1、BRITISH STANDARD BS 4140-17: 1986 ISO 2828:1973 Methods of test for Aluminium oxide Part 17: Determination of fluorine content ISO title: Aluminium oxide primarily used for the production of aluminium Determination of fluorine content Alizarin complexone and lanthanum chloride spectrophotometric met
2、hod NOTEIt is recommended that this Part be read in conjunction with the general information given in BS4140-0 “General introduction” which is issued separately. UDC 661.862.22:546.16:543.42BS4140-17:1986 This British Standard, having been prepared under the directionof the Chemicals Standards Commi
3、ttee, was published under the authority ofthe Executive Board and comesinto effect on 28February1986 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference CIC/24 Draft for comment 85/52366 DC ISBN 0 580 14994 3 Amendments issued since publication Amd. No.
4、Date of issue CommentsBS4140-17:1986 BSI 11-1999 i Contents Page National foreword ii 1 Scope and field of application 1 2 References 1 3 Principle 1 4 Reagents 1 5 Apparatus 2 6 Procedure 2 7 Expression of results 3 8 Test report 3 Publications referred to Inside back coverBS4140-17:1986 ii BSI 11-
5、1999 National foreword This Part of BS 4140 is identical with ISO2828:1973 “Aluminium oxide primarily used for the production of aluminium Determination of fluorine content Alizarin complexone and lanthanum chloride spectrophotometric method”, published by the International Organization for Standard
6、ization (ISO). The method supersedes clause17 of Addendum No.3 (1974) to BS4140:1967. Parts17 to19 of this standard collectively supersede Addendum No.3 (1974) to BS4140:1967 which is withdrawn. Terminology and conventions. The text of the International Standard has been approved as suitable for pub
7、lication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full po
8、int on the baseline as the decimal marker. In British Standards it is current practice to use the symbol “L” for litre (and its submultiples) rather than “l”. Wherever the words “International Standard” appear, referring to this standard, they should be read as “British Standard”. ISO/R 1693:1970, w
9、hich is referred to in the text, has been revised as ISO1693:1976. The Technical Committee has reviewed the provisions of ISO1693:1976 and has decided that they are acceptable for use in conjunction with this standard. Clause4 of BS5050:1974 is related to ISO1693:1976. This standard prescribes metho
10、ds of test only, and should not be used or quoted as a specification defining limits of purity. Reference to this Part should indicate that the method of test used complies With BS4140-17:1986. A British Standard does not purport to include all the necessary provisions of a contract. Users of Britis
11、h Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard ISO/R 802:1968 (Revised as ISO 802:1976) BS 4140 Methods of test for alumini
12、um oxide Part 1:1986 Preparation and storage of test samples (Identical) ISO/R 2073:1971 (Revised as ISO 2073:1976) Part 13:1986 Preparation of sample solution by treatment with hydrochloric acid under pressure (Identical) Summary of pages This document comprises a front cover, an inside front cover
13、, pages i and ii, pages1 to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS4140-17:1986 BSI 11-1999 1 1 Scope and field of application Th
14、is International Standard specifies a spectrophotometric method, using alizarin complexone and lanthanum chloride, for the determination of the fluorine content of aluminium oxide primarily used for the production of aluminium. The method is applicable to fluorine (F) contents greater than0,003%. 2
15、References ISO/R 802, Aluminium oxide primarily used for the production of aluminium Preparation and storage of test samples. ISO/R 1693, Cryolite (natural and artificial) Determination of fluorine content Modified Willard-Winter method. ISO/R 2073, Aluminium oxide primarily used for the production
16、of aluminium Preparation of sample solution for analysis by means of attack by hydrochloric acid under pressure. 3 Principle Dissolution of a test portion by attack by sulphuric acid under pressure. Separation of the fluorine by distillation. Formation of a blue-coloured complex between the fluorine
17、 and the combined alizarin complexone/lanthanum chloride reagent at a pH between4,5 and4,6. Addition of acetone to increase the stability and sensitivity of the fluorine complex. Spectrophotometric measurement of the complex at a wavelength of about620nm. 4 Reagents Distilled water, or water of equi
18、valent purity, shall be used in the test. 4.1 Sulphuric acid, approximately17,5N solution. Carefully add, in small portions,50ml of sulphuric acid, approximately1,84g/ml, about96% (m/m) solution, to about50ml of water and, after cooling, dilute to100ml. 4.2 Sulphuric acid, approximately24N solution.
