支撐式液膜萃取分離鋅與鎘離子之效率與質傳

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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(2002年)

摘要

針對特定電鍍及螢光染料工業使用大量鋅鎘金屬後所排放之金屬廢水，以支撐式薄膜萃取模組分別回收 Cd2+ 與 Zn2+ 再利用。選取二(2—乙基己基)磷酸 (D2EHPA)、2-乙基己基膦酸單-2-乙基己基酯 (PC88A) 與氯化三辛甲基銨 (Aliquat 336)，以煤油為稀釋劑，探討溶劑萃取之平衡關係和支撐式液膜之動力實驗。
由D2EHPA (0.1 mol/dm3) 及PC88A (0.2 mol/dm3) 分別萃取Zn (II) 與Cd (II) 生成之錯化物為：
D2EHPA (HX) 與Zn2+ 形成 、D2EHPA與Cd2+ 形成 與 ；PC88A (HY) 與Zn2+ 形成 與 、PC88A與Cd2+ 形成 與
Aliquat 336 (0.06 ~ 0.15 mol/dm3) 自氯化鹽溶液中萃取 Zn (II) 之萃取平衡關係式為 。至於Aliquat 336 (0.005 ~ 0.02 mol/dm3) 萃取 Cd (II) 之萃取平衡關係式為
酸性萃取劑對Zn2+的萃取速率大於Cd2+，隨著初始pH的增加，萃取效率逐漸增加；萃取劑濃度的增加可提升Zn2+ 的質傳通量；[Zn2+]/[Cd2+] 比值的增加，萃取劑的選擇率皆提高。鹼性萃取劑對Cd2+ 的萃取速率大於Zn2+；[Zn2+]/[Cd2+] 比為7最不易分離雙成分，其傳送通量亦不大；萃取劑濃度的提升未能有效的增加Cd2+ 質傳通量，反倒有抑制的作用。
利用萃取平衡常數及質傳係數建立理論傳送模式，以數值分析法獲得理論值，與實驗值比較其誤差百分比在5％內。

關鍵字

支撐式液膜 ； 鋅 ； 鎘 ； 萃取

並列摘要

Some effluents discharged form electroplating and the fluorescence dyeing industries often include Zn2+ and Cd2+. A supported liquid membrane (SLM) was used to separate Zn2+ and Cd2+ from such synthetic solutions. The extraction equilibrium of Zn2+ and Cd2+ and the kinetics of SLM with the acidic extractants di(2-ethylhexyl)phosphoric acid (D2EHPA) and 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (PC88A) and the basic extractant tri-octyl methylammonium chloride (Aliquat 336) in kerosene were investigated.
The compositions of the extracted species for the extraction of Zn2+ and Cd2+ with D2EHPA (0.1 mol/dm3) and PC88A (0.2 mol/dm3) were determined. D2EHPA (HX) with Zn2+ form , D2EHPA with Cd2+ form and , PC88A (HY) with Zn2+ from and , PC88A with Cd2+ form and .
The extraction equilibria of Zn2+ and Cd2+ from chloride solutions with Aliquat 336 were determined to be and , respectively.
From the experimental data of using the acidic extractants, the extraction efficiency increased with increasing initial pH values; and the extraction efficiency of Zn2+ was better than that of Cd2+. The flux of Zn2+ increased with increasing extractant concentration. In the binary system of Zn2+/Cd2+, the separation factor increased by increasing metal concentration ratios. In the case of basic extractant, the extraction efficiency of Cd2+ was better than that of Zn2+. When Zn2+/Cd2+ is 7 ( b = 1), neither of it is easy to separate in the binary system with the increasing metal concentration ratios. The increase in extractant concentration cannot lead to and without increased flux of Cd2+.
The theoretical values calculated from the mass transfer model considering the extraction chemistry and mass transfer coefficient were compared with experimental results. The error was less than 5%.

並列關鍵字

HASH(0xb051054)

參考文獻

Aouad, N.; Miquel-Mercier; Bienvenüe, E.; Tronel-Peyroz, E.; Jeminet, G.; Juillard, J.; Seta, P. “Lasalocid (X537A) as a selective carrier for Cd (II) in supported liquid membranes,” J. Membr. Sci., 139, 167-174 (1998).

Bateman, B. R., Way, J. D. and Larsob, K. M. “An Apparatus for the measurement of gas fluxes through immobilized liquid membranes,” Sep. Sci. Technol., 19(21), 67-73 (1983).

Chiarizia, R. “The stability of supported liquid membranes containing long-chain amines as carriers,” J. Membr. Sci., 55, 65-77 (1991).

Daiminger, U. A.; Geist, A. G.; Nitsch, W. and Plucinski, K. “Efficiency of hollow fiber modules for nondispersive chemical extraction,” Ind. Eng. Chem. Res., 35, 184-191 (1996),

Daoud, J. A.; Ei-Reefy, S. A.; Aly, H. F. “Permeation of Cd (II) ions through a supported liquid membrane containing Cyanex 302 in kerosene,” Sep. Sci. Technol., 33, 537-549 (1998).