正滲透作為低耗能脫鹽程序，符合永續能源發展的條件，除了探討當前主流的幾種脫鹽技術，比較彼此之間在技術成熟度、能耗以及限制因子上的差異，並針對正滲透進行更進一步的討論，此脫鹽技術關鍵在於薄膜與提取液兩大方面，本研究聚焦於將離子液體[P4444][Mal]作為提取液應用之探討，觀察此具備相分離現象的離子液體在不同濃度、溫度、時間相分離時性質上的變化，透過紫外線-可見光分光光譜儀 (UV-Visble spectrometers)，來觀察不同濃度相分離產生的臨界溫度，結果在離子液體重量百分濃度30%至70%具有室溫相分離的特性，其餘較低或是較高濃度之比重需要較高之環境溫度，才能產生相分離現象，其相圖呈現U型分佈，以離子液體重量百分濃度為50 %時具有最低臨界相變溫度(LCST)。
濃度與相分離之關聯性直接影響到正滲透脫鹽程序在操作濃度上的調控，在系統中提取液濃度隨著滲透壓所帶來的水通量而下降，導致離子液體水溶液產生相分離現象，進一步處理相分離產生的上層液(Water-rich)以及下層液(Ionic Liquid-rich)，上層液為所需乾淨水資源的主要來源，依使用需求透過不同處理方式來去除與回收少量殘留離子液體，即可得到乾淨再生水資源，而下層液為高濃度離子液體，可繼續回到正滲透系統中作為提取液使用。
觀察主要材料的相分離特性，來將離子液體應用在正滲透薄膜脫鹽程序中，離子液體與水分子間交互作用力隨著濃度變化而改變，進而導致相分離現象發生，從相變化圖來看含水量偏高或是偏低時分散相所佔比例較少，達到兩相分離所需溫度也急遽升高，推測造成原因為分散相與溶劑之作用力會隨著兩者數量差距擴大而增加。

Forward osmosis as a low-energy desalination process, in line with the conditions of sustainable energy development, in addition to the current mainstream of several desalination technology, compared with each other in the technical maturity, energy consumption and limiting factors on the difference. For further discussion on Forward osmosis, the key to this desalination technology is the membrane and draw solution two aspects, this study focused on the ionic liquid [P4444] [Mal] as the application of draw solution to observe the phase separation of the ionic liquid at different concentrations (UV-Visible spectrometer) to observe the critical temperature of phase separation produced by different concentrations. As a result, the ionic liquid has phase separation at percentage of 30% to 70% by weight. The results are shown in phase diagram. At room temperature, the lower or the higher concentration of the ionic liquid need for a higher temperature in order to produce phase separation phenomenon. The phase diagram showing U-like distribution, the ionic liquid weight percentage of 50% has the lowest Low Critical Solution Temperature (LCST).
        The correlation between the concentration and the phase separation directly affects the system of the forward osmosis process. In the system, the concentration of the ionic liquid in the system decreases with the water flux caused by the osmotic pressure, resulting in the phase separation of the ionic liquid aqueous solution, (Ionic Liquid-rich), the upper layer liquid is the main source of the required clean water resources, according to the demand through different treatment to remove and recover a small amount of residual ionic liquid. After retreatment can get clean water resources. Other side, the lower liquid for the high concentration of ionic liquid, can continue to return to the forward osmosis system used as draw solution.
        The interaction between the ionic liquid and the water molecules changes with the change of the concentration, which leads to the phase separation phenomenon. From the phase change diagram. When the water content is too high or low, the proportion of the dispersed phase is small, and the temperature required for the separation of the two phases is also increased rapidly. The reason is that the force of the dispersed phase and the solvent increases with the widening of ionic liquid and water.

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