1、BRITISH STANDARD BS 6092-9: 1981 ISO 3201:1975 Methods of Sampling and test for sodium and potassium silicates for industrial use Part 9: Determination of iron content ISO title: Sodium and potassium silicates for industrial use Determination of iron content 1,10-Phenanthroline photometric method NO
2、TEIt is recommended that this Part be read in conjunction with the information in the “Generalintroduction” published separately as BS6092-0. UDC 661.683/.684:546.32284 + 546.33284:543.42.062:546.72BS6092-9:1981 This British Standard, having been prepared under the directionof the Chemicals Standard
3、s Committee, was published under the authorityofthe Executive Boardand comes into effect on 27 February 1981 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference CIC/22 Draft for comment 73/55424 DC ISBN 0 580 12043 0 National foreword This Part of BS6092
4、 is identical with ISO3201 “Sodium and potassium silicates for industrial use Determination of iron content 1, 10-Phenanthroline photometric method”, published in1975 by the International Organization for Standardization (ISO). Terminology and conventions. The text of the International Standard has
5、been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is especially drawn to the following. The comma has been used throughout as a decimal marker. In British Stand
6、ards it is current practice to use a full point on the baseline as the decimal marker. Where the words “International Standard” appear, referring to this standard, they should be read as “British Standard”. Additional information Water. Water complying with the requirements of clause4 is specified i
7、n BS3978 “Water for laboratory use”. In the revised edition of BS3984:1966 “Sodium silicates” the mass of the test portion (see6.1) and the volume of the test solution (see6.4.1) taken for colour development (see6.4.2) will be adjusted so as to fit the method to the specification limits. WARNING. Hy
8、droxylammonium chloride specified in4.2 is corrosive and irritant. Avoid contact with eyes and skin. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard
9、 does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporate
10、d. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date of issue CommentsBS6092-9:1981 BSI 11-1999 i Contents Page National foreword Inside front cover 1 Scope 1 2 Field of application 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6
11、Procedure 1 7 Expression of results 2 8 Test report 2 Publications referred to Inside back coverii blankBS6092-9:1981 BSI 11-1999 1 1 Scope This International Standard specifies a 1, 10-phenanthroline photometric method for the determination of iron content of sodium and potassium silicates for indu
12、strial use. 2 Field of application The method is applicable to products having iron contents greater than2mg/kg. 3 Principle Prior reduction of the trivalent iron by hydroxylammonium chloride. Formation of the divalent iron/1, 10-phenanthroline complex in a buffered medium. Photometric measurement o
13、f the coloured complex at a wavelength of about510nm. 4 Reagents During the analysis, use only reagents of recognized analytical reagent grade and only distilled water or water of equivalent purity. 4.1 Hydrochloric acid, approximately 2N solution. 4.2 Hydroxylammonium chloride (NH 2 OH.HCl), 100g/l
14、 solution. 4.3 Buffer solution, pH 4,9. Dissolve 272 g of sodium acetate trihydrate (CH 3 COONa.3H 2 O) in approximately 500ml of water. Add 240ml of glacial acetic acid approximately 1,05g/ml, 99 to 100% (m/m) or about17,4N to the solution, dilute to 1000ml and mix. 4.4 Bromine water, saturated at
15、room temperature. 4.5 1,10-Phenanthroline hydrochloride monohydrate (C 12 H 8 N 2 .HCl.H 2 O), 2,5g/l solution. This reagent may be replaced by 1, 10-phenanthroline monohydrate (C 12 H 8 N 2 .H 2 O), 2,5g/l solution. 4.6 Iron, standard solution corresponding to 0,200g of Fe per litre. Dissolve 1,404
16、3g of ammonium iron(II) sulphate hexahydrate (NH 4 ) 2 Fe(SO 4 ) 2 .6H 2 O, weighed to the nearest 0,0001g, in 200ml of water. Add 20ml of sulphuric acid, approximately 1,84g/ml, cool to room temperature, dilute to the mark in a 1000ml one-mark volumetric flask and mix. 4.7 Iron, standard solution c
17、orresponding to0,010g of Fe per litre. Transfer 25,0ml of the standard iron solution (4.6) to a500ml one-mark volumetric flask, dilute to the mark and mix. Prepare this solution at the time of use. 1 ml of this standard solution contains 0,010mg of Fe. 4.8 Methyl orange, 0,5g/l solution. 5 Apparatus
