高濃度酸性溶液中鈷與鎳之萃取分離

Extraction Separation of Co(II) and Ni(II) from Concentrated Acids Solutions

高向前(Hsiang-Chien Kao)

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

本論文研究強酸溶蝕溶液中低及高濃度鈷與鎳之萃取分離，實驗共分為三部分，首先探討萃取平衡，由平衡實驗中找出最佳的分離條件。當採用酸性萃取劑(D2EHPA、PC88A)時，其萃取率都不到20﹪，而經過均勻皂化後的鈉型萃取劑(Na-D2EHPA、Na-PC88A)，雖然萃取效果有明顯的提昇，但Co2+、Ni2+會同時被萃取至有機相中，無法達到分離之效果。若採用鹼性萃取劑，三級胺鹽(TOA)時其萃取率都低於10%，經過質子化後之TOA其萃取率有明顯的提昇。然而實驗結果發現採用四級銨鹽Aliquat 336 (R4NCl)當萃取劑，煤油為稀釋劑，自HCl酸液中可得到較佳的分離萃取效果，且萃取劑也不需前處理。於單成分萃取平衡實驗中，可得到平衡常數關係式：
log Kex,CoCl4= 3.77－0.65[ log(R4NCl)]1.2
log Kex,NiCl4 = 2.33－0.42[ log(R4NCl)]1.6
接著以平衡實驗中得到的條件，分別利用中空纖維薄膜接觸器及旋轉圓盤萃取塔進行萃取分離實驗；於中空纖維薄膜接觸器中採用一階段，萃取及反萃取同時操作程序是可行的，於高濃度系統中原先進料鈷鎳比[Co2+]0 /[Ni2+]0 =15，經實驗10 h後於反萃取段之鈷鎳比提升至[Co2+]s/[Ni2+]s =81；於旋轉圓盤萃取塔實驗中則採用兩階段萃取實驗，先進行1 h萃取實驗，其進料相之鈷鎳比為[Co2+]0/[Ni2+]0 =16；而後再將有機相送入反萃取槽中進行反萃取2 h，於反萃取中鈷鎳比提升可提升為164，可得到高純度(99.3 %)的Co2+。

關鍵字

萃取分離 ； 鈷 ； 鎳 ； 中空纖維接觸器 ； 旋轉圓盤萃取塔

並列摘要

In this paper, the extraction separation of cobalt and nickel at high and low levels from concentrated acid solutions was studied. First, the optimal separation conditions were found from batch equilibrium experiment. The extraction efficiency of metals was low when the acidic extractants D2EHPA and PC88A as well as the basic extractants TOA were used, but it increased apparently using the modified acidic extractants Na-D2EHPA and Na-PC88A as well as the protonated TOA. On the other hand, the experimental results indicated that the better extraction efficiency could be obtained from hydrochloric acid solution when Aliquat 336 (R4NCl) dissolved in kerosene was used as extractant. The equilibrium constants of Aliquat 336 system obtained from single-component equilibrium experiments were expressed as follows:
log Kex,CoCl4= 3.77－0.65[ log(R4NCl)]1.2
log Kex,NiCl4 = 2.33－0.42[ log(R4NCl)]1.6
Simultaneous extraction and stripping of cobalt and nickel from hydrochloric acid solutions with Aliquat 336 in hollow-fiber membrane contactors (HFMC) and rotating disc contactor (RDC) were studied. In HFMC system, the concentration ratio of cobalt and nickel ([Co2+]0 /[Ni2+]0) in the feed phase was 15 and increased to 81 in the stripping phase after 10-h operation. Two-stage experiments were operated in RDC system. Extraction experiments were performed for 1h at a feed-phase concentration ratio [Co2+]0 /[Ni2+]0 of 16 . Then, the organic phase was stripping for 2-h and nearly pure cobalt could be obtained in the stripping phase. The concentration ratio of cobalt and nickel was increased to 164.

並列關鍵字

HASH(0xab6b19c)

參考文獻

Alonso A. I.; Galan B.; Irabien A.; Ortiz I., “Separation of Cr(VI) with Aliquat 336: Chemical equilibrium modeling,” Sep. Sci. Technol., 32, 1543-1555 (1997).

Alonso A. I.; Irabien A.; Ortiz I., “Nondispersive extraction of Cr(VI) with Aliquat 336: Influence of carrier concentration,” Sep. Sci. Technol., 31, 271-282 (1996).

Akita, S. and Takeuchi, H. “Sorption and separation of metals from aqueous solution by a macromolecular resin containing tri-n-octylamine,” J. Chem. Eng. Jpn., 23, 439-443（1990）

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).

Flett, D. S. “Solvent Extraction in Scrap and Waste Processing,” J. Chem. Technol. Biotechnol., 29, 258-272（1979）.