Intermolecular packing of sugar-based surfactant and phenol in a micellar phase

Surfactants have been used to enhance the removal of phenol from aqueous system; therefore, the interaction between surfactants and phenol is important for selection of the surfactant and understanding the process. In this work, sugar based surfactant, n-dodecyl-beta-D-maltoside (DM), was utilized to separate phenol from aqueous solution using ultrafiltration. 2-D NMR and Cryo-TEM techniques were employed to obtain information on the orientation of phenol molecules in the micellar phase and the shape transition of the micelles. The flux was found to decrease linearly with the solute concentration and the equilibrium constant was found to be constant. 2-D NMR spectra have shown that phenol molecules reside in the palisade layer of the DM micelles with the benzene ring interacting with the hydrocarbon chain of DM molecules, especially the first methylene group. Cryo-TEM results have shown the shape transition from spherical to worm-like due to the presence of phenol. The results will help understand the interaction between surfactants and phenol and the select the optimum surfactant reagents and operational conditions for micellar enhanced ultrafiltration process.