ELECTRICAL PROPERTIES OF INTERFACES: The existence of difference in electrical potential across a solid–liquid interface is demonstrated by the following phenomena: Electrophoresis: Movement of dispersed particles through a liquid medium under the influence of an electric field. Electro-osmosis: Movement of […]
SOLUBILIZATION: It can be defined as the preparation of a thermodynamically stable isotropic solution of a substance normally insoluble or very slightly soluble in a given solvent by the addition of component or by any suitable methods. SOLUBILITY: The maximum […]
Hydrophilic–Lipophilic Balance Concept: The HLB concept was introduced by Griffin in 1947 to classify nonionic surfactants but has since been applied to ionic surfactants as well. In this system, each surfactant is assigned a number between 1 and 20, representing […]
Many attempts have been made to develop a mathematical expression that relates the amount of the adsorbate per unit weight of adsorbent to a function of the solute concentration remaining in the solution at a fixed temperature. The most frequently […]
BET isotherm: Langmuir and Freundlich isotherms are based on the formation of a saturated monolayer of the adsorbate on the surface of the adsorbent. The BET isotherm assumes that a multimolecular layer of adsorbate molecules covers the surface of the […]
ADSORPTION PHENOMENA: Adsorption is the process in which materials of one phase (adsorbate) accumulate or concentrate at the interfacial surface of the other phase (adsorbent). It is a spontaneous phenomenon driven by a reduction of the surface free energy. Adsorption […]
Spreading Coefficient (S): In general, spreading of a liquid occurs when the work of adhesion between two liquids exceeds the work of cohesion between the molecules of each liquid. Work of adhesion (Wa)- Consider a liquid drop with surface tension […]
Ring Detachment Method (du Nouy tensiometer): The du Nouy’s ring method is similar to the Wilhelmy plate method, but it uses a ring or loop of wire. A platinum or Iridium wire of ~4 cm in circumference is suspended from […]