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

Abstract

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 (Γ), minimum area per molecule (A min), and interaction parameters at bulk (β M ) and interface (β σ ) were calculated. In the presence of nonionic surfactants, lowering of CMC, CVC, and surface tension at these two concentrations of DDAB were observed. The β M and β σ 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.

Influence of Surfactant Concentration on Spontaneous Emulsification Kinetics

“…These results are also consistent with previous studies that reported about the synergistic interactions between non-ionic and cationic surfactants. − For instance, the adsorption of CTAB was enhanced due to the synergies between CTAB and TX-100 (Triton X-100, a non-ionic surfactant) . A similar behavior was also reported for the surfactant mixture of DDAB (didodecyldimethylammonium bromide, a cationic surfactant) and Igepal CO-890 (polyoxyethylene-40 nonylphenyl ether, a non-ionic surfactant) in oil-in-water emulsions . In fact, while CTAB and SDS are good emulsifiers, it turns that below the CMC, CTAB is a less efficient oil-in-water emulsion stabilizer , than SDS that provides very stable emulsions already at concentrations well below the CMC …”

“…64 A similar behavior was also reported for the surfactant mixture of DDAB (didodecyldimethylammonium bromide, a cationic surfactant) and Igepal CO-890 (polyoxyethylene-40 nonylphenyl ether, a non-ionic surfactant) in oilin-water emulsions. 65 In fact, while CTAB and SDS are good emulsifiers, it turns that below the CMC, CTAB is a less efficient oil-in-water emulsion stabilizer 66,67 than SDS that provides very stable emulsions already at concentrations well below the CMC.…”

Playing Favorites: Preferential Adsorption of Nonionic over Anionic Surfactants at the Liquid/Liquid Interface

“…The results in Figure indicate a preferential adsorption of Span-80 at the oil/water interface over that of AOT. While some previous studies have investigated and reported on synergic interactions between nonionic and charged surfactants, ,− the results in Figure are consistent with results in literature specifically investigating the adsorption behavior of anionic surfactants in mixed systems, reporting that nonionic surfactants inhibit anionic surfactant adsorption at the surface. ,− To further investigate this preferential adsorption behavior of nonionic Span-80 here, surface pressure measurements of varying surfactant ratios were made, and the results are reported in Table . The solutions containing Span-80 alone were fully equilibrated at the surface after 1 h, at which point their surface pressure values were recorded.…”

Renewable dissymmetric sulfonate gemini surfactants from addition of sodium hydrogensulfite to alkyl linoleate

“…The emulsion droplet size gets reduced as the increasing hydrophobicity of the surfactants, and SBLD has superior emulsifying ability and stability. This might be due to the strong interaction between the hydrocarbon tails of surfactants and the oil molecules by van der Waals forces leading to the size contraction of oil droplets 61 …”