1、BRITISH STANDARD BS4993-2: 1974 Methods of test for Aluminium fluoride for industrial use Part2: Determination of iron content UDC 661.862.361:546.623161:543.432:546.72BS4993-2:1974 This British Standard, having been approved by the ChemicalsIndustry StandardsCommittee, waspublished under theauthori
2、tyof theExecutive Boardon 28 February1974 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference CIC/24 Drafts for comment/approval 71/53613 and73/50651 ISBN 0 580 08095 1 Co-operating organizations The Chemicals Industry Standards Committee, under whose su
3、pervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: British Steel Industry Chemical Industries Association* Department of Health and Social Security Department of Trade and Industry Fertilize
4、r Manufacturers Association Limited Ministry of Agriculture, Fisheries and Food National Sulphuric Acid Association Royal Institute of Public Health and Hygiene Soap and Detergent Industry Association The industrial organization marked with an asterisk in the list, together with the following, were
5、directly represented on the committee entrusted with the preparation of this British Standard: Aluminium Federation Society for Analytical Chemistry British Ceramic Research Association Society of Chemical Industry Amendments issued since publication Amd. No. Date of issue CommentsBS4993-2:1974 BSI
6、10-1999 i Contents Page Cooperating organizations Inside front cover Foreword ii 1 Scope 1 2 Field of application 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Procedure 2 7 Calculation 3 8 Note on procedure 4 Publications referred to Inside back coverBS4993-2:1974 ii BSI 10-1999 Foreword This Britis
7、h Standard has been prepared under the authority of the Chemicals Industry Standards Committee in order to provide methods for the analysis of aluminium fluoride. For some years the United Kingdom has participated in the work of preparing methods of test applicable to aluminium fluoride for industri
8、al use, organized by Sub-Committee7 “Alumina and related compounds” of Technical Committee47 “Chemistry” of the International Organization for Standardization(ISO). As international agreement is reached on the methods, it is proposed to publish them as parts of this British Standard. This part is ba
9、sed on the International Standard ISO2368, “Aluminium fluoride for industrial use Determination of iron content 1,10-phenanthroline photometric method”, modified to take into account the comments made by the UnitedKingdom during its development. This standard prescribes methods of test only, and sho
10、uld not be used or quoted as a specification defining limits of purity. Reference to the standard should be in a form of words indicating that the methods of test used conform to BS4993. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Stand
11、ards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This stand
12、ard 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.BS4993-2:1974 BSI 10-1999 1 1 Scope This Part of BS4993 specifies a photometric method for the determination of the iron content of aluminium fl
13、uoride for industrial use. NOTEThe titles of the British Standards referred to in this standard are listed on the inside back cover. 2 Field of application The method is applicable to the determination of iron contents, expressed as Fe 2 O 3 , greater than0.020%. 3 Principle A test portion is dissol
14、ved by either alkaline or acid fusion, and preliminary reduction of iron(III) is carried out by means of hydroxylammonium chloride. The iron(II)-1,10-phenanthroline complex is formed in a buffered medium(pH value between3.5 and4.2) and measured photometrically at a wavelength of510nm. 4 Reagents The
15、 reagents used shall be of recognized analytical reagent quality. Water complying with the requirements of BS3978 shall be used throughout. 4.1 Sodium carbonate, anhydrous. 4.2 Boric acid, (H 3 BO 3 ). 4.3 Potassium pyrosulphate, (K 2 S 2 O 7 ), finely crushed. 4.4 Nitric acid, approximately8N solut
16、ion. Dilute540ml of nitric acid, 1.40g/ml, approximately68%(m/m) solution, with water and dilute to1000ml. 4.5 Hydrochloric acid, approximately 6N solution. Dilute515ml of hydrochloric acid, 1.18g/ml, approximately38%(m/m) solution, with water and dilute to1000ml. 4.6 Hydroxylammonium chloride, 10g/
17、l solution. Dissolve10g of hydroxylammonium chloride(NH 2 OH.HCl) in water and dilute to1000ml. 4.7 1,10-phenanthroline, 2.5g/l solution. Dissolve2.5g of1,10-phenanthroline monohydrate(C 12 H 8 N 2 .H 2 O) in water and dilute to1000ml. 4.8 Buffer solution. Dissolve272g of sodium acetate trihydrate i
18、n approximately500ml of water and filter the solution. Add240ml of glacial acetic acid, approximately17.4N, and dilute to1000ml. 4.9 Sodium acetate, 500g/l solution. Dissolve50g of sodium acetate trihydrate in water, dilute to100ml and filter. 4.10 Acetic acid, dilute solution. Dilute500ml of glacia
