Dialysis

Name:
Dialysis
Detailed information:
The separation of small molecules from macromolecules in a solution by means of a semipermeable membrane such as parchment or collodion. The rates of diffusion of the small and the large molecules are so widely different that the former will readily pass through the membrane, whereas the latter will penetrate with extreme difficulty. For example the diffusion rates are about 2.3 for sodium chloride, 7 for cane sugar, and from 50 to 100 for proteins and other macromolecules. This differential led Thomas Graham to define substances that would pass through the membrane easily as crystalloids and those having a tendency to be retained by the membrane as colloids.See Colloid Chemistry; Electrodialysis; Graham, Thomas.