Abstract:

The dielectric relaxation behavior of the sodiumdodecyl benzene sulfonate (SDBS) surfactant was investigated in a concentration range from0.1 to 80 mmol·L-1 by dielectric relaxation spectroscopy (DRS) method. Near the critical micelle concentration (CMC) of SDBS, significant relaxation phenomena of SDBS solutions around the frequency 107 Hz were observed. The dielectric data of the overall concentration were fitted by using the Cole-Cole equation, which revealed information about the relationship between dielectric parameters and concentration. Although the relaxation increment (△ε) increased with the concentration of SDBS (cs), this change exhibited two kinds of linear relationship, which intersected at an inflexion near 36 mmol·L-1. On the other hand, the curve of relaxation time (τ0) and concentration reached the lowest point at 45 mmol·L -1. Based on the spherical micelle model, the dielectric phenomena are due to the amount of bound Na+ counter-ions and the change in micellar volume.

Key words: Micelle, SDBS, Dielectric spectroscopy, Dielectric relaxation, Counter-ion