1、BRITISH STANDARD BS 6092-4: 1981 ISO 1691:1976 Methods of Sampling and test for sodium and potassium silicates for industrial use Part 4: Determination of carbonate content ISO title: Sodium and potassium silicates for industrial use Determination of carbonates content Gas-volumetric method NOTEIt i
2、s 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+546.33284:543.279.062:546.264BS6092-4:1981 This British Standard, having been prepared under the directionof the Chemicals Standards Comm
3、ittee, was published under the authorityofthe Executive Boardand comes into effect on 27February1981 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 12038 4 National foreword This Part of BS6092 is iden
4、tical with ISO1691 “Sodium and potassium silicates for industrial use Determination of carbonates content Gas-volumetric method”, published in1976 by the International Organization for Standardization (ISO). Terminology and conventions. The text of the International Standard has been approved as sui
5、table 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 Standards it is current p
6、ractice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “British Standard”. Cross-references There is no British Standard corresponding directly to ISO1686 to which reference is made in3
7、.3. Technically equivalent information on sampling is given in BS6092-0. The standards listed in the Annex are intended for information only. Corresponding British Standards are listed in BS6092-0. A British Standard does not purport to include all the necessary provisions of a contract. Users of Br
8、itish Standards 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, pages i and ii, pages 1 to 6, an inside back cover and a back co
9、ver. 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. Amendments issued since publication Amd. No. Date of issue CommentsBS6092-4:1981 BSI 11-1999 i Contents Page National foreword I
10、nside front cover 1 Scope and field of application 1 2 Reference 1 3 Preliminary test 1 4 Sodium or potassium silicates containing neither sulphides nor chlorates 1 5 Sodium or potassium silicates containing sulphides 4 6 Sodium or potassium silicates containing chlorates 5 7 Test report 5 Annex ISO
11、 Publications relating to sodium and potassium silicates forindustrialuse 6 Figure Apparatus for gas-volumetric determination of carbonates content 3 Publications referred to Inside back coverii blankBS6092-4:1981 BSI 11-1999 1 1 Scope and field of application This International Standard specifies a
12、 gas-volumetric method for the determination of the carbonates content, expressed, respectively, as sodium carbonate or potassium carbonate, of sodium and potassium silicates for industrial use. Three cases, defined by a preliminary test, are envisaged: 1.1 Sodium or potassium silicates containing n
13、either sulphides nor chlorates. 1.2 Sodium or potassium silicates containing sulphides. 1.3 Sodium or potassium silicates containing chlorates. 2 Reference ISO 1686, Sodium and potassium silicates for industrial use Samples and methods of test General. 3 Preliminary test 3.1 Principle Boiling of an
14、acidified test portion containing methyl orange and with a lead acetate paper strip in the vapour. The presence of sulphides produces blackening of the paper and the presence of chlorates decolorizes the methyl orange. 3.2 Reagents During the analysis, use only reagents of recognized analytical grad
15、e and only distilled water or water of equivalent purity, free from carbon dioxide. 3.2.1 Hydrochloric acid, approximately6 N solution. 3.2.2 Methyl orange, 0,5g/l solution. 3.2.3 Lead acetate paper, cut into strips about15mm 80mm. 3.3 Procedure Place about5g of the test sample (see ISO1686) in a300
16、ml conical flask. Add150ml of water and3 drops of the methyl orange solution (3.2.2). Neutralize with the hydrochloric acid solution(3.2.1) and add an excess of5ml of thisacid. Fix a lead acetate paper strip (3.2.3) inside the neck of the conical flask, curling it over the outside of the flask. Boil
17、 the solution for5min and select the procedure to be followed according to the following table. 4 Sodium or potassium silicates containing neither sulphides nor chlorates 4.1 Principle Measurement of the volume of carbon dioxide evolved from a test portion by reaction with a hydrochloric acid soluti
18、on. 4.2 Reagents Reagents specified in3.2 and 4.2.1 Distilled water, or water of equal purity, free from carbon dioxide at ambient temperature. Eliminate any carbon dioxide present either by boiling the water for10min and cooling in the absence of atmospheric carbon dioxide or, more simply, by bubbl
