Viscoelasticity and mass transfer in phenol–CTAB aqueous systems

Abstract

The rheological and mass transport properties of phenol in micellar solutions of hexadecyltrimethylammonium bromide (CTAB) were studied by rheometry and spectrophotometry. The presence of phenol located between headgroups of the CTAB diminishes the repulsive forces between the cationic groups and induces a sharp increase in viscosity that is attributed to the one-dimensional micellar growth favoring the formation of worm-like micelles. It is found that the mass transfer of phenol between two immiscible phases is significantly retarded by the presence of CTAB. The transfer is particularly slow when the diffusion takes place from a surfactant solution phase to an organic phase. This behavior is attributed to the phenol– surfactant interaction that leads to micellar growth and viscoelastic behavior. However, at elevated temperature, viscosity decreases and mass transfer increases. This particular rheological behavior offers the possibility of regulating the mass transfer, which might be interesting for applications.