engleski

The effect of trace amounts of dodecyl alcohol on the physicochemical properties of sodium dodecyl-sulfate : electrochemical study at the mercury-electrode sodium-chloride interface

Effects of dodecyl alcohol (DOH) on the physicochemical properties of sodium dodecyl sulfate (SDS), surface tension at the air/water interface, and adsorption behavior at the mercury electrode have been studied. Investigations were carried out in a wide concentration range of SDS (2.1 × 10−7−5.2 × 10−3 mole dm−3) in the presence of trace quantities of DOH (0.5 and 1.4 wt%). Two samples of SDS of different degrees of purity were used. Adsorption studies were performed by phase-sensitive a.c. voltammetry, double-layer capacity measurements, and faradaic current measurements of the Cd2+ reduction process on the electrode surface covered by the adsorbed layer of surfactant. The investigated mixtures showed significant differences in the adsorption behavior in comparison with individual components of the mixtures, changes in the double-layer capacity, and increased permeability of the adsorbed layer for Cd2+ reduction. These effects were observed in a narrow concentration range of surfactant near the critical micellar concentration of SDS. Electrochemical methods are proposed as a test of purity for SDS chemicals, especially in highly concentrated electrolyte solutions where other methods are not satisfactory.

sodium dodecyl sulfate ; dodecyl alcohol

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