1. It is a surface phenomenon and refers to the uniform distribution of a substance through another at the surface e.g. solution of H2 in Pd. 2. It is the phenomenon in which a layer of ions, molecules or aggregates of molecules condense upon the surface with which they come in contact. 3. It is defined as the concentration of a substance at the interface or boundary between heterogeneous phases e.g. solid/ gas or two immisci.ble liquids Adsorbate y It is the substance which is adsorbed at the surface of another substance y Examples are: gases, dyes, water vapors etc. Adsorbent y It is the substance which adsorbs the other substance at its surface. y Examples are: activated charcoal, bone charcoal, alumina, silica gel, kaolin and filler¶s earth. Order Of Adsorption I. Liquid/ Solid adsorption II. Solid/ Gas adsorption III. Liquid/ Gas adsorption IV. Liquid/ Liquid adsorption yPositive adsorption yNegative adsorption ySorption How adsorption occurs Types of Adsorption y Vander walls or physical adsorption y Chemisorption Factors effecting the adsorption y Solubility of adsorption y Nature of Adsorbate y Nature of adsorbent y Concentration of adsorbent y Pressure y Temperature y pH y Affinity between adsorbent and adsorbate y Stirring Pharmaceutical Applications of adsorption 1. Activated charcoal 2. Physiological Importance 3. Purification 4. Preparation of Vitamin B1 5. Gas masks 6. Heterogeneous Catalysts 7. Bacterial filtration 8. Solid-liquid chromatography 9. Emulsification 10.Decolonization 11.Adsorption of water vapors