逆微乳膠法合成奈米碳酸鈣之研究與有機相之回收

Abstract

研究上常用逆微乳膠法製造奈米粒子，但是卻遲遲沒有工業化大量生產。逆微乳膠法無法大量生產的原因為其界面活性劑與油相的價格昂貴，若無法回收界面活性劑和油相，在成本上無法與其它方法競爭。本實驗室已採用AOT/water/isooctane逆微乳膠系統進行碳酸鈣之合成，製造出六角片狀、甜甜圈和圓盤片狀碳酸鈣，並已證明其再現性良好。此方法雖可製備不同晶貌之產品，但在回收及規模放大等問題仍待解決。 本研究針對其再現性良好的粒子做更深入的探討，探討上述粒子改變反應時間以及規模放大對粒子晶貌的影響，並且使用反應廢液做回收實驗，尋找回收的可行方法。 在反應規模放大部份，發現將反應體積放大七倍後六角片狀產物仍然具有相同形狀且品質均勻。在廢液回收部份則使用甲醇做去乳化劑，加入廢液中使微乳液分層，藉由相分離將水分移至下層中，而上層為欲回收之液體。因為甲醇沸點低，我們可將上層液體蒸餾移除去乳化劑，達到回收有機相(AOT and isooctane)之目的。實驗結果顯示，回收之有機相在加入界面活性劑與油相調控逆微乳液之組成後，可重現六角片狀之晶貌，且其粒徑與使用新鮮化學藥品製備之產品相同。

To produce nanoparticles, recent work has focused on the reverse- microemulsion technique. However, it is not developed into an industrial process because the cost of surfactant and oil is quite high. It is essential to recover surfactant and oil from waste liquid when we use reverse- microemulsion technique to manufacture nanoparticles. In our laboratory, the AOT/water/isooctane reverse microemulsion system was used to synthesized calcium carbonate nanoparticles with the shape of hexagonal plate, disk and donut and the reproducibility is good. Although we can use this method to synthesize particles of different shape and size, the problem of recovery and scale-up still need to be solved. In this study, the systems with good reproducibility were study further. The effects of reaction time and experimental scale on the particle morphology were investigated. Besides, experiments were repeated with the organic phase (surfactant and oil) recovered by different techniques in order to seek a reliable recovering method. In the scale-up tests, we find out that the quality of particles with hexagonal plate-like shape does not change from that in the small scale. To recover organic phase, methanol is used as demulsifier to achieve phase separation of reverse microemulsion. After phase separation, water is removed from microemulsion and settles to the lower phase, and the organic pahse stays in upper phase. Because the boiling point of methanol is low, we can remove it by distillation and thus recover organic phase. Finally, we have successfully used recovered organic phase to reproduce CaCO3 with hexagonal plate-like shape by readjusting the microemulsion composition.