What are the basic types of ion exchange resins?

1. Strong acid cationic resin

This type of resin contains a large number of strongly acidic groups, such as sulfonic acid group-SO3H, which easily dissociates H+ in the solution, so it is strongly acidic. After the resin is dissociated, the negatively charged groups contained in the body, such as SO3-, can adsorb and bind other cations in the solution. These two reactions exchange the H+ in the resin with the cations in the solution. Strong acid resin has a strong dissociation ability, and can dissociate and produce ion exchange in acid or alkaline solutions.

After the resin is used for a period of time, it needs to undergo regeneration treatment, that is, the ion exchange reaction is carried out in the opposite direction with chemicals to restore the functional groups of the resin to its original state for reuse. The above-mentioned cationic resin is regenerated with strong acid. At this time, the resin releases the adsorbed cations and combines with H+ to restore the original composition.

2. Weak acid cationic resin

This type of resin contains weakly acidic groups, such as carboxyl-COOH, which can dissociate H+ in water and become acidic. The remaining negatively charged groups after the resin dissociates, such as R-COO- (R is a hydrocarbon group), can adsorb and combine with other cations in the solution to produce cation exchange. The acidity of this resin is weak, and it is difficult to dissociate and perform ion exchange at low pH. It can only work in alkaline, neutral or slightly acidic solutions (such as pH 5-14). This kind of resin is also regenerated with acid (it is easier to regenerate than strong acid resin).

3. Strongly basic anion resin

This type of resin contains strong basic groups, such as a quaternary amine group (also known as a quaternary amine group)-NR3OH (R is a hydrocarbon group), which can dissociate OH-in water and become strongly basic. The positively charged groups of this resin can adsorb and combine with the anions in the solution to produce anion exchange.

This kind of resin is very dissociative and can work normally at different pH. It uses strong alkali (such as NaOH) for regeneration.

4. Weakly basic anion resin

This type of resin contains weakly basic groups, such as primary amino groups (also known as primary amino groups) -NH2, secondary amino groups (secondary amino groups) -NHR, or tertiary amino groups (tertiary amino groups) -NR2, They can dissociate from OH in water and become weakly alkaline. The positively charged groups of this resin can adsorb and combine with the anions in the solution to produce anion exchange. In most cases, this resin adsorbs all other acid molecules in the solution. It can only work under neutral or acidic conditions (such as pH 1-9). It can be regenerated with Na2CO3 and NH4OH.

C100E 03

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