納米氣泡對(duì)污染物的吸附及其影響因素探究
發(fā)布時(shí)間：2018-07-31 17:49
【摘要】：納米氣泡是人們?cè)谘芯克械膬蓚�(gè)疏水表面間的疏水長(zhǎng)程作用機(jī)制時(shí)提出的。特別是2000年納米氣泡原子力圖像的發(fā)表以及隨后大量的實(shí)驗(yàn)驗(yàn)證,固液界面上存在納米氣泡的觀點(diǎn)逐漸被越來(lái)越多的人所接受。近年來(lái),界面問(wèn)題越來(lái)越受到人們的廣泛關(guān)注,納米氣泡的產(chǎn)生及應(yīng)用等有關(guān)問(wèn)題也成為人們研究的熱點(diǎn)。經(jīng)典熱力學(xué)表明納米氣泡在水中存在時(shí)間僅為幾微秒,然而大量實(shí)驗(yàn)表明界面納米氣泡在溶液中可以存在幾天,原子力顯微鏡也直接觀察到了納米氣泡。研究表明,納米氣泡在界面上的穩(wěn)定存在對(duì)納米科技、界面科學(xué)、流體力學(xué)、生物學(xué)和其他領(lǐng)域都有廣泛的影響。此外,納米氣泡會(huì)引起流體在界面的滑移,減少流動(dòng)阻力,并與表面粘附、膠體分散、礦石浮選、廢渣處理等方面密切相關(guān)。因此,界面納米氣泡具有十分重要的研究應(yīng)用價(jià)值。目前原子力顯微鏡(AFM)是直接探測(cè)固液界面納米氣泡的最有力手段。在用AFM對(duì)納米氣泡成像時(shí),通常選用表面較為平整的基底。主要有高序熱解石墨(HOPG),云母,金,聚苯乙烯薄膜,以及修飾過(guò)的硅。產(chǎn)生納米氣泡的方法有很多,如直接浸漬法,兩種溶劑替換以及快速加熱,電化學(xué)法等。其中,醇水替換被廣泛應(yīng)用并被證明是能高度重復(fù)的在不同基底上獲得大量納米氣泡的有效方法。同樣,也能使用其它有機(jī)溶劑與水替換來(lái)產(chǎn)生納米氣泡。然而,有機(jī)溶劑與水的替換存在著一些局限性,例如不能用于生物膜上,溶劑中易引入有機(jī)污染物等。為了探究在原子級(jí)平整的電極表面能否生成納米氣泡,我們采用了循環(huán)伏安法法,用電化學(xué)工作站監(jiān)測(cè)電極表面雙電層電容的變化。實(shí)驗(yàn)中我們采用溶液替換法利用雙電層電容與相對(duì)介電常數(shù)的關(guān)系來(lái)推測(cè)電極表面的納米氣泡生成與否。實(shí)驗(yàn)結(jié)果表明,該方法同樣可以在電極表面生成納米氣泡。我們分別用深度脫氣后的醇水、鹽水在電極表面替換,我們發(fā)現(xiàn)這時(shí)候的雙電層電容和裸電極相比幾乎沒(méi)有什么變化,也就是說(shuō)雙電層的介質(zhì)幾乎沒(méi)有什么改變,這時(shí)在電極表面幾乎沒(méi)有納米氣泡生成。我們還探究了鹽溶液的濃度和種類對(duì)納米氣泡生成的影響。鹽溶液的濃度越大,鹽溶液與水的濃度差就越大,產(chǎn)生的納米氣泡就越多。這是由于高濃度的鹽溶液所含自由離子較多,成核驅(qū)動(dòng)力比較大,形成晶胚就會(huì)多,可以在電極表面形成更多的成核位點(diǎn)。由于納米氣泡的特殊性質(zhì),在生活生產(chǎn)中的應(yīng)用前景也十分廣闊。我們通過(guò)模擬重金屬污染和有機(jī)物污染兩大類,用交流阻抗法研究了超聲法在電極表面產(chǎn)生的納米氣泡對(duì)水中污染物的吸附作用。通過(guò)電化學(xué)工作站檢測(cè)出電極表面超聲后的阻抗比裸電極在污水中的阻抗大,這說(shuō)明了超聲法產(chǎn)生的納米氣泡能夠增強(qiáng)污染物的吸附。而且隨著超聲時(shí)間的增長(zhǎng),納米氣泡會(huì)越來(lái)越多,但是增長(zhǎng)率會(huì)有所下降,最后幾乎趨于穩(wěn)定,阻抗值也越來(lái)越大,也就是說(shuō)納米氣泡的多少會(huì)影響水中污染物的吸附。
[Abstract]:Nano bubbles are proposed by people to study the mechanism of hydrophobic long-range interaction between two hydrophobic surfaces in water. In particular, the publication of the atomic force images in 2000 and a large number of experiments have proved that the existence of nano bubbles on the solid-liquid interface has gradually been accepted by more and more people. In recent years, the interface problem has become more and more popular. To people's widespread concern, the production and application of nano bubbles have become a hot spot of research. Classical thermodynamics shows that the existence of nanoscale in water is only a few microseconds. However, a large number of experiments show that the nano bubbles can exist in the solution for several days, and the original sub force microscope also directly observed the nano bubbles. It is shown that the stability of nanoscale on the interface has a wide influence on nanotechnology, interface science, fluid mechanics, biology and other fields. In addition, the nano bubbles will cause the fluid to slip at the interface, reduce the flow resistance, and closely related to surface adhesion, colloid dispersion, ore flotation, waste residue treatment and so on. Surface nanoscale has very important research and application value. At present, atomic force microscopy (AFM) is the most powerful means for direct detection of nanoscale in solid-liquid interface. When using AFM to imaging nanoscale, the surface of the surface is usually used. There are mainly high order pyrolytic graphite (HOPG), mica, gold, polystyrene film, and modified There are many ways of producing nanoscale, such as direct impregnation, two solvent replacement, rapid heating, electrochemical method, etc. in which alcohol water replacement is widely used and proved to be an effective method for obtaining a large number of nanoscale bubbles on different substrates. However, there are some limitations in the substitution of organic solvents and water, such as the inability to use the organic pollutants in the biofilm. In order to explore the formation of nano bubbles on the surface of the atom level flat electrode, we used the cyclic voltammetry to monitor the double layer capacitance on the electrode surface. In the experiment, we use the solution substitution method to make use of the relationship between the double layer capacitance and the relative dielectric constant to speculate on the formation of nano bubbles on the electrode surface. Experimental results show that the method can also produce nano bubbles on the surface of the electrode. At this time, there is little change in the double layer capacitance compared with the bare electrode, that is to say, there is little change in the medium of the double layer. At this time, there are almost no nanoscale bubbles on the surface of the electrode. We also explore the effect of the concentration and type of salt solution on the formation of nanoscale. The greater the concentration of salt solution, the concentration of salt solution and the concentration of water. The greater the degree difference is, the more nano bubbles are produced, which is due to the more free ions in the high concentration of salt solution, the larger the driving force of the nucleation, the formation of more crystal embryos and the formation of more nucleation sites on the surface of the electrode. Two kinds of heavy metal pollution and organic matter pollution are proposed. The adsorption of nano bubbles produced by ultrasonic method on the surface of the electrode is studied by the method of AC impedance. The impedance of the electrode surface after ultrasonic is detected by the electrochemical workstation. The impedance of the bare electrode in the sewage is larger than that of the bare electrode. This shows the nano bubble energy produced by the ultrasonic method. With the increase of the ultrasonic time, there are more and more nanoscale bubbles, but the growth rate will decrease. Finally, it tends to stabilize, and the impedance value is increasing. That is, the number of nano bubbles will affect the adsorption of pollutants in the water.
