Synthesis of UiO-66-NH2@SiO2 with a multistage pore structure for effective adsorption of organic pollutants

Abstract We reported anchoring mesoporous silica onto the microporous metal–organic frameworks (MOF) (UiO-66-NH2) to obtain a hierarchical porous framework (UiO-66-NH2@SiO2). This strategy maintains the high specific surface area (SA) of the MOF and addresses the mass transfer issue frequently encountered in microporous materials, providing more possibilities for subsequent modified structural frameworks. The structural characteristics of UiO-66-NH2@SiO2 were evaluated by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, surface analysis and X-ray photoelectron spectroscopy. In this work, the specific SA of the composite material was 196.667 m2/g, which decreased due to the occupation of some pores by anchored silica. Adsorption experiments showed that the composite material had a better adsorption effect (Congo red, 393.83 mg/g; bromophenol blue, 446.46 mg/g) than UiO-66-NH2, with electrostatic interaction and hydrogen bonding being the main driving forces. Therefore, this is a material that has a positive impact on dye adsorption. The strategy proposed in this work has potential applications not only in the construction of new materials but also in the exploration of dye adsorbents.