Effects of Metal Ions on the Critical Micelle Concentration of Ionic Surfactan (CTAB)

The effect of metal ions (Cu(II), Zn(II), Ni(II), Ce(III), La(III), Fe(III)) on the critical micelle concentration (CMC) of ionic surfactant hexadecyltrimethylammonium bromide (CTAB)) was investigated at 25 degrees C by using conductivity method. A series of general empirical expressions about the relationship between the CMC values for CTAB and the concentrations of metal ions have been derived. The results showed that the CMC values for CTAB decreased with increasing the concentrations of metal ions. This can be interpreted by the counterion effect and the entropy driving effect.