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

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 para meters, i.e. degrees of counterion binding (beta) and aggregation numbers ( n) were determined at different temperatures. The mass action model (MAM) w as applied to calculate other micellization parameters like number of count erions per micelle (m) and micellization constant (K-c), and was also used to obtain concentration changes of counterions [Nai], surfactant ions [DS-] and micelles [Mn] with respect to total surfactant concentration. The ioni c conductance changes of the counterions (lambda (Na+)), surfactant ions (l ambda (DS-)) and micelles (lambda (Mn)) with respect to total ionic strengt h were evaluated by using Debye-Huckel-Onsager equations. The ionic conduct ivity and CMC of ionic micellar solutions and consequently all micellizatio n parameters are influenced by temperature. The parameters like m,n and bet a decline, whereas ionic concentrations [Na+], [DS-] and [Mn] and ionic con ductances (lambda (Na+)), (lambda (DS-)) and (lambda (Mn)) increase with ri se in temperature. (C) 2001 Elsevier Science B.V. All rights reserved.