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1、BRITISH STANDARD BS ISO 8008:2005 Aluminium oxide primarily used for the production of aluminium Determination of specific surface area by nitrogen adsorption ICS 71.100.10 ? Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:28:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 8008:2005 T
2、his British Standard was published under the authority of the Standards Policy and Strategy Committee on 23 January 2006 BSI 23 January 2006 ISBN 0 580 47298 1 National foreword This British Standard reproduces verbatim ISO 8008:2005 and implements it as the UK national standard. It supersedes BS 41
3、40-23:1987 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee CII/24, Raw materials for the aluminium industry, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-refe
4、rences The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards
5、Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the respo
6、nsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover,
7、the ISO title page, pages ii to v, a blank page, pages 1 to 7 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:28:42 G
8、MT+00:00 2006, Uncontrolled Copy, (c) BSI INTERNATIONAL STANDARD ISO 8008 Second edition 2005-10-15 Reference number ISO 8008:2005(E) Aluminium oxide primarily used for the production of aluminium Determination of specific surface area by nitrogen adsorption Oxyde daluminium principalement utilis po
9、ur la production de laluminium Dtermination de la surface spcifique par adsorption dazote BS ISO 8008:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:28:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:28:42 GMT+00:00 2006, Unc
10、ontrolled Copy, (c) BSI iii Contents Page 1Scope 1 2Normative references 1 3Principle 1 4Reagents . 1 5Apparatus . 2 6Sampling and sample preparation . 2 7Procedure . 3 8Calculation and reporting of results 4 9Precision . 4 10Quality control 4 11Test report 4 Annex A (informative) Difference between
11、 single- and multi-point-determined BET SSA 6 Annex B (informative) Results of test programme 7 BS ISO 8008:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:28:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv Foreword ISO (the International Organization for Standardization) is a worldw
12、ide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on th
13、at committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in
14、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 r
15、equires 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. ISO 8008 was prepared by Techn
16、ical Committee ISO/TC 226, Materials for the production of primary aluminium. This second edition cancels and replaces the first edition (ISO 8008:1986), which has been technically revised. BS ISO 8008:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:28:42 GMT+00:00 2006, Uncontrolled
17、Copy, (c) BSI v Introduction This International Standard is based on Australian Standard AS 2879.4-2003, Alumina Determination of specific surface area by nitrogen adsorption. BS ISO 8008:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:28:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI
18、vi blank Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:28:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 1 Aluminium oxide primarily used for the production of aluminium Determination of specific surface area by nitrogen adsorption WARNING Persons using this International Standard should
19、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 regul
20、atory 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
21、; if a single-point method is used, a lower result will be obtained. NOTEAnnex A provides an explanation of the difference between single- and multi-point determined BET SSA. This International Standard is applicable to aluminas having a surface area between and . 2Normative references The following
22、 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
23、For determining precision of analytical method(s) Guide to the planning and conduct 3Principle 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 for
24、m a monolayer of gas molecules on the sample surface. The surface area can then be calculated using the basic theory developed by Brunauer-Emmett-Teller1). A test sample is degassed at . The degassing process can be carried out using either vacuum or a flowing nitrogen stream. After degassing, the s
25、ample 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.
26、 Soc. 60, p.309 (1938). 50 m2/g90 m2/g 150 C BS ISO 8008:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:28:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 4.1Liquid nitrogen, with a boiling point of at 2). CAUTION Particular care should be taken when handling cryogenic liquids. 4.2Ni
27、trogen gas, high purity. 4.3Other gases, as specified by the instrument manufacturers. 4.4Reference alumina Alcan International Limited3) Alumina Surface Area Standard ALU-114): which is a commercial product sold by Alcan International Limited as part of their in-house commitment to supply reference
28、 materials to the alumina/aluminium industry. The certified value at confidence level of ALU-11 for single-point analysis is and for multi-point analysis is . NOTEAnnex A provides an explanation of the difference between single- and multi-point determined BET SSA. 5Apparatus 5.1Surface-area analyser
29、, employing low temperature () nitrogen adsorption. The instrument should be capable of multi-point or single-point analysis. 5.2Degassing equipment, suitable for degassing a sample at an elevated temperature () using either a flowing nitrogen stream or a vacuum system capable of maintaining a vacuu
30、m of . Sample tubes shall include sealing devices to prevent contact between air and the sample after degassing. 5.3Analytical balance, capable of weighing to an accuracy of . 6Sampling and sample preparation A test sample is prepared from the laboratory sample using a riffle or a rotary divider, ta
