近年來石化能源漸漸枯竭，然而人類為追求高品質生活仍促使科技蓬勃發展，石油的需求量因而持續上升。石油枯竭的隱憂，終會是人們無法擺脫的夢魘，如何減緩石油消耗，尋找替代能源已成為主要課題，而生質能源中，則以生質酒精較受矚目。因此，本研究利用空氣式薄膜蒸餾法(Air-gap membrane distillation，AGMD)及空氣掃掠薄膜蒸餾法(Sweeping-gas membrane distillation，SGMD)將此兩種方法應用於乙醇水溶液分離系統中，探討AGMD、SGMD所適用的PVDF膜材條件、溫度對於通量及乙醇選擇性的影響。
研究結果顯示：AGMD模組中，以PVDF 761A之膜材所製成的平板膜效果較佳，乙醇的選擇性隨著膜材的高分子濃度增加而上升，也會隨著凝聚劑之IPA濃度增加而提高效果。在SGMD模組中，以PVDF 720之膜材製成之中空纖維膜，在拉伸25 mm、進料端溫度70oC、空氣流速240 mL/min時的選擇性為5.71效果最佳，且由實驗結果可得知，乙醇的選擇性會隨著進料端溫度的上升、空氣掃流的流速的下降及拉伸長度的改變，而有所影響。並探討PVDF中空纖維膜於長時間連續操作之實驗結果。 In recent years, advancement in science and technology along with increasing world population has caused a great increase in demand and consumption for oil. Natural resources such as fossil fuels are naturally being depleted in the process. In order to prevent the continuous depletion of fossil fuels, finding alternative energy sources such as geothermal, wind, and biomass energy has gained much attention. Biomass is a renewable energy source, where it can be converted into biofuel such as ethanol. Two methods in ethanol distillation system are investigated such as air-gap membrane distillation (AGMD) and sweeping-gas membrane distillation (SGMD). The effect of membrane conditions, temperature and flux on ethanol selectivity and separation efficiency was studied.
In the AGMD module equipped with flat late PVDF membrane, an increase in IPA concentration of coagulate solution would increase the efficiency of ethanol purification as well. In SGMD module equipped with PVDF 720 hollow fiber, the following optimum conditions are used membrane stretch of 25 mm, feed-side temperature at 70�C and air flow rate of 240 mL/min. From the results, the purification effect of ethanol is affected by changes in the feed-side temperature, air sweep flow velocity and stretches the length of the hollow fiber, which in turn affects membrane selectivity and flux.
