The name of ion exchange resin consists of classification name, skeleton (or gene) name and basic name. The pore structure is divided into gel-type and macroporous type, where the physical pore structure is called macroporous resin, and “macroporous” is added in front of the name. Classification of acidic should be added before the name of the “Yang”, classification of alkaline, before the name of the “Yin”. For example, large pore strong acidic styrene cation exchange resin.

Basic Classification

Ion exchange resins can also be classified into styrene-based resins and acrylic-based resins according to the type of matrix. The type of chemically active groups in the resin determines the main properties and categories of the resin. They are first classified into two categories: cation resins and anion resins, which can be ion exchanged with cations and anions in solution, respectively. Cation resin is divided into two categories of strong acid and weak acid, and anion resin is divided into two categories of strong alkaline and weak alkaline (or then divided into medium-strong acid and medium-strong alkaline category).

Basic Types

1. strong acidic cation resin:

This type of resin contains a large number of strong acidic groups, such as sulfonic acid group - SO3H, easy to dissociate H+ in solution, so it is strongly acidic. After the dissociation of the resin, the negatively charged groups contained in the body, such as SO3-, can adsorb and bind other cations in solution. These two reactions make the H+ in the resin and the cations in the solution exchange with each other. Strongly acidic resins have a strong dissociation ability and can dissociate and produce ion exchange in either acidic or alkaline solutions.

After a period of time, the resin is regenerated, i.e., chemicals are used to make the ion exchange reaction proceed in the opposite direction, so that the functional groups of the resin return to their original state for reuse. For example, the cation resin mentioned above is regenerated with strong acid, at which time the resin releases adsorbed cations, and then combines with H+ to restore the original composition.

2. Weakly acidic cation resin:

This kind of resin contains weak acidic groups, such as carboxy-COOH, which can dissociate H+ in water and become acidic. Resin dissociation of the remaining negatively charged groups, such as R-COO- (R for the hydrocarbon group), can be adsorbed and combined with other cations in the solution, resulting in cation exchange. The acidity of this resin is weak, and it is difficult to dissociate and carry out ion exchange at low pH, and it can only work in alkaline, neutral or slightly acidic solution (e.g. pH5-14). This kind of resin is also regenerated by acid (easier to regenerate than strong acidic resin).

3. Strongly basic anion resin:

This type of resin contains strong alkaline groups, such as quaternary amine groups (also known as tetramine groups) - NR3OH (R for the hydrocarbon group), can be dissociated in water OH- and strongly alkaline. The positively charged groups of this resin can adsorb and bind with the anions in solution, thus producing anion exchange.

This resin is highly dissociable and works well at different pH. It is regenerated with strong base (such as NaOH).

4. Weakly basic anion resin:

This kind of resin contains weakly basic groups, such as primary amine group (also called amine group)-NH2, secondary amine group (diamine group)-NHR, or tertiary amine group (tertiary amine group)-NR2, which can dissociate OH- in water and are weakly basic. The positively charged groups of these resins can adsorb and bind to anions in solution, resulting in anion exchange. This resin in most cases adsorbs the entire other acid molecules in solution. It can only work under neutral or acidic conditions (e.g., pH 1 to 9). It can be regenerated with Na2CO3, NH4OH.

Transformation of ionic resin

The above are the four basic types of resin. In actual use, the resin is often transformed into other ionic type operation to adapt to various needs. For example, often the strong acidic cation resin and NaCl role, transformed into sodium-type resin and then use. When working, the sodium-type resin releases Na+ and Ca2+, Mg2+ and other cations in the solution to exchange and adsorb to remove these ions. No H+ is released during the reaction, which prevents the pH of the solution from dropping and the resulting side effects (e.g., sucrose conversion and equipment corrosion). This resin can be regenerated with brine (without strong acid) after running with sodium type. Another anion resin can be transformed into a chlorine-type reuse, the work of the release of Cl- and adsorption exchange of other anions, its regeneration only with saline solution. Chlorine type resin can also be converted to bicarbonate type (HCO3-) operation. Strong acidic resin and strong alkaline resin in the transformation of sodium type and chlorine type, no longer has a strong acidic and strong alkaline, but they still have the other typical properties of these resins, such as strong dissociation and work in a wide pH range.