User:HarikaBanalla/Evaluate an Article

Which article are you evaluating?
Dialysis (chemistry)

The link above contains information about DIALYSIS. Dialysis is the process by which molecules in solution are separated through a semipermeable membrane (dialysis tubing).

Why you have chosen this article to evaluate?
I chose this article because the process of dialysis involves removing molecules from our bodies and I am very interested in learning more about our own bodily functions.

The concept of dialysis was introduced in 1861 by Scottish chemist Thomas Graham. He separated sucrose (small molecule) and dissolved gum arabic (large molecule) from an aqueous solution.

He also named solutes that cross membranes as diffusible solutes or crystalloids, and solutes that do not cross membranes as membrane colloids. Semipermeable membranes are made of cellulose or synthetic polymers.

Dialysis is based on three principles.


 * Diffusion is caused by Brownian motion of molecules, resulting in a net movement of molecules from regions of high concentration to regions of low concentration until equilibrium is reached.
 * Osmosis - Liquid moves from a region of high water concentration to a region of low water concentration and reaches equilibrium across a semi-permeable membrane.
 * Ultrafiltration convection of water caused by hydrostatic  or osmotic forces. During dialysis, ultrafiltration removes waste molecules  and excess liquid from the sample.

Evaluate the article
Dialysis is a process used to alter the matrix of molecules in a sample by differentiating molecules by size classification.

In dialysis, a sample and dialysate buffer are separated by a semi-permeable membrane that induces a differential diffusion pattern that allows molecules to separate.

Equipment used for dialysis is simple and efficient.

Requires sample, dialysate buffer, dialysate membrane in tubing or cassette, and container to hold buffer.

Dialysis membranes are manufactured and characterized according to their molecular weight limit (MWCO). MWCO usually refers to the lowest average molecular weight of a standard molecule that does not effectively dissolve across membranes during prolonged dialysis.

There are two types of dialysis


 * Diffusion dialysis, a natural separation process that uses anion exchange membranes (AEM) and cation exchange membranes (CEM) depending on the compounds to be separated. Anion exchange membranes (AEM) allow the passage of anions while impeding the passage of cations due to co-ion repulsion and electroneutrality, same as cation exchange membranes (CEM).
 * Electrodialysis is the process of separating molecules driven by an ion exchange membrane and an electric potential, commonly used to remove ions from aqueous solutions.

There are 3 types of electrodialysis methods


 * 1) Donnan dialysis separation method in which exchange ions are exchanged between two aqueous solutions separated by a CEM or AEM membrane
 * 2) Reverse electrodialysis
 * 3) Electrodialysis - an electromembrane process using three chambers that combines electrodialysis and electrolysis.

Easy dialysis procedure


 * Prepare the dialysate membrane according to the instructions
 * Place the sample in dialysis tubing, under gentle agitation, into the outer chamber containing the dialysis buffer, dialyze at room temperature for 2 hours, change the dialysis buffer and dialyze for another 2 hours, repeat until equilibrium is reached.

The advantages of dialysis are low energy consumption, low operating costs, and easy operation under normal pressure without polluting the environment.

The limitations of dialysis are low treatment capacity, low treatment efficiency, no removal of microorganisms, no removal of organic impurities, and the need for post-treatment.

The article above failed to identify the equipment, the process that the scientist uses to separate sucrose and dissolved gum arabic.

The photos in the article do not clearly describe the information contained in the article. This article does not mention hemodialysis, one of the widely practiced dialysis today.