was obtained. [ABSTRACT FROM AUTHOR]