How ion exchange resin works
The exchange reaction of the ion exchange resin is similar to the replacement reaction in the solution. The exchangeable ions carried by the functional groups immobilized on the polymer backbone can be dissociated in the aqueous solution. For example, the hydrogen ions can be dissociated from the sulfonic acid resin. Such ions can move freely over a wide range and diffuse into the solution. At the same time, the same type of ions in solution, such as sodium ions, can also diffuse from the solution into the polymer meshes and pores. When the concentration difference between the two ions is large, an exchange driving force is generated to cause the exchange between them. The larger the concentration difference, the faster the exchange speed. Using the driving force relationship of this concentration difference, the exchangeable ions on the resin undergo a reversible exchange reaction. For example, when the concentration of sodium ions in the solution is large, the hydrogen ions on the sulfonic acid resin can be exchanged. When all the hydrogen ions are exchanged with sodium ions, the resin is said to be saturated with sodium ions. Then, if the solution is changed to an acid with a higher concentration, the hydrogen ions in the solution can replace the sodium ions on the resin, and the resin is "regenerated" to the H+ type. The exchange reaction for other ion exchange resins is similar (further discussion can be found in a later blog post). Through this reversible exchange principle, and the functional groups immobilized on the resin have different affinities for different ions, the ion exchange resin can be used for ion separation, replacement, concentration, impurity removal and catalytic chemical reactions, etc. .
Due to the stability of the polymer skeleton in the ion exchange resin, the reversible exchange reaction can be repeated on the resin, and the service life is long. In the industrial production process, the production process can be simplified, the production time can be shortened, and the production efficiency and product quality can be improved.
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