Reaction mass of calcium dihydroxide and calcium peroxide

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

07 June 2021 - 11 June 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Test method according to OECD Guideline 105.

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

GLP compliance:

no

Remarks:

non-GLP study but conducted according to OECD TG 105

Type of method:

flask method

Key result

Water solubility:

> 100 - <= 1 000 mg/L

Conc. based on:

test mat.

Incubation duration:

96 h

Temp.:

20 °C

pH:

>= 11.2 - <= 12.2

Details on results:

Due to the nature of the test item, an exact water solubility value cannot be determined. From the calcium, pH and H2O2 measurements, the solubility of the test item was estimated to be between 100 and 1000 mg/L.

The pH were relatively stable over time and was proportional to the amount of Sample in each flask. The H2O2 was relatively stable for 100 mg/L and 1000 mg/L, with the flask containing 10000 mg/L showing a sharp decline after 24 hours. Calcium completely dissolved in the flask prepared with 100 mg/L, as the calcium concentration remained relatively unchanged at each time point. The flasks with greater amounts of CaO2 showed increasing amounts of calcium over time at slightly different rates. These observations indicate that saturation of calcium peroxide had been achieved in these flasks, with the increases in calcium concentration being equilibrium-driven owing to degradation of hydrogen peroxide.

Table 1. Data collected from supernatant samples

Flask contents	Time point (hours)	pH	H2O2 (mg/L)	Calcium (g/L)
100 mg/L	24	11.2	15.6	0.043
	48	11.4	15.3	0.044
	96	11.2	13.6	0.044
1000 mg/L	24	11.6	6.63	0.109
	48	11.8	7.80	0.132
	96	11.7	6.69	0.174
10000 mg/L	24	12.1	27.2	0.378
	48	12.2	6.56	0.462
	96	12.2	10.2	0.562

Conclusions:

The solubility of the test item was estimated to be between 100 and 1000 mg/L in a test perfomed according to OECD TG 105.

Executive summary:

The water solubility test was conducted with the reaction mass of calcium dihydroxide and calcium peroxide in accordance with OECD TG 105 following the flask method. Three mixtures of water and the test substance (100, 1000 and 10000 mg/L) were stirred for 24, 48 and 96h, and were centrifuged to remove any undissolved material. An exact water solubility value cannot be determined by measurement of calcium peroxide due to its reactivity when brought into contact with water. The solubility was determined from measurements of pH, hydrogen peroxide, and calcium by inductively coupled plasma optical emission spectroscopy (ICP-OES). The solubility of the test item was estimated to be between 100 and 1000 mg/L.

 

 

 

Description of key information

Key study: Test method OECD 105. The solubility of the test item was estimated to be between 100 and 1000 mg/L.

Key value for chemical safety assessment

Water solubility:

100 mg/L

at the temperature of:

20 °C

Additional information

The substance is composed of calcium hydroxide and calcium peroxide. Calcium hydroxyde dissociates in calcium ion and hydroxyl ions. Calcium peroxide hydrolyses into calcium hydroxide and hydrogen peroxide. The solubility was determined from measurements of pH, hydrogen peroxide, and calcium.