1、BRITISH STANDARD BS7427:1991 ISO5647:1990 Method for Determination of titanium dioxide content of paper and boardBS7427:1991 This BritishStandard, having been prepared under the directionof the Paper and PrintingStandards Policy Committee, was published underthe authority of the Standards Board and
2、comesintoeffect on 28February1991 BSI01-2000 The following BSI references relate to the work on this standard: Committee reference PAM/11 Draft for comment89/38424 DC ISBN 0 580 19444 2 Committees responsible for this BritishStandard The preparation of this BritishStandard was entrusted by the Paper
3、 and Printing Standards Policy Committee (PAM/-) to Technical Committee PAM/11, upon which the following bodies were represented: British Fibreboard Packaging Association British Paper and Board Industry Federation (PIF) British Printing Industries Federation British Telecommunications plc Envelope
4、Makers and Manufacturing Stationers Association Her Majestys Stationery Office Man-made Fibres Producers Committee Ministry of Defence Pira (the Research Association for the Paper and Board, Printing and Packaging Industries) Post Office Society of British Printing Ink Manufacturers University of Ma
5、nchester Institute of Science and Technology Amendments issued since publication Amd. No. Date CommentsBS7427:1991 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Definition 1 4 Principle 1 5 Reagents 1 6 Apparatus 1 7 S
6、election of the sample 2 8 Preparation of ash solution 2 9 Reagent blank solution 2 10 Spectrophotometric procedure 2 11 Flame atomic absorption spectrophotometric procedure 3 12 Expression of results 3 13 Test report 4 Table 1 Set of calibrating solutions 2 Table 2 Set of calibrating solutions 3 Pu
7、blication(s) referred to Inside back coverBS7427:1991 ii BSI 01-2000 National foreword This BritishStandard has been prepared under the direction of the Paper and Printing Standards Policy Committee. It is identical with ISO5647 “Paper and board Determination of titanium dioxide content”, published
8、by the International Organization for Standardization (ISO). 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
9、 legal obligations. Cross-references International Standard Corresponding BritishStandard ISO186:1985 BS3430:1986 Method for sampling to determine the average quality of paper and board (Identical) ISO287:1985 BS3433:1986 Method for determination of moisture content of paper and board by the oven-dr
10、ying method (Identical) ISO2144:1987 BS3631:1984 Method for determination of ash of paper and board (Technically equivalent) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This standard has been updated
11、(see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS7427:1991 BSI 01-2000 1 WARNING The method specified in this International Standard involves the use of some hazardous chemicals and of gases that can form explosi
12、ve mixtures with air. Care shall be taken to ensure that the relevant safety precautions are observed. 1 Scope This International Standard specifies a method for determining titanium dioxide content in all kinds of paper and board, in particular coated or filled products. It comprises two procedures
13、 for the final determination of titanium, one of them relying on spectrophotometry and the other on flame atomic absorption spectrophotometry. The limits of the determination depend on the amount of sample taken(8.1). NOTE 1The method is designed for the determination of titanium dioxide. Titanium p
14、resent in other forms, for example as a constituent of clay, will not interfere in the determination. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the edition
15、s indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently va
16、lid International Standards. ISO186:1985, Paper and board Sampling to determine average quality. ISO287:1985, Paper and board Determination of moisture content Oven-drying method. ISO2144:1987, Paper and board Determination of ash. 3 Definition For the purposes of this International Standard, the fo
17、llowing definition applies. titanium dioxide content the titanium dioxide content of paper or board (expressed on an oven-dry basis), determined after ashing the sample and dissolving the ash by the method specified in this International Standard 4 Principle Titanium dioxide is determined by ashing
18、the sample and dissolution of the ash in sulfuric acid and ammonium sulfate. Determination of the titanium by spectrophotometry, applying hydrogen peroxide, or by flame atomic absorption spectrophotometry, adding potassium chloride. 5 Reagents During the analysis, unless otherwise stated, use only r
