DFT Investigation of Alkyl Sulfate Surfactant Adsorption at the Air-Water Interface

Abstract

The interaction of alkyl sulfate surfactant with water molecules was studied by using DFT. It was revealed for the first time that alkyl sulfate surfactant formed stable hydrate with six water molecules when it was saturation adsorption at the air-water interface. The influence of alkyl chain length on the hydration area and the structure of hydrophilic group of complexes CH₃ (H₂O)₆ (m = 0–8) was investigated. The calculated results showed that: (1) the hydration area of the hydrophilic group was 53.6 Å², which was in good agreement with the experimental results; (2) change in the length of alkyl chain had almost no effect on the structure and hydration area of the hydrophilic group.

Keywords:

• Anionic surfactant
• density functional theory
• hydration

This work was supported by the National Natural Science Foundations of China (Grant Nos. 20676051 and 20573048).