Effect of Electrolytes on Solution and Interfacial Behaviors of Double Chain Cationic-Nonionic Surfactant Mixtures for Hydrophobic Surface Wetting and Oil/Water Emulsion Stability Applications

The solution behaviors of the binary mixture of double chain cationic surfactant didodecyldimethylammonium bromide (DDAB) with nonionic surfactants of varied head groups, EO-9 and EO-40, in the presence and absence of electrolytes were studied and found nonideal behavior. The different physicochemical properties such as Gibb's surface excess (Gamma), minimum area per molecule (A(min)), and interaction parameters at bulk (beta(M)) and interface (beta(sigma)) were calculated. In the presence of nonionic surfactants, lowering of CMC, CVC, and surface tension at these two concentrations of DDAB were observed. The beta(M) and beta(sigma) values indicate strong interaction between DDAB and EO-40 mixed system. Further, addition of electrolytes to the mixed systems show increased interaction and change of physicochemical properties because of the combination of electrical and salting out effects.

Automated summary

The study investigates the solution behaviors of the binary mixture of double chain cationic surfactant DDAB with nonionic surfactants EO-9 and EO-40 under different conditions, showing nonideal behavior. Coexistence of nonionic surfactants leads to a decrease in CMC, CVC, and surface tension of DDAB at two concentrations.