以具分散反萃取相支撐式液膜分離並回收Ni2+-Zn2+-Al3+多成分金屬離子

Separation and Recovery of Ni2+-Zn2+-Al3+ Multi-component Metal Ions by Supported Liquid Membrane with Strip Dispersion

黃靖軒(Chin-Hsuan Huang)

指導教授 ： 王大銘

共同指導教授 ： 謝子陽(Tzu-Yang Hsien)

國立臺灣大學/工學院/化學工程學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.01580

摘要

現今無電鍍鎳程序的使用廣泛，根據不同產業的需求，反應後所產生的廢液往往含有多種金屬離子。若能將其中的金屬離子加以分離回收，不但能加以再利用，亦可減少對環境造成的汙染。因此本研究之目的在於設計一系列的程序，經由三階段的程序將鎳、鋅、鋁三種離子各自分離回收，並且分別將鎳離子及鋅離子濃縮至高濃度。
研究中首先利用鋁離子遇鹼性溶液容易形成沉澱析出的特性，逐毫升加入1M的碳酸鈉溶液，以解決使用具分散反萃取相支撐式液膜回收時沉澱物會造成中空纖維膜組的膜孔阻塞的問題。並藉由觀察溶液pH值改變量的變化來判斷停止加入碳酸鈉之時機，以避免加入過量的碳酸鈉造成鎳、鋅離子因沉澱而造成的過多的損耗。
在鎳、鋅離子分離的程序中，利用萃取劑D2EHPA於低pH值環境中能有效地回收鋅離子並且具有良好選擇性的特性。使用0.5M D2EHPA及2M H2SO4（25 mL）做為萃取劑及稀釋劑，並為了徹底消除第三相的生成，於有機相中加入2 vol%的修飾劑十二醇。將第一階段程序結束後的進料溶液（470 mL）與上述之有機溶液及反萃取液導入具分散反萃取相支撐式液膜中，並將進料溶液調整至pH = 2.5。在此條件可成功抑制第三相的生成，於20分鐘內將1000 mg/L的鋅離子完全萃取至萃取劑當中，並在180分鐘內將之濃縮至18700 mg/L，而鎳離子濃度的損失趨近於零。
在鎳離子回收濃縮的程序中，將前一個程序殘留的進料溶液重新導入膜組，且因為D2EHPA在進料pH值大於3.0的環境中對於鎳離子才會具有較佳的萃取速率，因此利用微電腦酸鹼度控制器將進料溶液的pH值控制在3.0以上，使用第二階段程序殘留的萃取劑及修飾劑，並加入25 mL新的2M H2SO4做為反萃取液，結果可在60分鐘內完成萃取反應，並在180分鐘內將含930 mg/L鎳離子的進料溶液（410 mL）濃縮至14800 mg/L。藉由此一系列三階段的程序，可成功地將鎳、鋅、鋁三成份加以分離並且回收。

關鍵字

支撐式液膜 ； 萃取 ； 分離 ； D2EHPA

並列摘要

The waste water from electroless nickel process often contains various metal ions, depending on different industrial processes. Recovery and purification of the metal ions, allowing for reuse of them, have great merits for cost reduction and pollution control. The present research aims at developing processes for recovery and separation of Ni2+-Zn2+-Al3+ ions, and concentration of the recovered zinc and nickel ions.
Aluminum ions were first precipitated out from a ternary solution of Ni2+, Zn2+, Al3+ (1000 mg/L each) by addition of sodium carbonate solution, to prevent their precipitation that might block the pores in hollow-fiber modules in the following “supported liquid membrane with strip dispersion” process. A suitable pH value was determined that can almost totally precipitate the aluminum ions without much loss of the nickel and zinc ions in the solution.
For separation of zinc and nickel ions, we adopted D2EHPA as the ion extractant, which at low pH effectively extracted zinc ions but with very low extraction for nickel ions. We used 0.5M D2EHPA as the extractant and H2SO4 as the stripping solution, along with 2 vol% of 1-dodecanol as the modifier that prevent the formation of the third phase during extraction. The feed solution obtained after the precipitation process was then pumped into a hollow-fiber module to be in contact with an oil phase that contained the extractant and modifier, with the stripping solution as the dispersed phase in the oil. The process is called “supported liquid membrane with strip dispersion”. During the process, the pH value of the feed solution was maintained at 2.5. The results indicated that by using the process the 1000 mg/L of Zn2+ contained in a 470 mL solution can be completely extracted within 20 minutes and be concentrated to 18700 mg/L in about 180 minutes with nearly no loss of nickel ions.
After the removal of Zn2+, the feed solution was resent back to the liquid-membrane process, with the used extractant, and modifier, but with new stripping solution. By controlling the pH in the feed solution to stay above 3.0, the 930 mg/L Ni2+ contained in a 410 mL solution was concentrated to 14800 mg/L within 180 minutes.
With the process described above, we can successfully separate nickel, zinc and aluminum ions and recover them from the solution.

並列關鍵字

supported liquid membrane ； extraction ； separation ； D2EHPA

參考文獻

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