Abstract
Abstract The critical micelle concentration, cmc, of sodium perfluorooctanoate, SPFO, and sodium dodecyl sulfate, SDS, in the presence of two homologous series of alkanols (l-alkanols and ω-phenyl-l-alkanols) at very low concentrations of the alkanols Ca, was measured by a differential specific conductivity method. The free energy of transfer per CH2 group in the alkanols from water to the respective micelles, ΔG°(CH2), has been estimated from a linear relation of the rate of cmc-decrease, Δcmc/ΔCa, with the number of carbon atoms in the alkyl chain of alkanols. The respective values of ΔG°(CH2) obtained for two series of homologues added to a given surfactant are in good agreement with each other: ΔG°(CH2) is −1.73 kJ mol−1 in the SPFO system and −2.30 kJ mol−1 in the SDS system. The former has been found to be smaller in magnitude than the latter. On the basis of ΔG°(CH2), a thermodynamic parameter has been proposed which characterizes the degree of modification of a medium from its pure liquid state to surfactant micelles or to interfaces composed of a hydrocarbon or a fluorocarbon.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have