Analytical Sciences

Ion-Pair Formation of a Copper(II)-Ammine Complex with an Anionic Surfactant and the Recovery of Copper(II) from Ammonia Medium by the Surfactant-Gel Extraction Method

Takayuki NAKAI,* Yoshiko MURAKAMI,* Yoshiaki SASAKI,* Isamu FUJIWARA,** and Shoji TAGASHIRA* 

*Department of Chemistry, Faculty of Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8512, Japan
**The Center for Waste Water Treatment, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8511, Japan

The extraction and separation of copper(II), zinc(II), cobalt(II), and cadmium(II) were investigated. Both copper(II) and zinc(II) formed ammine-complexes, while cadmium(II) and cobalt(II) formed hydroxide precipitates in an ammonia medium. By the addition of sodium dodecylsulfate (SDS), a copper(II) complex formed an ion-pair (copper-ammine-DS), which was extracted into the SDS phase. However, a zinc(II) complex did not form an ion-pair, and was soluble in water. Copper(II) ion was recovered by stripping (back-extraction) after the addition of hydrochloric acid. This method was applied to the separation of copper(II) in a brass alloy.

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