Total Organic Content or Total Oxidizable Carbon (TOC) needs to be removed from pharmaceutical water and ultrapure water. When TOC content of water needs to be managed in ppm or ppb levels, TOC reduction with ultraviolet radiation plays a key part. Great care is required in designing, manufacturing and using TOC reduction systems because even traces of contamination from wetted parts like O rings can cause TOC levels to rise above acceptable limits.
Shortwave UV radiation of 185nm wavelength is used for TOC reduction in multiple ways.
Layman’s version of How TOC reduction with UV works
TOC is not a single type of chemical but includes a huge number of organic substances with molecular structures of varying complexity and characteristics. Actual dynamics of TOC reactions are not always understood as multiple types of TOC reduction reactions can work in parallel depending on operating conditions e.g.: pH, temperature, presence of trace elements, time, etc. factors with the potential to vary from installation to installation.
- 1. Breakdown of molecular bonds with high energy 185 radiation: Depending on the strength of molecular bonds and operating conditions, 185nm radiation can dissociate some molecular bonds and break down some TOC compounds..
- Generation of OH radicals in water: OH radicals are extremely strong oxidants and react with all available organic matter, breaking down complex TOC compounds in the process..
- Ozone generation: High energy 185nm UV radiation generates small amounts of Ozone from dissolved Oxygen) which reacts with
All the above mechanisms can be active to varying degrees and are affected by 254nm wavelength which often acts as a catalyst for such reactions. Because of the large number of factors with the potential to affect TOC reduction reactions, it is generally best to conduct pilot trials before investing in a TOC reduction UV unit.
Advance UV Systems makes customized TOC reduction systems and would be happy to offer pilot units to suit your TOC reduction requirements. Please contact us to discuss your TOC reduction requirement with us.