Extraction and Separation of Cadmium(II), Iron(III), Zinc(II), and Europium(III) by Cyanex302 Solutions Using Hollow Fiber Membrane Modules

Abstract

The mass transfer behaviors of Cd(II), Fe(III), Zn(II), and Eu(III) in sulfuric acid solution using microporous hollow fiber membrane (HFM) containing bis(2,4,4‐trimethylpentyl)monothiophosphinic acid (commercial name Cyanex302) were investigated in this paper. The experimental results showed that the values of the mass transfer coefficients (K _w) decreased with an increase of H⁺ concentration and increased with an increase of extractant Cyanex302 concentration. The mass transfer resistance of Eu³⁺ was the largest because K _w value of Eu³⁺ was the smallest. The order of mass transfer rate of metal ions at low pH was Cd > Zn > Fe > Eu. Mixtures of Zn²⁺ and Eu³⁺ or of Zn²⁺ and Cd²⁺ were well separated in a counter‐current circulation experiment using two modules connected in series at different initial acidity and concentration ratio. These results indicate that a hollow fiber membrane extractor is capable of separating the mixture compounds by controlling the acidity of the aqueous solution and by exploiting different mass transfer kinetics. The interfacial activity of Cyanex302 in sulfuric acid solution was measured and interfacial parameters were obtained according to Gibbs adsorption equation.

Keywords:

• Cadmium(II)
• Iron(III)
• Zinc(II)
• Europium(III)
• Hollow fiber membrane
• Cyanex302

Acknowledgments

This project is supported by the National Program entitled “Basic Research of Rare Earths” (G1998061301) and National Natural Science Foundation of China (29771028, 29801004) and the national “863” program (2002AA647070).