BS 2924-1-1983 Aqueous extracts of paper board and pulp - Method for determination of pH《纸、纸板与纸浆的水提取物 pH值的测定方法》.pdf

1、BRITISH STANDARD BS 2924-1: 1983 ISO 6588:1981 Aqueous extracts of paper, board and pulp Part 1: Method for determination of pH ISO title: Paper, board and pulps Determination of pH of aqueous extracts UDC 676.014/.017:541.132.3BS2924-1:1983 This British Standard, having been prepared under the dire

2、ctionof the Paper StandardsCommittee, was published under the authorityofthe Board of BSIandcomes into effect on 31 October 1983 BSI 07-1999 First published, as part of BS2924, December 1957 First revision September 1968 First published, as BS 2924-1, October 1983 The following BSI references relate

3、to the work on this standard: Committee reference PAM/11 Draft for comment 79/64428 DC ISBN 0 580 13449 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Paper Standards Committee (PAM/-) to Technical Committee PAM/11 upon which the foll

4、owing bodies were represented: British Fibreboard Packaging Association British Paper and Board Industry Federation (PIF) British Printing Industries Federation British Wood Pulp Association Envelope Makers and Manufacturing Stationers Association Her Majestys Stationery Office Man-made Fibres Produ

5、cers Committee Ministry of Defence Paper Sack Development Association Ltd. Pira (the Research Association for the Paper and Board, Printing and Packaging Industries) Post Office Society of British Printing Ink Manufacturers University of Manchester Institute of Science and Technology Amendments issu

6、ed since publication Amd. No. Date of issue CommentsBS2924-1:1983 BSI 07-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Field of application 1 3 References 1 4 Principle 1 5 Reagents 1 6 Apparatus 1 7 Sampling and preparation of the sample 1 8 Procedu

7、re 1 9 Expression of results 2 10 Test report 2 Annex A Preparation of standard buffer solutions 3 Publications referred to Inside back coverBS2924-1:1983 ii BSI 07-1999 National foreword This Part of this British Standard has been prepared under the direction of the Paper Standards Committee. It is

8、 identical with ISO6588:1981 “Paper, board and pulps Determination of pH of aqueous extracts” published by the International Organization for Standardization (ISO) and supersedes clause 3 of BS2924:1968. Part 2 of this standard is identical with ISO6587:1980 “Paper, board and pulps Determination of

9、conductivity of aqueous extracts” and supersedesclause4 of BS2924:1968. Part 3 of this standard is presently under consideration and, when published, will supersede clauses 5 and 6 of BS2924:1968, at which time BS2924:1968 will be withdrawn. Terminology and conventions. The text of the international

10、 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 drawn especially to the following. The comma has been used as a decimal marker. In British St

11、andards 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 Part of this standard, they should be read as “this Part of this British Standard”. A British Standard does not purport to include all the n

12、ecessary 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. Cross-references International standard Corresponding British Standard ISO 186:1977 BS3430:1980 M

13、ethod for sampling for testing paper and board (Identical) ISO 287:1978 BS3433:1980 Method for determination of moisture content of paper and board by the oven-drying method (Identical) ISO 638:1978 BS4502:1980 Method for determination of dry-matter content of pulps (Identical) ISO 6587:1980 a BS292

14、4 Aqueous extracts of paper, board and pulp Part 2:1983 Method for determination of conductivity (Identical) IEC 554-2:1977 BS5626 Cellulosic papers for electrical purposes Part 2:1979 Methods of test (Identical) a Since ISO 6587 has now been published, footnote 1) to clause 2 is no longer appropria

15、te. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 4, 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 theins

16、ide front cover.BS2924-1:1983 BSI 07-1999 1 1 Scope This International Standard specifies a method for the determination of the pH of an aqueous extract of paper, board or pulps. The pH value is not a quantitative measure of the total content of acid or base in the material extracted. 2 Field of app

17、lication This method is applicable to all kinds of paper, board and pulps yielding an extract having a conductivity exceeding0,2mS/m when determined in accordance with ISO6587, except for papers used for electrical purposes. For high purity papers used for electrical purposes, the method used should

18、 be that given in IEC Publication 554-2. 3 References ISO 186, Paper and board Sampling for testing. ISO 287, Paper and board Method for the determination of moisture content of paper (oven-drying method). ISO 638, Pulps Determination of dry matter content. ISO 6587, Paper, board and pulps Determina

19、tion of conductivity of aqueous extracts 1) . IEC Publication 554-2, Specification for cellulosic papers for electrical purposes Part 2: Methods of test. 4 Principle Extraction of a sample of2g for1h with 100ml of cold or boiling distilled water. Measurement of the pH of the extract at20to 25 C. 5 R

20、eagents 5.1 Distilled or deionized water Distilled or deionized water shall be used throughout the test. The conductivity of the water shall not exceed 0,1mS/m after boiling and cooling as specified in8.1.2. (See note2.) NOTE 1Usually both distillation and deionization are required. Unless great car

21、e is exercised when distilling, and with the materials employed in the condenser and subsequent surfaces with which the condensed vapour may come in contact, the distillate may not reach the required level of conductivity. If deionization is applied without distillation, there may be a buffering act

22、ion due to organic acids present, unless the deionization process includes the use of strongly basic ion-exchange material. NOTE 2When it is not possible to obtain water of the specified purity, water with a higher conductivity may be used, but the conductivity of the water used shall be stated in t

