Preparation And Adsorption Properties Of A New Type Of Metal Organic Framework Materials

Metal-organic framework material, a new type of porous materials developed in recent years, is formed by metal ions or clusters as the center, with the development of the research, those simple ligand such as BDC and BTC gradually developed into complex ligand with amino and other functional groups. With dwindling water resources, the necessity of water treatment is becoming more and more outstanding, as a porous material, metal-organic frameworks with good adsorption performance, have great research value in sewage treatment.In this study ZIF-61 and MOF-235 were synthesized. The characterization methods of FT-IR, XRD and SEM were used to characterize the synthesized materials. Adsorption kinetics and thermodynamic curves were determined. And the corresponding model is used to fit the model. The repeated use and reproducibility of the materials were determined.The adsorption of fluorescein sodium by crystal materials MOF-235 was in accordance with the quasi two stage kinetic model, and the Ea was about 14.08 kJ·mol-1. The reaction rate is controlled by chemical adsorption. Adsorption is an endothermic reaction, the maximum adsorption capacity was 1229.14 mg·g-1 at 20?. Adsorption thermodynamics is in accord with the Langmuir adsorption model, which is the chemical adsorption of the single molecule layer on the surface of the adsorbent. The entropy change and enthalpy change of adsorption reaction were 165.78 J·mol-1·K-1 and 19.36 kJ·mol-1, respectively. Gibbs free energy change were -29.21,-32.53 and -35.84 kJ·mol-1 at 20,40 and 60? respectively.ZIF-61 crystal materials were synthesized. The adsorption kinetics of malachite green accords with pseudo two order kinetics model, chemical adsorption, activation energy is 33.97 kJ·mol-1.Adsorption is an endothermic reaction, the maximum adsorption capacity is 6500mg·g-1 at 20?. Adsorption thermodynamics is in accord with the Langmuir adsorption model, which is the chemical adsorption of the single molecule layer on the surface of the adsorbent. The entropy change and enthalpy change of adsorption reaction were 195.9 J·mol-1·K-1 and 33.57 kJ·mol-1 respectively. Gibbs free energy change were -23.83,-27.75 and-31.66 kJ·mol-1 at 20,40 and 60?. ZIF-61 can be used for regeneration after simple washing with ethanol, it can be used for 5 times and the adsorption capacity still retained 90%.