copper sulphide and zinc chloride sulphate hydroxide, recovery products from copper and zinc dusts

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29 Nov 2019 - 04 Mar 2020

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Series on Testing and Assessment No. 29 (23-Jul-2001): Guidance document on transformation/dissolution of metals and metal compounds in aqueous media

GLP compliance:

yes

Type of method:

other: This study was performed in order to determine the transformation and/or dissolution of Sulphide Precipitate via measurement of Zink (Zn) per ICP-OES in aqueous media.

Specific details on test material used for the study:

Name Sulphide Precipitate
Batch no. 20190601
Appearance blackish-green, wet sticky solid
Composition 2.9 % Cu; 18.0 % Zn; 0.5 % Fe; 0.1 % Pb; 0.7 % Cd; 0.4 % As; 0.3 % Sb; 0.1 % Sn; 0.0 % Bi; 0.0 % Br; 2.7 % Cl; 1.1 % F
CAS No. unknown
EC-No. 951-963-7
Molecular formula not stated
Molecular weight not stated
Purity 100 % (UVCB)
Homogeneity homogeneous
Vapour pressure not stated
Stability in solvents H2O: not stated; EtOH: not stated; acetone: not stated; CH3CN: not stated; DMSO: not stated
Solubility in solvents H2O: not stated; EtOH: not stated; acetone: not stated; CH3CN: not stated; DMSO: not stated
Production date not stated
Expiry date 31. Dec. 2025
Storage room temperature (20 ± 5 °C)
Stability stable under storage conditions

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

160 µg/L

Element analysed:

Zn

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

Mean value from days 1, 4 and 7.

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

1 388 µg/L

Element analysed:

Zn

Loading of aqueous phase:

10 mg/L

Incubation duration:

7 d

Test conditions:

Mean values from days 1, 4 and 7.

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

11 056 µg/L

Element analysed:

Zn

Loading of aqueous phase:

100 mg/L

Incubation duration:

7 d

Test conditions:

Men values from days 1, 4 and 7.

Details on results:

The following mean vales and RSD were calculated:
Analysis Data for Zn (Flasks 3 – 5, 1 mg/L)
Flask # Conc. after 2 h [µg/L] Conc. after 6 h [µg/L] Conc. after 1 d [µg/L] Conc. after 4 d [µg/L] Conc. after 7 d [µg/L]
3 118.9 136.4 152.3 141.6 127.5
4 129.1 159.4 186.7 166.6 155.0
5 128.9 165.4 188.8 169.9 156.9
Mean 125.6 153.7 175.9 159.3 146.5
RSD [%] 4.6 10.0 11.7 9.7 11.2

Analysis Data for Zn (Flasks 6 – 8, 10 mg/L)
Flask # Conc. after 2 h [µg/L] Conc. after 6 h [µg/L] Conc. after 1 d [µg/L] Conc. after 4 d [µg/L] Conc. after 7 d [µg/L]
6 1181 1309 1497 1395 1271
7 1266 1433 1622 1462 1358
8 715.8 933.1 1200 1368 1322
Mean 1054 1225 1440 1408 1317
RSD [%] 28.1 21.2 15.0 3.4 3.3

Analysis Data for Zn (Flasks 9 – 11, 100 mg/L)
Flask # Conc. after 2 h [µg/L] Conc. after 6 h [µg/L] Conc. after 1 d [µg/L] Conc. after 4 d [µg/L] Conc. after 7 d [µg/L]
9 6333 9081 11691 10300 10202
10 6197 8613 11498 10562 10410
11 6518 9313 12315 11244 11283
Mean 6350 9002 11835 10702 10631
RSD [%] 2.5 4.0 3.6 4.6 5.4

A duplicate determination was performed from each flask. Measurement data for Zn are presented in the following table:

               

