1 โดย รองศาสตราจารย์ เรือง ศรี วัฒเนสก์ CHEM 324 : Physical Chemistry IV Part II Department of Chemistry, Faculty of Science, CMU. August 2009 Introduction to Colloid & Surface Chemistry

2 Content ö The Colloidal State : Classification & preparation Surfactant & micellization ö The Properties of Colloidal Dispersion (Size & shape determination) : Colligative properties Kinetic properties Optical property ö Colloidal Stability and Its Applications The electrical double layer ö The gas-liquid and liquid-liquid interfaces ö The adsorption of gas on the solid surface ö The liquid-solid interface

3 References 1.Atkins, P. W., Physical Chemistry, 8th ed., Oxford University Press, Oxford, Hiemenz, P. C. and Rajagopalan, R., Principles of Colloid Chemistry and Surface Chemistry : Revised and Expanded, 3rd ed., Marcel Dekker, New York, Hiemenz, P. C., Principles of Colloid Chemistry and Surface Chemistry, Marcel Dekker, New York, Hunter, R, J., Introduction to Modern Colloid Science, Oxford University Press, Oxford, Shaw, D. J., Colloid &Surface Chemistry, 4th ed., Butterworth, Oxford, and other websiteshttp://wikipedia.com

4 Evaluation Assignment/Homework/Quiz20 points Report/Presentation20 points Final Exam 60 points Total 100 points (50%) (Final exam : Sept 24, 2009 : pm.)

5 1. The Colloidal State Definition :  particle with linear dimension between cm (10 A O ) and cm (1  ) nm  Other definitions particle weight/ particle size etc.

6 Length Scales C-C bond 0.1 nm Radius of Gyration 1 nm Micelles 10 nm Vesicles Emulsion Droplets 100 nm Latex Particles “Colloidal Crystals”1000 nm

7 Homogeneous Mixtures (True composition and properties) Property True solution ColloidSuspension Particle type Ions, small molecules Large molecules, particles Large particles Particle size0.1-1 nm1-100 nm100 nm and larger Tyndall effect NoYes

8 Colloidal Systems Dispersed Medium Gas Liquid Solid Cont. Medium Gas NONE Liquid Aerosol Liquid Aerosol Fog, mist Fogmist Solid Aerosol Solid Aerosol Smoke, air particulates Smoke particulates Liqui d Liqui d Foam Whipped cream Emulsion Emulsion Milk, mayonnaise, hand cream Milk mayonnaiseSol PaintPaint, pigmented ink, blood pigmented ink blood Solid Solid Foam Solid Foam Aerogel, styrofoam, pumice Aerogel styrofoam pumice Gel GelatinGelatin, jelly, cheese, opal cheeseopal Solid Sol Solid Sol Cranberry glass, ruby glass Cranberry glassruby g

9 aerosols, emulsions, sol,foam, paste Colloidal Colloidal Dispersion Macromolecular Colloids Silica gel Zeolite Basalt Associated Colloids Micelle formation Surfactants “surface active agents”

10 CMC determinations

11 Common Surfactant Classes

12 C 12 E 6 adsorbed at the air-water interface in the presence of oil

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15 Biocolloids myoglobin haemoglobin Megaspore wall from a fossil of Salvinia cerebrata. Nano “golf balls” Multiple Colloids

16 Preparation of Colloidal Systems Two basic methods of forming a colloid : reduction of larger particles to colloidal size condensation of smaller particles into colloidal particles i.e. spontaneous dispersion in the proper solvent metal evaporation in an electric arc to form a metal vapor cools. solid reduction in a colloid mill. emulsion preparation by homogenization with the addition of an emulsifying agent. Condensation of smaller particles to form a colloid usually involves chemical reactions—typically displacement, hydrolysis, or oxidation and reduction making colloidal gold, colloidal silver.colloidal goldcolloidal silver

17 Some areas of Science and Technology in which particles in the colloidal size range are regularly encountered Analytical chemistry : adsorption indicators, ion exchange, nephelometry, precipitate filterability, chromatography, and decolorization Physical chemistry : nucleation; superheating, supercooling and supersaturation; and liquid crystals Biochemistry and molecular biology : electrophoresis; osmotic and Donnan equilibria and other membrane phenomena; viruses, nucleic acids, and proteins; and hematology

18 Chemical manufacturing : catalysis, soaps and detergent, paints, adhesives, ink; paper and paper coating; pigment; thickening agents; lubricants Environmental science : aerosols, fog and smog, foams, water purification and sewage treatment; cloud seeding; clean rooms Materials science : powder metallurgy, alloys, ceramics, cement, fibers, and particles of all sorts Petroleum science, geology and soil science : oil retrieval, emulsification, soil porosity, floatation, and ore enrichment Household and consumer products : milk and dairy products, beer, water proofing, cosmetics, and encapsulated products

19 Assignment -1 1.Search from Journals or websites to find an example, in any branches of Science, of which particles in the colloidal-size range are encountered. 2.Write up in your own words a concise report in A4 paper. 3.Report is due on August 21, (10 points)