硝酸溶液中鑭與釹離子之批次及連續非分散式萃取分離

Batch and Continuous Non-dispersive Extraction Separation of La(Ⅲ) and Nd(Ⅲ) Ion from Nitrate solutions

顏沛欣(Pei-Hsin Yen)

指導教授 ： 莊瑞鑫

元智大學/工程學院/化學工程與材料科學學系/碩士(2004年)

摘要

隨著科技的蓬勃發展，各種新型製程與材料的使用越來越多元化，電子產品廢液中常含有鑭系金屬等多種成分。本文主要針對鑭和釹金屬離子廢水，加以探討其回收再利用之可行性。
首先探討La3+/H2O-PC88A (2-Ethylhexyl phosphonic acid mono-2-ethylhexyl ester)/kerosene、Nd3+/H2O-PC88A/kerosene萃取系統的平衡。對於單成分系統的總平衡計量式可分別寫成：
La3+ + (HX)2 --- LaX3(HX)3 + 3H+
Nd3+ + (HX)2 --- NdX3(HX)3 + 3H+
在25℃下，所得萃取平衡常數為kex,La=2.30*10-5、kex,Nd=2.39*10-4。
動力學方面，萃取速率與水相金屬離子濃度、有機相PC88A濃度有關，而與水相氫離子濃度無關；反萃取速率則與水相氫離子濃度、有機相金屬複合物的濃度有關，而與有機相中游離之PC88A濃度幾乎無關。
在薄膜萃取系統中，藉由改變pH值、水相金屬離子總濃度、及不同金屬離子比例，探討其對萃取效果之影響。由實驗結果得知，萃取速率隨著進料相金屬離子總濃度、金屬離子比例及萃取劑濃度的增加而提昇。為探討金屬離子在中空纖維薄膜中的理論質傳現象，本文應用液-液萃取所得到的平衡常數及質傳之基本理論，建立理論傳送模式，其中包括金屬離子的水相擴散、有機相擴散及薄膜擴散等方程式；利用FORTRAN 6.1作數值運算後，求得傳送過程中濃度之時間變化，與實驗值比較。

關鍵字

鑭 ； 釹 ； 萃取 ； 非分散式 ； 中空纖維膜

並列摘要

With the rapid increase in high technology, many processes and materials processing use various types of heavy metals, especially lanthanum ion and neodymium ion. The aim of this article was to study the feasibility of recycling lanthanum ion and neodymium ion from industrial effluents.
The equilibria of the extraction systems La3+/H2O-PC88A/kerosene Nd3+/H2O-PC88A/kerosene were first investigated. For single-metal systems,
La3+ + (HX)2 --- LaX3(HX)3 + 3H+
Nd3+ + (HX)2 --- NdX3(HX)3 + 3H+
The equilibrium constant of kex,La and kex,Nd were 2.30*10-5 and 2.39*10-4, respectively, at 25 oC.
In kinetic experiments, the extraction rate showed dependence to metal ion concentration in the aqueous phase and concentration of PC88A in the organic phase, but did not depend on hydrogen ion concentration in the aqueous phase; The stripping rate also revealed dependence to concentration of hydrogen ion concentration in the aqueous phase and metal-complex concentration in the organic phase.
For the mass transfer of metal in hollow fiber, the theoretical values calculated from the mass transfer model considering the extraction chemistry and mass transfer coefficient were compared with experimental results. Based on the experimental data obtained from liquid-liquid extraction, a transport model was presented considering aqueous layer diffusion, membrane diffusion, and organic layer diffusion.. The extraction efficiency of metal ion increased with increasing the initial metal ion concentrations, extractant concentrations, and metal ion concentration ratios.

並列關鍵字

La ； Nd ； Extraction ； Non-dispersive ； Hollow Fiber Membrane

參考文獻

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