19、ing air free from carbon dioxide through it for15min: (Free the air from carbon dioxide by passing it through a column containing pellets of sodium hydroxide.) Store the water in the absence of atmospheric carbon dioxide. 4.2.2 Hydrochloric acid, approximately 1,19g/ml, about38% (m/m) or approximate
20、ly12N solution. 4.2.3 Sodium chloride, coloured acid solution. Dissolve263g of sodium chloride in water. Add5ml of a sulphuric acid solution, approximately1,84g/ml, about96% (m/m) or approximately36N solution. Dilute to1000ml, add a small amount of the methyl orange solution(3.2.2) and mix. 4.2.4 So
21、dium hydroxide, approximately1,22g/ml, about20% (m/m) or approximately6N solution. Dissolve120g of sodium hydroxide in water. Cool to ambient temperature, dilute to500ml and mix thoroughly. 4.3 Apparatus Ordinary laboratory apparatus and 4.3.1 Apparatus as shown in theFigure. Appearance Case number
22、Procedure solution paper red white 1.1 Clause4 red blackened 1.2 Clause5 colourless white 1.3 Clause6BS6092-4:1981 2 BSI 11-1999 4.4 Procedure 4.4.1 Test portion Weigh, to the nearest0,001g, 4,9 to5,1g of the test sample (see ISO1686). 4.4.2 Determination 4.4.2.1 PREPARATION OF THE APPARATUS Fill th
23、e burette (B) of the apparatus (4.3.1) with the sodium chloride solution (4.2.3), through the levelling bottle (F). Pour into the absorber (C) the sodium hydroxide solution (4.2.4). (Renew this solution after approximately100 determinations.) The burette (B) and the absorber (C) being filled up to t
24、he stopcock (R 1 ) and the mark (a) respectively, and the stopcocks (R 1 ) and (R 2 ) being closed, quantitatively transfer the test portion (4.4.1), previously mixed with10ml of water, to the flask(A). Dilute to approximately40ml so as to reduce the dead space to a volume slightly greater than100ml
25、 volume above the level of the liquid in the flask (A) plus the volume of the condenser tube(D) up to the cock (R 1 ). Place in the flask (A) three porcelain or glass beads of diameter approximately2mm, together with a few pieces of pumice stone, the volume of which should be approximately equal to
26、that of the beads. Close the flask and the stopcock (R). Open the stopcock (R 1 ) to connect the flask (A) and the burette (B) and lower the levelling bottle (F). Check the tightness of the apparatus by appropriately handling the cocks and the levelling bottle. 4.4.2.2 EVOLUTION AND MEASUREMENT OF C
27、ARBON DIOXIDE By means of the dropping funnel, pour20ml of the hydrochloric acid solution (4.2.2) into the flask (A), taking care to avoid loss of gas. Heat the flask and maintain the solution at boiling point for5min while running cold water through the condenser. Then stop heating and add sodium c
28、hloride solution (4.2.3) by means of the funnel, lowering the levelling bottle (F) still further so as to make the solution in the flask (A) rise in the condenser tube up to the cock (R 1 ). Then close the latter and wait5min to allow the gas to reach the temperature of the water-jacket. Measure the
29、 volume of gas, V 0 , at atmospheric pressure P and at the temperature t of the water in the jacket. For this purpose, move the levelling bottle (F) so as to bring the sodium chloride solution(4.2.3) to the same level both in the flask and in the burette (B); read the volume of the latter. Adjust th
30、e cocks (R 1 ) and (R 2 ) so that the burette (B) and the absorber (C) are connected, then raise the levelling bottle (F) so that the gas is transferred to the absorber where the carbon dioxide is absorbed. Then transfer the non-absorbed gas back to the burette (B) by lowering the levelling bottle (
31、F) and, after adjusting the level of the sodium hydroxide solution (4.2.4) to the gauge mark (a) on the absorber (C), close the cock (R 2 ) and read the volume of the residual gas. Repeat these operations until a constant volume V 1is obtained. The difference (V 0 V 1 ) represents the volume of the
32、carbon dioxide contained in the test portion, measured at atmospheric pressure and at the temperature of the water-jacket.BS6092-4:1981 BSI 11-1999 3 Figure Apparatus for gas-volumetric determination of carbonates contentBS6092-4:1981 4 BSI 11-1999 4.5 Expression of results The content of sodium car
33、bonate (Na 2 CO 3 ) or of potassium carbonate (K 2 CO 3 ), expressed as a percentage by mass, is given, according to the case, by the formulae where V 0 is the volume, in millilitres, of the gas before absorption of the carbon dioxide; V 1 is the volume, in millilitres, of the gas after absorption o
34、f the carbon dioxide; t is the temperature, in degrees Celsius, of the water contained in the water-jacket; P is the atmospheric pressure, in millibars, during the determination; NOTEIf the atmospheric pressure P is measured in pascals (or kilopascals), multiply this value by0,01 (or by10) to conver
