BS-6075-7-1981 ISO-3197-1975.pdf
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1、BRITISH STANDARD BS 6075-7: 1981 ISO 3197:1975 Methods of Sampling and test for sodium hydroxide for industrial use Part 7: Determination of chloride content (photometric method) ISO title: Sodium hydroxide for industrial use Determination of chlorides content Photometric method NOTEIt is recommende
2、d that this Part be read in conjunction with the information in the “General introduction” published separately as BS 6075-0. UDC 661.322.1:546.33 36:543.42.062:546.131 Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:09:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6075-7:1981 This Brit
3、ish 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 10-1999 The following BSI references relate to the work on this standard: Committee reference CIC/22 Dra
4、ft for comment 73/54863 DC ISBN 0 580 12057 0 Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:09:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6075-7:1981 BSI 10-1999i Contents Page National forewordii 1Scope and field of
5、 application1 2Reference1 3Principle1 4Reactions1 5Reagents1 6Apparatus1 7Procedure2 8Expression of results2 9Test report3 National appendix A Removal of mercury from waste solutions4 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:09:56 GMT+00:00
6、2006, Uncontrolled Copy, (c) BSI BS 6075-7:1981 ii BSI 10-1999 National foreword This Part of BS 6075 is identical with ISO 3197 “Sodium hydroxide for industrial use Determination of chlorides content Photometric method”, published in 1975 by the International Organization for Standardization (ISO).
7、 The National appendix to this Part of this standard describes a procedure to remove mercury from waste solutions from the analytical procedures described herein. This procedure is technically equivalent to that described in ISO 5790 “Inorganic chemical products for industrial use General method for
8、 determination of chloride content Mercurimetric method” (which has not been implemented as a British Standard). 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 con
9、ventions 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 practice to use a full point on the baseline as the decimal marker. Wherever the words “Internat
10、ional Standard” appear, referring to this standard, they should be read as “British Standard”. Additional information Water. Water complying with the requirements of clause 5 is specified in BS 3978 “Water for laboratory use”. Nitric acid, approximately 1.42 g/ml, about 70 % (m/m) solution, which is
11、 the corresponding reagent available in the UK, is suitable for use in place of the solution specified in 5.2. Test portion. For some grades of sodium hydroxide it may be necessary to adjust the mass of the test portion (see 7.1) to ensure that the amount of chloride present in the test solution com
12、plies with the requirements for the test method. In BS 4130 “Sodium hydroxide (technical grades)”, details of a suitable mass for the grades specified are given. WARNING. Mercury (II) thiocyanate, specified in 5.3, is toxic (with danger of cumulative effects) and is irritant, particularly in the for
13、m of dust. Avoid breathing dust. Avoid contact with skin and eyes. Avoid pollution of waste water with mercury from waste solutions using, for example, the procedure for removal of mercury described in the National appendix to this Part of this standard. NOTETextual error. In the heading to 5.3 “thi
14、coyanate” should be read as “thiocyanate”. Cross-references International StandardCorresponding British Standard BS 6075 Methods of sampling and test for sodium hydroxide for industrial use ISO 981:1973Part 2:1981 Determination of chloride content (mercurimetric method) (Identical) ISO 3195:1975Part
15、 5:1981 Sampling and preparation of main test solution (Identical) Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:09:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6075-7:1981 BSI 10-1999iii A British Standard does not purport to include all the necessary provisions of a contract. Users
16、 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 This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 4, an inside back cover and a ba
17、ck 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. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:09:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank License
18、d Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:09:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6075-7:1981 BSI 10-19991 1 Scope and field of application This International Standard specifies a photometric method for the determination of the chlorides content of sodium hydroxide for industria
19、l use. The method is applicable to products having chloride contents, expressed as chlorine (Cl), between 2 mg/kg and 50 mg/kg. NOTEFor contents exceeding 50 mg/kg, use the method specified in ISO 981, Sodium hydroxide for industrial use Determination of chlorides content Mercurimetric method, or re
20、duce the volume of the test solution according to the note in 7.4.3. 2 Reference ISO 3195, Sodium hydroxide for industrial use Sampling Test sample Preparation of the main solution for carrying out certain determinations. 3 Principle Quantitative displacement of the thiocyanate (SCN) ions of the mer
21、cury(II) thiocyanate by the chloride (Cl) ions contained in the test portion. Reaction of the SCN ions with iron(III) nitrate to form iron(III) thiocyanate (red). Photometric measurement of the colour at a wavelength of about 450 nm. 4 Reactions 2NaCl + Hg(SCN)2 F HgCl2 + 2NaSCN 3NaSCN + Fe(NO3)3 F
22、3NaNO3 + Fe(SCN)3 5 Reagents The preparation and storage of the reagents, as well as the sampling and determination, shall take place in an atmosphere free from chlorine and hydrochloric acid. During the analysis, use only reagents of recognized analytical reagent grade and only double-distilled wat
23、er, or water of equivalent purity. 5.1 Nitric acid, approximately 1,40 g/ml, about 68 % (m/m) solution or approximately 14 N solution, having a chlorides content, expressed as chlorine (Cl), not exceeding 0,5 mg/kg. 5.2 Iron(III) nitrate solution corresponding to 8 g of Fe per litre. Pour 80 ml of w
24、ater into a 500 ml conical flask, and add 4,0 g of pure (99,5 % minimum) iron wire. Cautiously add 80 ml of the nitric acid solution (5.1). Heat gradually and then boil in a ventilated fume cupboard until the reaction is complete and nitrous fumes have been completely eliminated. Decolorize the solu
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