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研究生:鍾志平
論文名稱:界面動態效應與氣泡合併程序之研究
指導教授:楊毓民楊毓民引用關係
學位類別:碩士
校院名稱:國立成功大學
系所名稱:化學工程研究所
學門:工程學門
學類:化學工程學類
論文種類:學術論文
論文出版年:1997
畢業學年度:85
語文別:中文
論文頁數:139
中文關鍵詞:界面動態效應氣泡合併程序
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  • 被引用被引用:1
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在本論文中,以高速攝影機觀測並測量水中雙泡成長合併之過程,並探討添加單一界面活性劑(SDS99%、SDS95%以及Triton X-100)對雙泡間薄膜合併時間的影響。同時透過不同的減薄理論加上破裂理論來預測添加了上述界面活性劑及正醇類水溶液中雙泡成長合併的時間,並與實驗測量值進行比較。除此之外,並利用合併時間的實驗值透過表面黏滯力減薄理論如表面波動破裂理論來求得氣液表面黏度值。
由實驗結果發現水中添加少許界面活性劑的確能增加合併時間,這主要是由於界面活性劑能增加雙泡間液膜的黏滯力及表面彈性。而由理論分析配合實驗值之比較結果來看,添加了正醇類之水溶液申的雙泡合併時間與表面彈性減薄模型加上表面波動破裂模型之預測結果相近,而添加SDS99%,SDS95%,以及Triton X-100之水溶液中雙泡合併時間,則與表面黏滯力減薄模型加上表面波動破裂模型的預測結果較符合,顯示了這一類界面活性劑可能在吸附機構上有所不同。
分析表面張力對濃度的變化,對五醇類水溶液而言;碳數愈高,則-(dγ/dC)愈大,使得利用Andrew模型求表面張力差值Δγ時,造成較大的誤差。而由於SDS99%,SDS95%及Truton X-100吸附至表面的速率較快,因此造成Andrew模型中對Δγ的高估,使得以表面彈性減薄模型如表面波動破裂模型的預測值遠大於實驗值,此一吸附速率的影響也同時可以解釋SDS99%為何較Triton X-lOO能增加薄膜的穩定性。
另外在已知合併時間值後,利用表面黏滯力減薄模型如表面波動破裂模型所構成的的合併理論來模擬純水以及SDS水溶液的氣液表面黏度值與文獻值做比較,發現兩結果相近。因此利用合併時間值來透過此合併理論求得表面黏度值的有其實際的可行性。


In this paper, high speed cinematography was used to observe the coalescence process between two bubbles growing in aqueous solution. The effect of adding surfactants (SDS99%, SDS95%, and Triton X-100) to the stability of the thin aqueous film between the two bubbles were studied. Different drainage models combined with breaking model were used to predict the coalescence time between two growing bubble with addition of surfactants mentioned above and n-alcohols. The predictied results were then compared with experimental data. Besides, the coalescence time can also be used to predict, through the combined drainage model and breaking model, the surface viscosities.
In the consequence of experiments, we found that adding some surfactants into water can dramatically increase the coalescence time. This is due to the fact that the surfactant could increase the surface viscosity as well as surface elasticity of the thin liquid film between the two bubbles. According to the theoretic analysis and experimental data, the predicted results by using surface elasticity model combined with surface wave model could match the experimental data of n-alcohols solution very well. In the other hand, the predicted results using surface viscosity model combined with surface wave model can only match the experimental data in SDS99%, SDS95%, and the Triton X-100 solution systems. This result shows that there should be some difference, such as adsorption mechanism, between the two kinds of surfactants.
Analyzing surface tension dependence upon surfactant concentration, we found that the value of -(dγ/dC) for n-alcohols increases as increase in the carbon number, this result in a large deviation on surface tension difference Δγ when Andrew model was used. Consequently, the value of Δγ, when surfactants such as SDS99%, SDS95%, and Triton X-100 are used, may also be over predicted. This can be explained from the high adsorption rate of these surfactants onto the gas/liquid interface so that the actual Δγ should be lower than calculated. This effect can also be used to explain why the film in SDS99% system is more stable than in the Triton X-100 system.
In the other way, after knowing the coalescence time in certain aqueous systems, such as pure water or SDS solution, etc., we can predict the surface viscosity in gas/liquid interface. By comparing with the experimental data from other studies, the results were found to match very well. This indicates that the coalescence time, once known, can be used to predict, through this coalescence model, to obtain the surface viscosity for different surfactant selections.

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