Zeolite, cuboidal, crystalline, synthetic, non-fibrous

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:

key study

Study period:

Jul. 27 - Dec. 9, 2021; experimental phase: Jul. 27 - Aug. 26, 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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

Version / remarks:

Jul. 23, 2001

Deviations:

yes

Remarks:

The pH screening and the reproducibility tests were not performed as the suitable buffer solution with the highest measured Si concentration was determined during the previous study of the similar test item.

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Remarks:

measurement of Silicon and Aluminium per ICP-OES in aqueous media

Specific details on test material used for the study:

Name: SYLOSIV A4 (A Zeolite)
Batch no.: 1000361205
CAS no.: 1318-02-1
Composition: Zeolite (crystalline Aluminium silicate) 95-100 %
Storage: room temperature (20 ± 5 °C)
Expiry date: 31. Jan. 2022
Stability: stable under storage conditions
Appearance: off-white powder
Purity: not applicable, UVCB
Homogeneity: homogeneous
Production date: 01. Dec. 2020
EC no.: 215-283-8 (930-915-9)
Molecular formula: not stated
Molecular weight: not stated
Vapour pressure: 0 hPa

Key result

Type of test:

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

Mean dissolved conc.:

< 10 µg/L

Element analysed:

silicon

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Key result

Type of test:

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

Mean dissolved conc.:

4.5 µg/L

Element analysed:

aluminium

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Details on results:

In this study, the maximum concentration of total dissolved Si and Al was determined in order to identify compounds of SYLOSIV A4 which undergo either dissolution or rapid transformation.
The calibration was performed using the certified Si and Al stock solutions (1000 mg/L nominal each). All validation conditions for the range of 10 – 250 µg/L Si and 3 – 50 µg/L Al in pH 8.5 buffer solution were fulfilled. The correlation coefficient r was > 0.99 and the back calculated concentrations of the calibration standards lay in the demanded ranges 100 ± 15 % and 100 ± 20 % (low concentration) of the nominal values.
The accuracy was in the range of 100 ± 5 % with the mean value of 95.3 % for Si and 100.6 % for Al. Therefore, no recovery rates were used for calculation in the study. The condition “RSD ≤ 20 % per level” was fulfilled for both elements.
The pH screening test and reproducibility test were not performed as the suitable buffer solution with the highest measured Si concentration was determined during the previous study of the similar test item.
The full test was performed with 1 mg/L (three replicates) over a period of 28 days with samplings after 2 h, 6 h, 1 d, 4 d, 7 d, 14 d, 21 d and 28 d. Two flasks were prepared as blanks without addition of test item.
The concentration of Si in the test item solutions was in the similar range as in the blank solutions. During the full test the concentration of Si has continuously increased in all flasks (inclusive blank solutions). Some parts of the aeration system made of glass may be a reason for this result. Therefore, the value below the LOQ of Si was stated as the result of the dissolution test.
The concentration of Al was below the LOQ on days 0 – 21 (< 3 µg/L). Therefore, the calculation of the kinetic was not possible. On day 28, the concentration of Al was stated as 4.5 µg/L with the relative standard deviation of 20 %.

Conclusions:

The following concentrations of Al and Si were stated at 20.1 – 21.1 °C and pH 8.5 ± 0.2 for 1 mg/L nominal load on day 28:
4.5 µg/L Al and < 10 µg/L Si.

Executive summary:

This study was performed in order to determine the transformation and/or dissolution of SYLOSIV A4 via measurement of Silicon (Si) and Aluminium (Al) per ICP-OES in aqueous media. The full test was performed with 1 mg/L (three replicates) over a period of 28 days. The concentration of Si in the test item solutions was in the similar range as in the blank solutions. During the full test the concentration of Si has continuously increased in all flasks (inclusive blank solutions).  Therefore, the value below the LOQ of Si was stated as the result of the dissolution test. The concentration of Al was below the LOQ on days 0 – 21 (< 3 µg/L). Therefore, the calculation of the kinetic was not possible. On day 28, the concentration of Al was stated as 4.5 µg/L with the relative standard deviation of 20 %.