19、 Carefully add, in small portions,200ml of sulphuric acid, approximately1,84g/ml, about96% (m/m) solution, to100ml of water and, after cooling, dilute to300ml. 4.3 Combined reagent To prepare this reagent mix, in order, the solutions4.3.1, 4.3.2 and4.3.3, add250ml of the acetone (4.4) and then dilut
20、e to1000ml. 4.3.1 Alizarin complexone solution Dissolve0,154g of alizarin complexone (1,2-dihydroxy-anthraquino-3-yl methylamine-NN-diacetic acid) in about100ml of water to which has been added1ml of ammonia solution ( approximately0,91g/ml, about24% (m/m) solution). After dissolution, add1ml of gla
21、cial acetic acid ( approximately1,05g/ml, about17,4N solution). 4.3.2 Buffer solution Dissolve34g of sodium acetate trihydrate (CH 3 .COONa.3H 2 O) and15ml of glacial acetic acid ( approximately1,05g/ml, about17,4N solution), in about150ml of water. 4.3.3 Lanthanum chloride solution Dissolve0,372g o
22、f lanthanum chloride heptahydrate (LaCl 3 .7H 2 O) in about100ml of water. NOTEAfter mixing the solutions, allow to stand for at least24h and, preferably,2 to3 days before use. The mixed solution is stable for about2 weeks. The pH is between4,55 and4,60. 4.4 Acetone, approximately0,80g/ml. 4.5 Fluor
23、ine, standard solution corresponding to0,200g of fluorine (F) per litre. Weigh, to the nearest0,0001g,0,4420g of extra pure anhydrous sodium fluoride (NaF) previously heated to600 C in a platinum crucible and allowed to cool in a desiccator. Transfer to a beaker of suitable capacity (for example,100
24、ml) and dissolve in water. Transfer the solution quantitatively toa1000ml one-mark volumetric flask, dilute to the mark and mix. 1 ml of this standard solution contains0,200mg ofF. Store the solution in a plastics flask. NOTEIf extra pure sodium fluoride is not available, recrystallize the product.
25、Dissolve about5g of pure sodium fluoride in125ml of water and, after dissolution, filter under vacuum through a small Buchner funnel. Then evaporate the solution, in a platinum dish, down to approximately60ml. Cool to about50 C and separate the sodium fluoride crystals by centrifuging. Wash the crys
26、tals three times, always by centrifuging, with small quantities of cold water. Transfer the product to a platinum dish and dry in an electric oven, with natural draught, at110 2 C. Remove the dish from the oven, cool in a desiccator, grind the product in an agate mortar, and then pass it through a s
27、ieve with a mesh size of355m (see ISO/R565). Put the sieved sodium fluoride in a platinum dish, heat for2h at600 C, and allow to cool in a desiccator. 4.6 Fluorine, standard solution corresponding to0,010g of fluorine (F) per litre. Transfer50,0ml of the standard solution (4.5) to a1000ml one-mark v
28、olumetric flask, dilute to the mark and mix. 1 ml of this standard solution contains10g of F. Prepare this solution immediately before use.BS4140-17:1986 2 BSI 11-1999 4.7 Fluorine, standard solution corresponding to0,0020g of fluorine (F) per litre. Transfer50,0ml of the standard solution (4.6) to
29、a250ml one-mark volumetric flask, dilute to the mark and mix. 1ml of this standard solution contains2 g of F. Prepare this solution immediately before use. 5 Apparatus Ordinary laboratory apparatus, and 5.1 Apparatus specified in ISO/R 2073 5.2 Apparatus for the steam distillation of fluorine, as sp
30、ecified in5.3, 5.4 and5.5 of ISO/R1693. 5.3 Burette, graduated in0,05ml divisions (seeISO/R385). 5.4 Spectrophotometer 6 Procedure 6.1 Test portion Weigh, to the nearest0,001g, about1g of the laboratory sample, dried at300 C, prepared as described in2.3 of ISO/R802. The mass of test portion should b
31、e reduced to0,5g if the expected fluorine content is higher than0,1%. 6.2 Blank test Carry out a blank test at the same time as the determination following the same procedure and using the same quantities of all the reagents used in the test, but omitting the pure aluminium oxide. 6.3 Preparation of
32、 the calibration curve 6.3.1 Preparation of standard colorimetric solutions, corresponding to measurements carried out with an optical path length of1cm. Into a series of nine100ml one-mark volumetric flasks, place the volumes of the standard fluorine solution (4.7) indicated in the following table.
