醇類對水中有機溶質揮發影響之研究

Effect of alcohols on volatilization of organic solutes from water

蕭松旺(Sung-Wang Hsiao)

指導教授 ： 趙煥平

中原大學/工學院/土木工程研究所/碩士(2011年)

https://doi.org/10.6840/cycu201100822

摘要

摘 要
在過去的研究中發現界面活性劑在溶液中可降低有機物之揮發速率，且可分增溶效應與表面阻滯兩種作用機制，界面活性劑同時具親水基與疏水基，在水溶液中傾向聚集於界面並將疏水基朝外，導致有機物揮發在界面受到阻滯，醇類與界面活性劑具有類似之性質，同樣具有親水基與疏水基，因此在溶液中同樣可能累積於氣液交界面，或是增加有機物溶解度，但醇類揮發速率遠較界面活性劑高，累積在交界面之醇類對其他有機物揮發速率之影響並不一定與界面活性劑相同，若醇類可吸引其他有機物累積於交界面，在醇類揮發時將有機物一併帶離液面，則可能與界面活性劑產生不同之結果，為此，本研究將探討醇類對於有機物從水中揮發之影響。
本研究中選用了三種不同水溶解度的醇類，分別為甲醇、丁醇及庚醇測試對有機物的揮發影響，而實驗之有機物則包括七種單環芳香烴化合物，他們具有接近之亨利常數與明顯的水溶解度差異，利用不同濃度及種類醇類加入溶液，測試選擇有機物質傳係數之變化以確認醇類之影響，最後加入風速擾動的影響，觀看在此情況下有機物在風速與靜止條件下質傳係數比值變化，以探討醇類對揮發之影響機制。
研究結果發現在靜置的情況下，甲醇能使有機物水溶解度增加並且有產生抑制揮發之效果，而丁醇及庚醇卻能使有機物的揮發效果增加，在風速擾動情況下所選擇有機物的KOL與風速呈線性關係，其加入醇類後關係性從純水的線性轉變成凹面向下的曲線。研究結果顯示低碳數醇類以增溶效應抑制有機物揮發，高碳數醇類自氣液交界面揮發時會將其他有機物一併帶離，形成共揮發(Co-volatilization)效應，也進一步證實有機物在交界面濃度為決定揮發之關鍵因子。
關 鍵 字 : 醇類、揮發、質傳係數(KOL)、共揮發效應。

關鍵字

質傳係數(KOL) ； 共揮發效應。 ； 醇類 ； 揮發

並列摘要

Abstract
The objective of this study is to investigate the effects of alcohols in the solution on volatilization rates of organic solutes. The selected alcohols include methanol, butanol, and heptanol with added concentrations of 100, 300 and 500 ppm. The seven target organic compounds with water solubility from 1780 to 55 mg/L mixed with alcohols to test mass transfer coefficient KOL under 0~6.0 m/s wind speeds. The effects of the alcohols on emissions of organic solutes were determined via the obtained KOL values. Also, the mechanism of alcohol affecting organic solute emission was elucidated using the KOL ratio of organic compounds under the static and wind turbulence conditions. The result indicates the presence of alcohol with less carbon number, such as methanol, could reduce the KOL values of the organic compounds. The reason is ascribed to that the alcohols can enhance the solubilities of the test organic compounds. On the contrary, presence of alcohol with high carbon number, such as butanol and heptanol could increase the KOL values of the organic compounds. The reason of increased volatilization rates of solutes was considered as alcohols accumulate in the interface, which affects the volatilization of organic solutes. This phenomenon is called as co-volatilization. Moreover, the result demonstrates the interaction of organic compounds in the interface relative to solution is a dominant factor to determine emission of the organic solutes.

Keywords: Alcohol, Co-volatilization, Two-film theory, Organic solutes

並列關鍵字

Organic solutes ； Alcohol ； Two-film theory ； Co-volatilization

參考文獻

Chao, H.-P. (2009a) “A New Approach for Estimating Emissions of Organic Solutes and Organic Solvents under Wind Speeds”, Atmospheric Environment, 43, 2045-2051.

Chao, H.-P. (2009b) “Volatilization Characteristics of Organic Solutes in Stirred Solution”, Journal of Environmental Management, 90, 3422-3428.

Chao, H.-P.; Lee, J.-F. and Lee, C.-K.(2000) "Effects of Dissolved Chemicals on the Volatilization Rates of BTEX" Journal of Environmental Science and Health Part A, A35(6), 869-881.

Chao, H.-P. ; Lee, J.-F. ; Lee, C.-K. ; Huang, F.-C. and Annadurai, G. (2008) “Volatilization Reduction of Monoaromatic Compounds in Nonionic Surfactant Solutions”, Chemical Engineering Journal, 142, 161-167.

Chao, H.-P. ; Lee, J.-F.; Lee, C.-K. and Huang, H.-C.(2005a)" Volatilization Characteristics of Organic Compounds in the Coagulation Process", Journal of Environmental Engineering-ASCE,131(9), 1253-1259.