Solubilization of polycyclic aromatic hydrocarbons by novel ester-bonded Gemini prolinol-based surfactant and its binary mixtures with conventional surfactants

Abstract

Aqueous interactions of a novel ester-bonded Gemini prolinol-based surfactant, 2,2′-((adipoylbis(oxy))bis(methylene))bis(1-dodecyl-1-methylpyrrolidin-1-ium) bromide C12-6-C12PB, with dodecyl sodium sulfate (SDS), dodecyl trimethyl ammonium bromide (DTAB), tetradecyl trimethyl ammonium bromide (TTAB), or cetyltrimethyl ammonium bromide (CTAB) were studied using conductomeric measurement. The experimental critical micelle concentration (CMC) was lower than the ideal CMC, and the negative interaction parameters indicate that there is a synergistic interaction between the surfactants in the binary solution. The solubilization capacities of single and binary surfactant systems towards polycyclic aromatic hydrocarbons (PAHs) (i.e., naphthalene, anthracene, and pyrene) were evaluated and are discussed in terms of the molar solubilization ratio (MSR), micelle-water partition coefficient (Km), and free energy of solubilization (). C12-6-C12PB and SDS respectively had the minimum and maximum MSR when presented individually in the solution. The MSR values in the binary system are greater than those in the single surfactant system, and this indicates that synergism in a mixed system enhances PAH solubility. With a molar ratio of 0.7:0.3, C12-6-C12PB/SDS had a relatively greater solubilization capacity for PAHs because of large aggregates. The negative value of indicates the spontaneity of the solubilization process.