33、 Add to each flask20ml of the acetone (4.4) and40ml of the combined reagent (4.3). Check that the pH of each solution is between4,5 and4,6, adjusting if necessary by the addition of glacial acetic acid or a500g/l ammonium acetate solution. Dilute the contents of each flask to the mark andmix. Allow
34、the flasks to stand for1h protected from light. 6.3.2 Spectrophotometric measurements After1h, carry out the spectrophotometric measurements using the spectrophotometer (5.4) at a wavelength of about620nm, after having adjusted the instrument to zero absorbance against the compensation solution. 6.3
35、.3 Preparation of the calibration chart Plot a graph having, for example, the numbers of milligrams of fluorine contained in100ml of the standard colorimetric solutions as abscissae and the corresponding values of the absorbance as ordinates. 6.4 Determination 6.4.1 Preparation of the test solution
36、Prepare the test solution using the apparatus specified in5.1, following the technique in a sealed tube described in ISO/R2073, substituting, in all cases,5,5ml of the sulphuric acid solution (4.1) and5ml of water for the specified quantities of hydrochloric acid and water. If the mass of the test p
37、ortion is0,5g, however, the volumes of sulphuric acid solution (4.1) and water shall be3ml and2,5ml respectively. 6.4.2 Distillation Place the test solution (6.4.1) in the distillation flask of the apparatus (5.2). Then carry out the distillation procedure by the method described in6.3.2 of ISO/R169
38、3, but with the following details: distillation with sulphuric acid: use65ml of the sulphuric acid solution (4.2); temperature of distillation: 150 1 C. 6.4.3 Colour development Take an aliquot portion of the distillate containing between2g and60g of fluorine, of which the volume shall not exceed30m
39、l, and transfer it to a100ml one-mark volumetric flask. Add20ml of the acetone (4.4) and40ml of the combined reagent(4.3). Check that the pH is between4,5 and4,6, adjusting, if necessary, by the addition of glacial acetic acid or a500g/l ammonium acetate solution. Dilute to the mark and mix. Allow t
40、o stand for1h protected from light. Standard fluorine solution(4.7) Corresponding mass offluorine ml g 0 a 0 1,0 2 2,0 4 4,0 8 5,0 10 10,0 20 15,0 30 20,0 40 30,0 60 a Compensation solution.BS4140-17:1986 BSI 11-1999 3 6.4.4 Spectrophotometric measurement After1h, carry out the spectrophotometric me
41、asurement using the spectrophotometer (5.4) at a wavelength of about620nm, after having adjusted the instrument to zero absorbance against the blank test solution(6.2). 7 Expression of results By means of the calibration chart (6.3.3), determine the quantity of fluorine corresponding to the value of
42、 the absorbance. The fluorine content, expressed as a percentage by mass of fluorine (F), is given by the formula: where 8 Test report The test report shall include the following particulars: a) the reference of the method used; b) the results and the method of expression used; c) any unusual featur
43、es noted during the determination; d) any operation not included in this International Standard or those documents to which reference is made, or regarded as optional. m 0is the mass, in grams, of the test portion; m 1is the mass, in milligrams, of fluorine found in the aliquot portion of the test s
44、olution; D is the ratio between the volume of the distillate and the volume of the aliquot portion taken for the colour development. m 1 D 10m 0 -4 blankBS4140-17:1986 BSI 11-1999 Publications referred to See national foreword.BS 4140-17: 1986 ISO 2828:1973 BSI 389 Chiswick High Road London W4 4AL B
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