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Environmental fate & pathways

Adsorption / desorption

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Description of key information

An experimental determination of the adsorption/desorption potential of the reaction mass of calcium carbonate and calcium dihydroxide and calcium peroxide is not required due to the rapid hydrolysis and dissociation of the constituents present in this reaction mass. Instead, the behaviour of the degradation products is assessed based on available information.

Key value for chemical safety assessment

Additional information

As the reaction mass of calcium carbonate and calcium dihydroxide and calcium peroxide rapidly hydrolyses and dissociates in aqueous environment, the potential of the thus formed chemical species to adsorb to soil and sediment is examined:

·     For hydrogen peroxide no remarkable adsorption to soil and sediment is expected based on its high polarity and water solubility. An estimated Koc value of 1.58 L/kg is available in the REACH registration dossier for hydrogen peroxide. Furthermore, Mackay Level 1 modelling indicates that the substance will partition into the aquatic compartment for > 99% at 20°C, and that negligible fractions will be found in the air, soil or sediment compartment.

·     For the hydroxyl anions a Koc or Kd value is not relevant as the behaviour of this anion depends on the buffer capacity of the receiving environment.

·     For the calcium cations measured Kd values ranging from 5.3 to 49.1 L/kg were determined according to the REACH registration dossier for calcium dihydroxide.

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