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Title: Solubilization of phenol and benzene in cationic micelles: Binding sites and effect on structure

Journal Article · · Journal of Physical Chemistry; (USA)
DOI:https://doi.org/10.1021/j100341a063· OSTI ID:5145441

The effect of phenol and benzene additives on micellar structure in aqueous solutions of dodecyltrimethylammonium bromide has been studied by means of various experimental measurements. The solution properties studied include additive solubilities, tracer diffusion coefficients, electrical conductivity, viscosity, and ultraviolet absorbance. From the trace diffusion measurements the degree of partitioning of phenol into the micelles was calculated as a function of phenol concentration. A procedure for determining surfactant aggregation number and micelle concentration in ionic surfactant systems by means of diffusion and electrical conductivity data is presented. The solubilization of phenol and benzene in this system causes the micelles to swell, and it was observed that phenol addition leads to a greater increase in the size of aggregates than addition of benzene. Ultraviolet absorbance measurements revealed that the site of solubilization within the micelles is different for the two additives: Benzene solubilizes in the central core, while at low concentrations phenol is taken up in the outer palisade layer. However, the site of phenol solubilization, the shape of the micelles, and the physical properties of DTAB/phenol solutions change at a concentration of 1 mol of phenol solubilizate per mole of surfactant. Due to the saturation of the palisade layer with surfactant and additive molecules, phenol added to the DTAB system beyond this transition point most likely binds to the exterior of the micelles.

OSTI ID:
5145441
Journal Information:
Journal of Physical Chemistry; (USA), Vol. 93:4; ISSN 0022-3654
Country of Publication:
United States
Language:
English