Reference 2

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Feb. 17 - Oct. 28, 2021; experimental phase: Feb. 17 - Jun. 17, 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

Jul. 27, 1995

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Specific details on test material used for the study:

Name: Zeocros CG180 (P Zeolite)
Batch no.: 2020-531
Appearance: off-white powder
Composition: Zeolite (crystalline Aluminium silicate) 95-100 %
CAS No.: 1318-02-1
EC-No.: not stated
Molecular formula: not stated
Molecular weight: not stated
Purity: not applicable, UVCB
Homogeneity: homogeneous
Production date: Dec. 2020
Expiry date: 01. Jan. 2022
Storage: room temperature (20 ± 5 °C)
Stability: stable under storage conditions

Key result

Water solubility:

ca. 0.046 - ca. 0.049 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 1 - <= 3 d

Temp.:

20 °C

pH:

ca. 6.9 - ca. 7.1

Remarks on result:

other: Al2O3 concentration

Key result

Water solubility:

ca. 1 008.9 - ca. 1 083.1 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 1 - <= 3 d

Temp.:

20 °C

pH:

ca. 6.9 - ca. 7.1

Remarks on result:

other: Na concentration

Key result

Water solubility:

ca. 25.67 - ca. 30.59 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 1 - <= 3 d

Temp.:

20 °C

pH:

ca. 6.9 - ca. 7.1

Remarks on result:

other: SiO2 concentration

Key result

Water solubility:

ca. 74.69 - ca. 80.15 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 4 - <= 9 d

Temp.:

20 °C

pH:

>= 9.9 - <= 10.05

Remarks on result:

other: Al2O3 concentration

Key result

Water solubility:

ca. 97.51 - ca. 99.37 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 1 - <= 9 d

Temp.:

20 °C

pH:

>= 9.9 - <= 10.05

Remarks on result:

other: Na cocentration

Key result

Water solubility:

ca. 6.837 - ca. 7.151 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 8 - <= 10 d

Temp.:

20 °C

pH:

>= 9.9 - <= 10.05

Remarks on result:

other: SiO2 concentration

Details on results:

The first performance of the main test (1) was aborted and the study was started again (main test 2) as the measurements via ICP-OES were not stable. The main test 2 was per-formed without adjustment of pH value at pH 9.90 – 10.05. Using ICP-OES, the water solubility of SiO2 was calculated as 7.109 ± 0.051 mg/L, corresponding to a relative standard deviation of 0.7 %. Additionally, the concentration of silicon in the filtrated solutions was determined via photometry. The mean concentration of SiO2 determined via photometry was calculated as 6.880 ± 0.142 mg/L, corresponding to a relative standard deviation of 2.1 %. The determination of the solubility of SiO2 in water using two different methods (ICP-OES and photometry) showed very similar results. The water solubility of SiO2 was stated as 6.994 ± 0.157 mg/L (mean value of two methods). A continuous decrease of the measured Si values was observed during the test. The water solubility of Na was calculated as 98.44 ± 0.93 mg/L, corresponding to a relative standard deviation of 0.9 %. The water solubility of Al2O3 was calculated as 77.42 ± 2.73 mg/L, corresponding to a relative standard deviation of 3.5 %.
The main test 3 was performed with adjustment of pH value to 7.0 ± 0.1. The water solubil-ity of SiO2 using ICP-OES was calculated as 26.26 ± 1.30 mg/L, corresponding to a rela-tive standard deviation of 4.9 %. The mean concentration of SiO2 determined via photometry was calculated as 30.00 ± 1.77 mg/L, corresponding to a relative standard deviation of 5.9 %. The determination of the solubility of SiO2 in water using two different methods (ICP-OES and photometry) showed similar results. The water solubility of SiO2 was stated as 28.13 ± 2.46 mg/L (mean value of two methods). The solubility of Na was calculated as 1046 ± 37.1 mg/L, corresponding to a relative standard deviation of 3.5 %. The water solu-bility of Al2O3 was calculated as 47.16 ± 1.48 µg/L, corresponding to a relative standard deviation of 3.1 %. In the filtrated test item solutions the pH value was in the range of 7.48 – 7.56, while in the unfiltered solutions the pH was 7.0 ± 0.1. As a reason for this difference is possible a presence of undissolved test item in the unfiltered solutions which may influence the pH value.