Fl.	Content	Conc.Znin µg/L at following sampling points
		0 h^1	2 h	6 h	1 d	4 d	7 d
1	blank	< 1	< 1	2.77	8.40	5.58	6.90
		< 1	< 1	2.03	4.62	5.71	6.97
2	blank	< 1	< 1^2	1.02	< 1	< 1	1.24
		< 1	< 1	< 1	< 1	< 1	< 1
3	1.0 mg/L	< 1^2	117.8	136.4	151.8	145.0	128.0
		< 1	120.0	136.3	152.8	138.1	127.0
4	1.0 mg/L	< 1	134.6	158.8	186.7^3	166.7	151.6
		< 1	123.6	160.0	186.7^3	166.5	158.5
5	1.0 mg/L	< 1	127.9	163.2	191.5	171.5	157.0
		< 1	129.9	167.5	186.2	168.3	156.9
6	10 mg/L	< 1	1238	1302	1499	1337	1268
		< 1	1124	1317	1495	1454	1274
7	10 mg/L	< 1^2	1325	1425	1625	1464	1357
		< 1	1206	1440	1618	1459	1358
8	10 mg/L	< 1	716.5	943.4	1200	1370	1320
		< 1	715.2	922.9	1201	1367	1324
9	100 mg/L	< 1^2	6288	9045	11751	< 1^4	10193
		< 1	6379	9118	11631	10300	10210
10	100 mg/L	< 1	6013	8582	11484	10532	10405
		< 1^2	6382	8644	11512	10592	10414
11	100 mg/L	< 1^2	6510	9327	12351	11241	11261
		< 1	6527	9298	12279	11248	11305

¹the LOQ of Zn is 1 µg/L

²second measurementas a contamination was observed during the first measurement (2-4 µg/L Zn)

³repetition of the measurement as an error was observed during the sample preparation

⁴ error during the sample preparation

 

Slightly contamination was observed in the flask 1 (blank solution).

Conclusions:

The following concentrations of Zn were stated as a mean value from days 1, 4 and 7:
1 mg/L 160.6 µg/L;
10 mg/L 1388 µg/L;
100 mg/L 11056 µg/L.

Executive summary:

In this study, the maximum concentration of total dissolved Zink was determined in order to identify compounds of Sulphide Precipitate which undergo either dissolution or rapid transformation.

The calibration was performed using a certified Zn stock solution (1000 mg/L nominal each). All validation conditions for the range of 1 – 100 µg/L Zn in pH 5.5 buffer solution were fulfilled.During the study the calibration was performed two times in pH 5.5 buffer solution as the first calibration was invalid. Therefore, the data of calibration 2 were presented in the final report only. As the accuracy in pH 8.5 buffer solution lay outside the range of 70 – 110 %, the calibration (3) was additionally performed in pH 8.5 buffer solution.

The correlation coefficient r was > 0.99 of each calibration.The back calculated concentrations of the calibration standards layin the demanded ranges 100 ± 15 % and 100±20 % (low concentration) of the nominal values of each calibration. The accuracy in pH 7.0 buffer solution lay in the range of 70 – 110 % only. For the determination of Zn in pH 7.0 buffer solution the recovery rate 80.6 % was taken into account in the calculation of Zn concentration in the screening test. For the determination of Zn in pH 8.5 buffer solution, the calibration was additionally performed in pH 8.5 buffer solution and this calibration function was used for calculation of Zn concentration in pH 8.5 buffer during the screening test.

After the screening test, pH 5.5 was chosen for the reproducibility and full test based on the highest measured concentrations of Zn. The reproducibility test was performed with 100 mg/L test item (nominal) in pH 5.5 buffer solution over a period of 24 hours. Five vessels were prepared; each flask was measured in triplicate. A within-vessel variation of max. 10% and a between-vessel variation of max. 20% is demanded. These conditions were fulfilled. Therefore, for the full test three flasks per concentration with double determination were used.

The full test was performed with three different concentrations of the test item (nominal loads 1, 10 and 100 mg/L, three replicates each) over a period of 7 days with samplings after 2 h, 6 h, 1 d, 4 d and 7 d. Two flasks were prepared as blanks without addition of test item. No linear dependency of measured concentrations on time was observed for each nominal load. As the result a mean value of days 1, 4 and 7 was stated.

The pH values in the flasks 1 – 5 (blanks and 1 mg/L nominal concentration) lay in the demanded range 5.5±0.2 during the whole full test. The pH value in the flasks 6 – 8 and 9 – 11 lay in the range of 5.60 – 6.07 and 6.01 – 6.29 after addition of the test item, respectively. The adjustment of the pH value in the demanded range of 5.5±0.2 (flasks 9 – 11) was unsuccessful during the whole test as test item has changed the pH value.

