Molten NaCl-induced MOF-derived carbon-polyhedron decorated carbon-nanosheet with high defects and high N-doping for boosting the removal of carbamazepine from water

Abstract

The efficient removal of endocrine-disrupting pollutants (EDCs) from water is a crucial issue for improving the quality of drinking water. Herein, hierarchically structured carbon composites (HCCs) composed of carbon-polyhedron decorated carbon nanosheets were fabricated using the zeolite imidazole framework-8 (ZIF-8) as the precursor in the presence of molten NaCl. The as-prepared hierarchical carbon composites showed higher specific surface areas, more defects, high N-doping, and hydrophilicity compared with the NaCl-free ZIF-8-derived carbon polyhedrons (CPs). In addition, the as-prepared HCCs exhibited boosted adsorption performances for the removal of the model EDC, namely carbamazepine (CBZ), surpassing CPs and commercial powdered activated carbon (AC). The adsorption kinetics showed that HCCs possessed a higher sorption rate as compared to CPs and AC. In the initial 5 min, the adsorption amount of CBZ on HCCs reached 94.9% of the adsorption quantity at equilibrium. Furthermore, the maximum adsorption capacity of CBZ on HCCs is 248.7 mg g⁻¹, which is superior to that of CPs and AC. X-ray photoelectron spectroscopy characterizations indicated that the predominant factors for controlling the adsorption of CBZ on HCCs are π–π electron donor–acceptor interactions and hydrogen bonding, although, some of the adsorbed CBZ molecules were decomposed by oxidation. Finally, a fixed-bed experiment demonstrated that the HCCs have great potential as a filler for the purification of tap water.