| Summary: | 碩士 === 中原大學 === 化學工程研究所 === 81 === PC 應用於空氣富氧化膜上, 俱有高的氧、氮選擇比和機械強度,但氣體透
過率太低。本研究採用濕式相轉換製備非對稱薄膜, 利用非溶劑 (醇類)
的添加和金屬鹽溶液(salt/DMF)與 PC 產生錯合作用, 以改善 PC膜的氣
體透過率。首先利用非溶劑添加於 PC 鑄膜液中製備非對稱富氧化薄膜,
探討沉澱媒介, PC 濃度, 及非溶劑量對成膜性(機構)氣體透過率及薄膜
形態的影響,鑄膜液在沉澱介面與醇類間液-液相分離(liquid-liquid
pha se separation)的速率隨沉澱媒介之莫耳體積增加而減緩。 在以甲
醇為沉澱媒介之鑄膜液中添加正丙醇所得膜之 氧/氮 選擇比為 4,證實有
效改善未添加非溶劑 PC 膜的氣體分離特性。後者之氧/氮選擇比6.46。
其次探討過渡金屬鹽與 PC 所生成的錯合體結構對氣體分離性能之影響
。 研究中針對鑄膜液PC 含量、過渡金屬鹽種類及沉澱媒介等因素進行分
析。薄膜因金屬鹽添加所生成之錯合體結構藉由 FTIR 與 EA 予以鑑定,
在 PC 鑄膜液中添加氯化鈷而氧/氮選擇比為3.53。添加氯化鐵之膜, 氧
氣校正通量比未添加金屬鹽之 PC膜提升 20 倍,而 氧/氮 選擇比為6.83
。 於鑄膜液中添加溶劑(DMF),並無霧狀現象產生,所以不屬於非溶劑的添
加,以乾式法製備的 PC 膜由於 DMF 沸點高,易停留於膜內,形成高度微多
孔性薄膜, 可大幅增加氣體透過率, 但不具選擇性;若以溼式法取代, 則
溶劑與 DMF, 可被沉澱媒介溶出, 所以 DMF停留於膜內的時間極短, 薄膜
表面生成緻密的皮層,且皮層下仍保有多孔性的結構,因此不能大幅增加氣
體通量, 氧、氮選擇比亦維持4以上。 本實驗分別利用乾/溼混合製程及
溼式製程, 製備不同結構的氣體分離薄膜。乾/溼製程製得薄膜由於皮層
已在溶劑揮發時先形成, 使得在浸入沉澱媒介時發液-液生相分離速率減
緩, 形成較低孔隙度薄膜結構, 氣體通量較低的薄膜, 而溼式法在適當的
鑄膜液及沉澱媒介組成控制下, 可得到較高氣體透過率、高氧氮選擇性的
富氧氧化薄膜。比較顯示溼式製程較具開發價值。
Polycarbonate (PC) membranes posess high oxygen/nitrogen
selectivity and mechanical strength, but have low gas
permeability. This study attempts to utilize nonsolvent
additive and complex formation between the PC matrix and
transition metal salt to improve the gas pressure-normalized
fluxes of PC membrane by wet phase inversion. The first phase
of this study has been prepared the nonsolvent added PC
membrane. The formation of asymmetric oxygen enrichment
membranes were studied with respect to the type of coagulation
media, polycarbonate concentration, and nonsolvent content in
the casting solution. The gas pressure-normalized fluxes and
membrane morphologies for the prepared membranes were
investigated. The rate of liquid-liquid phase separation
decreases with increasing the alcohol molar volume of
coagulation medium. The gas separation performance for
nonsolvent added polycarbonate membranes was better than that
of the membrane without additive with pressure-normalized
fluxes. The second phase investigated the PC/metal salt complex
membrane with utilizing the complex structure to improve the
gas separation performances. The effects of PC content in the
casting , kind of added metal salts、 coagulation medium on
membrane formation、 morphology, and gas separation
performances of the complex membranes have been reported. The
PC/DMF/Metal salt complex structure is characterized by the
study of FTIR and EA.
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