Methods of Colloid Preparation

COLLOIDS

colloids

Buchner funnel used in ultra filtration

Dialysis

Colloidal gold how color changes with increasing particle size

Methods of preparing colloids

For lyophillic

1. SOLVATION

For lyophobic

Methods for preparing lyophobic colloids

Dispersion

Methods

Condensation or

Aggregation Methods

Dispersion

Methods

Electrical dispersion

Bredig’s Arc Method

Bredig’s Arc Method

Mechanical Dispersion

Colloid mill

Ultrasonic dispersion

High Intensity Ultra sonic generators

Bredig’s Arc Method

High Intensity Ultra sonic generators

Ultrasonic generators

How?

Colloid mill

Colloid mill

Peptisation

Peptisation

Similarly a precipitate of AgCl on shaking with dilute solution of AgNO3, adsorbs Ag+ ion and gets peptised to colloidal particles of type AgCl / Ag+

• Similarly a precipitate of AgCl on shaking with dilute solution of AgNO3, adsorbs Ag+ ion and gets peptised to colloidal particles of type AgCl / Ag+

• Cellulose nitrate is peptised by ethanol. The colloidal solution so obtained is known as Colloidion.

condensation

Supersaturation Chemical reaction

Superaturation

By decreasing temperature

By changing solvent

Process of crystal growth

By change in solvent

Alcohol + sulphur

Supersaturated solution

Excess of water

Nuclei of crystal

Crystal growth

Sulphur colloidal sol

Chemicalreaction

Reduction

Oxidation

• Sulphur

Hydrolysis

• Ferric chloride

• Chromium and Almunium Salts

Double decomposition

• This causes Au3+ ions to be reduced to neutral gold atoms. As more and more of these gold atoms form, the solution becomes supersaturated, and gold gradually starts to precipitate in the form of sub-nanometer particles. The rest of the gold atoms that form stick to the existing particles, and, if the solution is stirred vigorously enough, the particles will be fairly uniform in size.

Association Colloids

Or amphiphilic colloids

amphiphiles

Amphiphilic molecule? Is it colloidal?

Phenomenon of micelle formation

phenomenon

CMC

Aggregation number

In water and in oil

Some shapes

When spherical? When laminar?

Effect on… (surface tension)

Are micelles solid?

In lyophillic sols?

Types of association colloids?

gegenions

Types of Amphiphiles