Calcium cyanamide

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2019-02-22

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD Series on Testing and Assessment No. 29: Guidance document on transformation/dissolution of metals and metal compounds in aqueous media

Version / remarks:

23 July 2001

Principles of method if other than guideline:

The test substance was dispersed in water to get a 10% aqueous suspension. Filled in a bottle this suspension was agitated on a shaker for defined times at ambient conditions. For each sampling date a separate bottle was prepared. At each sampling date the suspension was filtrated and the filtrate was analyzed for cyanamide, dicyandiamide, calcium and pH-value. The total period of the test was 28 days with 8 sampling dates (1, 2, 3, 4, 7, 14, 21 and 28 days).

GLP compliance:

no

Type of method:

flask method

Specific details on test material used for the study:

Calcium cyanamide technical grade

Key result

Type of test:

other: Transformation of calcium cyanamide to hydrogen cyanamide

Mean dissolved conc.:

>= 7.76 - <= 35.3 g/L

Element analysed:

Cyanamide

Loading of aqueous phase:

100 g/L

Incubation duration:

28 d

Test conditions:

in Water at 18 - 24°C; loading with calcium cyanamide technical grade

Key result

Type of test:

other: Transformation of calcium cyanamide to hydrogen cyanamide

Mean dissolved conc.:

>= 2.49 - <= 20.5 g/L

Element analysed:

Cyanoguanidine (Dicyandiamide)

Loading of aqueous phase:

100 g/L

Incubation duration:

28 d

Test conditions:

in Water at 18 - 24°C; loading with calcium cyanamide technical grade

Key result

Type of test:

other: Transformation of calcium cyanamide to hydrogen cyanamide

Mean dissolved conc.:

>= 4.6 - <= 16.9 g/L

Element analysed:

Calcium

Loading of aqueous phase:

100 g/L

Incubation duration:

28 d

Test conditions:

in Water at 18 - 24°C; loading with calcium cyanamide technical grade

Details on results:

Table 1 shows the results of the different sampling dates from day 1 to day 28. Listed are the concentrations of cyanamide, dicyandiamide, calcium and the pH-value of the filtrate. Further species as result of side- or secondary reactions (such as urea, ammonia, N-cyanourea) have not been analysed.
The analysis results show, that cyanamide and dicyandiamide formed thereof are the main dissolved species formed from calcium cyanamide technical grade in contact with water. Side reactions of both species, forming urea, ammonia and others (not quantitatively determined in this study) account for the decrease of the sum of cyanamide and dicyandiamide.
Based on an initial calcium cyanamide content of 67.7% in the test item, only approx. 20% are still present after 28 days as cyanamide. As expected, the majority is dimerized to dicyandiamide.
The pH value of the filtrate remains almost constant at approx. 12 over the whole period of the test.
The calcium concentration fluctuates in the first week between 11 and 17 g/L, and decreased continuously to 4.6 g/L in the next 3 weeks. The reason has not been investigated, but it is probably the effect on solubility of calcium ions of hydrogen cyanamide, dicyandiamide and the other substances generated.

Table 1: Results for the transformation of test item calcium cyanamide technical grade in aqueous media as a function of time

Sampling date [days]	Cyanamide [g/L]	Dicyandiamide [g/L]	Calcium [g/L]	pH-value
1	35.3	2.49	12.8	12.2
2	32.2	4.96	16.9	12.1
3	29.1	7.32	14.9	12.1
4	26.5	9.17	14.1	12.2
7	21.8	12.9	11.4	12.1
14	15.0	17.0	7.4	12.2
21	11.0	19.3	6.0	12.3
28	7.76	20.5	4.6	12.4

Conclusions:

The analysis results show, that cyanamide and dicyandiamide formed thereof are the main dissolved species formed from calcium cyanamide technical grade in contact with water. Based on an initial calcium cyanamide content of 67.7% in the test item, only approx. 20% are still present after 28 days as cyanamide. As expected, the majority is dimerized to dicyandiamide.

Executive summary:

The intention of the test was to determine the solubility of calcium cyanamide technical grade in aqueous media. Due to the fact that calcium cyanamide reacts immediately with water, a determination of water solubility of the substance in its proper definition is not possible.

The test substance was dispersed in water to get a 10% aqueous suspension. Filled in a bottle this suspension was agitated on a shaker for defined times at ambient conditions. For each sampling date a separate bottle was prepared. At each sampling date the suspension was filtrated and the filtrate was analyzed for cyanamide, dicyandiamide, calcium and pH-value. The total period of the test was 28 days with 8 sampling dates (1, 2, 3, 4, 7, 14, 21 and 28 days).

The analysis results show, that cyanamide and dicyandiamide formed thereof are the main dissolved species formed from calcium cyanamide technical grade in contact with water. Side reactions of both species, forming urea, ammonia and others (not quantitatively determined in this study) account for the decrease of the sum of cyanamide and dicyandiamide.

Based on an initial calcium cyanamide content of 67.7% in the test item, only approx. 20% are still present after 28 days as cyanamide. As expected, the majority is dimerized to dicyandiamide.

The pH value of the filtrate remains almost constant at approx. 12 over the whole period of the test.

The calcium concentration fluctuates in the first week between 11 and 17 g/L, and decreased continuously to 4.6 g/L in the next 3 weeks. The reason has not been investigated, but it is probably the effect on solubility of calcium ions of hydrogen cyanamide, dicyandiamide and the other substances generated.

Reference 2

Endpoint:

water solubility

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Description of key information

Upon dissolution in water calcium cyanamide technical grade is transformed to (hydrogen) cyanamide. Therefore, it is technically not possible to determine the water solubility of calcium cyanamide technical grade itself.

Additional information

A test was conducted to further investigate the dissolution behaviour of calcium cyanamide technical grade in water. A 10% aqueous suspension of the test item was prepared, and samples were taken after defined time points for up to 28 days. At each sampling, the test suspension was filtrated, and the filtrate was analysed for cyanamide, dicyandiamide, calcium and pH-value.

The analysis results show, that cyanamide and dicyandiamide formed thereof are the main dissolved species formed from calcium cyanamide technical grade in contact with water. Side reactions of both species, forming urea, ammonia and others (not quantitatively determined in this study) account for the decrease of the sum of cyanamide and dicyandiamide.

Based on an initial calcium cyanamide content of 67.7% in calcium cyanamide technical grade, only approx. 20% are still present after 28 days as cyanamide. As expected, the majority is dimerized to dicyandiamide.

The pH value of the filtrate remains almost constant at about 12.5 over the whole period of the test.