以微孔性薄膜自水溶液中萃取回收有機羧酸

Recovery of Carboxylic Acids from Aqueous Solutions Using Microporous Membrane-Based Extraction

陳進東(Jinn-Dong Chen)

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(1997年)

摘要

本文的目的在於探討有機羧酸（乳酸、檸檬酸），在含三正辛胺
（TOA）的親油性微孔性薄膜及中空纖維（Hollow fiber） 中之動力
傳送過程。使用的微孔性薄膜材質為二氟乙烯膜（PVDF）、中空纖維
薄膜的材質為聚丙稀（Polypropylene）， 兩者均屬於疏水性之薄膜
，萃取溶液是以TOA為萃取劑，二甲苯為溶劑。 另一目的為：嘗試以
一反應機構式來表示薄膜中形成複合物的反應動力學，再以一質傳機
構式來表示薄膜傳送過程中的理論傳送結果，進而探討實驗值與理論
值偏差的原因，以及修正的方法。

為描述羧酸在平板式液膜中的理論質傳現象， 本文應用液-液萃
取所得的動力參數及質傳係數，以建立理論傳送模式，其中包括羧酸
的水相擴散、有機相擴散、薄膜擴散及界面化學反應等速率方程式。
在中空纖維方面，由於系統不同，質傳係數必須以另一關係式求得。

由理論模式所算出的結果比較實驗的結果得知：平板式液膜方面
，羧酸初濃度較低時實驗值與理論值相當的符合，而在較高的萃取劑
濃度時，質傳係數需做適當的修正方能得到良好的驗證。在中空纖維
方面，亦可得在低羧酸初濃度時實驗值與理論值亦相當的符合，但由
於形成複合物的反應中是以反應控制的方式傳送，且隨著萃取劑濃度
的增加而黏度變大，所以必須對反應速率常數做適當的修正。

關鍵字

萃取 ； 薄膜 ； 中空纖維 ； 有機羧酸 ； 理論

並列摘要

The transport of carboxylic acids (citric acid and lactic
acid)through a flat-type microporous membrane and hollow-fiber
was investigated in this paper. Tri-n-octylamine was diluted
in xylene and used as mobile carriers that was adsorbed in a
microporous poly-vinyl difluoride (PVDF) support and a poly-
propylene hollow-fiber. The experiments were performed in a
stirred membrane-based cell.

Based on the experimental data obtained from liquid-liquid
extraction (kinetics and equilibria parameters) and hydrodynamics
of the apparatus (mass transfer coefficients), a transport model
including film diffusion in the aqueous phase, the membrane
diffusion, the organic diffusion, and the interfacial chemical
reaction was proposed to describe the transport rate.

The results of the transport model in flat-type microporous
membrane and hollow fiber membrane were compared with the
experimental results. According to the effects of viscosity,
mass transfer and rate coefficients were adjusted to get
validity of the transfer model. It was observed that diffusion-
controlling is major, decreasing mass transfer(decreasing 19.6
and 9 times in citric acid, 10 and 17.6 times in lactic acid)
in microporous membrane system can get better fit. In addition,
chemical reaction-controlling is important in hollow fiber
model. And, decreasing rate coefficients (decreasing 3.85 and
7 times in citric acid, 4.3 and 6.6 times in lactic acid) can
get better fit.

並列關鍵字

Extraction ； Membrane ； Hollow fiber ； Carboxylic Acids ； Model

參考文獻

1. Basu, R. and Sirkar, K. K. "Citric Acid Extraction with Microporous Hollow Fibers" , Solvent Extr. Ion Exch., 10, 119-121 (1992).

2. Bizek, V., Horacek, J. and Kousova, M. "Amine Extraction of Hydroxycarboxylic Acids. 1. Extraction of Citric Acid with 1-Octanol/n-Heptane Solutions of Trialkylamine" , Ind. Eng. Chem. Res., 31, 1554-1562 (1992).

3. Bohrer, M. P. "Diffusional Boundary Layer Resistance for Membrane Transport" , Ind. Eng. Chem. Fundam., 22, 72-78 (1983).

4. Chaudhuri, J. B. and Pyle, D. L. "Emulsion Liquid Membrane Extracion of Organic Acid. 1. A Theoretical Model for Lactic Acid Extraction with Emulsion Swelling" , Chem. Eng. Sci., 47, 41-48 (1991).

5. Chaudhuri, J. B. and Pyle, D. L. "Emulsion Liquid Membrane Extracion of Organic Acid. 2. Experimental" , Chem. Eng. Sci., 47, 41-48 (1992).