The conditions RSD < 10 % (within-vessel)and < 20 % (between-vessel) were fulfilled in all flasks at each sampling point except the RSD between 6 – 8 flasks after 2 and 6 h. This was considered as uncritical as the result of dissolution of Zn with 10 mg/L nominal load was stated as a mean value of days 1 – 7.

No linear dependency of measured concentrations on time was observed. Usage of the first order model was also not possible for the determination of kinetic as the equilibrium was observed after 24 h. Two sampling points (2 h and 6 h) are not enough for calculation of kinetic. Therefore, the determination of kinetic was not possible. 

The mass balance lay in the range of 66.6 – 82.3 %.The difference is possible a result of the dissolution of another compounds of the test item (UVCB) which were not analyzed during the study.

Description of key information

The following concentrations of Zn were stated as a mean value from days 1, 4 and 7:

1 mg/L                      160.6 µg/L;

10 mg/L                  1 388 µg/L;

100 mg/L              11 056 µg/L.

Key value for chemical safety assessment

Water solubility:

11 mg/L

at the temperature of:

21 °C

Additional information

In this study, the maximum concentration of total dissolved Zink was determined in order to identify compounds of Sulphide Precipitate which undergo either dissolution or rapid transformation.

The calibration was performed using a certified Zn stock solution (1000 mg/L nominal each). All validation conditions for the range of 1 – 100 µg/L Zn in pH 5.5 buffer solution were fulfilled.During the study the calibration was performed two times in pH 5.5 buffer solution as the first calibration was invalid. Therefore, the data of calibration 2 were presented in the final report only. As the accuracy in pH 8.5 buffer solution lay outside the range of 70 – 110 %, the calibration (3) was additionally performed in pH 8.5 buffer solution.

The correlation coefficient r was > 0.99 of each calibration.The back calculated concentrations of the calibration standards layin the demanded ranges 100 ± 15 % and 100±20 % (low concentration) of the nominal values of each calibration. The accuracy in pH 7.0 buffer solution lay in the range of 70 – 110 % only. For the determination of Zn in pH 7.0 buffer solution the recovery rate 80.6 % was taken into account in the calculation of Zn concentration in the screening test. For the determination of Zn in pH 8.5 buffer solution, the calibration was additionally performed in pH 8.5 buffer solution and this calibration function was used for calculation of Zn concentration in pH 8.5 buffer during the screening test.

After the screening test, pH 5.5 was chosen for the reproducibility and full test based on the highest measured concentrations of Zn. The reproducibility test was performed with 100 mg/L test item (nominal) in pH 5.5 buffer solution over a period of 24 hours. Five vessels were prepared; each flask was measured in triplicate. A within-vessel variation of max. 10% and a between-vessel variation of max. 20% is demanded. These conditions were fulfilled. Therefore, for the full test three flasks per concentration with double determination were used.

The full test was performed with three different concentrations of the test item (nominal loads 1, 10 and 100 mg/L, three replicates each) over a period of 7 days with samplings after 2 h, 6 h, 1 d, 4 d and 7 d. Two flasks were prepared as blanks without addition of test item. No linear dependency of measured concentrations on time was observed for each nominal load. As the result a mean value of days 1, 4 and 7 was stated.

The pH values in the flasks 1 – 5 (blanks and 1 mg/L nominal concentration) lay in the demanded range 5.5±0.2 during the whole full test. The pH value in the flasks 6 – 8 and 9 – 11 lay in the range of 5.60 – 6.07 and 6.01 – 6.29 after addition of the test item, respectively. The adjustment of the pH value in the demanded range of 5.5±0.2 (flasks 9 – 11) was unsuccessful during the whole test as test item has changed the pH value.

The conditions RSD < 10 % (within-vessel)and < 20 % (between-vessel) were fulfilled in all flasks at each sampling point except the RSD between 6 – 8 flasks after 2 and 6 h. This was considered as uncritical as the result of dissolution of Zn with 10 mg/L nominal load was stated as a mean value of days 1 – 7.

No linear dependency of measured concentrations on time was observed. Usage of the first order model was also not possible for the determination of kinetic as the equilibrium was observed after 24 h. Two sampling points (2 h and 6 h) are not enough for calculation of kinetic. Therefore, the determination of kinetic was not possible. 

The mass balance lay in the range of 66.6 – 82.3 %.The difference is possible a result of the dissolution of another compounds of the test item (UVCB) which were not analyzed during the study.