Fabrication of UiO-66(Zr)-NH2-encapsulated boehmite-chitosan granules and their application for adsorptive denitrogenation of liquid fuel.

Herein, boehmite-chitosan granules (d ∼ 2-3 mm) encapsulating different amounts of UiO-66(Zr)-NH2 (BCS@UN-x) were efficiently prepared using a combined sol-gel and oil-drop method. The granules were characterised using FE-SEM, XRD, FT-IR, TGA, XPS, and N2 sorption. Incorporating UiO-66(Zr)-NH2 frameworks into the boehmite-crosslinked chitosan matrix yielded composite granules with enhanced porosity and stability, as well as a higher abundance of functional groups, which are beneficial for the adsorption of N-containing compounds (NCCs) from n-octane. In batch experiments, the BCS@UN granules loaded with 14 wt% UiO-66(Zr)-NH2 achieved adsorption capacities of ∼120 mg g-1 for quinoline (QUI) and ∼132 mg g-1 for indole (IND). The adsorption isotherms of the NCCs onto the granules followed the Langmuir model, achieving maximum capacities of 203 mg g-1 for QUI and 215 mg g-1 for IND. In addition, breakthrough adsorption tests indicated that 1.0 g of the prepared BCS@UN granules could effectively purify ∼9.7 L and ∼12.0 L of liquid fuel containing QUI and IND at concentrations of 1 mg L-1, respectively. Notably, these granular adsorbents could be rapidly recovered during the process and exhibited good stability. Adsorption mechanism analyses suggested that UiO-66(Zr)-NH2, integrated into an AlOOH-chitosan matrix, produced a synergistic effect that accelerated the removal efficiency of NCCs by the resulting granules. The findings indicated that producing granular adsorbents encapsulated with the nanocolloid UiO-66(Zr)-NH2 via a boehmite-chitosan system is a promising strategy for broadening their practical applications.