- 學位論文
探討不同阻垢劑對於薄膜蒸餾之效能影響
Study of the Effect of Different Antiscalants on Membrane Distillation Performance
摘要
中文摘要 本研究係利用平板式直接接觸法進行薄膜蒸餾系統試驗，探討薄膜結垢對於滲透通量及阻擋率之影響。為了有效清除薄膜上之結垢，本研究在進料溶液中各別添加檸檬酸及不同之阻垢劑，並探討一最適化之參數，期望能有效解決薄膜結垢之因素以延長薄膜使用壽命。 薄膜蒸餾經常伴隨著結垢的產生，不僅影響滲透通量也會降低鹽之阻擋率，若不即時改善待薄膜加速結垢則勢必增加用膜成本。此結垢通常為無機鹽類之結垢，適當地使用前處理或添加化學藥劑能有效地抑制薄膜結垢。為了節省前處理所花費之成本及省去利用化學藥劑清洗薄膜之時間，本節直接於進料溶液中添加少量之檸檬酸。檸檬酸係一種螯合劑，在水溶液中會產生R-COO-與結垢中的金屬離子結合，所形成之化合物會在水中溶解成一穩定狀態，以達到除垢的目的。除了在進料溶液中添加檸檬酸，吾人也在進料溶液中分別添加二種阻垢劑，除垢劑經常用於水處理上，以去除水垢及金屬離子等，本研究添加阻垢劑同樣期望能改善薄膜結垢。經由實驗證實，在進料溶液中加少量之檸檬酸及阻垢劑皆能提升滲透通量且薄膜表面形態有較佳之效果。 本研究中主要利用聚偏氟乙烯（Polyvinylidenefluoride, PVDF）商業膜材與中原大學薄膜中心自行製備之聚四氟乙烯（Polytetrafluoroethylene, PTFE）薄膜進行薄膜蒸餾試驗。研究發現PTFE薄膜之滲透通量皆比PVDF還高，其原因可歸咎於PTFE之接觸角較PVDF高，可避免膜孔被潤濕而降低滲透通量。高孔隙度使PTFE單位面積內能有更多的蒸氣分子通過膜孔以利於滲透流體冷凝並收集之。另外，由選擇層與支撐層所組成的複合薄膜PTFE其蒸氣所走的路徑較單層薄膜PVDF短，因此其質傳阻力較低而利於增加滲透通量。 關鍵字：薄膜蒸餾、薄膜結垢、檸檬酸、阻垢劑
並列摘要
Abstract In this study, the use of flat plate in direct contact membrane distillation system, test method, the flux of membrane fouling and blocking rate for the impact. In order to effectively remove the scale on the film, the study individually in the feed solution of citric acid and different inhibitors, and to explore an optimization of parameters, desired scale of the film can be an effective solution to extend the membrane life factors . Membrane distillation is often accompanied by scaling of production, not only affect the flux rate will reduce the salt block, if not immediately improve the speed until the film is bound to increase membrane fouling costs. This scaling is usually inorganic salts of the scale, the proper use of pre-treatment or added chemicals can effectively inhibit the membrane fouling. To save the cost of pre-treatment costs and eliminating the use of chemical cleaning film of the time, this section directly in the feed solution, add a small amount of citric acid. Department of a chelating agent citric acid, in aqueous solution will produce R-COO-and scaling of metal ions, the formation of compounds dissolved in water into a steady state, in order to achieve the purpose of cleaning. In addition to the feed solution, citric acid, I also feed solution were added two kinds of inhibitors, detergents are often used for water treatment to remove scale and metal ions, inhibitors of this study add also hope to improve the film scale. Confirmed by experiments, the feed solution by adding a small amount of citric acid and inhibitors have encountered to enhance the flux and film surface morphology have better results. In this study, the main use of polyvinylidene fluoride (Polyvinylidenefluoride, PVDF) membrane and the commercial center of Chung Yuan Christian University self-prepared film of PTFE (Polytetrafluoroethylene, PTFE) membrane for membrane distillation experiments. The study found that the flux of PTFE film are even higher than PVDF, PTFE of the reason can be attributed to the high contact angle than the PVDF can be avoided by wetting the membrane pore and reduce the flux. PTFE high porosity so that the internal energy per unit area of the vapor molecules have more holes to facilitate the penetration of fluid through the membrane and collect the condensate. In addition, by selecting the layer and support layer composite film of the PTFE vapor path that is short compared with single-layer thin-film PVDF, so the mass transfer resistance is lower and help to increase the flux. Keywords: membrane distillation, membrane scaling, citric acid, antiscalants