The usual explanation offered for solubilization leads to solubilized species being regarded as distributed between a micellar phase and an bulk aqueous phase. with the micellar phase playing the same role as the organic solvent in ordinary liquid-liquid extraction. Water-insoluble metal chelates are made soluble in micellar solutions of nonionic surfactants. When the two phases can be separated physically, it should be possible to concentrate the metal chelates into a small volume of the micellar phase in a similar manner to ordinary liquid-liquid extraction. This can be carried out depending on the fact that a micellar solution of a nonionic surfactant separates into two phases above a certain temperature, defined as the cloud point. Polyoxyethylene nonyl phenyl ether . with on average 7.5 ethylene oxide units (PONPE-7.5), was used . The cloud point of a dilute micellar solution of PONPE-7.5 is 10, and hence the solution is turbid at room temperature, The two phases are readily separated by centrifuging. The zinc chelate of 1-(2-pyridylazo)-2-naphthol was quantitatively extracted from 80 g of the solution into a small volume (1.3 ml) of the lower phase rich in PONPE-7.5. Nonionic surfactants will be useful as a new solvent for liquid-liquid extraction of metal ions.
CITATION STYLE
Watanabe, H. (1982). Nonionic Surfactants in Photometric Determination of Trace Metals. In Solution Behavior of Surfactants (pp. 1305–1313). Springer US. https://doi.org/10.1007/978-1-4613-3494-1_38
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