Preparation Of High Efficiency Self-Propulsion Particles And Study On Photoinduced Particle Cluster Motion

In recent years,the process of social industrialization has accelerated.At the same time,the problem of water environment is becoming more and more serious.In view of the refractory and persistent residual trace pollutants in water,researchers have developed a series of micro-/nanoparticles with catalytic activity by fabricated the precise characteristics of micro-nanotechnology.Moreover,researchers have developed various research systems for degradation of pollutants in water using these micro-/nanopartic les.The key characteristic of these functionalized active particles is their autonomous motion.On the basis of previous studies on the kinematic characteristics of active particles,the preparation method of self-driving catalyst particles was mastered through experimenta l verification.In addition,the mechanism of photocatalytic particle swarm movement under light was preliminarily investigated by numerical simulation.In this dissertation,hollow glass microspheres were used as substrates and platinum was deposited on the surface of glass microspheres by interfacial protection.Catalyst particles with asymmetrical distribution of surface components were prepared by this method,and the favorable self-driving behavior of catalyst particles was realized.By controlling the concentration of surfactant DDAB,the platinum coating ratio on the surface of glass beads can be effectively changed.The higher the concentration of DDAB is used,the less the distribution of platinum is coated.Conversely,the lower DDAB is used,the more platinum is coated.Under the influence of reaction time and the concentration of DDAB,the catalyst particles prepared by this method have higher catalytic activity than those prepared by physical method.Even in the low concentratio n hydrogen peroxide aqueous solution environment,the average self-propulsion velocity of catalyst particles caused by bubble collapse is as high as 1169.8?m/s.In addition,in the process of studying the combination of floating catalyst particles with photocatalytic materials,the phenomenon of Ultrafast Photoinduced Motion(UPM)of uniform photocatalyst particles under different light fields was found.The experime nt of UPM shows that different frequencies of light can induce different motion modes.The higher the frequency of light is,the more intense the induced particle cluster motion is,and the particle velocity can reach the order of mm/s.The smaler the frequency of light is,the gentler the particle cluster motion is,and the particle velocity is in the order of ?m/s,or the particles do not move any more.By analyzing the motion phenomenon of the UPM,this paper deduces the motion mechanism of the homogeneous photocatalyst particle cluster under the condition of light,and proposes a repulsion model.The numerical simulation software COMSOL Multiphysics 5.0 is used to calculate the model,which is mainly included creeping flow module and fluid particle tracking module.The main idea of this model is the size and mode of interaction between particles.The charged quantity and number density of particles are simulated as the main conditions.Through the four-way coupling of the interaction force between particles and the interaction force between particles and fluids,the calculated results of the model are basically consistent with the experimental phenomena.The simulation results are expressed by particle trajectory and flow direction.The above conclusions indicate that,on the one hand,it is feasible to prepare floating self-driving catalyst particles with hollow glass beads as support in specific test methods.The self-propulsion velocity of the catalyst particles prepared by this method is as high as millimeter/second,which is much faster than that of the catalyst particles prepared by physical method.The experimental results provide a new reference for the preparation of various functional catalyst particles.On the other hand,the validity of the proposed model is verified by comparing the simulation results with the experimental results.The model validates that under the action of external light field,the velocity of catalyst particle cluster can reach several hundred microns/seconds.In conclusion,the preliminary study on the movement behavior of catalyst particles provide a theoretical basis for the application of enhanced degradation of pollutants in water.