Study on influence of Co-Solvent on the Critical Micelle Concentration (CMC) of aqueous sodium lauryl sulphate solution by conductance & surface tension measurement

Abstract

We have studied the critical micelle concentration (CMC) of sodium lauryl sulphate (SLS) in water and ethanol-water system by surface tension and conductance measurement method. The CMC obtained in aqueous solution is compared with those obtained in ethanol co-solvent solutions. Different concentrations of SLS in water and 10% and 20% ethanol solutions were prepared to study the influence of co-solvent on the CMC of SLS solution. The drop number method was used for the measurement of surface tension whereas direct conductance values are utilized in conductance measurement for determination of CMC. It is observed that the CMC of SLS solution decreases with increasing percentage of ethanol suggesting the formation of micelles are favored at lower concentration of ethanol.