Adsorption on solid adsorbent. Ionochange adsorption (rule of Paneta-Fainsa-Gana)

Langmuir equation. Adsorption isotherm of Longmuir.

Orientation of molecule in surface layer. Longmuir paling.

The orientation of nematic liquid crystals (LCs) close to solid surfaces is of high interest both for fundamental physics and

for application in liquid crystal displays (LCDs). All liquid crystal cells used for displays are coated with polymeric

alignment layers on their inside. Via an anisotropic surface–LC interaction the surface imposes a well-defined orientation onto the bulk material and thereby defines the ground (“off”) state of the cell. This phenomenon is often termed “surfaceorientational anchoring.”

The Langmuir equation (also known as the Langmuir isotherm, Langmuir adsorption equation or Hill-Langmuir equation) relates the coverage or adsorption of molecules on a solid surface to gas pressure or concentration of a medium above the solid surface at a fixed temperature. The equation was developed by Irving Langmuir in 1916. The equation is stated as:

θ is the fractional coverage of the surface, P is the gas pressure or concentration, α is a constant.

The constant α is the Langmuir adsorption constant and increases with an increase in the binding energy of adsorption and with a decrease in temperature.

Adsorption is the phenomenon in which a substance (an adsorbate) is condensed and held in a liquid state on the surface of an adsorbent. Molecular sieve and silica gel are the main types of adsorbents that typically are used.

Дата добавления: 2014-12-08