Production And Application Of Nanobubbles From The Inspiration Of Nature

Surface and interface science is a discipline that has emerged in recent decades involving materials science,condensed matter physics,organic polymer materials and other fields.When scientists study many issues involving matter,they often assume it an infinitely extending and continuous material to simplify a lot in calculations and get a simple numerical solution.However,this logic does not apply to the junction of twophase or even three-phase matter.At these surface and interface locations,the properties of the material are always significantly different from conventional calculations or experience.The same is true for bubbles in water,especially at the nanoscale.Since the first figure obtained in 2000,nanobubbles have attracted the attention of many researchers with their unique physical and chemical properties.The existence of nanobubbles runs counter to several classic theories applicable in physics today.According to Laplace's equation,the internal pressure of nanobubbles could reach dozens or even hundreds of atmospheric pressures,such a huge pressure is enough to make the bubbles dissolve in a few milliseconds.And according to Young's equation,the contact angle of nanobubbles in water with various hydrophobic or hydrophilic surfaces is dozens of degrees(from water side)greater than the theoretically calculated value.These inexplicable phenomena naturally lead to a large number of attacks or even difficulties.In addition,due to the defect of the detection instruments,it is currently difficult to detect the external morphology and internal information of the nanobubbles at the same time,which in turn makes it difficult to directly respond to criticism.However,despite the slow progress in basic scientific research,nanobubbles are in full bloom in terms of practical applications,including surface cleaning,animal and plant breeding,medical imaging,and mineral flotation.The activity in practical applications is driving the in-depth exploration of the distribution,preparation,and properties of nanobubbles.Based on a number of abnormal phenomena in natural water,this paper develops some methods to produce nanobubbles through oscillation and decompression processes,and studies the properties of nanobubbles with the change of experimental parameters.On the one hand,it is helpful to explain many anomalies in natural water bodies;on the other hand,it also provides an important experimental basis for explaining the stability mechanism of nanobubbles.Finally,the application of nanobubbles in dust removal is explored.This dissertation is divided into three parts.Firstly,from the abnormal data detected by acoustic wave detectors in oceanography,the phenomenon of breaking waves were summarized into the physical behavior of vibration,and it is also a method commonly used when mixing solutions in scientific research.Through the measurement of the size and concentration of the generated nanobubbles by the nanoparticle tracking analysis,it is found that the oscillation can indeed generate nanobubbles,and its formation depends on the oscillation time and frequency.This method is easy to operate,pollution-free,and the formed nanobubbles have good stability.Therefore,it can be speculated that the rivers,lakes,and seas where oscillating behaviors occur frequently may be filled with bulk nanobubbles.And the oscillation of the solution in the experiment may also produce nanobubbles,which will have a significant impact on the subsequent experiments.Secondly,considering that in addition to oscillations,there is also a common phenomenon in nature,namely pressure changes.In order to explore whether the pressure change can also promote the formation of nanobubbles similar to the previous part,this part carried out an exploratory experiment.Based on Henry's law,surface and bulk nanobubbles can both be prepared using an appropriate decompression method.The experimental results also show that the particle size of nanobubbles increases with the duration of decompression.This method has high efficiency and is suitable for various containers and interfaces,which is conducive to the subsequent investigation of properties and applications.Finally,the influence of water droplets containing nanobubbles on wettability of hydrophobic surface was investigated by using nanobubbles that are prepared by decompression method,and it was found that the presence of nanobubbles would make droplets more easily infiltrate the hydrophobic interface,and this phenomenon was extended to spray dust removal system.After studying the removal effect of dust particles with different properties,it is found that nanobubble solution has a good removal effect on hydrophobic pollution particles,and an attempt was made to improve the current high-pressure spray to promote the application range of nanobubble.