Dialysis is the removal of colloid solutions and solutions of polymers of low-molecular substances, capable to get through some natural (bullish bubble, vegetable parchment) and artificial (cellophane, collodion) membrane. Equipment for dialysis called dialyzers. The simplest of them is the dialysator Graham (Fig. 1) - glass cylinder, the bottom of which is covered cializations membrane. The cylinder fill the colloidal solution and immersed in a vessel with liquid, against which the conduct dialysis. Low-molecular substances penetrate through the membrane into the outer liquid and changing its removed from the colloidal solution. For colloidal particles validazione membrane is impermeable. In electrodialyzer (Fig. 2) process dialysis (electrodialysis) is considerably accelerated, as under the action of electric field ions low molecular weight substances are moving purposefully and quickly leave cialisinuaeto liquid.
Dialysis is widely used for the purification of proteins and other biopolymers, removal of toxic substances from the blood into the apparatus " artificial kidney" (see artificial Kidney).

Fig. 1. The dialysator Graham (the arrows show the direction of a liquid): 1 - cylinder; 2 - validationa membrane; 3 - a vessel with the solvent. Fig. 2. Electrodialyzer: 1 - electrodes connected to a DC source; 2 - a plastic bag; 3 - deliberately solution; 4 - flowing solvent