Preparation And Application Of MOF Micromotor

Artificial micro/nanomotor has attracted more and more attention because of its autonomous movement in wastewater treatment.When it is combined with metal-organic framework MOFs with large specific surface area and high porosity,its adsorption and catalytic properties can be significantly improved,which is conducive to the treatment of pollutants.Compared with traditional adsorbents and photocatalysts,MOFs micromotor can accelerate the reaction,improve the concentration of pollutants in the environment,and solve the problems of low efficiency of adsorption and catalytic.Preparation of magnetic micromotor can effectively control the the movement of adsorbent and solve the problem of difficult recovery of materials.Therefore,we combine the adsorbent and photocatalyst with the micromotor,respectively,to obtain new composite materials with high adsorption and catalytic properties for the adsorption and degradation of pollutants in water.The specific research content and conclusions are summarized as follows:1.Natural kapok was used as the biological template to prepare magnetic?-Fe₂O₃/?-Al₂O₃/MnO₂ micromotor through twice impregnation and calcination,and then the magnetic?-Fe₂O₃/?-Al₂O₃/MnO₂ micromotor was dispersed in the precursor solution of ZIF-8,and the ZIF-8 micromotor was obtained through in-situ growth of ZIF-8.The microstructure,crystal structure and properties of ZIF-8 micromotor were characterized by SEM,TEM,IR,XRD and specific surface area.For the motion study of micromotor,the influence of different concentration of hydrogen peroxide solution was studied under an optical microscope.The drag force and velocity of ZIF-8 micromotor were also studied.The adsorption performance of ZIF-8 micromotor toward dye Congo red and antibiotic doxycycline were investigated.The results showed that the ZIF-8 micromotor has asymmetric tubular structure derived from kapok and is covered with a layer of ZIF-8.We have studyed the influence of activation temperature and quantity of ZIF-8 precursor on the absorption performance of ZIF-8 micromotor,indicating that the best activation temperature was 150?and the quantity of precursor was 4 mmol.According to the motion analysis of the micromotor,the drag force and speed of the micromotor increased with the increase of concentration of H₂O₂.The maximum drag force of ZIF-8micromotor was 48.9 pN and the maximum speed could reach 150 m/s.From the adsorption experiments,the adsorption processes of Congo red and doxycycline by ZIF-8 micromotor were agreement with the pseudo-second-order kinetic model,and the adsorption amounts can reach up to 378 and 400 mg/g,respectively.In addition,the ZIF-8 micromotor still had faster movement speed and better adsorption performance in real water environment.2.Kapok was used as the biological template for its own asymmetric tubular morphology.The?-Fe₂O₃ microtubes were prepared by hydrothermal method,and then uio-66 was loaded on the?-Fe₂O₃ microtubes by solvent thermal method.Finally,?-Fe₂O₃/UiO-66 micromotors were prepared by photoreduction of KMnO₄ to form MnO₂ particles on?-Fe₂O₃/UiO-66.The?-Fe₂O₃/UiO-66 micromotor was characterized and analyzed by SEM,TEM,IR and XRD.The results showed that?-Fe₂O₃/UiO-66 micromotors retained the natural tubular morphology of kapok,?-Fe₂O₃ nanosheets were cross-grown on the surface of microtubes,and uio-66 cubic nanoparticles and MnO₂ particles were densely distributed on microtubes.The micromotor with asymmetry structure could be propelled by decomposition of H₂O₂.The motion of the micromotor was observed in different concentrations of H₂O₂ solution,and it was found that the motion speed increased with the increase of fuel concentration,and the fastest motion speed in 5%H₂O₂ solution was 90.1 m/s.The photodegradation of methylene blue by?-Fe₂O₃/UiO-66 micromotor by photo-Fenton reaction was analyzed,and the results showed that the catalytic degradation process of methylene blue by micromotor was in accordance with the pseudo first-order kinetic model.The catalytic performance was the best when the solution pH=9 and H₂O₂concentration was 12%.The catalytic performance of?-Fe₂O₃/UiO-66 in the moving state was significantly improved by about 3 times as much as that of the non-motor.The?-Fe₂O₃/UiO-66 micromotor can also be reused attributed to the good stability.