Equilibrium and dynamic interfacial behavior of tetra (2-ethyl hexyl) diglycolamide (TEHDGA) - TritonX-100 mixtures
Year: 2016
Journal: J. Mol. Liq.
Authors: Basu, M; Choudhury, S; Sharma, JN; Hassan, PA
In this work we have explored the interfacial and association behavior of N,N,N',N'-tetra-2-ethylhexyl diglycolamide (TEHDGA) - TritonX-100 mixtures in order to assess the usefulness of TEHDGA as an agent for micelle -mediated extraction processes. A molar ratio of 20:1 (TritonX-100:TEHDGA) showed complete solubilisation of TEHDGA in the TritonX-100 solution. From the surface tension versus concentration plot, the free energies of micellization and adsorption were calculated and found to be comparable. Surface excess plots of pure TritonX-100 and mixture of TritonX-100-TEHDGA yielded lower area per molecule for the mixture owing to efficient packing of the hydrocarbon chains due to hydrophobic interactions. Effective diffusion coefficients of pure and mixed surfactant systems were obtained at various concentrations below and above the critical micelle concentration (cmc) by using dynamic surface tension measurements. DLS measurement showed presence of mixed micelles of smaller size in case of mixture as compared to pure TritonX-100 indicating the interaction of TEHDGA with TritonX-100. This interaction was also confirmed by measuring surface pressure-area isotherm and from Brewster angle microscopic studies at the air water interface. (C) 2016 Elsevier B.V. All rights reserved.