19、eagents of recognized analytical grade and only distilled water or water of equivalent purity(5.1). 5.1 Distilled water or deionized water, conductivity less than1mS/m. 5.2 Sulfuric acid, (H 2 SO 4 ), density1,84g/ml. 5.3 Ammonium sulfate, (NH 4 ) 2 SO 4 5.4 Diluted sulfuric acid In a beaker with ab
20、out500ml of water(5.1) add carefully100ml of sulfuric acid(5.2) and40g of ammonium sulfate(5.3). Dilute to1litre with water(5.1). 5.5 Standard titanium dioxide solution,500mg of TiO 2 per litre. Weigh0,500g of titanium dioxide (TiO 2 ) in a500ml beaker, add40,0g of ammonium sulfate(5.3) and100ml of
21、sulfuric acid(5.2). In a fume hood, gradually heat the mixture to boiling and then boil for5min to10min. Cover the beaker and allow the solution to cool to room temperature and, while stirring, pour it carefully into a larger beaker containing about300ml of water(5.1). When the solution has reached
22、room temperature decant it quantitatively into a1000ml volumetric flask. Rinse both beakers with water and add the rinsings to the volumetric flask. Make up to the mark with water(5.1). 5.6 Hydrogen peroxide, solution containing30g of H 2 O 2 per litre. (This solution is only required for the spectr
23、ophotometric procedure.) 5.7 Potassium chloride, solution containing20g of KClper litre. (This solution is only required for the flame atomic absorption spectrophotometric procedure.) 5.8 Hydrochloric acid (HCl), solution6mol/l. 6 Apparatus In addition to the usual laboratory apparatus the following
24、 are required. 6.1 Dishes, of platinum or quartz. Wash the platinum dishes thoroughly and remove any traces of impurities by cleaning with fine sand. Soak and boil the dishes in the6mol/l hydrochloric acid solution(5.8). Avoid contact with metals other than platinum. Wash the quartz dishes thoroughl
25、y and soak and boil them in the6mol/l hydrochloric acid solution(5.8).BS7427:1991 2 BSI 01-2000 6.2 Spectrophotometer or filter photometer, for determining absorbance at410nm. It shall have10mm cells provided with lids. (This apparatus is only required for the spectrophotometric procedure.) 6.3 Atom
26、ic absorption spectrophotometer, fitted with an acetylene and dinitrogen monoxide burner and a titanium hollow-cathode lamp. (This apparatus is only required for the flame atomic absorption spectrophotometric procedure.) 7 Selection of the sample Select a representative sample in accordance with ISO
27、186. Tear the air-dry sample into pieces of suitable size. Use protective cotton gloves. Do not use cut or punched edges or other parts where metallic contamination may have occurred. 8 Preparation of ash solution 8.1 Carry out the determination in duplicate. Weigh, to the nearest0,01g, two test por
28、tions of about10g of paper or board and place each test portion in a clean dish(6.1). Determine the moisture content of a separate test sample as prescribed in ISO287. NOTE 2Select the amount of sample to be ashed, taking into account the anticipated titanium dioxide content. If a10g portion is ashe
29、d, the optimum range of the titanium dioxide content is from1,5g/kg to8g/kg (spectrophotometric procedure) or from0,8g/kg to3,2g/kg (flame atomic absorption spectrophotometric procedure). 8.2 Ash the test portion as described in ISO2144. Allow the dish to cool in a desiccator. If the ash content of
30、the sample is of interest, weigh the dish with its contents and calculate the amount of ash obtained. 8.3 Transfer the ash to a250ml glass beaker. Add4g of ammonium sulfate(5.3) and10ml of the sulfuric acid(5.2). Mix well and cover the beaker with a watch glass. Heat in a fume hood until fumes of su
31、lfur trioxide are evolved, and continue heating for30min. Allow the solution to cool to room temperature and then carefully add it, drop by drop, to about50ml of water contained in another beaker. Allow the solution to cool and decant it into a100ml volumetric flask. Rinse both beakers with water an
32、d add the rinsings to the flask. Finally, make up to the mark with water, and mix well. 9 Reagent blank solution Prepare a reagent blank solution, using4g of ammonium sulfate(5.3) and10ml of sulfuric acid(5.2) in a glass beaker, as described in8.3. 10 Spectrophotometric procedure 10.1 Preparation of
33、 the calibration graph Into one of a series of six50ml volumetric flasks, place25,0ml of the reagent blank solution (clause9). Into the remaining five50ml volumetric flasks, transfer the quantities of the standard titanium dioxide solution(5.5), shown in Table 1. To each flask, add7,5ml of the hydro
34、gen peroxide solution(5.6), and make up to the mark with the diluted sulfuric acid(5.4), and mix well. Table 1 Set of calibrating solutions For each solution, measure within1h of the preparation, the absorbance at410nm using10mm cells. Use the diluted sulfuric acid(5.4) in the reference cell. Constr
