The hierarchical porous material HP-UiO-NH2-X was prepared by an environmentally friendly method using water as a modulator and used for adsorption of ofloxacin

Abstract

Hierarchical Porous Metal-Organic Frameworks (HP-MOFs) are widely recognized for their broad applications in adsorption, owing to their structural tunability and diverse pore types. However, existing synthesis methods often face challenges, including prolonged synthesis times, high energy consumption, and complex procedures. In this study, we utilized water, an environmentally friendly modulator, to successfully synthesize hierarchical porous UiO-series materials via a one-step solvothermal method. HP-UiO-66-NH₂-X with varied pore structures was synthesized by adjusting the H₂O/Zr⁴⁺ ratio in the precursor. The adsorption performance of the resulting materials for ofloxacin (OFL) was subsequently evaluated. Characterization results demonstrated that this approach effectively modulated the coordination between organic ligands and metal centers, leading to ligand defects and the precise tuning of the UiO-66-NH₂ framework's pore structure. When the H₂O/Zr⁴⁺ ratio was 22.2 (M/M), the synthesized HP-UiO-66-NH₂-2 material exhibited optimal adsorption performance (233.1 mg/g) and excellent selectivity. The adsorption process involved multiple interactions, including electrostatic interactions, pore filling, metal coordination, hydrogen bonding, and π-π interactions. In adsorption-desorption cycling tests, HP-UiO-66-NH₂-2 maintained over 90 % removal efficiency after 10 cycles, demonstrating its excellent reusability and stability. Therefore, this study proposes an environmentally friendly and simplified synthesis strategy, successfully producing HP-UiO-66-NH₂-X materials with remarkable performance in removing OFL. This approach offers a novel perspective for improving the performance and applicability of environmentally friendly materials.