Gonzalez-Perez et al. and what was also observed for cationic
surfactant solutions [23,24]. In case of (etilefrine HCl + NaCl)
systems, the values of (a) did not show a specific pattern with
either the increase in temperature or NaCl concentration. The
temperature-dependent values of (a) are represented in table 3.
3.1.3. Effect of additive on CMC
The CMC of an amphiphile is affected by the degree of counter
ion binding. Increased binding of the counter ions to the head
groups of the amphiphilic molecules leads to a decrease in the
CMC and an increase in aggregation number [25]. The presence
of excess counter ions from the electrolyte with the amphiphile
solution reduces the repulsion between the head groups of the
amphiphile which in turn promotes the association and decreases
the CMC [26–28].
The CMC values of etilefrine HCl were measured in the presence
of a different concentration of NaCl, 0.025, 0.05, 0.075 and
0.1 mol kg1, at different temperatures. In all conditions, the presence
of various concentrations of NaCl with etilefrine HCl was
found to decrease the CMC values, (table 3)..