18、 Ordinary laboratory apparatus and: 5.1 Spectrophotometer or 5.2 Photoelectric absorptiometer, fitted with filters providing maximum transmission between500 and520nm. 5.3 Platinum crucible, with lid. Upper diameter about 30mm, height about 30mm. 6 Procedure 6.1 Test portion Weigh, to the nearest 0,0
19、1 g, in a weighing bottle fitted with a ground glass closure, a quantity of the test sample corresponding to approximately 5g of the anhydrous product. 6.2 Blank test Pour 25ml of water, a volume of the hydrochloric acid solution (4.1) 15ml in excess of that used to neutralize the test portion (see6
20、.4.1), 5drops of the methyl orange solution (4.8) and 5ml of the bromine water (4.4) (to decolorize the indicator) into a 600ml beaker. Boil for 5min, cool to room temperature and transfer quantitatively to a 250ml one-mark volumetric flask. Dilute to the mark, mix, and then proceed as specified in6
21、.4.2. 6.3 Preparation of the calibration curve 6.3.1 Preparation of the standard colorimetric solutions, relating to photometric measurements carried out with cells of 4cm or 5cm optical path length. Into a series of five 100ml one-mark volumetric flasks, transfer the quantities of the standard iron
22、 solution (4.7) indicated in the following table: Standard iron solution (4.7) Corresponding mass of Fe ml mg 0 a 2,5 0,025 5,0 0,050 10,0 0,100 15,0 0,150 a Compensation solution.BS6092-9:1981 2 BSI 11-1999 Add 5 ml of the hydrochloric acid solution (4.1) and the amount of water required to dilute
23、to about50ml to each flask. Then add5ml of the hydroxylammonium chloride solution (4.2), 5ml of the1, 10-phenanthroline hydrochloride solution(4.5) and 25ml of the buffer solution (4.3). Dilute to the marks, mix and wait for 10min. 6.3.2 Photometric measurements Carry out the photometric measurement
24、s with the spectrophotometer (5.1), at a wavelength of about510nm, or with the photoelectric absorptiometer(5.2), fitted with suitable filters, after having, in each case, adjusted the instrument to zero absorbance against the compensation solution. 6.3.3 Preparation of the calibration chart Plot a
25、graph having, for example, the numbers of milligrams of iron (Fe) contained in 100ml of the standard colorimetric solutions on the abscissa and the corresponding values of absorbance on the ordinate. 6.4 Determination 6.4.1 Preparation of the test solution Transfer the test portion (6.1) to a 600ml
26、beaker. Add 175ml of water and neutralize cautiously with the hydrochloric acid solution (4.1) in the presence of 5drops of the methyl orange solution (4.8). Add an excess of 15ml of this acid and then add 5ml of the bromine water (4.4). Boil for 5min, cool to room temperature, transfer quantitative
27、ly to a 250ml one-mark volumetric flask, dilute to the mark and mix. NOTEIf the resultant solution is turbid, discard it and weigh, to the nearest 0,01g, a new test portion, corresponding to 1g of the anhydrous product. Place it in a platinum crucible, previously cleaned by heating in a furnace and
28、rinsing with hydrochloric acid and with water. Add 5g of potassium sodium carbonate and heat slowly until the mix is fused. After cooling, dissolve in 100ml of hot water, added in portions, and transfer quantitatively to a 600ml beaker. Dilute to 150ml and proceed according to the instructions given
29、 in6.4.1 from “neutralize cautiously”. Adjust the blank test (6.2) by also adding5g of potassium sodium carbonate. 6.4.2 Colour development Transfer not more than50,0 ml of the test solution(6.4.1), containing less than 0,150mg of iron, to a 100ml one-mark volumetric flask. Add5ml of the hydroxylamm
30、onium chloride solution(4.2), 5ml of the 1, 10-phenanthroline hydrochloride solution(4.5) and 25ml of the buffer solution (4.3). Dilute to the mark, mix and wait10min. 6.4.3 Photometric measurement Carry out the photometric measurement on the solution (6.4.2) as specified in6.3.2, after having adjus
31、ted 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 Fe corresponding to the value of the absorbance measured. The iron (Fe) content is given, in milligrams per kilogram, by the formu
32、la where m 0 is the mass, in grams, of the test portion; m 1 is the mass, in milligrams, of Fe found in the aliquot portion of the test solution; V is the volume, in millilitres, of test solution(6.4.1) taken for the determination. 8 Test report The test report shall include the following particular
33、s: a) the reference of the method used; b) the results and the method of expression used; c) any unusual features noted during the determination; d) any operation not included in this International Standard, or regarded as optional.BS6092-9:1981 BSI 11-1999 Publications referred to See national fore
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