LIQUID–LIQUID INTERFACE STUDY OF HYDROCARBONS, ALCOHOLS, AND CATIONIC SURFACTANTS WITH WATER

Abstract

Molecular interaction dynamics at liquid–liquid interface (LLI), involved nondispersive solution as compared with the interaction in bulk phase. Thereby, interfacial tension (IFT, mN/m) of LLI for four saturated hydrocarbons, six alcohols, and three cationic surfactants are reported at 298.15 K. The pentane, hexane, heptane, octane hydrocarbons and pentanol, hexanol, heptanol, 1-octanol, 2-octanol, and 1-decanol alcohols were used and IFT data were compared with 4 mm kg-1 dodecyltrimethylammoniumbromide (DTAB), trimethylsulfoxoniumiodide (TMSOI), methyltrioctylammoniumchloride (MTOAC) surfactants studied in benzene–water LLI. The IFT data are noted as hydrocarbons > DTAB > TMSOI > alcohols > MTOAC. The hydrocarbons and alcohols decreased IFT within 16 to 49% and 87 to 92%, respectively, whereas the surfactants within 78.3 to 95.9%. The alcohols developed interaction similar to surfactants and are denoted as nonionic surfactants for making mixtures of low IFT with hydrophilic and hydrophobic interactions to the level of the surfactants. The pentanol and MTOAC caused similar decrease in IFT so the pentanol developed the hydrophilic and hydrophobic interactions of the strength of MTOAC. Comparatively, the hydrocarbons showed lower decrease but the octane showed 49% decrease in IFT. Thus, the hydrocarbon with longer alkyl chain and the alcohol with shorter behave as good surfactants. The hydrocarbons with inductive effect on sigma bond between carbon atoms in alkyl chain also weakened the IFT and influenced the hydrophobic interactions. The MTOAC with four octyl units reduced 96% IFT so inductive effects monitor LLI dynamics.