Conclusions:

Main test 2 performed without adjustment of pH value at pH 9.90 – 10.05:
The water solubility of SiO2 was stated as 6.994 ± 0.157 mg/L (mean value of two methods). A continuous decrease of the measured Si values was observed during the test. The water solubility of Na was calculated as 98.44 ± 0.93 mg/L. The water solubility of Al2O3 was calculated as 77.42 ± 2.73 mg/L.

Main test 3 was performed with adjustment of pH value to 7.0 ± 0.1:
The water solubility of SiO2 was stated as 28.13 ± 2.46 mg/L (mean value of two methods). The solubility of Na was calculated as 1046 ± 37.1 mg/L. The water solubility of Al2O3 was calculated as 47.16 ± 1.48 µg/L

Executive summary:

This study was performed in order to determine the water solubility of Zeocros CG180 via measurement of Silicon (Si), Aluminium (Al) and Sodium (Na) per ICP-OES and Si per photometer. Determination of the water solubility of Zeocros CG180 was performed as follows: The quantity of test item necessary to saturate the desired volume of water was used analogously to all silica samples. 50 g/L test item in water was used. Measurements of three replicates were performed until equilibrium was reached. Then, all other replicates were sampled and analysed. Undissolved particles were measured using Tyndall device.

The first performance of the main test (1) was aborted and the study was started again (main test 2) as the measurements via ICP-OES were not stable.

Reference 3

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Feb. 11 - Oct. 28, 2021; experimental phase: Feb. 12 - Jun. 11, 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

Jul. 27, 1995

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Specific details on test material used for the study:

Name: SYLOSIV A4 (A Zeolite)
Batch no.: 1000361205
Appearance: off-white powder
Composition: Zeolite (crystalline Aluminium silicate) 95-100 %
CAS No.: 1318-02-1
EC-No.: 215-283-8 (930-915-9)
Molecular formula: not stated
Molecular weight: not stated
Purity: not applicable, UVCB
Homogeneity: homogeneous
Production date: 01. Dec. 2020
Expiry date: 31. Jan. 2022
Storage: room temperature (20 ± 5 °C)
Stability: stable under storage conditions

Key result

Water solubility:

ca. 0.204 - ca. 0.232 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 1 - <= 4 d

Temp.:

20 °C

pH:

ca. 6.9 - ca. 7.1

Remarks on result:

other: Al2O3 concentration

Key result

Water solubility:

ca. 728.9 - ca. 754.1 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 1 - <= 4 d

Temp.:

20 °C

pH:

ca. 6.9 - ca. 7.1

Remarks on result:

other: Na concentration

Key result

Water solubility:

ca. 49.68 - ca. 54.18 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 3 - <= 4 d

Temp.:

20 °C

pH:

ca. 6.9 - ca. 7.1

Remarks on result:

other: SiO2 concentration

Key result

Water solubility:

ca. 69.48 - ca. 87.58 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 2 - <= 8 d

Temp.:

20 °C

pH:

>= 11.61 - <= 11.7

Remarks on result:

other: Al2O3 concentration

Key result

Water solubility:

ca. 210.7 - ca. 220.9 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 1 - <= 8 d

Temp.:

20 °C

pH:

>= 11.61 - <= 11.7

Remarks on result:

other: Na cocentration

Key result

Water solubility:

ca. 96.9 - ca. 104.3 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 3 - <= 8 d

Temp.:

20 °C

pH:

>= 11.61 - <= 11.7

Remarks on result:

other: SiO2 concentration

Details on results:

