《BS-6092-4-1981 ISO-1691-1976.pdf》由会员分享，可在线阅读，更多相关《BS-6092-4-1981 ISO-1691-1976.pdf（12页珍藏版）》请在三一文库上搜索。
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 “General introduction” published separately as BS 6092-0. UDC 661.683/.684:546.32284 + 546.33284:543.279.062:546.264 Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:09:47 GMT+00:00 2006, Uncontrolled Copy, (c)
3、BSI BS 6092-4:1981 This British Standard, having been prepared under the direction of the Chemicals Standards Committee, was published under the authority of the Executive Board and comes into effect on 27 February 1981 BSI 11-1999 The following BSI references relate to the work on this standard: Co
4、mmittee reference CIC/22 Draft for comment 73/55424 DC ISBN 0 580 12038 4 National foreword This Part of BS 6092 is identical with ISO 1691 “Sodium and potassium silicates for industrial use Determination of carbonates content Gas-volumetric method”, published in 1976 by the International Organizati
5、on for Standardization (ISO). Terminology and conventions. The text of the International Standard has 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 espec
6、ially drawn to the following. The comma has been used throughout as a decimal marker. In British Standards it is current practice 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
7、 Standard”. Cross-references There is no British Standard corresponding directly to ISO 1686 to which reference is made in 3.3. Technically equivalent information on sampling is given in BS 6092-0. The standards listed in the Annex are intended for information only. Corresponding British Standards a
8、re listed in BS 6092-0. 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 does not of itself confer immunity from legal obligations. Summary of pages
9、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 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. Am
10、endments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:09:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6092-4:1981 BSI 11-1999i Contents Page National forewordInside front cover 1Scope and field of application1 2Reference1 3Preli
11、minary test1 4Sodium or potassium silicates containing neither sulphides nor chlorates1 5Sodium or potassium silicates containing sulphides4 6Sodium or potassium silicates containing chlorates5 7Test report5 Annex ISO Publications relating to sodium and potassium silicates for industrial use6 Figure
12、 Apparatus for gas-volumetric determination of carbonates content3 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:09:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:09:47 GMT+00:00 2
13、006, Uncontrolled Copy, (c) BSI BS 6092-4:1981 BSI 11-19991 1 Scope and field of application This International Standard specifies a gas-volumetric method for the determination of the carbonates content, expressed, respectively, as sodium carbonate or potassium carbonate, of sodium and potassium sil
14、icates for industrial use. Three cases, defined by a preliminary test, are envisaged: 1.1 Sodium or potassium silicates containing neither sulphides nor chlorates. 1.2 Sodium or potassium silicates containing sulphides. 1.3 Sodium or potassium silicates containing chlorates. 2 Reference ISO 1686, So
15、dium and potassium silicates for industrial use Samples and methods of test General. 3 Preliminary test 3.1 Principle Boiling of an 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 pr
16、esence of chlorates decolorizes the methyl orange. 3.2 Reagents During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity, free from carbon dioxide. 3.2.1 Hydrochloric acid, approximately 6 N solution. 3.2.2 Methyl orange, 0,5 g/l so
17、lution. 3.2.3 Lead acetate paper, cut into strips about 15 mm 80 mm. 3.3 Procedure Place about 5 g of the test sample (see ISO 1686) in a 300 ml conical flask. Add 150 ml of water and 3 drops of the methyl orange solution (3.2.2). Neutralize with the hydrochloric acid solution (3.2.1) and add an exc
18、ess of 5 ml of this acid. 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 the solution for 5 min and select the procedure to be followed according to the following table. 4 Sodium or potassium silicates containing neither su
19、lphides nor chlorates 4.1 Principle Measurement of the volume of carbon dioxide evolved from a test portion by reaction with a hydrochloric acid solution. 4.2 Reagents Reagents specified in 3.2 and 4.2.1 Distilled water, or water of equal purity, free from carbon dioxide at ambient temperature. Elim
20、inate any carbon dioxide present either by boiling the water for 10 min and cooling in the absence of atmospheric carbon dioxide or, more simply, by bubbling air free from carbon dioxide through it for 15 min: (Free the air from carbon dioxide by passing it through a column containing pellets of sod
21、ium hydroxide.) Store the water in the absence of atmospheric carbon dioxide. 4.2.2 Hydrochloric acid, approximately 1,19 g/ml, about 38 % (m/m) or approximately 12 N solution. 4.2.3 Sodium chloride, coloured acid solution. Dissolve 263 g of sodium chloride in water. Add 5 ml of a sulphuric acid sol
22、ution, approximately 1,84 g/ml, about 96 % (m/m) or approximately 36 N solution. Dilute to 1 000 ml, add a small amount of the methyl orange solution (3.2.2) and mix. 4.2.4 Sodium hydroxide, approximately 1,22 g/ml, about 20 % (m/m) or approximately 6 N solution. Dissolve 120 g of sodium hydroxide i
23、n water. Cool to ambient temperature, dilute to 500 ml and mix thoroughly. 4.3 Apparatus Ordinary laboratory apparatus and 4.3.1 Apparatus as shown in the Figure. Appearance Case number Procedure solutionpaper redwhite1.1Clause 4 redblackened1.2Clause 5 colourlesswhite1.3Clause 6 Licensed Copy: shef
24、fieldun sheffieldun, na, Wed Dec 06 14:09:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6092-4:1981 2 BSI 11-1999 4.4 Procedure 4.4.1 Test portion Weigh, to the nearest 0,001 g, 4,9 to 5,1 g of the test sample (see ISO 1686). 4.4.2 Determination 4.4.2.1 PREPARATION OF THE APPARATUS Fill the buret
