Micellization parameters and electrostatic interactions in micellar solution of sodium dodecyl sulfate (SDS) at different temperatures

Abstract

The effect of concentration on electrical conductance of SDS solution from 293.15–313.15 K above and below the CMC was studied. The micellization parameters, i.e. degrees of counterion binding ( β) and aggregation numbers ( n) were determined at different temperatures. The mass action model (MAM) was applied to calculate other micellization parameters like number of counterions per micelle ( m) and micellization constant ( K c), and was also used to obtain concentration changes of counterions [Na +], surfactant ions [DS −] and micelles [Mn] with respect to total surfactant concentration. The ionic conductance changes of the counterions λ Na + , surfactant ions λ DS − and micelles ( λ Mn) with respect to total ionic strength were evaluated by using Debye–Huckel–Onsager equations. The ionic conductivity and CMC of ionic micellar solutions and consequently all micellization parameters are influenced by temperature. The parameters like m, n and β decline, whereas ionic concentrations [Na +], [DS −] and [Mn] and ionic conductances λ Na + , λ DS − and ( λ Mn) increase with rise in temperature.