改質之聚醚醯亞胺薄膜結構對油水乳化分離影響

Abstract

為了減少回收金屬銦離子的操作步驟，液液萃取成為能同時萃取與反萃取的重要方法，對此衍生出眾多類型的液液萃取，通稱為液膜。其中，近年開發的ESMS_circulation液膜在連續式的系統中，因萃取劑與進料相會形成微乳液，導致已萃取完成的進料相無法從系統中移除，因此希望藉由薄膜技術達到油水分離的效果。本研究使用經PEG-diamine化學改質過的聚醚醯亞胺(Modified Polyetherimide)高分子，並溶解於NMP與2P溶劑中，最後以濕式法刮製成膜。 NMP系統製備出巨型孔洞的截面結構，由於底層為封閉的細胞型孔洞，導致純水通量低；2P系統因溶解參數差值大與氫鍵的緣故，製備出無巨孔且有節點的海綿狀結構，導致2P系統機械強度不好，然而其連通的雙連續結構與改質後薄膜的親水性，使其純水通量最大；水添加劑則由於2P系統因易膠化的緣故，導致高分子無法溶解，而NMP + 2 wt% water系統則是發現雖然巨型孔洞減少，然而其水接觸角最低，因而使純水透過率也有所上升，此外，在12 wt%裡發現底層結構為連通的孔洞，因此在油水分離的透過率效能與2P系統接近。 由於非極性與低黏度的緣故，使得Isopar-L/水對Modified PEI的分離只會讓水透過薄膜，但當採用0.6 M DE2HPA作為油相其中的成分時，則由於油相的黏度與DE2HPA同時帶有親水與疏水基團，使其與Modified PEI吸引而讓油相透過薄膜。另外，透過調整DE2HPA濃度，可以證明油相中親水基團的數量與黏度，會影響水相或油相透過薄膜。除了油相的黏度外，其他的實驗設計也間接證明材料與油相性質的影響，主要是帶正電之高分子與帶負電之親水油相的靜電吸引，將導致油相容易吸附在帶有親水基團的PEI薄膜內，從而影響油水透過的結果。

To reduce the operation steps of recovering indium metal ions, liquid-liquid extraction has become an important method that can extract and strip at the same time, for which various types of liquid-liquid extraction are developed, commonly called liquid membrane. Among them, the continuous system of ESMS_circulation liquid membrane developed in recent years; however, the extractant and the feed phase will form a microemulsion, resulting in the extracted feed phase cannot be removed from the system, therefore, it is hoped that the effect of oil/water separation can be achieved by membrane technology. In this study, a polymer, modified polyetherimide, chemically modified by PEG-diamine is used, dissolved in NMP and 2P solvent, and is finally cast into a film by wet immersion method. The NMP system has macrovoids in the cross-sectional and due to the cellular closed pores at the lower layer, leading to low pure water permeability. On the account of the large difference between solubility parameters and the effect of hydrogen bonding, the sponge-like structure without macrovoids and nodes was formed, bringing about poor mechanical strength in 2P system, but its connected, bi-continuous structure and the hydrophilicity of the modified PEI made its pure water permeability the largest. The water additive is insoluble in 2P system due to easy gelatinization, while the NMP + 2 wt% water system finds that although the amount of macrovoids are reduced, it has the lowest water contact angle, so that the pure water permeability also increases, in addition, the structure in lower layer is found that the pore is connected in 12 wt%; hence, the efficiency of permeability for oil/water separation is close to that of the 2P system. Due to the non-polarity and low viscosity, the separation of Isopar-L/water by Modified PEI only allows water to pass through the membrane, but when 0.6 M DE2HPA is used as a component of the oil phase, due to the viscosity of the oil phase and DE2HPA with both hydrophilic and hydrophobic groups, the oil phase is attracted by Modified PEI and is hard to swept away the oil phase from the membrane surface by stir bar, therefore, it makes the oil phase have more opportunity to pass through the Modified PEI membrane. Moreover, in different concentration of DE2HPA, it can be proved that the number of hydrophilic groups in the oil phase and its viscosity will affect the water phase or oil phase to permeate the membrane. In addition to the viscosity of the oil phase, other experimental designs also indirectly prove the influence of the properties of the modified polymer and the oil phase, mainly the electrostatic interaction of positively charged of polymers and negatively charged of amphiphilic oil phase, which will cause the oil phase to be easily adsorbed and interact in the Modified PEI membrane with hydrophilic groups, thereby affecting the results of oil-water separation.