應用界面活性劑於超臨界二氧化碳中萃取金屬鹽類

Abstract

應用界面活性劑於超臨界二氧化碳中萃取金屬鹽類 學生：王志謙 指導教授：余艇博士 國立交通大學應用化學所 摘 要 水溶性的金屬離子在添加適當的螯合劑作用後，可用有機溶劑從水中萃取出，但是萃取過後的大量有機溶劑，變成新的問題待處理。超臨界流體可以取代傳統有機溶劑進行萃取，並且在萃取完成後，一經洩壓便可氣化與萃取物分離，達到濃縮的效果。本實驗試圖於超臨界二氧化碳中加入界面活性劑來萃取金屬鹽類。幾乎所有商業化的界面活性劑在超臨界二氧化碳中溶解度皆不理想。然而，在超臨界二氧化碳中加入有機修飾劑可以有效改善這些界面活性劑的溶解度。我們發現界面活性劑didodecyldimethylammonium bromide ( DDAB )和sodium bis-2-ethylhexyl sulfosuccinate ( AOT ) 可於超臨界二氧化碳中形成反微胞，進而萃取金屬鹽類。在壓力225 bar、修飾劑乙醇濃度 i 20 % v/v、溫度35 ℃、W0值為4的實驗條件下使用界面活性劑A0T於超臨界二氧化碳中萃取氯化鑭、氯化銪、醋酸鈾，收集20 ml二氧化碳體積，計算回收率分別為49.18 % 、43.79 %、43.08 %。另外，我們也使用非離子性界面活性劑－tetraethylene glycol n-lauryl ether，雖然在二氧化碳中溶解度較高卻無法萃取出金屬鹽類。

Extraction of metal salts using supercritical fluid carbon dioxide with surfactants Student：Chih-Chien Wang Advisor：Dr. Tiing Yu Institute of Applied chemistry National Chiao Tung University Abstract Extraction of metal salts using surfactant-containing supercritical fluid carbon dioxide (SF CO2) was investigated in this study. Only mediocre solubilities of almost all commercially-available surfactants in neat SF CO2 have been reported in the literature. However, adding organic modifier to SF CO2 can increase the surfactant solubilities drastically. The high surfactant solubilities for didodecyldimethylammonium bromide (DDAB) and sodium bis-2-ethylhexyl sulfosuccinate (AOT) ensured formation of reverse micelle in SF CO2 for dissolving metal salts. Extraction of lanthanum chloride heptahydrate, europium chloride and uranyl acetate dehydrate was examined. The recoveries for these three compounds doped in filter papers were 49.18 %, 43.79 % and 43.08 % respectively using AOT-containing SF CO2. Extraction recoveries were also investigated under various temperatures and pressures. Water-to-surfactant ratio had little effect on the extraction recoveries. In addition, a nonionic surfactant, teraethylene glycol n-lauryl ether, was investigated and was found unable to solubilize metal salts in SF CO2.