Emulsion

These slide will help you to gaining the basic concept on emulsion.

1. Emulsion Sarder Istiaque Ahmed 111-29-308 Daffodil International University

2. A mixture of two or more liquids that are normally Immiscible . One liquid phase is dispersed is dispersed as globules in the other liquid phase.

3. Advantages Mask the unpleasant taste. Sustained release   medication. Inert and chemically non-reactive. Reasonably odorless and cost effective .  Disadvantages Thermodynamically unstable and have short shelf-life . Leads to creaming and cracking  . leads to phase inversion.

4. Phase in Emulsion The dispersed liquid is known as the Internal or Discontinuous phase. T he dispersion medium is known as the External or Continuous phase.

5. Types Of Emulsion Oil in Water (O/W ) Water in Oil (W/O ) Water in Oil in water emulsion. Based on size of liquid droplets : Macroemulsions ( 0.2 – 50 mm) Microemulsions ( 0.01 – 0.2 mm)

6. Identification Tests For Emulsion Dye test. Dilution test. Electrical conductivity test. Fluorescence test . Cobalt chloride test.

7. Emulsifying Agent S oluble in both oil and water and enable oil to be uniformly dispersed in water as an emulsion . Emulsifying agents can be classified according to: 1 ) Chemical structure : Synthetic Emulsifying Agents ( Sodium stearate , Benzalkonium chloride). Natural Emulsifying Agents (Acacia, Tragacanth , Gelatin) Finely Dispersed Solids ( Bentonite , Veegum ) Auxilary Agents 2 ) Mechanism of action: Monomolecular Multi-molecular Solid particle films.

8. HLB Value The hydrophilic- lipophilic balance of a  surfactant  is a measure of the degree to which it is hydrophilic or  lipophilic . Has an arbitrary scale of 1 - 18 . Low HLB Indicates? Low number of hydrophilic groups on the Molecule thus imparting Lipophilic character. E.g. Spans have low HLB numbers. High HLB indicates? Emulsifier has a large number of hydrophilic groups on the molecule thus imparting hydrophilic Character. E.g. Tweens have higher HLB numbers

9. Theories Of Emulsification  Electric double layer theory. Phase volume theory. Hydration theory of e mulsions. Adsorbed film and interfacial tension t heory. Figure: Electric Double Layer

10. Figure: Interfacial Tension Theory Figure: Surface Tension

11. Methods Of Preparation Of Emulsion 1) Dry Gum Methods 2 ) Wet Gum Methods 3 ) Bottle Method 4 ) Beaker Method. 5 ) In situ Soap Method. 

12. Instability