35、t it to millibars. p is the vapour pressure, in millibars, of the solution sodium chloride (4.2.3) at the temperature of the water contained in the jacket. Vapour pressures are given in the table below for temperatures from10 to30 C: m is the mass, in grams, of the test portion(4.4.1); 0,00198is the
36、 factor for the conversion of the volume of carbon dioxide, in millilitres, to the mass of carbon dioxide, in grams; is the factor for the conversion of the mass of carbon dioxide to the corresponding mass of Na 2 CO 3 ; is the factor for the conversion of the mass of carbon dioxide to the correspon
37、ding mass of K 2 CO 3 . 4.6 Precision of the method The results obtained with this method are reproducible to the nearest 0,04% (m/m) in absolute value. 5 Sodium or potassium silicates containing sulphides In the case of sodium or potassium silicates containing sulphides, the acidification of the pr
38、oduct causes the liberation of hydrogen sulphide which is absorbed in the sodium hydroxide solution at the same time as the carbon dioxide, giving a result in excess of the true value. A preliminary treatment of the test portion is therefore necessary. The method is applicable to products containing
39、 up to5g of sulphides, expressed as Na 2 S, per kilogram. 5.1 Principle Oxidation of the sulphides by hydrogen peroxide and boiling of the test portion before acidification. Determination according to the method specified in clause4. 5.2 Reagents Reagents specified in3.2 and4.2, and: 5.2.1 Hydrogen
40、peroxide, 30% (m/m). 5.3 Apparatus See4.3. 5.4 Procedure Follow the procedure specified in4.4, applying the following modifications: in4.4.2.1, 4th paragraph, place in the flask (A), before the porcelain or glass beads, 5 drops of the hydrogen peroxide solution (5.2.1); at the end of4.4.2.1, open th
41、e cock (R 1 ), lower the levelling bottle (F) and boil the contents of the flask (A) for5min, while running cold water through the condenser. Cool to a temperature slightly above ambient temperature, to prevent the liquid in the burette from being drawn into the condenser. 5.5 Expression of results
42、See4.5. Temperature, t C 10 12 14 16 18 20 22 24 26 28 30 Vapour pressure, p mbar 11 12 13 15 17 19 21 24 27 30 33 106 44 - 138,2 44 -BS6092-4:1981 BSI 11-1999 5 6 Sodium or potassium silicates containing chlorates In the case of sodium or potassium silicates containing chlorates, acidification of t
43、he product causes the liberation of chlorine, which is absorbed in the sodium hydroxide solution at the same time as the carbon dioxide, giving a result in excess of the true value. A preliminary treatment of the test portion is therefore necessary. The method is applicable to products containing up
44、 to10g of chlorates, expressed as NaClO 3 , per kilogram. 6.1 Principle Prior reduction of the chlorates to chlorides by addition of iron(II) sulphate. Determination according to the method specified in clause4. 6.2 Reagents Reagents specified in3.2 and4.2, and: 6.2.1 Iron(II) sulphate solution, con
45、taining28g of iron(II) sulphate heptahydrate (FeSO 4 .7H 2 O) and4drops of the hydrochloric acid solution (3.2.1) in100ml. 6.3 Apparatus See4.3. 6.4 Procedure Follow the procedure specified in4.4.3, applying the following modification: in4.4.2.1, 3rd paragraph, place in the flask(A), after the test
46、portion (4.4.1), 5ml of the iron(II) sulphate solution (6.2.1). 6.5 Expression of results See4.5. 7 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 features noted during the det
47、ermination; d) any operation not included in this International Standard or in the International Standard to which reference is made, or regarded as optional.BS6092-4:1981 6 BSI 11-1999 Annex ISO publications relating to sodium and potassium silicates for industrial use ISO 1686, Samples and methods
48、 of test General. ISO 1687, Determination of density at20 C of samples in solution Methods using density hydrometer and pyknometer. ISO 1688, Determination of dry matter Gravimetric method. ISO 1689, Calculation of the ratioor . ISO 1690, Determination of silica content Gravimetric method by insolub
49、ilization. ISO 1691, Determination of carbonates content Gas-volumetric method. ISO 1692, Determination of total alkalinity Titrimetric method. ISO 2122, Preparation of solution of products not easily soluble in boiling water and determination of matter insoluble in water. ISO 2123, Determination of dynamic viscosity. ISO 2124, Determination of silica content Titrimetric method. ISO 3200, Determination of sulphates content Barium sulphate gravimetric method. ISO 3201, Determination of iron conten
