Principles of Dialysis:
– Dialysis changes the matrix of molecules based on size through diffusion, osmosis, and ultrafiltration.
– Diffusion allows small molecules to pass through the membrane while restricting large molecules.
– Osmosis involves fluid movement across a semi-permeable membrane to achieve equilibrium.
– Ultrafiltration removes waste molecules and excess fluids from the sample.
Types of Dialysis:
– Diffusion Dialysis:
– Uses concentration gradient for separation.
– Anion exchange membranes allow anions to pass, while cation exchange membranes obstruct cations.
– Electrodialysis:
– Uses ion-exchange membranes and electrical potential for separation.
– Includes Donnan dialysis, reverse electrodialysis, and electro-electrodialysis processes.
Procedure and Variables Optimization:
– Equipment needed for dialysis includes membranes, dialysate buffer container, and temperature control.
– Variables for optimization include sample volume, molecule size, membrane type, and dialysis endpoint subjectivity.
– Dialysis membranes are characterized by Molecular Weight Cut-Off (MWCO) limits which determine molecule diffusion rates.
Laboratory Dialysis Formats and Applications:
– Formats include dialysis tubing, dialyzers, and preformatted devices like Slide-A-Lyzer and Float-A-Lyzer.
– Applications range from purifying solutions to recovery processes such as alkali waste recovery and de-alcoholization of beer.
Advantages, Disadvantages, and Additional Dialysis Methods:
– Advantages and Disadvantages:
– Diffusion dialysis is energy-efficient with easy operation but has lower processing capability.
– Electrodialysis offers high recovery rates, low pressure, and no fouling issues.
– Additional dialysis methods include Haemodialysis, Microdialysis, Osmosis, and Peritoneal dialysis.
In chemistry, dialysis is the process of separating molecules in solution by the difference in their rates of diffusion through a semipermeable membrane, such as dialysis tubing.
Dialysis is a common laboratory technique that operates on the same principle as medical dialysis. In the context of life science research, the most common application of dialysis is for the removal of unwanted small molecules such as salts, reducing agents, or dyes from larger macromolecules such as proteins, DNA, or polysaccharides. Dialysis is also commonly used for buffer exchange and drug binding studies.
The concept of dialysis was introduced in 1861 by the Scottish chemist Thomas Graham. He used this technique to separate sucrose (small molecule) and gum Arabic solutes (large molecule) in aqueous solution. He called the diffusible solutes crystalloids and those that would not pass the membrane colloids.
From this concept dialysis can be defined as a spontaneous separation process of suspended colloidal particles from dissolved ions or molecules of small dimensions through a semi permeable membrane. Most common dialysis membrane are made of cellulose, modified cellulose or synthetic polymer (cellulose acetate or nitrocellulose).