The main test 1 was performed without adjustment of pH value at pH 11.61 – 11.70. Using ICP-OES, the water solubility of SiO2 was calculated as 103.5 ± 1.8 mg/L, corresponding to a relative standard deviation of 1.7 %. Additionally, the concentration of silicon in the filtrated solutions was determined via photometry. The mean concentration of SiO2 determined via photometry was calculated as 97.83 ± 2.90 mg/L, corresponding to a relative standard deviation of 3.0 %. The determination of the solubility of SiO2 in water using two different methods (ICP-OES and photometry) showed very similar results. The water solubility of SiO2 was stated as 100.6 ± 3.7 mg/L (mean value of two methods). The water solubility of Na was calculated as 215.8 ± 5.1 mg/L, corresponding to a relative standard deviation of 2.4 %. The water solubility of Al2O3 was calculated as 78.53 ± 9.05 mg/L, corresponding to a relative standard deviation of 11.5 %. During the measurements of Al and Na on day 6, fluctuating values of QC samples were observed. This was considered as uncritical as during the measurement of the flasks 1B – 1C (7 – 8d) and flasks 2 – 4 on day 8 the measurement was stable.
The main test 2 was performed with adjustment of pH value to 7.0 ± 0.1. The water solubil-ity of SiO2 using ICP-OES was calculated as 51.90 ± 2.31 mg/L, corresponding to a rela-tive standard deviation of 4.5 %. The mean concentration of SiO2 determined via photometry was calculated as 51.96 ± 2.55 mg/L, corresponding to a relative standard deviation of 4.9 %. The determination of the solubility of SiO2 in water using two different methods (ICP-OES and photometry) showed almost identical results. The water solubility of SiO2 was stated as 51.93 ± 2.25 mg/L (mean value of two methods). The solubility of Na was calculated as 741.5 ± 12.6 mg/L, corresponding to a relative standard deviation of 1.7 %. The water solubility of Al2O3 was calculated as 0.218 ± 0.014 mg/L, corresponding to a relative standard deviation of 6.4 %. In the filtrated test item solutions the pH value was in the range of 7.63 – 7.74, while in the unfiltered solutions the pH was 7.0 ± 0.1. As a rea-son for this difference is possible a presence of undissolved test item in the unfiltered solutions which may influence the pH value.

Conclusions:

Main test 1 without adjustment of pH value at pH 11.61 – 11.70:
The water solubility of SiO2 was stated as 100.6 ± 3.7 mg/L (mean value of two methods). The water solubility of Na was calculated as 215.8 ± 5.1 mg/L. The water solubility of Al2O3 was calculated as 78.53 ± 9.05 mg/L.

Main test 2 with adjustment of pH value to 7.0 ± 0.1:
The water solubility of SiO2 was stated as 51.93 ± 2.25 mg/L (mean value of two methods). The solubility of Na was calculated as 741.5 ± 12.6 mg/L. The water solubility of Al2O3 was calculated as 0.218 ± 0.014 mg/L.

Executive summary:

This study was performed in order to determine the water solubility of SYLOSIV A4 via measurement of Silicon (Si), Aluminium (Al) and Sodium (Na) per ICP-OES and Si per photometer. Determination of the water solubility of SYLOSIV A4 was performed as follows: The quantity of test item necessary to saturate the desired volume of water was used analogously to all silica samples. 50 g/L test item in water was used. Measurements of three replicates were performed until equilibrium was reached. Then, all other replicates were sampled and analysed. Undissolved particles were measured using Tyndall device.

Reference 4

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Feb. 11 - Oct. 28, 2021; experimental phase: Feb. 12 - Jun. 16, 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

Jul. 27, 1995

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Specific details on test material used for the study:

Name: Na Y Zeolite (Y Zeolite)
Batch no.: RZ200094/1
Appearance: off-white powder
Composition: Zeolite (crystalline Aluminium silicate) 95-100 %
CAS No.: 1318-02-1
EC-No.: 215-283-8 (930-915-9)
Molecular formula: not stated
Molecular weight: not stated
Purity: not applicable, UVCB
Homogeneity: homogeneous
Production date: 01. Dec. 2020
Expiry date: 31. Jan. 2022
Storage: room temperature (20 ± 5 °C)
Stability: stable under storage conditions

Key result

Water solubility:

< 0.019 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 1 - <= 9 d

Temp.:

20 °C

pH:

ca. 6.9 - ca. 7.1

Remarks on result:

other: Al2O3 concentration

Key result

Water solubility:

ca. 342.5 - ca. 410.5 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 8 - <= 9 d

Temp.:

20 °C

pH:

ca. 6.9 - ca. 7.1

Remarks on result:

other: Na concentration

Key result

Water solubility:

ca. 52.82 - ca. 68.64 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 7 - <= 9 d

Temp.:

20 °C

pH:

ca. 6.9 - ca. 7.1

Remarks on result:

other: SiO2 concentration

Key result

Water solubility:

