Genistein adsorption performance and mechanism by metal-organic frameworks based on triangular aromatic ligands

Abstract

Objective： To improve the adsorption of genistein by zirconium-based metal-organic frameworks （MOFs） with triangle aromatic ligands. Methods： Two MOFs （MOF-808 and PCN-777） containing different sizes of triangle aromatic ligands were synthesized by hydrothermal method for adsorption of genistein. The synthesis of MOFs was determined by a series of characterization methods, and the adsorption performance was compared with that of a linear binary carboxylic acid ligand-constructed MOF （UiO-66）, to evaluate the effects of pore characteristics, hydrophobicity changes, and other factors on the adsorption performance, and to explore the adsorption mechanism by XPS analysis. Results： Compared with linear ligand-constructed UiO-66, the pore sizes of triangular aromatic ligand-constructed MOFs （MOF-808, and PCN-777） increased from 0.65 nm to 1.81 nm and 3.55 nm, respectively, and the water contact angles increased from 47.91° to 110.68° and 128.23°, respectively. The adsorption capacity and adsorption efficiency of genistein in linear ligand-constructed UiO-66 was 40.08 mg/g and 39.98%, respectively, while the adsorption capacity and adsorption efficiency of genistein in MOFs constructed by triangular aromatic ligand （MOF-808, PCN-777） was increased to 61.80 mg/g, 81.75 mg/g and 61.63%, 81.52% respectively. Conclusion： Metal-organic frameworks （MOFs） can be used for the adsorption and enrichment of genistein. Compared with linear ligands, the introduction of triangular aromatic ligands with different sizes changes the pore size and hydrophobicity of MOFs, enhances the internal accessibility of MOFs, and provides more adsorption sites, which improves the adsorption effect of genistein. The adsorption mechanism of genistein in PCN-777 is based on the synergistic combination of metal-chelating interactions, π-π interactions, and hydrophobic interactions.

Keywords

• zr-based metal-organic framework
• genistein
• triangle aromatic ligands
• pore size
• synergistic adsorption mechanism