25、te (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 approximately 100 determinations.) The burette (B) and the absorber (C) being filled up to the sto
26、pcock (R1) and the mark (a) respectively, and the stopcocks (R1) and (R2) being closed, quantitatively transfer the test portion (4.4.1), previously mixed with 10 ml of water, to the flask (A). Dilute to approximately 40 ml so as to reduce the dead space to a volume slightly greater than 100 ml volu
27、me above the level of the liquid in the flask (A) plus the volume of the condenser tube (D) up to the cock (R1). Place in the flask (A) three porcelain or glass beads of diameter approximately 2 mm, together with a few pieces of pumice stone, the volume of which should be approximately equal to that
28、 of the beads. Close the flask and the stopcock (R). Open the stopcock (R1) 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 CARBON
29、DIOXIDE By means of the dropping funnel, pour 20 ml 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 for 5 min while running cold water through the condenser. Then stop heating and add sodium chl
30、oride 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 (R1). Then close the latter and wait 5 min to allow the gas to reach the temperature of the water-jacket. Measure the v
31、olume of gas, V0, 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 the c
32、ocks (R1) and (R2) 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 (F) and,
33、 after adjusting the level of the sodium hydroxide solution (4.2.4) to the gauge mark (a) on the absorber (C), close the cock (R2) and read the volume of the residual gas. Repeat these operations until a constant volume V1 is obtained. The difference (V0 V1) represents the volume of the carbon dioxi
34、de contained in the test portion, measured at atmospheric pressure and at the temperature of the water-jacket. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:09:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6092-4:1981 BSI 11-19993 Figure Apparatus for gas-volumetric determination of c
35、arbonates content Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:09:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6092-4:1981 4 BSI 11-1999 4.5 Expression of results The content of sodium carbonate (Na2CO3) or of potassium carbonate (K2CO3), expressed as a percentage by mass, is given,
36、 according to the case, by the formulae where V0is the volume, in millilitres, of the gas before absorption of the carbon dioxide; V1is the volume, in millilitres, of the gas after absorption of the carbon dioxide; tis the temperature, in degrees Celsius, of the water contained in the water-jacket;
37、Pis the atmospheric pressure, in millibars, during the determination; NOTEIf the atmospheric pressure P is measured in pascals (or kilopascals), multiply this value by 0,01 (or by 10) to convert it to millibars. pis the vapour pressure, in millibars, of the solution sodium chloride (4.2.3) at the te
38、mperature of the water contained in the jacket. Vapour pressures are given in the table below for temperatures from 10 to 30 C: mis the mass, in grams, of the test portion (4.4.1); 0,001 98is the factor for the conversion of the volume of carbon dioxide, in millilitres, to the mass of carbon dioxide
39、, in grams; is the factor for the conversion of the mass of carbon dioxide to the corresponding mass of Na2CO3; is the factor for the conversion of the mass of carbon dioxide to the corresponding mass of K2CO3. 4.6 Precision of the method The results obtained with this method are reproducible to the
40、 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 product causes the liberation of hydrogen sulphide which is absorbed in the sodium hydroxide solution at the same
41、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 to 5 g of sulphides, expressed as Na2S, per kilogram. 5.1 Principle Oxidation of the sulphides by hydrogen p
42、eroxide and boiling of the test portion before acidification. Determination according to the method specified in clause 4. 5.2 Reagents Reagents specified in 3.2 and 4.2, and: 5.2.1 Hydrogen peroxide, 30 % (m/m). 5.3 Apparatus See 4.3. 5.4 Procedure Follow the procedure specified in 4.4, applying th
43、e following modifications: in 4.4.2.1, 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 of 4.4.2.1, open the cock (R1), lower the levelling bottle (F) and boil the contents of the flask (A) for 5 min, while runn
44、ing 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 See 4.5. 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
45、24 27 30 33 106 44 - - 138,2 44 - - Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:09:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6092-4:1981 BSI 11-19995 6 Sodium or potassium silicates containing chlorates In the case of sodium or potassium silicates containing chlorates, acidifica
46、tion of the 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 cont
47、aining up to 10 g of chlorates, expressed as NaClO3, 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 clause 4. 6.2 Reagents Reagents specified in 3.2 and 4.2, and: 6.2.1 Iron(II) sulphate s
48、olution, containing 28 g of iron(II) sulphate heptahydrate (FeSO4.7H2O) and 4 drops of the hydrochloric acid solution (3.2.1) in 100 ml. 6.3 Apparatus See 4.3. 6.4 Procedure Follow the procedure specified in 4.4.3, applying the following modification: in 4.4.2.1, 3rd paragraph, place in the flask (A
49、), after the test portion (4.4.1), 5 ml of the iron(II) sulphate solution (6.2.1). 6.5 Expression of results See 4.5. 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 determination; d) any operation not included in this International Standard or in the International Standard to which reference is made, or regarded as optional. Licensed Copy: sheffieldun sheffieldun,