Cation Exchange Resins

 

Cation Exchange Resins contain negatively charged functional groups, which attract positively charged ions in solution. One of its applications is separating positive ions from contaminated water.

 

Cation Exchange Resins are also further classified into two sub-groups:

 

• Strong acid cation (SAC) resins: They are made of polystyrene with a sulfonate functional group (SO3-) that is either charged with hydrogen ions (H+) or sodium ions (Na2+).
• Weak acid cation (WAC) resins: They are composed of acrylic polymer with carboxylic acid groups as functional groups and have a high affinity for hydrogen ions. These are commonly used to remove alkalinity-associated cations.
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Anion Exchange Resins

 

Anion Exchange Resins contain positively charged functional groups, which attract negatively charged ions in solution. They contain amine as a functional group in their matrix.

 

These also are used to purify water as well, by removing negatively charged contaminants. The two subcategories of anion resins are:
 

Strong base anion (SBA) resins: These resins consist of a polystyrene matrix that has been chloromethylated and then aminated with dimethylamine. They either yield chloride ions or hydroxide ions during the exchange reaction.
Weak base anion (WBA) resins: They are also composed of a polystyrene matrix. Their degree of ionization is regulated or controlled by the pH of the solution. Additionally, since they lack exchangeable ions,they act as acid absorbers for removing ions from strong mineral acids.