Solubilization of polycyclic aromatic hydrocarbons in structurally different gemini and monomeric surfactants: A comparative study

Solubilization capabilities of structurally different gemini surfactants i.e. alkanediyl-alpha-omega-bis(dimethylhexadecylammonium bromide) (C-16-10-C-16, 2Br(-), C-16-12-C-16, 2Br(-)), butanediyl-1,4-bis (dimethyldodecylammonium bromide) (C-12-4-C-12, 2Br(-)), 2-butanol-1,4-bis (dimethyldodecylammonium bromide) (C-12-4(OH)-C-12, 2Br(-)), 2,3-butanedio1-1,4-bis (dimethyldodecylammonium bromide) (C-12-4(OH)(2)-C-12, 2Br(-)) and cationic monomeric surfactants viz. alkyltriphenylphosphonium bromide [R = C-16 (CTPB), C-14 (TTPB)], cetyldialkylethanolammonium bromide [R = CH3, (CDMEAB), C2H5 (CDEEAB)] for three polycyclic aromatic hydrocarbons (PAHs); phenanthrene (Phe), fluorene (Fluo) and acenaphthene (Ace) have been studied spectrophotometrically at 300 K.The result showed that the solubility of PAHs increases linearly with increasing surfactant concentration, as an implication of association between the PAHs and micelles. Molar solubilization ratio (MSR), micelle water partition coefficient (K-m) and Gibbs free energy of solubilization (Delta G degrees(s)) for PAHs have been determined in aqueous medium. The order of solubilization of PAHs for the examined surfactants is found to be: Phe > Fluo > Ace. C-16 series of investigated gemini surfactants exhibited greater solubilization ability than other tested C-12 gemini series and monomeric surfactant systems thus suggesting that C-16 gemini series is superior than other surfactants. Findings of the present investigation may be useful to understand the role of appropriate surfactant system for the solubilization of toxic hydrophobic organic compounds. (C) 2015 Elsevier B.V. All rights reserved.