Dispersion system

1. Dispersion system:

One or several substances disperse in another substance serving as medium.

Domain: dispersed phase

Continuous phase: dispersion medium

According to the size of dispersed phase

r / m Atom number

name Phase number uniformity

< 10-9 < 103 Molecular

dispersion

Single phase uniform

10-7~10-9 103~109 Colloidal

dispersion

multiphase uniform

10-7~10-4 > 109 Coarse

dispersion

multiphase nonuniform

1.2 Classification of dispersion systems

Dispersion medium

Dispersed phase

name Examples

Gas liquid Liquid aerosol Fog, liquid sprays

Solid Solid aerosol Smoke, dust

liquid

Gas foam Whipped cream

Liquid Emulsion Milk

solid sol paint, mud

solid

gas solid foam expanded PS

liquid gel jellies, opal

solid Solid suspension colored glasssmoky crystal

1.2 Classification of dispersion system according to state

Lyophilic sols:

The colloidal particles interact strongly with the dispersion medium.

Solution of macromolecules (not “true” solution)

Lyophobic sols:

The colloidal particles and the dispersion medium has no tendency to interact.

Fe(OH)3 sol

1.2 Classification of colloids

--- according to dispersion state

1862, Graham:

samples Diffusion Semi-permeable membrane

Crystalloids Salt, sugar Rapid Permeable

Colloids Protein, Fe(OH)3 slow Non-permeable

Colloids, sol, gel, peptization, dialysis.

1.3 What is colloids?

Fundamental concepts

10-4 ~ 10-5 mol dm-3, sol;

10-2 ~ 10-1 mol dm-3, precipitation, crystal,

2~3 mol dm-3, gel

1908, Weimarn: Ba(CNS)2 + MgSO4:

1907, BanmapH

sol gel

precipitation

concentration

dia

met

er