Preparation of hierarchically floral ZIF-8 derived carbon@polyaniline@Ni/Al layered double hydroxides composite with outstanding removal phenomenon for saccharin

In this work, ZIF-8 derived carbon@polyaniline@Ni/Al layered double hydroxides (denoted as ZC@PANI@NiAl-LDH) composite has been successfully designed via the facial synthesis of the ZIF-8, followed by high-temperature pyrolysis, oxidative polymerization of polyaniline, and in-site growth of NiAl-layered double hydroxides. Meanwhile, the composite acts as an advanced adsorption material for the scavenging of saccharin from aqueous solutions. Moreover, benefiting from the unique three-dimensional (3D) hierarchically floral structure and various functional groups, the as-prepared ZC@PANI@NiAl-LDH composite presents a high adsorption capacity (498.5 mg/g) for saccharin, superior to other reported adsorbents. Besides, the ZC@PANI@NiAl-LDH possesses rapid adsorption kinetics and excellent reusability performance. Furthermore, Fourier transformed infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses initially reveal the possible adsorption mechanism, including electrostatic interactions, π-π interactions, and hydrogen bonding. Quantum chemical theory calculations further indicate the above adsorption mechanism. Significantly, based on the Hirshfeld surface analyses, saccharin behaves as the H-bond acceptor, while the NiAl-LDH works as the H-bond donor. This work provides a feasible strategy to design advanced materials for practical wastewater treatment.