Adsorption at Liquid Interfaces

Definition of Adsorption at Liquid Interfaces

• Adsorptions at liquid interfaces involves the accumulation of molecules (adsorbates) at the boundary between two phases, reducing surface or interfacial tension.

Mechanism of Adsorption at Liquid Interfaces

• Surface Activity: Molecules with both hydrophilic and hydrophobic regions orient themselves at interfaces.
• Gibbs Adsorptions Isotherm: Describes the relationship between surface tension and concentration.

  • • • • $\Gamma = -\frac{1}{RT} \left( \frac{\partial \gamma}{\partial \ln C} \right)_T$

• where:
  • Γ is the surface excess concentration.
  • R is the gas constant.
  • T is the temperature.
  • γ is the surface tension.
  • C is the concentration of the adsorbate.

Factors Influencing Adsorption

• Concentration: Higher concentrations increase adsorptions  until saturation.
• Molecular Structure: Amphiphilic molecules adsorb more readily.
• Temperature: Generally, adsorptions decreases with increasing temperature.

Applications

• Emulsion Stabilization: Surfactants adsorb at oil-water interfaces.
• Foam Formation: Proteins and surfactants stabilize gas-liquid interfaces.
• Drug Delivery: Adsorptions affects drug release from carriers.

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