< 0.019 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

3 d

Temp.:

20 °C

pH:

>= 9.88 - <= 10.03

Remarks on result:

other: Al2O3 concentration

Key result

Water solubility:

ca. 270.5 - ca. 295.7 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

3 d

Temp.:

20 °C

pH:

>= 9.88 - <= 10.03

Remarks on result:

other: Na cocentration

Key result

Water solubility:

ca. 260.8 - ca. 281 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

3 d

Temp.:

20 °C

pH:

>= 9.88 - <= 10.03

Remarks on result:

other: SiO2 concentration

Details on results:

During the first main test, the RSD of Si and Na concentrations in the test item solutions was > 30 %. Inhomogeneity of the test item was assumed as a reason for this result. Thus, the test was repeated and the test item was finely crushed before usage. Flasks 1C and 2 – 4 were prepared during the repetition only. The results of the main test 2 were used in the evaluation only. The main test 2 was performed without adjustment of pH value at pH 9.88 – 10.03. The measurements from the flasks 2 – 4 were used in the calculation of the mean as the value in the flask 1C was stated as an outlier (Grubbs test). Using ICP-OES, the water solubility of SiO2 was calculated as 276.9 ± 10.5 mg/L, corresponding to a relative standard deviation of 3.8 %. Additionally, the concentration of silicon in the filtrated solutions was determined via photometry. The mean concentration of SiO2 determined via photometry was calculated as 265.0 ± 6.5 mg/L, corresponding to a relative standard deviation of 2.4 %. The determination of the solubility of SiO2 in water using two different methods (ICP-OES and photometry) showed similar results. The water solubility of SiO2 was stated as 270.9 ± 10.1 mg/L (mean value of two methods). The mean value of both methods determined in the main test 1 is comparable with the main test 2, but the RSD was > 30 % (272.6 ± 94.0 mg/L). The water solubility of Na was calculated as 283.1 ± 12.6 mg/L, corresponding to a relative standard deviation of 4.4 %. The water solubility of Al2O3 was calculated as < 19 µg/L.
The main test 3 was performed with adjustment of pH value to 7.0 ± 0.1. The water solubil-ity of SiO2 using ICP-OES was calculated as 59.75 ± 7.77 mg/L, corresponding to a rela-tive standard deviation of 13.0 %. The mean concentration of SiO2 determined via photometry was calculated as 61.71 ± 9.12 mg/L, corresponding to a relative standard deviation of 14.8 %. The determination of the solubility of SiO2 in water using two different methods (ICP-OES and photometry) showed similar results. The water solubility of SiO2 was stated as 60.73 ± 7.91 mg/L (mean value of two methods). The solubility of Na was calculated as 376.5 ± 34.0 mg/L, corresponding to a relative standard deviation of 9.0 %. The water solubility of Al2O3 was calculated as < 19 µg/L.

Conclusions:

Main test 2 without adjustment of pH value at pH 9.88 – 10.03:
The water solubility of SiO2 was stated as 270.9 ± 10.1 mg/L (mean value of two methods). The water solubility of Na was calculated as 283.1 ± 12.6 mg/L. The water solubility of Al2O3 was calculated as < 19 µg/L.

Main test 3 with adjustment of pH value to 7.0 ± 0.1:
The water solubility of SiO2 was stated as 60.73 ± 7.91 mg/L (mean value of two methods). The solubility of Na was calculated as 376.5 ± 34.0 mg/L. The water solubility of Al2O3 was calculated as < 19 µg/L.

Executive summary:

This study was performed in order to determine the water solubility of Na Y Zeolite via measurement of Silicon (Si), Aluminium (Al) and Sodium (Na) per ICP-OES and Si per photometer. Determination of the water solubility of Na Y Zeolite was performed as follows: The quantity of test item necessary to saturate the desired volume of water was used analogously to all silica samples. 50 g/L test item in water was used. Measurements of three replicates were performed until equilibrium was reached. Then, all other replicates were sampled and analysed. Undissolved particles were measured using Tyndall device.
During the first main test, the RSD of Si and Na concentrations in the test item solutions was > 30 %. Inhomogeneity of the test item was assumed as a reason for this result. Thus, the test was repeated and the test item was finely crushed before usage. 

