Silver Stabilised Hydrogen Peroxides: An introduction
Silver Stabilised Hydrogen Peroxides (SSHP) are widely used as an alternative to chlorine for water system disinfection and legionella control. There are a number of these products on the UK market and as they are all based on 50%v/v hydrogen peroxide and contain between 350 ppm and 500 ppm silver ion. It is assumed that they are all the same and there is a general perception, shared by organisations like the Health and Safety Executive that the performance and efficacy of these products are identical.
In reality these products are very different, and like most things the devil is in the detail, and to understand why we need to examine the role of silver ion in these products.
The Role of Silver Ion
The Creation of Silver Ion in Silver Stabilised Hydrogen Peroxide
Silver ion in these products comes from the addition of silver nitrate, one of the very few soluble silver salts. SSHP are therefore, in theory very easy to make. You add silver nitrate to hydrogen peroxide in an acidic solution.
The Role of Silver Ion in Huwa-San Silver Stabilised Hydrogen Peroxide
Silver ion performs three very important roles in the product.
- Improves the stability of Huwa-San
- Allows the hydrogen peroxide in Huwa-San to kill bacteria
- Ensures that the Huwa-San will penetrate, remove and treat biofilm
Silver ion hydrogen bonds to the hydrogen peroxide creating a very stable product. SSHP’s should be much more stable than ordinary hydrogen peroxide.
Huwa-San will remain stable in the drum for 5 years whereas ordinary hydrogen peroxide will only be stable for a few weeks.
Huwa-San will remain stable in water for weeks whereas ordinary hydrogen peroxide will only be stable for a few hours.
Because of this stability SSHP’s are less corrosive than ordinary hydrogen peroxides.
Silver ion allows SSHP’s to target thiol groups on the external wall of the bacterium drawing a large quantity of peroxide directly on to the bacterium. This prevents the bacterium from emitting catalase, an enzyme that destroys hydrogen peroxide. In this mechanism silver ion is not destroyed so silver also acts as a catalyst, and it is this characteristic that allows SSHP’s to penetrate, remove, and treat biofilm.
Roam Technology’s Unique Formula
But here’s the bit that differentiates between these products. All waters likely to be treated with SSHP contain chloride – generally up to a few hundred parts per million. Chloride ion will react with silver ion in solution to form insoluble silver chloride. When this salt forms the effect of the silver ion is gone, and silver stabilised hydrogen peroxide becomes hydrogen peroxide. All the benefits described above disappear.
Huwa-San the improved and most stable SSHP
However Roam Technology found a way of delaying this double decomposition and as we are dealing with very low-level contamination, we are looking at the addition of low- level constituents to maintain silver ion stability. This creates a unique formula that is stable even in water with a high microbiological content or chloride content. Huwa-San is known to be effective in salt water environments.
When it comes to SSHP- Its important to do your homework
If you want to judge a Silver Stabilised Hydrogen Peroxide product do not look at the hydrogen peroxide content and silver ion content but look at a detailed analysis of the other very low-level constituents, that have been added to prevent silver chloride precipitation. This is the reason why other SSHP formulations are less stable than Huwa-San. Some manufacturers, in their attempt to produce stability, have introduced heavy metal contamination, some have even managed to introduce trichloromethanes (THM’s) into products that are sold as chlorine free. SafeSol have made a careful study of the products currently sold in the UK.
Folks who use SSHP products should request a full analysis of the SSHP they are buying, and ensure that they are not paying over the odds for a product that might ultimately be little better than ordinary hydrogen peroxide.
To learn more about Huwa-San and its uses please don’t hesitate to contact Safesol.
