ISO 8008:2005

INTERNATIONAL ISO
STANDARD 8008
Second edition
2005-10-15
Aluminium oxide primarily used for the
production of aluminium — Determination
of specific surface area by nitrogen
adsorption
Oxyde d'aluminium principalement utilisé pour la production de
l'aluminium — Détermination de la surface spécifique par adsorption
d'azote

Reference number
ISO 8008:2005(E)
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ISO 2005

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ISO 8008:2005(E)
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ISO 8008:2005(E)
Contents Page
1 Scope . 1
2 Normative references . 1
3 Principle . 1
4 Reagents . 1
5 Apparatus . 2
6 Sampling and sample preparation . 2
7 Procedure . 3
8 Calculation and reporting of results . 4
9 Precision . 4
10 Quality control . 4
11 Test report . 4
Annex A (informative) Difference between single- and multi-point-determined BET SSA . 6
Annex B (informative) Results of test programme . 7
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ISO 8008:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
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International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO8008 was prepared by Technical Committee ISO/TC226, Materials for the production of primary
aluminium.
This second edition cancels and replaces the first edition (ISO 8008:1986), which has been technically revised.
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ISO 8008:2005(E)
Introduction
This International Standard is based on Australian Standard AS 2879.4-2003, Alumina — Determination of
specific surface area by nitrogen adsorption.
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vi

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INTERNATIONAL STANDARD ISO 8008:2005(E)
Aluminium oxide primarily used for the production of
aluminium — Determination of specific surface area by nitrogen
adsorption
WARNING —Persons using this International Standard should be familiar with normal laboratory
practice. This International Standard does not purport to address all of the safety problems, if any,
associated with its use. It is the responsibility of the user to establish appropriate safety and health
practices and to ensure compliance with any national regulatory conditions.
1Scope
This International Standard specifies an instrumental method for the determination of specific surface area
(SSA) of smelter-grade alumina (SGA) by nitrogen adsorption by a single- or multi-point method. A multi-point
method is recommended due to the higher accuracy obtained; if a single-point method is used, a lower result
will be obtained.
NOTE Annex A provides an explanation of the difference between single- and multi-point determined BET SSA.
2 2
This International Standard is applicable to aluminas having a surface area between 50 m /g and 90 m /g.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
AS 2850-1986, Chemical analysis — Interlaboratory test programs — For determining precision of analytical
method(s) — Guide to the planning and conduct
3 Principle
The method is based on the ability of a material to adsorb nitrogen molecules on its surface at the boiling point
of liquid nitrogen. The instrument determines the quantity of nitrogen gas necessary to form a monolayer of gas
molecules on the sample surface. The surface area can then be calculated using the basic theory developed by
1) ◦
Brunauer-Emmett-Teller . A test sample is degassed at 150 C. The degassing process can be carried out
using either vacuum or a flowing nitrogen stream. After degassing, the sample is weighed. This mass, and the
monolayer volume determined by the instrument, is used to calculate the specific surface area.
4Reagents
Use only reagents of recognized analytical grade and only distilled water or water of equivalent purity.
1) S. Brunauer, P.H. Emmett and E. Teller, J. Am Chem. Soc. 60, p.309 (1938).
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ISO 8008:2005(E)
◦
2)
4.1 Liquid nitrogen, with a boiling point of −196 C at 101.3 kPa .
CAUTION — Particular care should be taken when handling cryogenic liquids.
4.2 Nitrogen gas, high purity.
4.3 Other gases, as specified by the instrument manufacturers.
4.4 Reference alumina
3) 4)
Alcan International Limited Alumina Surface Area Standard ALU-11 : which is a commercial product sold by
Alcan International Limited as part of their in-house commitment to supply reference materials to the
alumina/aluminium industry. The certified value at 95 % confidence level of ALU-11 for single-point analysis is
2 2
67,8± 2,9 m /g and for multi-point analysis is 69,1± 2,3 m /g.
NOTE Annex A provides an explanation of the difference between single- and multi-point determined BET SSA.
5 Apparatus
◦
5.1 Surface-area analyser, employing low temperature (−196 C) nitrogen adsorption. The instrument
should be capable of multi-point or single-point analysis.
◦
5.2 Degassing equipment, suitable for degassing a sample at an elevated temperature (150 C) using either
a flowing nitrogen stream or a vacuum system capable of maintaining a vacuum of < 0,2 mbar.
Sample tubes shall include se
...