The Spectra of Iodine in an Aqueous Solution of Nonionic and Anionic Surfactants

The interaction between pentaethylene glycol-dodecyl ether(C12E5) and sodium dodecyl sulfate (SDS) was investigated from the spectra of iodine in aqueous solution containing C12E5 and SDS. When SDS is added in the aqueous solution of C12E5 and iodine, the wave length of maxi-mum absorption shifted, and the absorbancy is reduced regularly, with the change of the con- centration of SDS added.Two break points are observed in the plot of absorbancy against the concentration of SDS added, the first break point being at the 1/10 molar ratio of SDS to C12E5, and the second break point at the equi-molar concentration. The break points and the slope of the plot indicate that the interaction between C12E5 and SDS increases rapidly from the concentration. of 1/10 molar ratio of SDS to C12E5, and that the interaction reaches a miximum at the equimolar concentration.These trends are observed for various concentration of C12E5.