Surface active agents

5,285 views
5,017 views

Published on

its mostly useful for msc students

Published in: Education, Business, Technology
0 Comments
11 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
5,285
On SlideShare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
458
Comments
0
Likes
11
Embeds 0
No embeds

No notes for slide

Surface active agents

  1. 1. SURFACTANTS PRESENTS BY PRADEEPKUMAR YADAV RAMNIRANJAN JHUNJHUNWALA COLLEGE MSC(II) (PHYSICAL CHEMISTRY) SEM – (III) ( 2013 – 14 ) 1
  2. 2. CONTENTS • • • • • • INTRODUCTION C.M.C MICELLAR SOLUBILIZATION TYPES OF SURFACTANTS PROPERTIES APPLICATIONS 2
  3. 3. SURFACTANTS  Molecules and ions that are absorbed at the interface is termed as Surfactants  Surfactants have two distinct regions in their chemical structure, one of which is water-liking or Hydrophilic and the other of which is water-hating or Hydrophobic.  These molecules are referred to as Amphiphilic or Amphipathic molecules or simply as Surfactants or Surface active agents. 3
  4. 4. SURFACTANTS The functional groups such as alcoholic (-OH), carboxylic acid (-COOH), sulphate (-SO4) & quaternary ammonium(NH4+) contribute to hydrophilic portion Alkyl chains contribute to lipophilic nature of molecules The polar end oriented towards the water as well as the non polar end projected upwards to space. 4
  5. 5. CMC • When a surfactant is placed in water it forms micelles at concentrations above its critical micelle concentration(CMC), they form aggregates known as micelles. • In a micelle, the hydrophobic tails flock to the interior in order to minimize their contact with water, and the hydrophilic heads remain on the outer surface in order to maximize their contact with water . 5
  6. 6. CMC • Critical micellar concentration is the concentration at which the monomeric surfactant molecules associates into small aggregates called micelles. • Diluting the surfactant solution to below the cmc causes the micelles to disperse or break up into single or non associated surfactant molecules. • Micelles are not static aggregates but dissociate, regroup and reassociate rapidly. • There is a dynamic equilibrium between single surfactant molecules and micelles. • The shape of micelles in dilute surfactant solutions is approximately spherical. 6
  7. 7. Micellar solubilization •Solubilization can be defined as the spontaneous dissolving of a substance by reversible interaction with the micelles of a surfactant in water to form a thermodynamically stable isotropic solution with reduced thermodynamic activity of the solubilized material. •At surfactant concentrations above the cmc the solubility increases linearly with the concentration of surfactant, indicating that solubilization is related to micellization. •The lower is the CMC value and higher the aggregation number , the more stable are the micelles. 7
  8. 8. Surfactants, Types •Anionic: Sodium dodecyl ( lauryl)sulfate ( SLS) •Cationic: Dodecyltrimethyl ammonium bromide(DTAB) •Nonionic: Tweens, Spans •Zwitterionic(Amphoteric): Lecithin(Phospholipids), Others • Nontraditional: Bile salts •Drugs: Dexverapamil-HCl, ibuprofen, and benzocaine. 8
  9. 9. Anionic surfactants • Sodium Lauryl Sulphate BP • Mixture of sodium alkyl sulphates, the chief of which is sodium dodecyl sulfate, C12 H25 SO4 – Na+ • It is very soluble in water at room temperature, and is used • pharmaceutically as a preoperative skin cleaner, having • Bacteriostatic action against gram-positive bacteria, and also in medicated shampoos • Component of emulsifying wax. 9
  10. 10. Cationic surfactants • cationic surfactants are important pharmaceutically because of their bactericidal activity against a wide range of gram-positive and some gram-negative organisms. • They may be used on the skin, especially in the cleaning of wounds. • Their aqueous solutions are used for cleaning contaminated utensils. 10
  11. 11. Non-ionic surfactants • These are not ionised in aqueous solution • Polyoxy ethylene sorbitan fatty acid esters • Sorbitan esters are supplied commercially as Spans and are mixtures of the partial esters of sorbitol and its monoand di-anhydrides with oleic acid. • They are generally insoluble in water (low hydrophile – lipophile balance (HLB) value) are used as water-in-oil emulsifiers and as wetting agents. 11
  12. 12. Non-ionic surfactants • Polysorbates are complex mixtures of partial esters of sorbitol and its mono and di-anhydrides condensed with an approximate number of moles of ethyleneoxide. • They are supplied commercially as Tweens. The polysorbates are miscible with water, as reflected in their higher HLB values, and are used as emulsifying agents for oil-in-water emulsions. 12
  13. 13. PROPERTIES - Wetting - Emulsification - Dispersion / Solubilization - Foaming / De-foaming - Detergency - Conditioning - Thickening 13
  14. 14. WETTING •Paraffin or new cotton cloth barely wetted by water, but when surfactant is added to water their surface easily becomes wet •Surfactant in floor cleaner as a wetting agent 14
  15. 15. EMULSIFICATION 15
  16. 16. EMULSIFICATION Examples of Emulsions 16
  17. 17. FOAMING EFFECT Foam consist of gas covered with thin liquid film. Surfactant molecule absorbed to interface between gas and liquid 17
  18. 18. DETERGENCY 18
  19. 19. APPLICATIONS  PHARMACEUTICAL ADJUVANTS They are added to the drugs in order to increase the product characteristics in the design of dosage forms in a variety of ways like solublising agents, wetting agents ,detergents, suspending ,foaming, emulsifying agents  INFLUENCES THE DRUG ACTION These are at low conc. Enhances the penetration of hexylresorcinol into pinworm ,ascaris.  • • • ANTIBACTERIAL ACTIVITY These are alter the integrity and lost the essential elements by leak Mainly cationic surfactants show activity But non ionic surfacants help in metabolism of organisms & facilitate their growth • Natural surfactants enhances the absorption of antibiotics 19
  20. 20. APPLICATIONS  FOAMING AGENTS: They can be used in shampoos & lathering shaving cream so it can produce stable foam when mixed with air pockets enclosed with thin film of liquid.  ANTI FOAMING AGENTS They can be used in fermentation process to prevents the foams in production .eg., octnol, ether, castor oil & silicones  • • • • SOME ARE DRUGS Phenothiazine & procaine-tranquilizer, local anesthetic Acridines-antibacterial Streptomycin-antibiotic Veratrum alkaloids-anti cancer 20
  21. 21. REFERENCE M. J. Rosen. Surfactants and Interfacial Phenomena (3rd edn.), John Wiley (2004) R. Zana (ed.). Dynamics of Surfactant Self-Assemblies, CRC Press (2005) 3. M. Abe & J. F. Scamehorn. Mixed Surfactant Systems, CRC Press (2004). 21
  22. 22. 22

×