| 摘要: | 摘 要 過去學者探討有機物自水中揮發行為時，大都著重於高揮發性有機物，對於較低揮發性有機物較少探討，但有機物本身之物化性質及環境條件也會支配其揮發速率。本研究選用十三種不同物化性質之有機物，以其亨利常數與水溶解度區分為四類，於各種環境條件（液相擾流、氣相擾動及溶液中添加界面活性劑或多苯環有機物）進行批次實驗，目的在探討有機物於不同環境條件下之揮發特性，並利用三種揮發模式（質量傳送模式、修正Knudsen擴散方程式、反應速率活化能觀念）描述其揮發行為，進而比較其適用性及應用性。 實驗結果顯示(1)液相擾流、氣相擾動系統中，亨利常數為決定有機化合物質傳速率之重要因子；對於有添加物於溶液中，則有機物的水溶解度為決定質傳速率之重要因子。在不同液相擾流強度下，高亨利常數有機物之質傳係數變化趨勢，大致呈向上彎曲狀，而低亨利常數有機物則呈現飽和彎曲狀，此差異可由有機物在交界面之濃度差來解釋；(2)有機物於界面活性劑或多苯環染料溶液中之質傳速率，可視為添加物濃度與有機物本身溶解度之函數關係，特別在多苯環染料溶液中，因苯環型有機物與其分子間作用力較明顯，所以質傳速率下降程度比直鏈型明顯。(3)相似物化特性之有機化合物，於各種環境變數下其質傳係數變化皆相似。(4)在三種揮發模式中：質傳理論適用於解釋高亨利常數有機物之揮發行為，但無法完全解釋溶液性質對其揮發行為之影響；修正Knudsen方程式較適用於低亨利常數之有機物；反應速率活化能觀念，雖可解釋環境變數之影響，但僅提供一觀念模式，無法量化所得之結果。 Abstract In the past, investigators who devoted to study the evaporate behavior of organic compounds from water solution merely put emphasize on the organic compounds with relatively high volatility, for the organic compounds with relatively low volatility which seldom be illustrated. Additionally, the volatility rate of organic compounds can be dominated by their physical and chemical characteristics. In this study thirteen organic compounds that can be classified for four types were selected and experiments were carried out, under different environmental conditions. (i.e., liquid stirring, gas mixing and surfactant or poly-benzene organic compounds addition to the solution.), The organic compounds be treated in batch experiment, for the purpose of evaporate behavior can be illustrated under different environmental coefficient conditions. Moreover, not only evaporate behavior can be described by three evaporate models (i.e., Mass Transfer Theory, Modified Knudsen Diffusion Equation, Reaction Rate Concept) but also the applicability and application of models can also be studied. Under liquid/gas stirring system, the Henry’s constant was a significant factor for the mass transfer rate of organic compounds. Additionally, under the solution mixing with soluble organic compounds, the solubility of the organic compounds was a dominant factor. The mass transfer coefficients of organic compound with relatively high Henry’s constant tended to upward increase with an increasing in the intensity of liquid stirring, The transfer coefficient of the organic compounds with the relatively low Henry’s constant tended to downward increase. The difference results can be explained for the concentration gradient within gas/liquid interface. The mass transfer rate of the organic compounds in surfactant or poly-benzene dyes solution can be regarded as the function of soluble organic compounds concentration and solubility. Particularly in poly-benzene dyes solution, for the interactions of non-benzene compounds were not significant from benzene compounds, a decrease of the mass transfer rate in the latter was more prominent than that in the former. The experiment results presented that the mass transfer coefficients for different organic compounds that had similar physical and chemical properties were very closely. Of three evaporate models, Mass Transfer Theory is largely responsible for the organic compound with relatively high Henry’s constant, but hard to explain the influence of the evaporate behavior from aqueous characteristics completely. Modified Knudsen Diffusion Equation is largely responsible for the organic compound with relatively low Henry’s constant. Reaction Rate Concept merely was applied to account for the influence resulted from the different environmental conditions. |
