As for resin, although it is used in many industries, what we talk about most now is the environmental protection industry. Ion exchange resins are very popular in the environmental protection industry. So, how is ion exchange resin used?
1, strong acid cation exchange resin (strong acid cation exchange resin)
Strong acid cation exchange resin contains a large number of strong acid groups, such as sulfonic acid group -SO3H, which easily dissociates H+ in the solution, so it is strongly acidic. After the resin dissociates, the negatively charged groups contained in the body, such as SO3-, Adsorption and binding of 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 both acidic or alkaline solutions. After the resin is used for a period of time, it needs to be regenerated, that is, the ion exchange reaction is carried out in the opposite direction with chemicals to restore the functional group of the resin to its original state for reuse. For example, a strong acid cation exchange resin is carried out with a strong acid. In the regeneration process, the resin releases the adsorbed cations, and then combines with H+ to restore the original composition.
2, weak acid cation exchange resin (weak acid cation exchange resin)
Weakly acidic cation exchange resins contain weakly acidic groups, such as carboxyl -COOH, which can dissociate H+ in water and become acidic. After the resin dissociates, the remaining negatively charged groups, such as R-COO- (R is a hydrocarbon group), can be combined with other cations in the solution to produce cation exchange.
Weakly acidic cation exchange resins have weak dissociation properties and are difficult to dissociate and perform ion exchange at low pH. They can only work in alkaline, neutral or slightly acidic solutions (such as pH 5-14). This type of resin also uses acids. Regeneration (easier to regenerate than strong acid resin).
3, strong base anion exchange resin (strong base anion exchange resin)
Strongly basic anion exchange resins contain strong basic groups, such as quaternary amine groups (also known as quaternary amine groups) -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.
Strongly basic anion exchange resin has strong dissociation and can work normally under different pH. It uses strong alkali (such as NaOH) for regeneration.
4, weakly basic anion exchange resin (weakly basic anion exchange resin)
Weakly basic anion exchange resins contain 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 are weakly alkaline. The positively charged groups of this resin can adsorb and combine with the anions in the solution to produce anion exchange.
Weakly basic anion exchange resins absorb all other acid molecules in the solution in most cases and can only work under neutral or acidic conditions (such as pH 1-9). It can be regenerated with Na2CO3 and NH4OH.
Although there are only four types of ion exchange resins: strong acid, weak acid, strong base, and weak base, each type has many models, so you can choose the right product according to your needs.