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Hydrophobic Substances And Release Studies Carried Gas Nanobubbles Capabilities

Posted on:2014-03-13Degree:MasterType:Thesis
Country:ChinaCandidate:W C ZhaoFull Text:PDF
GTID:2261330398498984Subject:Physical chemistry
Abstract/Summary:PDF Full Text Request
Twenty years ago, people proposed nanobubbles when they studied themechanism of hydrophobic long-range force between two hydrophobic surfaces inwater. After that the controversy about this has not stopped. With the developmentof modern detection technologies, especially the publication of AFM images of thenanobubble in2000and subsequent experimental validations, the view of existenceof nanobubbles on solid/liquid interface has been gradually accepted by more andmore people. The formation mechanism is generally believed that the excess gasmolecules tend to aggregated at nucleation centers (defects or voids) on the solidrepellent surface directly, and then stably exist on the solids and water interface inthe form of nanobubbles. Further, the larger the contact angle, the greater numberof stable nanobubbles.Nanobubbles are closely related with the physical and chemical phenomena. Ithas been found that many methods can produce the nano-bubbles, such assubstitution method, dipping method, exogenous method and electrochemicalmethod. On this basis we can apply nanobubbles into many different areas. On oneside, nanobubbles are advantageous. For example, on solving the problem ofbiological tissue hypoxia, nanobubbles mainly play their roles through enriched onthe surface of the hydrophobic particles, and then reached to the lesion sites afterblood circulation. In the ore flotation, due to the nanobubbles have the superiorproperties of specific surface area and high surface energy, they are possible toeffectively improve the efficiency of ore flotation. But it also has adverse side, mostof the hydrocarbon oily substances are soluble in water, if they adhere on the glasssurface, it is usually requires surfactants to remove. The reasons why ordinary watercan not clean them down are likely caused by the nanobubbles. Here we do somepreliminary researches of nanobubbles applications in two areas of biomedical andinterface chemistry.This paper analyzed the size of the nanobubbles on the solid/liquid interfacefirstly through atomic force microscopy (AFM) and synchrotron radiation small-angle X-ray (SAXS) techniques. It could determine the prerequisite of nanobubblesadsorbed on the hydrophobic particles. Subsequently, purge oxygen into thedispersion of hydrophobic particles under the high shear force. The excess oxygen onthe hydrophobic surface of the particles could form nanobubbles. These kind ofoxygen-filled formulations were injected into the degassed water, and the carryingmicro/nano bubbles abilities of hydrophobic particles were evaluated by thedetermination of the amount of dissolved oxygen in the water. The results showedthat these oxygen-filled formulations were able to provide oxygen to the hypoxicenvironment effectively; the provided amount of oxygen was related to the type ofsubstances and the particle size; ultrasonic treatment would improve the release ofthe oxygen.The nanobubbles on the solid/liquid interface could be removed by degassingtreatment. In the second part of this paper, author represented intuitively that thenanobubbles formed by the alcohol/water replacement on the solid/liquid interfaceof HOPG were disappeared after the degassed process of half an hour. Based on theresults of this, the insoluble oily organic dodecanese and solid powder nano-carbonin the glass tubes were dispersed by the degassed water respectively. After comparedwith ordinary water and analyzed with the thermodynamic theory, we can know thatthe degassed water can improve the insoluble material dispersion and the stability ofthe disperse system.
Keywords/Search Tags:nanobubbles, Atomic force microscope, hydrophobic material, dissolved gas, degassing treatment
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