31、king particular care to avoid loss of fine particles through dusting. A representative test portion of optimum mass (depending on the requirements of the instrument and anticipated surface area) shall be taken from the test sample. The mass of sample used should be such that the total surface area i
32、s in accordance with the recommendations of the manufacturer of the surface-area analyser (5.1) and with a minimum sample mass of . Clean all sample tubes prior to each batch of samples analysed. It is recommended that the tubes be cleaned in an ultrasonic bath. To speed up the drying process, it is
33、 recommended that the tubes be rinsed with ethanol before being put into the drying oven. 2). The unit atm is deprecated. 3)Alcan International Limited, Arvida R is the mass of sample tube, sealing device and test sample after degassing, in grams; is the mass of degassed test sample, in grams. g)Usi
34、ng sample mass (), and the procedures recommended by the instrument manufacturer, determine the specific surface area of the test sample. Record the specific surface area reported by the instrument, to the nearest . 150 C P/Po 0,162 nm2 Po 0,000 1 gm1 150 C 2 h 0,000 1 gm2 m3= m2m1 m1 m2 m3 m3 0,01
35、m2/g BS ISO 8008:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:28:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 8Calculation and reporting of results If the instrument reports only the total surface area, calculate the specific surface area of the test sample by: where is the spec
36、ific surface area of the test sample, in square metres per gram; is the total surface area of the test sample, in square metres, reported by the instrument; is the mass of degassed test sample, in grams. Record the calculated specific surface area to the nearest . Report the specific surface area th
37、us calculated, or the specific surface area recorded in 7.2 g) to the nearest whole unit. 9Precision A test programme of the method in this International Standard was carried out in accordance with AS 2850. From the results of this programme, a within-laboratory repeatability ( ) and between-laborat
38、ory reproducibility (), at the confidence level as given in Table 1, should be achieved. The results of the test programme are given in Annex B. 10Quality control The specific surface area of the reference alumina (4.4) shall be determined for every batch of samples, by repeating the procedure in 7.
39、2 and substituting the test sample with the reference material. If this result does not lie between for single-point determinations, or for multi- point determinations, then it shall be noted in the test report along with the certified value. 11Test report The test report shall contain the following
40、 information: a)reference to this International Standard, i.e. ISO 8008; b)identification of the sample; c)date on which the sample was taken; Table 1 Precision data for specific-surface-area determinations Determination Repeatability ( )Reproducibility () m2/gm2/g Single-point0,82,1 Multi-point1,02
41、,5 ASSA= S m3 ASSA S m3 0,01 m2/g r R95 % rR 67,82,9 m2/g69,12,3 m2/g BS ISO 8008:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:28:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 5 d)date on which the test was carried out; e)specific surface area of the test sample, expressed in squar
42、e metres per gram, to the nearest whole unit; f)whether the analysis was single-point or multi-point; g)information in accordance with Clause 10, if required; h)any unusual observations made during the course of the test which may have had an effect on the result. BS ISO 8008:2005 Licensed Copy: she
43、ffieldun sheffieldun, na, Mon Nov 27 04:28:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 6 Annex A (informative) Difference between single- and multi-point-determined BET SSA Differences between single- and multi-point SSA for SGA are typically between and . The single- point solution of the BET equ
44、ation is a simplification of the theory which results in a lower SSA than the multi- point solution. This difference can be calculated provided the constant is known for the material being analysed. The constant in the BET equation is a term that relates to the energy of interaction between the surf
45、ace and the adsorbate. For the single-point solution, the assumption is made that is large (greater than 100) resulting in terms in the BET equation simplifying. The BET-plot intercept goes to zero and the slope is inversely proportional to the monolayer volume. This simplification enables the BET e
46、quation to be solved by measuring the volume of adsorbate at a single partial pressure. The difference arising from the assumptions applied in the single-point formulation is: where is the partial pressure used in the single-point measurement; is the adsorbate/surface-interaction energy term determi
47、ned in the multi-point equation. For smelter grade aluminas, is typically between 100 and 200. Hence for and , the difference is at the level. This equates to the single-point analysis being lower than the multi-point analysis. 1 m2/g3 m2/g C C C Relative percentage difference=1001Cx/ Cx + (1x) x C
48、C C =150x =0,31,5 %70 m2/g 1,1 m2/g BS ISO 8008:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:28:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 7 Annex B (informative) Results of test programme A test programme of the method in this International Standard was carried out in accordanc
49、e with AS 2850. Samples of the Alcan ALU-11 reference material and two other samples from different refineries were analysed. Results were provided in quadruplicate by eleven, nine and six laboratories respectively for samples ALU-11, ALU-10 and S-119. The within-laboratory ( ) and between-laboratory () precision data (at confidence limits) and mean-specific-surface-area determinations calculated from the results are given in Table B.1. From these results, an absolute rep
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