Preparation Of MnO₂-based Catalytic Propelled Micromotor And Application For Sewage Treatment

The micromotor refers to a micro machine with a microscale,which can convert different energy into its own driving force to achieve autonomous movement.With the rapid development of micromotors,their performance in terms of energy,efficiency,navigation,and speed has improved significantly,expanding their applications in water quality testing,sewage removal and targeted drug delivery.The self-propelled external environment of the micromotor is mainly a solution environment.Due to its motion characteristics and full contact with the reactants,it has high reaction efficiency,and has broad application prospects in the field of wastewater treatment.In this paper,three kinds of carbon materials such as natural kapok fibers（KFs）,natural poplar fibers（PFs）and carbon nanotubes（MWCNT）aggregates are used as templates to prepare bubble-propelled micromotors with fast movement speed and high adsorption efficiency based on MnO₂Scanning electron microscope,X-ray diffractometer,Raman spectroscopy,thermogravimetry and other methods were used to systematically characterize the morphology,structure and composition of the micromotor.On this basis,study its motion laws and mechanisms,and explore the adsorption performance and adsorption mechanism of the resulting micromotor.The following beneficial conclusions are obtained:1.The KF@Fe₃O₄/MnO₂tubular micromotor was successfully prepared by using KFs as a template and annealing reduction method and hydrothermal method.At a low fuel concentration（3%H₂O₂）,the motion speed of the micromotor reached 476μm/s,and the direction of its movement can be effectively controlled by applying a magnetic field.The adsorption experiment of methylene blue（MB）confirmed that the degradation rate of MB by micromotor can be increased by two times compared with static adsorption,and the degradation rate of MB reached 88.3%in 10 min.Loaded magnetic Fe₃O₄particles can realize their recovered and reused,and still have a high degradation rate of MB after 3 cycles.2.The PF@Fe₃O₄/MnO₂tubular micromotor was successfully prepared by using PFs as a template.The speed of the motor reached 371.36μm/s in 10%H₂O₂solution,and the directional movement can be effectively controlled by using the magnetism of Fe₃O₄.The adsorption experiment showed that the degradation rate of MB by micromotor reached 96.4%in 10 min.Research its adsorption mechanism through adsorption kinetics,the adsorption mechanism of micromotor is pseudo-second-order kinetics,which belongs to chemical adsorption.3.The MWCNT/MnO₂micromotors was successfully prepared by using MWCNT aggregates as a template and a one-step hydrothermal method.The motion speed of the motor in 7.5%H₂O₂solution reached 359.31μm/s,and the motion speed can be effectively controlled by changing the number of loaded MnO₂nanoflakes and fuel concentration.The adsorption experiment showed that the adsorption of Congo red by the micromotor was improved by 4.8 times compared with the static adsorption.Its adsorption mechanism conforms to pseudo-secondary kinetics and belongs to chemical adsorption.In summary,this article prepared a MnO₂based micromotor.Compared with traditional static adsorption,this motor can achieve rapid motion under the catalysis of H₂O₂and can achieve efficient and rapid adsorption of organic dyes.This result has important guiding significance for expanding the application of MnO₂-based micromotors in sewage treatment.