Henry’s Law Constants for Fragrance and Organic Solvent Compounds in Aqueous Industrial Surfactants

Henry’s law constants ( k H ) were measured (at 30 °C) and modeled for a suite of fragrance and solvent compounds in aqueous solutions of three structurally diverse industrial surfactants: sodium dodecylbenzene sulfonate (NaDBS), tetradecylbenzyldimethyl ammonium chloride (TDBAC), and a linear alkyl ethoxylate, Neodol 1,9. k H values for limonene, β-pinene, toluene, and trichloroethene were examined as a function of surfactant concentration. When compared to TCE and toluene, the fragrances limonene and β-pinene with their larger values of molecular polarizability (ὰ mol = (17.94 ± 0.5) Å 3 and (17.34 ± 0.5) Å 3, respectively) and greater hydrophobic character exhibited greater affinity for micelles of the linear alkyl ethoxylate relative to those of NaDBS and TDBAC and greater selectivity overall in their interaction(s) with micelles of varying carbon content (C n ). Using a linear solvation energy relationship (LSER) of the form ln k H = C + s π 2 * + a Σα 2 + b Σβ 2 (π 2 * = solute dipolarity/polarizability; Σα 2 = overall solute hydrogen-bond-donor acidity; Σβ 2 = overall solute hydrogen-bond-acceptor basicity; C = a regression constant) as an additional correlation and characterization tool, we find the large negative coefficients on π 2 *, Σα 2, and Σβ 2 consistent with the inverse correlation between ln k H and the magnitude of solute–solvent interactions in the condensed phase; C decreases with increasing size of the micellar phase. The dominance of HBD and HBA interactions (Σα 2 and Σβ 2, respectively) in the LSER for the alkyl ethoxylate points to the role of the ethylene oxide outer portion of the Neodol 1,9 micelles along with the effect of intercalated water.