【學(xué)位授予單位】：上海師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X703;O647.3
本文編號(hào)：2156362
[Abstract]:Nano bubbles are proposed by people to study the mechanism of hydrophobic long-range interaction between two hydrophobic surfaces in water. In particular, the publication of the atomic force images in 2000 and a large number of experiments have proved that the existence of nano bubbles on the solid-liquid interface has gradually been accepted by more and more people. In recent years, the interface problem has become more and more popular. To people's widespread concern, the production and application of nano bubbles have become a hot spot of research. Classical thermodynamics shows that the existence of nanoscale in water is only a few microseconds. However, a large number of experiments show that the nano bubbles can exist in the solution for several days, and the original sub force microscope also directly observed the nano bubbles. It is shown that the stability of nanoscale on the interface has a wide influence on nanotechnology, interface science, fluid mechanics, biology and other fields. In addition, the nano bubbles will cause the fluid to slip at the interface, reduce the flow resistance, and closely related to surface adhesion, colloid dispersion, ore flotation, waste residue treatment and so on. Surface nanoscale has very important research and application value. At present, atomic force microscopy (AFM) is the most powerful means for direct detection of nanoscale in solid-liquid interface. When using AFM to imaging nanoscale, the surface of the surface is usually used. There are mainly high order pyrolytic graphite (HOPG), mica, gold, polystyrene film, and modified There are many ways of producing nanoscale, such as direct impregnation, two solvent replacement, rapid heating, electrochemical method, etc. in which alcohol water replacement is widely used and proved to be an effective method for obtaining a large number of nanoscale bubbles on different substrates. However, there are some limitations in the substitution of organic solvents and water, such as the inability to use the organic pollutants in the biofilm. In order to explore the formation of nano bubbles on the surface of the atom level flat electrode, we used the cyclic voltammetry to monitor the double layer capacitance on the electrode surface. In the experiment, we use the solution substitution method to make use of the relationship between the double layer capacitance and the relative dielectric constant to speculate on the formation of nano bubbles on the electrode surface. Experimental results show that the method can also produce nano bubbles on the surface of the electrode. At this time, there is little change in the double layer capacitance compared with the bare electrode, that is to say, there is little change in the medium of the double layer. At this time, there are almost no nanoscale bubbles on the surface of the electrode. We also explore the effect of the concentration and type of salt solution on the formation of nanoscale. The greater the concentration of salt solution, the concentration of salt solution and the concentration of water. The greater the degree difference is, the more nano bubbles are produced, which is due to the more free ions in the high concentration of salt solution, the larger the driving force of the nucleation, the formation of more crystal embryos and the formation of more nucleation sites on the surface of the electrode. Two kinds of heavy metal pollution and organic matter pollution are proposed. The adsorption of nano bubbles produced by ultrasonic method on the surface of the electrode is studied by the method of AC impedance. The impedance of the electrode surface after ultrasonic is detected by the electrochemical workstation. The impedance of the bare electrode in the sewage is larger than that of the bare electrode. This shows the nano bubble energy produced by the ultrasonic method. With the increase of the ultrasonic time, there are more and more nanoscale bubbles, but the growth rate will decrease. Finally, it tends to stabilize, and the impedance value is increasing. That is, the number of nano bubbles will affect the adsorption of pollutants in the water.
【學(xué)位授予單位】：上海師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X703;O647.3
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