Synthetic resins are the insoluble polymeric solids having giant hydrocarbon network containing reactive acidic or basic groups. These are superior to Zeolite because they can remove all types of cations as well as anions present in water. This resulting water is known as demineralised or deionised water.
These are two types:
Cation exchanger resins: they have acidic groups such as COOH or SO3H. They may be represented as resin—H+
Anion exchanger resins: they have basic groups such as–OH or– NH2. They may be represented as resin—OH or resin—NH3 +OH