Ion exchanger for targeted water treatment

Among other things, water contains dissolved invisible substances such as calcium, sodium, magnesium or carbonates. These dissolved minerals and salts form electrical charge carriers, the so-called ions. The amount of the individual ions in the water are different due to various influencing factors. Ion exchangers optimize the content of ions in the water, tailored to the field of application.

Ionenaustauscher - Kristallstruktur eines Ions

Ions as a product of the solution process of a substance

Water is a solvent in which naturally and artificially introduced substances dissolve. The solution process results in an interaction. This leads to the dissolution of the ionic bond to the original substance. The result is independent electrical charge carriers (ions) in the form of cations and anions. These give the water different properties that the consumer perceives as positive or negative depending on the application.

For example, a high proportion of dissolved calcium and magnesium influences the hardness of the water. The ion exchanger removes the excess calcium and magnesium cations and exchanges them for sodium cations. The result is significantly lower deposits in the form of scale in household appliances or industrial plants.

This is how ion exchangers work

Ion exchangers work on the principle “the stronger displaces the weaker”. The basis for this process is the binding ability of the ions. This depends on the height of the charge and the ionic radius. The higher the electric charge and the smaller the ionic radius, the stronger the ion’s bond strength. If water is to be softened, the ion exchange material is saturated with the weaker sodium (Na +). Now, the water enriched with the strong binding calcium (Ca² +) flows through the ion exchanger, displaces the Na +, and attaches itself. The Na + goes into the liquid instead of calcium.

Especially in the industrial sector, it is always necessary to reverse the ion exchange before discharge as wastewater. In this case, the regeneration takes place, as many weak binding ions displace the few strongly binding ions.

In order to introduce the low-bond ions at all, the ion exchanger must be filled with suitable material. These ion exchange materials are suitable for the process.

– Natural and artificial zeolites

– Clay minerals

– Chlorophyll

– Ion exchange resins (synthetic resins)

– Alumina

– Rotted cellulose (wood)

Which material is used depends on its reaction to the various cations and anions, and which ions are eventually exchanged or removed according to the intended use.

Ion exchange for every application

Depending on the application of the water, the ion exchange is always tailored to the requirements. The continuous development of intelligent resins further refines the process and optimizes the processes described below.

– Water softening

– Partial desalination of water

– Selective ion exchange

– Demineralization

During water softening, the ion exchanger exchanges the ions of calcium and magnesium for sodium ions. Thus, the process removes the hardness-forming salts. However, since too soft water has disadvantages, a targeted process is required. The process control takes place, inter alia, via the selection of the ion exchange material. In this form of water softening one speaks of salination.

Partial desalination decarbonates the water to prevent the formation of limestone. For this purpose, the ion exchanger exchanges the carbonic acid-bound calcium and magnesium ions (hydrogen carbonate) with hydrogen ions. The result is softer water with a lower salt content and the released carbonic acid character.

Selective exchange of anions or cations occurs during selective ion exchange. This process is only used in the industrial sector and uses special resins as the ion exchange material. As an example of application is the removal of dissolved heavy metal ions from galvanic wastewater.

In demineralisation, the ion exchanger produces pure water. He removes in a multi-step process all salts dissolved in the water. The result is demineralised water, also known as demineralised water.

Ion exchanger in practical use

The field of application of ion exchangers ranges from commercial use to private water softening systems. The ion exchanger is primarily the material used. The device surrounding the ion exchanger controls the function and ensures the necessary framework conditions.

Ion exchangers are integrated in dishwashing and coffee machines. Many water filters used in the private and commercial sectors are also equipped with appropriate materials to soften the water. Zeolite A is often used as an ion exchanger and softener in laundry detergents, and the granules of hydroponics ensure that the plants are supplied with important minerals via ion exchange.

In medicine, ion exchange also has a wide range of applications. For example, hypercholesterolemia and hyperkalemia are successfully treated according to this principle.

Ionenaustauscher, welcher oft in Kaffeemaschinen zum Einsatz kommt

Little historical digression

The ion exchanger has been an important companion of humanity for millennia. Although the procedural and chemical backgrounds were unknown, the principle was used very early. As proof serves the Second Book of Moses, where the reliable oldest reference to this process is deposited. As an ion exchanger rotted wood was used, which is ideal for the exchange of magnesium ions and turned for the people around Moses inedible water into tasty drinking water.

Purposefully developed ion exchangers were only used at the beginning of the 20th century. These were aluminosilicates that were able to absorb alkali and alkaline earth ions from solutions. These materials were followed by weakly acidic ion exchangers in the form of special carbons and basic phenolic resin-based exchangers.