Characteristics of system
example
Invisible in electron microscope Pass through ultrafilter and semipermeable membrane undergo rapid diffusion
Oxygen molecules, ordinary ions, glucose
• 2H3AsO3（w）+ 3H2S →As2S3（sol） +6H2O
•OH)3 （sol） +3HCl
• 2H2S(w）+ SO2(g) → 2H2O +3S (sol）
• Na2S2O3 +2HCl → 2NaCl +H2O +SO2 +S (sol)
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grinding method
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sonication dispersion method
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arc discharge method
• Owing to the intense heat generated by the arc, some of the metal of the electrodes is dispersed as vapor, which condenses to form colloidal particles.
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Lyophobic colloids
Lyophobic colloids is composed of materials that have little attraction. e.g. gold, silver, sulfur, arsenous sulfide, and silver iodide.
Grains of sand,most pharmaceutical emulsions and suspension, red blood cells
Types of Colloidal dispersion
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Lyophilic colloids
Systems containing colloidal particles that interact to an appreiable extent with the dispersion medium are referred to as lyophilic(solventloving)colloids. hydrophilic sols: gelatin, acacia, insulin, albumin Lipophilic colloids: rubber, polystyrene. A material that forms a lyophilic colloidal system in one liquid(e.g. water) may not do so in another liquid(e.g. benzene).
Not resolved by ordinary microscope (although may be detected under ultramicroscope) Visible in electron microscope Pass though filter paper Do not pass semipermeable membrane Diffusion very slowly
• 2HAuCl4+ 3HCHO +11KOH → 2Au(sol） 物理药剂学
Sol purification
• 1,dialysis method • 2,ultrafiltration
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dialysis method
•Semipermeable membrane
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dialysis method
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The methods to prepare lyophobic colloids
•Dispersion methods 1,grinding method 2,sonication dispersion method 3,arc discharge method
•Condensation methods 1,physical methods 2,chemical methods
Colloidal dispersion system
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size
class Molecular dispersion
Colloidal dispersion
Coarse dispersion
Particle size Less than 1 nm
From 1 nm to o.5 μm
Greater than o.5 μm
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Physical condensation methods
1,replacement of solvent
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Physical condensation methods
2, Steam quench method
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chemical condensation methods
Colloidal silver sols, natural and synthetic polymers, cheese, butter, jelly, milk, etc.
Visible under microscope Do not passthough normal filter paper Do not dialyze though semip物e理r药m剂ea学ble menmbrane Do not diffusion
•Electrodialysis
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ultrafiltration
•Semipermeable membrane
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ultrafiltration
• Electro ultrafiltration
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Association colloids
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CMC
the critical micelle concentration (CMC) is defined as the concentration of surfactants above which micelles form and all additional surfactants added to the system go to micelles.