有機物自水中揮發之研究; Organic Solute Emissions from Various Dilute Solutions

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题名:	有機物自水中揮發之研究;Organic Solute Emissions from Various Dilute Solutions
作者:	趙煥平;Huan-Ping Chao
贡献者:	環境工程研究所
关键词:	揮發;擾流;風速;界面活性劑;表面損失揮發模式;氣體動力學;kinetic gas equation;surfactant;liquid stirring;wind speed;volatilization characteristic
日期:	2003-11-14
上传时间:	2009-09-21 12:13:01 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	本研究主要內容包括建立新的揮發模式﹐解釋環境因子對揮發之影響及分析有機物在不同環境條件下的揮發特性。傳統以二層膜理論估算有機物之揮發量存在一些較不適用或無法精確估算的情形，包括擾流狀態、較適於估算高揮發性有機物、無法由物理化學性質解釋影響揮發之因子及對純物質揮發進行估算等四部份。為克服上述問題，本研究新提出之模式改以氣體動力學中估算有機物在真空下，單位時間內撞擊1 cm2平板的分子質量所用之方程式為基礎，並將氣相參數β與擾流參數α加入方程式中；其中β為風速與大氣壓力的函數，在相同的大氣條件下β接近常數，α為有機物在液體交界與溶液中濃度比值，其為擾流強度、亨利常數與化合物分子量的函數，此模式將原本以有機物在溶液中濃度為揮發量估算之方法轉變成以有機物在交界面濃度減少來決定揮發損失。此新提出之模式稱之表面損失揮發模式(surface depletion rate-limiting, SDRL)，另由實驗的結果證明了所提出揮發模式之有效性。對揮發之影響因子部份，證實揮發是系統能量與溶質與溶液間親和力之競爭。以此為依據，增加溫度與擾流強度會使系統能量增加從而增加揮發速率﹔加入界面活性劑或大分子有機物後，則會增加溶質與溶液間的親和力，使有機物的揮發受到抑制。對於有機物的揮發特性部份﹐以不同物化性質有機物置於不同的環境條件下﹐觀察彼此間揮發速率的差異﹐並以傳統的質量傳送理論、所提出之表面損失模式與活化能反應速率方程式解釋選擇化合物所表現出的揮發特性﹐同時也詳細探討了三種模式的適用性。 This study is to develop a new volatilization model and to elucidate volatilization characteristics of different organic compounds under various environmental conditions. The gas kinetic equation for the pure substance emission under the vacuum condition was extended to be the volatilization model by adding a gas parameter β and a liquid-turbulence coefficient α. The β value of different organic compounds at the given environmental condition was found to be a constant. The α is a function of the liquid turbulence, the wind speed, the Henry’s law constant and the molecular weight of the interested compounds. The volatilization of an organic solute from a solution is the result of two competing factors. The first consists of accelerative effects that include the thermal energy and the mixing intensity. The second consists of inhibitive effects, namely, the affinity that exists between the solute and the solution. Consequently, the solute emission rates depend on the environmental conditions (such as the liquid temperatures and the mixing intensities), wind speeds, and the solute and solution properties. The effects of the above-mentioned environmental conditions on volatilization will be discussed with the physico-chemical properties of the selected organic compounds in the section. On the other hand, the ratio of the volatilization rate constant for the organic compound to that for the reference substance depicts volatilization characteristics under different environmental conditions. It was found that Henry’s law constant for stirred liquid, wind speed and aqueous solubilities of compounds for the surfactant in the solution can determine the volatilization diversity. The results revealed that the organic compounds with the similar physico-chemical properties exhibited the nearly identical volatilization characteristic in the various environments. To select the reference compound on the basis of their physico-chemical properties is a more effective method for estimating the volatilization rates of solutes under various environmental conditions.
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