X-ray study of the electric double layer at the n-hexane/nanocolloidal silica interface

Abstract

The spatial structure of the transition region between an insulator and an electrolyte solution was studied with x-ray scattering.The electron density profile across the n-hexane/silica sol interface (solutions with 5-nm, 7-nm, and 12-nm colloidal particles) agrees with the theory of the electrical double layer and shows separation of positive and negative charges. The interface consists of three layers, i.e., a compact layer of Na+, a loose monolayer of nanocolloidal particles as part of a thick diffuse layer, and a low-density layer sandwiched between them. Its structure is described by a model in which the potential gradient at the interface reflects the difference in the potentials of "image forces" between the cationic Na+ and anionic nanoparticles and the specific adsorption of surface charge. The density of water in the large electric field (1-10 GV/m) of the transition region and the layering of silica in the diffuse layer is discussed.

9 pages, 9 figures

Cited by in corpus (11)

• Compact Layer of Alkali Ions at the Surface of Colloidal Silica
• Ion-Size Effect at the Surface of a Silica Hydrosol
• Vaporization and Layering of Alkanols at the Oil/Water Interface
• Kinetics of the Phospholipid Multilayer Formation at the Surface of the Silica Sol
• Study of DMPS Monolayers on a Water Substrate with Laboratory X-ray Reflectometer
• Diffuse X-Ray Scattering near a Two-Dimensional Solid - Liquid Phase Transition at the n-Hexane - Water Interface
• Crystals of Na+ ions at the surface of a silica hydrosol
• Laboratory X-ray Study of the Phospholipid Monolayers at the Water Surface
• X-Ray Scattering near a Liquid - Vapor Phase Transition at the n-Hexane - Water Interface
• Thermotropic Phase Transition in an Adsorbed Melissic Acid Film at the n-Hexane - Water Interface
• X-Ray Study of Thermotropic Mesophases of an n-Triacontanol Adsorption Film at the n-Hexadecane - Water Interface