Investigation of adsorption of surfactant at the air-water, interface with quantum chemistry method

Density functional theory (DFT) of quantum chemistry was used to optimize the configuration of the anionic surfactant complexes CH3(CH2)(7)OSO3- (H2O) (n=0-6) and calculate their molecular frequencies at the B3LYP/6-311+G* level. The interaction of CH3(CH2)(70)SO3- with 1 to 6 water molecules was investigated at the air-water interface with DFT. The results revealed that the hydration shell was formed in the form of H-bond between the hydrophilic group of CH3(CH2)(70)SO3- and 6 waters. The strength of H-bonds belong:; to medium. Binding free energy revealed that the hydration shell was stable. The increase of the number of water molecules will cause increases of the total charge of hydrophilic group and S10-09-C8 bond angle, but decreases of the alkyl chain length and the bond lengths of S10-O11, S10-O12 as well its S10-O13, respectively.