Effects Of Functional Modification And Lattice Structure Regulation Of Metal-Organic Framework On Liquid-phase Adsorption Performance

The major sudden emergencies concerning environmental pollution feature uncertainty and serious harm.Adsorption is the main method of treatment adopted in this kind of emergencies.Therefore,it is the key to develop adsorbent with high adsorption capacity,high adsorption rate and high selectivity.Metal-organic frameworks（MOFs）,a type of porous materials with high surface area,high porosity and excellent structural regulation,has been a new research hotspot in the field of adsorption.Using heavy metal and organic dyes in aqueous solution,and nitrogen-containing compounds in fuel as object pollutants,the study investigated the functional modification of MOFs and liquid-phase adsorption capacity over regulation of lattice structure,focusing on the influence of MOFs with Benzoic acid organic ligand and MOFs with Zinc base on the adsorption removal of heavy metal ions in aqueous solution,examining the influence and mechanism of amine functional modification strategy on the purification and separation of model fuel,designing and synthesizing lattice vacancy of HKUST-1,and exploring the adsorption capacity of HKUST-1 on the removal of dye molecules to shed new lights on developing new MOFs to overcome size-exclusion effect.The main research results of this study are as follows:（1）Six kinds of MOFs（UiO-66、MIL-101（Cr）、MIL-53（Fe）、ZIF-8、MOF-5、IRMOF-3）were prepared and employed as the receptors for adsorption lead ions.It was found that the Zn-BDC exhibited a much higher adsorption capacity than the other MOFs.This significant high adsorption over Zn-MOF can be explained by ion exchange between the central metal ions of Zn-MOF and lead ion in solution.A plausible adsorption mechanism is proposed based on the coordination theory.（2）MOFs,MIL-53（Al）-NH₂ and MIL-53（Al）,were synthesized and used as the adsorbents for the removal of nitrogen-containing compounds（quinoline and pyrrole）from model fuel.Compared with the adsorption capacity of MIL-53（Al）,MIL-53（Al）-NH₂ possesses a higher adsorption capacity for quinoline and pyrrole in the model fuel due to the hydrogen bonding interaction between MIL-53（Al）-NH₂ and the nitrogen-containing compounds.The used MIL-53（Al）-NH₂ could be regenerated by simple solvent washing with ethanol and reused in the adsorption process.（3）Using 1,3-Benzenedicarboxylic acid as the modulator,through changing the proportion of different ligands in the reactants,employing mixed ligand strategy method,the crystals of HKUST-1 with different ratio of lattice vacancy were prepared with comparatively large adsorption capacity of dye molecules.With the aid of instrumental characterization,the HKUST-1 skeleton structure was confirmed.The adsorption experiment revealed that the lattice vacancy in HKUST-1 significantly improve the combining ability of HKUST-1 with dye molecules.It was found that the pseudo-second-order kinetics model and the langmuir isotherm equation are preferable to characterize the adsorption process.