Preparation of Amidoxime-type Surfactants and Their Application to Ion Flotation

Abstract

The removal of heavy metal ions by the method of ion flotation using a series of synthesized amidoxime-type surfactants was investigated.
The cyanoethylated compounds (R-AN) were obtained by treating 1-dodecanol or 1-dodecanethiol with acrylonitrile, and acrylonitrile telomers (Ls nAN) were obtained by the solution polymerization of acrylonitrile using 1-dodecanethiol and 2, 2'-azobisisobutyronitrile as a solvent and an initiator, respectively. These compounds were treated with hydroxylamine to obtain the corresponding amidoxime-type surfactants (R-AOx and Ls nAOx) (Table 1∼4).
Hg(II), Fe (III), Cu (II), Pb (II), Zn (II) and Cd (II) were effectively remov ed by using RAOx in appropriated pH ranges. The minimum values after treatment at pH 3 were: Hg 1ppm, Fe 2 ppm, and Cu 4 ppm (Figs.1 and 2). The content of ⁶⁰Co (II) was reduced to O.5ppb from 5.8 ppb at pH 5. The scums formed with the collectors were colored (Hg: yellow, Fe: purple, Cu: green, Co: pink). Hg (II) was selectively floated at pH 3 from a solution containing other metal ions. This could be ascribed to the stabilities of complexes and the HLB values. By using nonionic surfactants together with Ls 9.8 AOx, the removal efficiency increased greatly in comparison with the case of using L, 9.8 AOx alone (Figs.3 and 4).
These collectors can be effectively removed at neutral pH; the residual concentration o f R12AOx is below 78 ppb.