Reference 5

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Feb. 17 - Oct. 28, 2021; experimental phase: Feb. 17 - Jun. 21, 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

Jul. 27, 1995

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Specific details on test material used for the study:

Name: KÖSTROLITH NaMSXP-TR (X Zeolite)
Batch no.: 2006090001
Appearance: off-white powder
Composition: Zeolite (crystalline Aluminium silicate) 95-100 %
CAS No.: 1318-02-1
EC-No.: 215-283-8 (930-915-9)
Molecular formula: not stated
Molecular weight: not stated
Purity: not applicable, UVCB
Homogeneity: homogeneous
Production date: 24. Nov. 2020
Expiry date: 31. Jan. 2022
Storage: room temperature (20 ± 5 °C)
Stability: stable under storage conditions

Key result

Water solubility:

ca. 0.02 - ca. 0.026 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 6 - <= 7 d

Temp.:

20 °C

pH:

ca. 6.9 - ca. 7.1

Remarks on result:

other: Al2O3 concentration

Key result

Water solubility:

ca. 754.4 - ca. 810.4 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 1 - <= 6 d

Temp.:

20 °C

pH:

ca. 6.9 - ca. 7.1

Remarks on result:

other: Na concentration

Key result

Water solubility:

ca. 27.75 - ca. 31.95 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 3 - <= 7 d

Temp.:

20 °C

pH:

ca. 6.9 - ca. 7.1

Remarks on result:

other: SiO2 concentration

Key result

Water solubility:

ca. 17.91 - ca. 19.61 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 4 - <= 5 d

Temp.:

20 °C

pH:

>= 10 - <= 10.03

Remarks on result:

other: Al2O3 concentration

Key result

Water solubility:

ca. 61.2 - ca. 61.86 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 2 - <= 5 d

Temp.:

20 °C

pH:

>= 10 - <= 10.03

Remarks on result:

other: Na cocentration

Key result

Water solubility:

ca. 22.14 - ca. 23.8 mg/L

Loading of aqueous phase:

50 g/L

Incubation duration:

>= 1 - <= 5 d

Temp.:

20 °C

pH:

>= 10 - <= 10.03

Remarks on result:

other: SiO2 concentration

Details on results:

The first performance of the main test (1) was aborted and the study was started again (main test 2) as the measurements via ICP-OES were not stable. The main test 2 was per-formed without adjustment of pH value at pH 10.00 – 10.03. Using ICP-OES, the water solubility of SiO2 was calculated as 22.68 ± 0.84 mg/L, corresponding to a relative stand-ard deviation of 3.7 %. Additionally, the concentration of silicon in the filtrated solutions was determined via photometry. The mean concentration of SiO2 determined via photometry was calculated as 23.25 ± 0.83 mg/L, corresponding to a relative standard deviation of 3.6 %. The determination of the solubility of SiO2 in water using two different methods (ICP-OES and photometry) showed very similar results. The water solubility of SiO2 was stated as 22.97 ± 0.83 mg/L (mean value of two methods). The water solubility of Na was calculated as 61.53 ± 0.33 mg/L, corresponding to a relative standard deviation of 0.5 %. The water solubility of Al2O3 was calculated as 18.76 ± 0.85 mg/L, corresponding to a relative standard deviation of 4.5 %.
The main test 3 was performed with adjustment of pH value to 7.0 ± 0.1. The water solubil-ity of SiO2 using ICP-OES was calculated as 28.44 ± 1.86 mg/L, corresponding to a rela-tive standard deviation of 6.5 %. The mean concentration of SiO2 determined via photom-etry was calculated as 31.26 ± 1.22 mg/L, corresponding to a relative standard deviation of 3.9 %. The determination of the solubility of SiO2 in water using two different methods (ICP-OES and photometry) showed similar results. The water solubility of SiO2 was stated as 29.85 ± 2.10 mg/L (mean value of two methods). The solubility of Na was calculated as 782.4 ± 28.0 mg/L, corresponding to a relative standard deviation of 3.6 %. The water sol-ubility of Al2O3 was calculated as 23.25 ± 2.79 µg/L, corresponding to a relative standard deviation of 12.0 %. In the filtrated test item solutions the pH value was in the range of 7.44 – 7.59, while in the unfiltered solutions the pH was 7.0 ± 0.1. As a reason for this difference is possible a presence of undissolved test item in the unfiltered solutions which may influence the pH value.