19、l acetic acid, approximately17.4N, with water and dilute to1000ml. 4.11 Standard iron solution, corresponding to an Fe 2 O 3content of0.200g/l. Dissolve a weighed quantity of high purity iron, of known iron content, in20ml of sulphuric acid(1+3), the mass of iron being such as will give0.2000g of ir
20、on(III) oxide(Fe 2 O 3 ). Cool the solution, transfer it quantitatively to a1000ml one-mark volumetric flask(BS1792), dilute to the mark and mix. 1ml of this standard solution contains0.200mg of Fe 2 O 3 . 4.12 Standard iron solution, corresponding to an Fe 2 O 3content of0.010g/l. Transfer50.0ml of
21、 the standard solution(4.11) to a1000ml one-mark volumetric flask(BS1792), dilute to the mark and mix. 1ml of this standard solution contains10 4g of Fe 2 O 3 . Prepare this solution immediately before use. 4.13 Indicator paper, covering the pH range3.5 to4.2 at intervals of0.2units. 5 Apparatus Ord
22、inary laboratory apparatus and the following are required. 5.1 Platinum dish, flat-bottomed, approximately80mm in diameter and approximately35mm deep, fitted with a platinum lid. 5.2 Electric furnace, capable of being controlled at550 25 C. 5.3 Electric furnace, capable of being controlled at750 25
23、C. 5.4 pH meter, fitted with a glass electrode. Essential requirements are given in BS2586, and in BS3145 or BS3422. 5.5 Spectrophotometer, or 5.6 Photoelectric absorptiometerBS4993-2:1974 2 BSI 10-1999 6 Procedure 6.1 Test portion. Weigh, to the nearest0.001g,1g of the dried test sample 1) . 6.2 Bl
24、ank test 6.2.1 Alkaline fusion. Weigh12g of the sodium carbonate(4.1) and4g of the boric acid(4.2) into the platinum dish(5.1). Mix thoroughly, preferably with a platinum spatula. Cover the dish with its lid and place it in the electric furnace(5.2), controlled at550 25 C, taking care to isolate the
25、 dish from the floor of the furnace by means of a support which avoids the risk of contamination. Maintain at550 25 C until the reaction subsides. Transfer the dish to the electric furnace(5.3), controlled at750 25 C, isolating it, as before, from the furnace floor, and allow to remain for a maximum
26、 of5min. Remove the dish from the furnace and allow to cool in the atmosphere. Add boiling water to the dish and heat gently until the contents are completely dissolved. After cooling slightly, transfer the contents of the dish to a beaker of suitable capacity containing20ml of the nitric acid(4.4).
27、 Carefully wash the dish and lid with18ml of the nitric acid(4.4) and then with hot water, collecting the washings in the beaker, and simmer gently for a few minutes until completely dissolved. Allow to cool slightly and transfer quantitatively to a one-mark volumetric flask(BS1792) of the same capa
28、city as that used for the preparation of the test solution(6.4.1). After cooling, dilute to the mark and mix thoroughly. 6.2.2 Acid fusion. Weigh10g of the potassium pyrosulphate(4.3) into the platinum dish(5.1). Cover the dish with its lid and place in the electric furnace(5.3), controlled at750 25
29、 C, taking care to isolate the dish from the floor of the furnace by means of a support which avoids the risk of contamination. Maintain at750 25 C for a maximum of10min. Remove the dish from the furnace and allow to cool in the atmosphere. Add10ml of water and10ml of the hydrochloric acid(4.5) to t
30、he dish. Rinse the lid and walls of the dish with hot water and simmer gently until the contents are completely dissolved. Allow to cool slightly and transfer the solution quantitatively to a one-mark volumetric flask(BS1792) of the same capacity as that used for the preparation of the test solution
31、(6.4.1). After cooling, dilute to the mark and mix thoroughly. 6.3 Preparation of calibration curve 6.3.1 Preparation of the standard matching solutions for photometric measurements with a1cm cell. Into each of a series of eight100ml one-mark volumetric flasks transfer respectively the volumes of th
32、e standard iron solution(4.12) shown in the following table. Add to each flask an amount of water sufficient to dilute to approximately50ml, then add5ml of the hydroxylammonium chloride solution(4.6),5ml of the 1,10-phenanthroline solution(4.7) and25ml of the buffer solution(4.8). Dilute to the mark
33、 and mix thoroughly. 6.3.2 Photometric measurements. After not less than10min, carry out the photometric measurements with the spectrophotometer(5.5), at a wavelength of510nm, or with the photoelectric absorptiometer(5.6), fitted with a suitable filter, after having adjusted the instrument to zero a
34、bsorbance against the compensation solution. 6.3.3 Preparation of the calibration chart. Prepare a calibration chart having, for example, the Fe 2 O 3contents, in milligrams per100ml of standard matching solutions, as abscissae and the corresponding values of absorbance as ordinates. 6.4 Determinati
