The Thermodynamics of a Detergent using Calorimetry.

Abstract

The heats of micellization and demicellization (DHmic and DHdemic) were measured for sodium dodecyl sulfate (SDS) using differential scanning calorimetry (DSC) and isothermal titration calorimetry (ITC).SDS is a synthetic detergent that spontaneously forms an aggregate of individual monomers known as a micelle at and above the critical micelle concentration.The micellization process is generally a thermodynamically favored, exothermic process.At elevated temperatures, micelle stability decreases and causes the onset of demicellization.Demicellization is an endothermic process and should theoretically take in the same amount of heat as is given off during the micellization process.In our studies, the enthalpies of micellization and demicellization, as well as the critical micelle concentration for SDS were determined from DSC and ITC data.In addition, the thermodynamic parameters were obtained as a function of SDS concentration.