Conclusions:

Main test 2 performed without adjustment of pH value at pH 10.00 – 10.03:
The water solubility of SiO2 was stated as 22.97 ± 0.83 mg/L (mean value of two methods). The water solubility of Na was calculated as 61.53 ± 0.33 mg/L. The water solubility of Al2O3 was calculated as 18.76 ± 0.85 mg/L.

Main test 3 performed with adjustment of pH value to 7.0 ± 0.1:
The water solubility of SiO2 was stated as 29.85 ± 2.10 mg/L (mean value of two methods). The solubility of Na was calculated as 782.4 ± 28.0 mg/L. The water solubility of Al2O3 was calculated as 23.25 ± 2.79 µg/L

Executive summary:

This study was performed in order to determine the water solubility of KÖSTROLITH NaMSXP-TR via measurement of Silicon (Si), Aluminium (Al) and Sodium (Na) per ICP-OES and Si per photometer. Determination of the water solubility of KÖSTROLITH® NaMSXP-TR was performed as follows: The quantity of test item necessary to saturate the desired volume of water was used analogously to all silica samples. 50 g/L test item in water was used. Measurements of three replicates were performed until equilibrium was reached. Then, all other replicates were sampled and analysed. Undissolved particles were measured using Tyndall device.

The first performance of the main test (1) was aborted and the study was started again (main test 2) as the measurements via ICP-OES were not stable.

Description of key information

Without adjustment of the pH value, the water solubility of SiO2 ranged between 6.994 ± 0.157 mg/L and 270.9 ± 10.1 mg/L. The water solubility of Na was calculated as between 61.53 ± 0.33 mg/L and 283.1 ± 12.6 mg/L. The water solubility of Al2O3 was calculated as between < 19 µg/L and 78.53 ± 9.05 mg/L.

With adjustment of pH value to 7.0 ± 0.1, the water solubility of SiO2 was stated as between 28.13 ± 2.46 mg/L and 60.73 ± 7.91 mg/L. The solubility of Na was calculated as between 376.5 ± 34.0 mg/L and 1046 ± 37.1 mg/L. The water solubility of Al2O3 was calculated as between < 19 µg/L and 0.218 ± 0.014 mg/L.

Additional information

Without adjustment of the pH value, the water solubility of SiO2 ranged between 6.994 ± 0.157 mg/L (type P zeolite) and 270.9 ± 10.1 mg/L (type Y zeolite). The water solubility of Na was calculated as between 61.53 ± 0.33 mg/L (type X zeolite) and 283.1 ± 12.6 mg/L (type Y zeolite). The water solubility of Al2O3 was calculated as between < 19 µg/L (type Y zeolite) and 78.53 ± 9.05 mg/L (type A zeolite).

With adjustment of pH value to 7.0 ± 0.1, the water solubility of SiO2 was stated as between 28.13 ± 2.46 mg/L (type P zeolite) and 60.73 ± 7.91 mg/L (type Y zeolite). The solubility of Na was calculated as between 376.5 ± 34.0 mg/L (type Y zeolite) and 1046 ± 37.1 mg/L (type P zeolite). The water solubility of Al2O3 was calculated as between < 19 µg/L (type Y zeolite) and 0.218 ± 0.014 mg/L (type A zeolite).

Furthermore, a study was performed in order to determine the transformation and/or dissolution of a type A zeolite via measurement of Silicon (Si) and Aluminium (Al) per ICP-OES in aqueous media. The full test was performed with 1 mg/L (three replicates) over a period of 28 days. The concentration of Si in the test item solutions was in the similar range as in the blank solutions. During the full test the concentration of Si continuously increased in all flasks (inclusive blank solutions).  Therefore, the value below the LOQ of Si was stated as the result of the dissolution test: < 10 µg/L Si. The concentration of Al was below the LOQ on days 0 – 21 (< 3 µg/L). Therefore, the calculation of the kinetic was not possible. On day 28, the concentration of Al was stated as 4.5 µg/L with the relative standard deviation of 20 %.