23、he test report. 5.2 Standard buffer solutions, having pH values such as4,0,6,9and9,2,commercially available or prepared as described in the annex. 6 Apparatus Ordinary laboratory apparatus and 6.1 Glassware of chemically resistant glass, flasks with ground glass joints, stoppers, beakers and water-c

24、ooled reflux condensers. All glassware shall be carefully rinsed with boiling distilled water (5.1) and allowed to dry before use. 6.2 Electric heater, adjustable to at least 200 W. 6.3 pH meter, fitted with glass and calomel or combined electrodes, capable of being read to at least0,05in pH. 6.4 Th

25、ermometer 7 Sampling and preparation of the sample 7.1 Sampling Sampling of paper and board shall be carried out in accordance with ISO186. Sampling of pulp shall be as representative as possible. 7.2 Preparation of sample Cut or tear the sample into pieces approximately5mm 5mm in size from portions

26、 that have not been touched by bare hands and ensuring that the sample is placed only on clean surfaces. Mix the pieces thoroughly. The sample shall not at any time be touched with the bare hands. Clean protective gloves shall be worn at all times to protect the sample and the pieces prepared from i

27、t. Store the prepared samples in clean covered containers. 7.3 Determination of dry matter content Determine the dry matter content in accordance with ISO287 for paper and board and ISO 638 for pulps. 8 Procedure 8.1 Preparation of aqueous extract 8.1.1 Weighing Weigh, to the nearest0,1g, exactly2g

28、(oven-dry basis) of the sample (7.2) into a flask of suitable size(6.1) and proceed as specified in 8.1.2 or 8.1.3. 1) At present at the stage of draft.BS2924-1:1983 2 BSI 07-1999 8.1.2 Hot extraction With a pipette, measure100ml of water (5.1) into a separate flask of similar size to that containin

29、g the pieces (6.1). Attach the reflux condenser (6.1) and heat the water to almost boiling. Remove the condenser, add the almost boiling water to the flask containing the pieces, attach the condenser to this flask, and boil gently for1h. Cool rapidly to20to 25 C with the condenser in place. Let the

30、fibres settle and then decant the extract into a small beaker (see6.1). Prepare the extract in duplicate. 8.1.3 Cold extraction With a pipette, measure100ml of water (5.1) into the flask (6.1) and add the pieces (8.1.1). Seal the flask with a ground glass stopper, and leave to stand for1h at20to 25

31、C. Shake the flask at least once during this time. Decant the extract into a small beaker (see6.1). 8.2 Determination of pH Calibrate the pH meter (6.3) with two buffer solutions (5.2) having pH values such that the pH of the extract is between the pH values of the buffer solutions. After calibratio

32、n, rinse the electrodes several times with water (5.1), and once in a small quantity of the extract (8.1.2 or 8.1.3). Check that the temperature of the extract is20to 25 C. Immerse the electrodes in the extract and measure the pH value. NOTEThe hot extract may be used in the determination of the con

33、ductivity in accordance with ISO6587, provided that the sample is drawn prior to the pH determination. During the measurement of the pH, potassium chloride will diffuse from the calomel electrode thus affecting the conductivity. Repeat the determination with the duplicate extract. 9 Expression of re

34、sults Express the pH to the nearest0,1unit as the mean of two determinations. The individual results should not differ by more than0,2;if they do, repeat the determination on two additional extracts, and report the mean and the range of all measurements. 10 Test report The test report shall include

35、the following particulars: a) all the indications necessary for complete identification of the sample; b) reference to this International Standard; c) the extraction procedure used (hot or cold); d) the results of the test; e) the conductivity of the water used, where this is greater than0,1mS/m; f)

36、 any unusual features observed in the course of the test; g) any operations not specified in this International Standard or in the International Standards to which reference is made, or regarded as optional, which might have affected the results; h) the number of determinations, if more than two.BS2

37、924-1:1983 BSI 07-1999 3 Annex A Preparation of standard buffer solutions All the reagents used shall be of recognized analytical reagent grade. The buffer solutions shall be renewed at least once a month. A.1 pH 4,0 Potassium hydrogen phthalate, 0,05mol/l solution. Dissolve10,21g of potassium hydro

38、gen phthalate (KHC 8 H 4 O 4 ) in distilled water in a 1 litre one-mark volumetric flask and dilute to the mark. The pH of this solution is4,00at 20 C and4,01at25 C. A.2 pH 6,9 Potassium dihydrogen orthophosphate and disodium hydrogen orthophosphate solution Dissolve3,39g of potassium dihydrogen ort

39、hophosphate (KH 2 PO 4 ) and3,54g of disodium hydrogen orthophosphate (Na 2 HPO 4 ) in distilled water in a 1 litre one-mark volumetric flask and dilute to the mark. The pH of this solution is6,87at 20 C and6,86at25 C. A.3 pH 9,2 Disodium tetraborate, 0,01mol/l solution. Dissolve3,80g of disodium te

40、traborate decahydrate (Na 2 B 4 O 7 .10 H 2 O) in distilled water in a 1 litre one-mark volumetric flask and dilute to the mark. The pH of this solution is9,23 at 20 C and 9,18 at25 C.4 blankBS2924-1:1983 BSI 07-1999 Publications referred to See national foreword.BS 2924-1: 1983 ISO 6588:1981 BSI 38

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