Silicon dioxide

Nanomaterial Zeta potential

Administrative data

Endpoint:

nanomaterial Zeta potential

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Materials and methods

Test guideline

Qualifier:

no guideline followed

Type of method:

vibration potential

Details on methods and data evaluation:

The zeta potential of the test item PERKASIL® SM 660 in water was determined by measuring the Colloidal Vibration Current (CVI) of a pre-treated dispersion of the test material.
The pre-treatment of the test item includes the production of a 10 wt.-% dispersion with a lab stirrer, ultra-sonication and centrifugation to get standardized condition for the CVI measurement.
The needed parameter particle size distribution of dispersion and density of raw material were measured by laser diffraction and He-Density method.

The measurement of CVI is conducted under constant stirring with a magnetic lab stirrer at 300rpm.
70mL of the sample are poured in the vessel of the CVI instrument. Additionally to the measurement of CVI, pH, conductivity and temperature should be monitored to determine the zeta potential as accurate as possible. If the pH value is below 6.5, it is standardized to this value by titration of NaOH solution.
The result for zeta potential is displayed with the unit millivolt (mV).

Deviation from the Study plan:
As the sponsor ordered additionally, the analysis of zeta potential as function of pH value was conducted by two titrations:
One completely prepared dispersion (see 5.1.2) was titrated with NaOH 1M solution and a second dispersion was titrated with HCl 1M solution. These two titrations had been merged to receive an overview about the whole pH range. To control the ionic strength in dispersion, aqueous conductivity was monitored continuously.

Test material

Test material information

Constituent 1

Reference substance name:

Silicon dioxide

EC Number:

231-545-4

EC Name:

Silicon dioxide

Cas Number:

7631-86-9

Molecular formula:

O2Si

IUPAC Name:

dioxosilane

Test material form:

solid: nanoform, no surface treatment

Details on test material:

Precipitated, Surface area / BET [m2/g]: 182

Specific details on test material used for the study:

Designation in Test Facility: PERKASIL® S 660
Date of Receipt: 15. June 2016
Condition at receipt: closed vessel, in proper conditions
Name: PERKASIL® KS 408 PD
Code No.: 1601257005
Appearance: White Powder
Composition: SiO2, synthetic amorphous
CAS No.: 7631-86-9
EINECS No.: 231-545-4
Molecular Formula: SiO2
Molecular Weight: 60,2
Purity: 95-100% SiO2
Homogeneity: homogeneous material
Production Date: not stated
Expiry Date: 2018
Storage: Room Temperature: (20 ± 5°C)
Hazard information: none
H-phrases: none
P-phrases: none

Reference material / nanomaterial and sample identification number

Reference

Reference substance name:

Unnamed

Data gathering

Instruments:

4.3 Analytical Instrument Laser Diffraction
4.3.1 CILAS 1190L
Specification: 1190L
Serial number: 3508
Software: Particle Expert V9.40
Date of Purchase: Feb. 2010
Producer: CILAS, Orleans, France
Usage and calibration following the corresponding AA-007 in the current version.

4.3.2 Method Parameters Laser Diffraction
• Measurement time: 60 seconds
• Ultrasonic: 60 seconds before measurement at 50W
• Pump speed: 320 rpm
• Stirrer speed: 120 rpm
• Data treatment: Fraunhofer theory


4.4 Analytical Instrument Helium Pycnometry:
Specification: Ultra Pyc 1200e
Serial number: 1221305080/1
Software: V5.03
Date of Purchase: Apr. 2010
Producer: Quantachrome Instruments, Florida, USA
Usage and calibration following the corresponding AA-009 in the current version.

4.5 Analytical Instrument Electroacoustic Spectrometry
Specification: DT 1202
Serial number: 562
Software: 5.6.37
Date of Purchase: Sep. 2014
Producer: Dispersion Technology, New York, USA
Usage and calibration following the corresponding AA-008 in the current version.

4.6 Instrument and Devices
The following instruments and devices were used in the performance of the study:
• Analytical Scales, OHAUS ARC 120
• Sonotrode, Bandelin
• Centrifuge, ThermoFisher Scientific
• Moisture Analyzer, Sartorius
• Lab Stirrer Eurostar, IKA
• pH-meter, Horiba
• Conductivity meter, Dispersion Technology
• Thermometer, Dispersion Technology
Usage and, if applicable, calibration of all instruments following the corresponding AA in the
current edition.

Reproducibility:

The results show good reproducibility and are in the expected range for these materials.

Results and discussion

Zeta potential

Key result

Zeta potential:

-40.23 mV

St. dev.:

0.236 mV

pH:

6.8

Medium:

Distilled Water with a conductivity below 10 μS/cm is used for production of the dispersion.

Applicant's summary and conclusion

Conclusions:

The CVI measurement was repeated two times with the following result:
Colloidal Vibration Current:
Mean Value [mV(s/g)1/2]: 1247612; Std. Deviation[mV(s/g)1/2]: 7053
Calculated Zeta Potential:
Mean Value [mV]: -40.23; Std. Deviation [mV]: 0.236

Executive summary:

The zeta potential of the test item PERKASIL® SM 660 in water was determined by measuring the Colloidal Vibration Current (CVI) of a pre-treated dispersion of the test material.

The pre-treatment of the test item includes the production of a 10 wt.-% dispersion with a lab stirrer, ultra-sonication and centrifugation to get standardized condition for the CVI measurement.

The needed parameter particle size distribution of dispersion and density of raw material were measured by laser diffraction and He-Density method.

The CVI measurement was repeated two times with the following results:

Colloidal Vibration Current:

Mean Value [mV(s/g)1/2]: 1247612; Std. Deviation[mV(s/g)1/2]: 7053

Calculated Zeta Potential:

Mean Value [mV]: -40.23; Std. Deviation [mV]: 0.236