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Environmental fate & pathways

Hydrolysis

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Description of key information

Troclosene sodium rapidly hydrolyses in water (t1/2 < 1 second).CYA does not undergo hydrolysis in the dark at 25°C at pH ranges from 5 through 9 over a period of 30 days.	

Key value for chemical safety assessment

Additional information

Troclosene sodium (NaDCC) rapidly hydrolyses in water. This is supported by a study cited in the literature (Matte 1990). The hydrolysis rate constant for monochloroisocyanuric acid was determined. The second and third chlorines on TCCA and the second chlorine on NaDCC will hydrolyse even faster since they are less strongly bound. TCCA and NaDCC hydrolyse rapidly in water, forming a range of compounds: hypochlorous acid, hypochlorite ions, Cl3CY, HCl2CY, Cl2CY, H2ClCY, HClCY, ClCY–2, H3CY (cyanuric acid), H2CY, HCY–2, CY–3(C3N3O3–3). Hydrolysis is an equilibrium reaction. The extent of hydrolysis, and the concentration of each of the above compounds, depends on the temperature, the pH and the initial concentration.

As the free available chlorine is reduced by reaction with various impurities in the water it is converted into chloride ions and additional free chlorine is released from the chlorinated isocyanurates in solution. Once all the available chlorine has been reduced, the stable reaction products are CYA or its salts and chloride salts. Therefore CYA or its sodium salt is the substance of interest for the environmental fate studies. A hydrolysis study is available for CYA (Hu 1981) which is considered to be the key study.