Ion exchanger service life
The typical service life of an ion exchanger is 4-7 years for anion exchangers and 10+ years for cation exchangers, in some applications up to 20 years. The service life does not refer to the time until the capacity of the ion exchanger resin is exhausted, i.e. until the ion exchanger has to be regenerated, but to the time until the ion exchanger resin has to be discarded, i.e. until the ion exchanger resin has to be replaced. This is unavoidable wear and tear over time. A mixed bed resin for demineralization (e.g. in a demineralization cartridge) typically contains 60% anion exchanger and 40% cation exchanger. A water softening system is operated exclusively with cation exchangers.
An anion exchanger loses its functional groups during this period of 4-7 years in normal operation. With cation exchangers, the chemical divinylbenzene C₁₀H₁₀, which is responsible for cross-linking, tends to be lost. In this case, the ion exchange resin balls break and ion exchange resin sludge is formed. Due to its smaller size, this sludge can then pass through the outlet sieves and be dragged into the process or into the wastewater.
In special applications, an ion exchanger with an actual service life of 10+ years may need to be replaced earlier, especially if impurities such as oils, greases, biological or oxidative substances come into contact with the exchanger. In this case, the service life of an actually long-lasting selective exchanger resin can be reduced to e.g. 1 year or to even just a single loading cycle or regeneration cycle. Particularly with regard to biological infestation, however, at least annual regeneration is necessary for applications that are not used very often.
In other special applications, however, the service life of an ion exchange resin can also be extended by regeneration. So-called polisher mixed bed resins (Ultra Pure Water mixed bed resins or UPW resins) of the demineralization cartridge are often used in the post-cleaning of already pre-cleaned ultrapure water flows (e.g. in the semiconductor sector by means of electrodeionization). These are of a higher quality than normal mixed bed resins and, according to the data sheet, cannot be regenerated. However, regeneration is still possible in a special process, which extends the application from a single use to a typical multiple use of ion exchange resins, but which requires separate monitoring of the UPW resins.
90% of the divinylbenzene responsible for the service life is produced by DOW for the global market. Supposedly inexpensive ion exchangers may save on this comparatively expensive component and are partly responsible for earlier resin wear. It has therefore been shown that in applications for ion exchanger regeneration, resins from well-known manufacturers such as Lanxess Lewatit or Purolite can have a longer service life.
Do you have further questions about ion exchangers, especially mixed bed resin or ion exchange resin? Please do not hesitate to contact us.