35、uct a calibration graph by plotting the absorbance readings against the corresponding titanium dioxide concentrations. 10.2 Preparation of the test solutions If the ash solution(8.3) contains undissolved matter, filter it through a hardened ashless filter. Do not wash the filter. With a pipette, tra
36、nsfer25,0ml of the filtrate to a50ml volumetric flask. Add15ml of diluted sulfuric acid(5.4) and7,5ml of the hydrogen peroxide solution(5.6). Make up to the mark with the diluted sulfuric acid(5.4) and mix well. 10.3 Spectrophotometric determination If the test solution(10.2) is turbid or coloured,
37、prepare a reference solution by transferring25ml of the filtrate to a50ml volumetric flask and making it up to the mark with diluted sulfuric acid(5.4). If the test solution is clear and colourless, use the diluted sulfuric acid(5.4) in the reference cell. Within1h, measure the absorbance at410nm in
38、10mm cells. Subtract the value obtained for the reagent blank (clause9) and read the titanium dioxide concentration from the calibration graph. Proceed to clause12. Standard titanium dioxide solution(5.5) ml Corresponding mass of TiO 2 mg/l Reagent blank (clause9) 5,0 10,0 15,0 20,0 25,0 0 50,0 100,
39、0 150,0 200,0 250,0BS7427:1991 BSI 01-2000 3 11 Flame atomic absorption spectrophotometric procedure 11.1 Preparation of the calibration graph 11.1.1 Preparation of the calibration solution Into one of a series of five50ml volumetric flasks, place25,0ml of the reagent blank solution (clause9) and ad
40、d2,5ml of the potassium chloride solution(5.7). Into the remaining four50ml volumetric flasks, transfer2,5ml of the potassium chloride solution(5.7) and add the quantities of the standard titanium dioxide solution(5.5) shown in Table 2. For each flask, make up to the mark with the diluted sulfuric a
41、cid(5.4), and mix well. Table 2 Set of calibrating solutions 11.1.2 Adjustment of apparatus Prepare the spectrophotometer for titanium measurement according to the manufacturers instructions using a wavelength of364,3nm. CAUTION To avoid explosion, it is necessary to light the burner with a mixture
42、of air-acetylene before switching to acetylene-dinitrogen monoxide. 11.1.3 Reagent blank determination Carry out a reagent blank determination (Table 2, term0) following the same mode of operation and utilizing the same quantities of reagent specified in11.1.1, but omitting the standard titanium sol
43、ution(5.5). Aspirate this solution into the flame, and adjust the instrument to zero absorbance against the reagent blank test solution. 11.1.4 Spectrophotometric measurement Aspirate the series of titanium calibration solutions(11.1.1) in succession into the flame and measure the absorbance for eac
44、h. Take care to keep the aspiration rate constant throughout the preparation of the calibration graph. Spray water through the burner after each measurement. 11.1.5 Plotting the calibration graph Plot a graph taking as abscissae the titanium dioxide concentrations, expressed in milligrams per litre,
45、 and, as ordinates, the corresponding values for the measured absorbance. NOTE 3If an instrument is used equipped with a system for automatic calculation of data, the instructions in the paragraph above may be disregarded. 11.2 Determination 11.2.1 Preparation of test solution Prepare the test solut
46、ion using the ash solution(8.3). If the solution contains suspended matter, allow this to settle. Transfer with a pipette25,0ml of the solution to a50ml volumetric flask. Add2,5ml of the potassium chloride solution(5.7), make up to the mark with diluted sulfuric acid(5.4) and mix well. 11.2.2 Spectr
47、ophotometric measurement Carry out the spectrophotometric measurement on the test solution prepared in11.2.1 as specified in11.1.4 after having adjusted the instrument to zero absorbance against the reagent blank test solution(11.1.3). Read the amount of titanium dioxide from the calibration graph.
48、NOTE 4If the readings obtained for the test solution exceed the range of the calibration solutions, an appropriate dilution of the test solution should be made using the diluted sulfuric acid(5.4). Add an appropriate volume of the potassium chloride solution(5.7) to keep the potassium concentration
49、at the same level as in the calibration solutions. 12 Expression of results Calculate the titanium dioxide w(TiO 2 ), expressed in grams per kilogram of an oven-dry sample using the following equation Standard titanium dioxide solution(5.5) ml Corresponding concentration of TiO 2mg/l Reagent blank (clause9) 5,0 10,0 15,0 20,0 0 50,0 100,0 150,0 200,0 where (TiO 2 ) is the titanium dioxide concentration, in milligrams per litre, of the test solution(10.2 for the spectrophotometric procedure, or11.2.1 for the flame absorption procedure), read from the
