A modulator-induced defect strategy to construct different mesopore ratios Zr-based metal-organic frameworks for ultrafast adsorption of heterocyclic aromatic amines

The platform of isostructural crystalline metal-organic frameworks (MOFs) with structural defects and additional pores is an emerging technology for rapidly removing hazardous small molecules. Herein, this paper designed a series of Zr-based MOFs (UiO-66) with different mesopore ratios by inducing linker/cluster missing through monocarboxylic acid modulators; besides their adsorption capacity and mechanism for heterocyclic aromatic amines (HAAs) were investigated. The UiO-66 defected with lauric acid (UiO-66-12A) showed the best adsorption performance and its adsorption capacity and rate for HAAs were 1.25-5.63 and 1.74-5.82 times higher than UiO-66, respectively. The zeta potentials of adsorbents in the presence of HAAs aqueous solutions underscore the pivotal role of electrostatic interactions during adsorption. Fourier Transform Infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) demonstrated that pi-pi stacking, coordination and hydrogen bonding interactions were also critical factors in promoting adsorption. Moreover, simulation calculations revealed that UiO-66 with missing clusters can provide more active sites and stronger interactions. These findings provided a novel and feasible strategy for the rapid removal of hazardous small molecules from complex food environments, which could improve the adsorption capacity and convenient processes of MOFs through building appropriate inherent microporous structures. The comprehensive and systematic understanding of the adsorption mechanism in this paper is conducive to the future advancement of nanomaterials.