The link between colloids and surfaces

The link between colloids and surfaces follows naturally from the fact that particulate matter has a high surface area to mass ratio. The surface area of a 1cm diameter sphere (4jtr ) is 3.14 cm, whereas the surface area of the same amount of material but in the form of 0.1 pm diameter spheres (i.e. the size of the particles in latex paint) is 314 000 cm. The enormous difference in surface area is one of the reasons why the properties of the surface become very important for colloidal solutions. One everyday example is that organic dye molecules or pollutants can be effectively removed from water by adsorption onto particulate activated charcoal because of its high surface area. This process is widely used for water purification and in the oral treatment of poison victims. 

Although it is easy to see that surface properties will determine the stability of colloidal dispersions, it is not so obvious why this can also 

Liquid Surface energy in ml m (at 20 °C) Type of intermolecular bonding 

The influence of this surface energy can also be clearly seen on the macroscopic shape of liquid droplets, which in the absence of all other forces will always form a shape of minimum surface area - that is, a sphere in a gravity-free system. This is the reason why small mercury droplets are always spherical. 

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