Separation and Recovery of Ni2+-Zn2+-Al3+ Multi-component Metal Ions by Supported Liquid Membrane with Strip Dispersion
Date Issued
2011
Date
2011
Author(s)
Huang, Chin-Hsuan
Abstract
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.
Subjects
supported liquid membrane
extraction
separation
Type
thesis
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