Write short note on electro-dialysis.

Explanation

Dialysis. It is a very important method of removal of soluble impurities from sols by a semipermeable membrane is known as dialysis.
This method is based on the principle that particles of true solutions which are smaller can pass through parchment paper or cellophane membrane. On the other hand, sol particles which are larger cannot pass through these membranes. A bag made up of such a membrane is filled with the colloidal solution and is then suspended in fresh water. The electrolyte particles pass out leaving behind the colloidal sol.
Movement of ions across the membrane can be expedited by applying electric potential through two electrodes. This method is faster than simple dialysis and is known as electrodialysis.

Significance or Application of Dialysis. The most important application of dialysis is in the purification of blood with the help of artificial kidney machine. The dialysis membrane permits excess ions and waste products like urea molecules to pass through whereas colloid sized particles of haemoglobin etc. do not pass through the membrane.