35、on 6.4.1 Preparation of the test solution 6.4.1.1 Alkaline fusion. Weigh12g of the sodium carbonate(4.1) and4g of the boric acid(4.2)into the platinum dish(5.1). Mix thoroughly, preferably with a platinum spatula. Add the test portion(6.1) to the mixture and mix thoroughly. Cover the dish with its l
36、id and place it in the electric furnace(5.2), controlled at550 25 C, taking care to isolate the dish from the floor of the furnace by means of a support which avoids the risk of contamination. 1) Methods for the preparation and storage of test samples of aluminium fluoride are in course of preparati
37、on and will be published as a part of this standard. Volume of standard iron solution(4.12) Corresponding mass ofFe 2 O 3 ml 0 a 1.0 2.5 5.0 10.0 15.0 20.0 25.0 4g 0 10 25 50 100 150 200 250 a Compensation solution.BS4993-2:1974 BSI 10-1999 3 Maintain at550 25 C until the reaction subsides(about30mi
38、n). Transfer the dish to the electric furnace(5.3), controlled at750 25 C, isolating it, as before, from the furnace floor. Keep the dish in the furnace for30min, making sure that the temperature of750 25 C is maintained for at least20min. Remove the dish from the furnace and allow to cool in the at
39、mosphere. Add boiling water to the dish and heat gently until the contents are completely dissolved. After cooling slightly, transfer the contents of the dish to a beaker of suitable capacity containing20ml of the nitric acid solution(4.4). Dissolve the residue(which consists essentially of iron (II
40、I) oxide) adhering to the walls of the dish in18ml of the nitric acid(4.4) and carefully wash the dish and its lid with hot water, collecting the washings in the beaker. Simmer the solution for a few minutes until completely dissolved. Allow to cool slightly and transfer quantitatively to a one-mark
41、 volumetric flask of either250ml or500ml capacity, according to the iron content to be determined. After cooling, dilute to the mark and mix thoroughly. 6.4.1.2 Acid fusion. Weigh10g of the potassium pyrosulphate(4.3) into the platinum dish(5.1). Add the test portion(6.1) and mix carefully with a pl
42、atinum spatula. Cover the dish with its lid and place in the electric furnace(5.3), controlled at750 25 C, taking care to isolate it from the floor of the furnace by means of a support which avoids the risk of contamination. Maintain for30min at750 25 C. Remove the dish from the furnace and allow to
43、 cool in the atmosphere. Add10ml of water and10ml of the hydrochloric acid(4.5) to the dish. Rinse the lid and walls of the dish with hot water and simmer gently until the solid is completely dissolved. Allow to cool slightly and transfer the solution quantitatively to a one-mark volumetric flask of
44、 either250ml or500ml capacity, according to the iron content to be determined. After cooling, dilute to the mark and mix. 6.4.2 Colour reaction 6.4.2.1 Colour development. Take an aliquot portion of the test solution(6.4.1) containing between504g and2504g of Fe 2 O 3and place it in a100ml one-mark v
45、olumetric flask. Dilute to approximately50ml with water. Add5ml of the hydroxylammonium chloride solution(4.6),5ml of the1,10-phenanthroline solution(4.7) and25ml of the buffer solution(4.8). Check the pH value of the solution using either the indicator paper(4.13) or the pH meter(5.4). This value s
46、hould be between3.5 and4.2; if not, adjust the pH value by slowly adding the required volume of the sodium acetate solution(4.9) or the acetic acid(4.10), as appropriate. Stir after each addition. Dilute to the mark and mix. 6.4.2.2 Photometric measurement. After not less than10min carry out the pho
47、tometric measurements on the sample solution and blank solution, following the procedure described in6.3.2, after having adjusted the instrument to zero absorbance against water. 7 Calculation By reference to the calibration chart(see6.3.3), read the iron contents corresponding to the values of the
48、photometric measurements. Iron content, expressed as a percentage by mass of Fe 2 O 3 , is given by the formula: where D is the ratio of volume of sample solution to volume of aliquot portion taken for the colour reaction; m O is the mass of the test portion(g); m 1 is the mass of iron(III) oxide (F
49、e 2 O 3 ) determined in the aliquot portion of the sample solution(mg); m 2 is the mass of iron(III) oxide (Fe 2 O 3 ) determined in the aliquot portion of the blank test solution(mg). m 1 m 2 () D 10m O - BS4993-2:1974 4 BSI 10-1999 8 Note on procedure Generally, the aliquot portion of the blank solution after treatment for photometric measurement shows a slight coloration. In this case, it is advisable to use it as the compensation solution. In this case, the formula for calculation becomes: where the symbols have th
