Reaction mass of calcium dihydroxide and calcium peroxide

Biodegradation in soil

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in soil: simulation testing

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
The biodegradation is relevant to organic substances regardless of the environmental compartment in which this property is investigated. This endpoint is specifically needed for organic substances and less relevant for inorganic substances.
In aqueous solution, the calcium peroxide decomposes into hydrogen peroxide and calcium hydroxide. The hydrogen peroxide will subsequently further decompose into water and oxygen. Furthermore, the calcium hydroxide dissociates when brought into aqueous medium. The different chemical reactions are:
CaO2 + 2 H2O -> Ca2 + + 2 (OH)- + H2O2
H2O2 + H2O -> 2 H2O + O2
Ca(OH)2 -> Ca2 + + 2 OH-
Hydrogen peroxide has a short half-life in natural waters due to the activity of micro-organisms. Furthermore, hydrogen peroxide is continuously formed in the environment and is ubiquitous in fresh- and seawater at natural background concentrations from some micrograms to some tens of microgram per litre. On the other hand, in aqueous medium, calcium (di)hydroxide will be completely dissociated into its ions as the water solubility is relatively high compared to the environmental background concentration of calcium and due to dilution effects. Depending on the properties of the test medium, calcium (di)hydroxide will be strongly neutralised in the initial period after application, by formation of calcium carbonate which will dissociate into calcium and carbonate ions. These ions are naturally ubiquitous in the environment; calcium will be assimilated by species present in the water and is necessary to maintain a good chemical balance in soils, water and plants and carbonate will become part of the carbon cycle.

Transformation products:

yes

No.:

#1

No.:

#2

Description of key information

Data waiving (study scientifically not necessary): The reaction mass of calcium dihydroxide and calcium peroxide is an inorganic multi-constituent substance that will not persist in the environment. Abiotic processes such as hydrolysis and dissociation are responsible for the fate of this multi-constituent substance in the environment. The constituent calcium peroxide is hydrolyzed to calcium hydroxide and hydrogen peroxide. The alkaline constituent calcium hydroxide will be neutralized in the environment, while hydrogen peroxide will be degraded by abiotic and biotic processes to oxygen and water.