ABSTRACT
C2.6.1.1 Classification of colloids The term colloid refers to systems where one phase is finely divided in another phase-with at least one of the dimensions in the range of about 1 nm to 1 µm. This encompasses a wide variety of systems, some of which will be mentioned below. In a narrower sense, the word colloid is often used to denote systems consisting of solid particles (or liquid droplets) suspended in a liquid. This contribution will mainly focus on such systems. On the one hand, these particles are (significantly) larger than the solvent molecules. On the other hand, they are sufficiently small to remain suspended and undergo vivid Brownian motion (after the British botanist Robert Brown, who published his observations on aqueous pollen suspensions in 1827). The term colloid (after the Greek word for ‘glue’) was coined by Thomas Graham in the 1860s, to denote substances such as gelatin, albumin and gums. In a solution, these would not pass a dialysis membrane.
