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Physical & Chemical properties

Nanomaterial porosity

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Administrative data

Endpoint:
nanomaterial porosity
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was regarded was reliable with restrictions. The used methodology is well-established. However, only very limited documentation of the data evaluation was provided in the full study report. Furthermore the procedure for data analysis and representation was not explained in detail. There were some concerns on validity as the data analysis have a significant influence to the result.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2011
Report date:
2011

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Instrumentation
A Micromeritics TriStar II (3020) was used for the collection of nitrogen adsorption / desorption isotherm data up to a saturation pressure of approximately 0.995 P/Po. The analysis was typically conducted to measure 45 adsorption relative pressure points and 23 desorption relative pressure points. Samples were outgassed overnight in vacuo at 300 degC using a Micromeritics VacPrep apparatus prior to analysis. In order to indicate any possible microporous nature of the materials additional relative pressure data were also collected at pressures lower than the usual starting point for analyses using this instrument. These were in the approximate range 0.005 to 0.01 P/Po. Whilst the data reduction methods available are unsuitable for application to the micropore range the characteristic shape of the adsorption isotherm at these low partial pressures would provide a good indication of the presence of micropores in the sample material. The sample tube dead space was measured for each analysis using helium (CP grade) thus providing warm and cold freespace values. Samples requiring only BET surface area analysis were analysed using the same equipment with the application of
the same freespace measurement technique. BET surface area was calculated using partial pressures in the nominal range 0.07 to 0.25.
Data Reduction. The samples for which the full adsorption/desorption isotherms were analysed graphical plots of the adsorption/desorption isotherm and BET surface area transform plot together with tabulated data for each are presented. The pore size distribution is presented as pore size by volume and area from the adsorption isotherm using the BJH method. The lower limit of BJH calculations in terms of pore size (by diameter) is extended below the typical value in order to highlight any possible microporous nature of the materials. The pore size distribution data presented in the BJH reports is applied to a maximum of 1000Å, although data below approximately 20Å should be considered only as a guide to the full porous nature of the materials. The total pore volume of the materials is calculated from the volume of nitrogen adsorbed at the maximum relative pressure obtained on the adsorption branch of the isotherm and is detailed on the summary report.
GLP compliance:
no
Type of method:
BET

Test material

Constituent 1
Test material form:
solid: nanoform

Data gathering

Instruments:
Micromeritics TriStar II
Calibration:
BAM Standard - Alumina BAM-PM-104
BAM Standard - Alumina BAM-PM-102

Results and discussion

Any other information on results incl. tables

Porosity

Sample

Porosity (cm3/g)

NM110

0.041538

NM111

0.071347

NM112

0.158354

NM113

0.013820

 

Applicant's summary and conclusion

Conclusions:
The porosity was determined to be 0.041538 cm3/g for NM-110, 0.071347 cm3/g for NM-111, 0.158354 cm3/g for NM-112 and 0.013820 cm3/g for NM-113 respectively.
Executive summary:

As study was conducted by the MCA in Cambridge, 2011 to determine the porosity of the NMs. A Micromeritics TriStar II (3020) was used for the collection of nitrogen adsorption / desorption isotherm data up to a saturation pressure of approximately 0.995 P/P0. The analysis was typically conducted to measure 45 adsorption relative pressure points and 23 desorption relative pressure points. Samples were outgassed overnight in vacuum at 300 °C using a Micromeritics VacPrep apparatus prior to analysis. In order to indicate any possible microporous nature of the materials additional relative pressure data were also collected at pressures lower than the usual starting point for analyses using this instrument. These were in the approximate range 0.005 to 0.01 P/P0. Whilst the data reduction methods available are unsuitable for application to the micropore range the characteristic shape of the adsorption isotherm at these low partial pressures would provide a good indication of the presence of micropores in the sample material. The sample tube dead space was measured for each analysis using helium (CP grade) thus providing warm and cold freespace values. Samples requiring only BET surface area analysis were analysed using the same equipment with the application of the same freespace measurement technique. BET surface area was calculated using partial pressures in the nominal range 0.07 to 0.25.

The pore size distribution is presented as pore size by volume and area from the adsorption isotherm using the BJH method. The pore size distribution data presented in the BJH reports is applied to a maximum of 1000 Å. The total pore volume of the materials is calculated from the volume of nitrogen adsorbed at the maximum relative pressure obtained on the adsorption branch of the isotherm. The porosity was determined to be 0.041538 cm3/g for NM-110, 0.071347 cm3/g for NM-111, 0.158354 cm3/g for NM-112 and 0.013820 cm3/g for NM-113 respectively.