以超音波改善懸浮溶液薄膜過濾之濾速

Flux Improvement in Membrane Filtration of Suspended Solutions under an Ultrasonic Field

林公璿(Kung-Hsuan Lin)

指導教授 ： 莊瑞鑫

元智大學/工程學院/化學工程與材料科學學系/碩士(2003年)

摘要

本論文主要利用超音波產生的空化現象及其特性，來改善傳統利用乳化型液膜處理廢水流程中的缺點，尤其是W/O乳液在超過濾過程中，薄膜產生嚴重的結垢現象，使過濾濾速降低；並探討W/O乳液在平板超過濾系統中，利用阻力串聯模式分析操作參數對濾速的影響。
實驗分為三個部份，首先利用超音波製備乳液，由實驗中找出最佳的操作條件，當採用當固定內水相100 mL，界面活性濃度3 vol%，內水相對油相體積比為2，操作功率在93 W下，在5 min內，其乳化程度可達100%。
利用製備乳液的條件，探討在超音波場下，比較平板過濾模組中，聚電解質及W/O懸浮乳液結垢模式不同時的超過濾濾速改善效果，由實驗結果可以發現，超音波改善薄膜結垢使濾速回復是可行的，對於聚電解質溶液可使濾速回復至80% 左右，而對於W/O懸浮乳液可回復至60% 左右；在阻力串聯模式分析中，濾速隨著阻力的增加而減少，這些阻力除薄膜本身外，還包括由結垢現象及濃度極化所引起。本文中，得出估算這些阻力的實驗公式，而影響阻力大小的因素包括操作壓力、乳液體積比、超音波操作功率及Tip高度等。
在超音波破乳的實驗中，利用乳液在低pH值環境下的不穩定，外加超音波63 W即會有破乳的現象。

關鍵字

超音波 ； 超過濾 ； W/O乳液 ； 結垢 ； 濃度極化 ； 阻力

並列摘要

In this paper, the characteristics of untrasonic waves like cavitation were applied to modify the processes of ultrafilitration (UF) for the separation of W/O emulsions from external phase. This is because the flux decline and serious fouling phenomena occurs in the ultrafiltration of W/O emulsions. The resistance-in-series model was used to determine the role of operating variables in this system.
Firstly, we used ultrasound to prepare W/O emulsions, and the optimal conditions were 100 mL of internal phase, 3 vol% of surfactant concentration, the ratio of internal phase to oil phase was 2 : 1, and 93 watt of operating power. Within 5 mins, ultrosound upped the volume of W/O emulsions to 100 %.
In the stirred cell, ultrasound can improve the flux during ultrafiltration of PEI solutions and W/O emulsions. In both solutions, the permeate fluxes were enhanced by 80 % and 60 % under an ultrasonic field.
In the resistance-in-series model, permeate flux decreases with an increase of the resistances caused by fouling phenomena (solute adsorption, etc.) and concentration polarization/gel layer formation. The correlation equations for estimating those resistances have been developed in this work. It was found that the resistances are functions of the applied pressure, volume ratio of W/O emulsions, operating power, and tip height.
Finally, we made use of unstable of W/O emulsions at low pH, and demulsified at 63 watts of operating power under the ultrasonic field.

並列關鍵字

untrasonic waves ； ultrafiltration ； W/O emulsions ； fouling ； concentration polarization ； resistances

參考文獻

蕭瑞昌，「利用水溶性幾丁聚醣以薄膜過濾法去除微量之金屬離子」，碩士論文，元智工學院，中壢(1997)。

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