1、BRITISH STANDARD BS 3903:1977 Incorporating Amendment No. 1 Methods of test for Sulphuric acid, oleum and liquid sulphur trioxide UDC 661.25:546.226325:543BS 3903:1977 This British Standard, having been prepared under the directionof the Chemical Standards Committee, was published under the authorit
2、yofthe Executive Boardon 29 April 1977 BSI 08-1999 First published July 1965 First revision April 1977 The following BSI references relate to the work on this standard: Committee reference CIC/20 Draft for comment 74/51098 DC ISBN 0 580 09228 3 Cooperating organizations The Chemical Standards Commit
3、tee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Association of Fatty Acid Distillers Chemical Industries Association* Chemical Society Analytical Division Department of
4、 Health and Social Security Department of Industry Department of Industry Laboratory of the Government Chemist Fertilizer Manufacturers Association Ltd Ministry of Agriculture, Fisheries and Food National Sulphuric Acid Association* Royal Institute of Public Health and Hygiene Soap and Detergent Ind
5、ustry Association* Society for Analytical Chemistry The organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: British Textile Employers Association Amendments issued si
6、nce publication Amd. No. Date of issue Comments 2529 April 1978 Indicated by a sideline in the marginBS 3903:1977 BSI 08-1999 i Contents Page Cooperating organizations Inside front cover Foreword ii Section 1. General 1 Scope 1 2 References 1 Section 2. Methods of test for acids containing up to 100
7、 % of H 2 SO 4 3 Determination of sulphuric acid content 1 4 Determination of residue on heating 1 5 Determination of sulphur dioxide content 2 6 Determination of arsenic content 4 7 Determination of ammoniacal nitrogen content 4 8 Determination of nitrogen oxides content 8 9 Determination of chlori
8、de content 11 10 Determination of iron and lead contents by atomic absorption spectroscopy 14 11 Determination of iron content 15 12 Determination of lead content 17 Section 3. Methods of test for oleums and liquid sulphur trioxide 13 Sampling of oleums 20 14 Dilution of oleums and liquid sulphur tr
9、ioxide for analysis 21 15 Determination of residue on heating of oleums and liquid sulphur trioxide 23 16 Determination of total acidity and calculation of free sulphur trioxide content of oleums 23 Figure 1 Apparatus for determination of sulphur dioxide content 3 Figure 2 Apparatus for determinatio
10、n of ammoniacal nitrogen content 6 Figure 3 Distillation apparatus for determination of nitrogen oxides content 9 Figure 4 Apparatus for use in determination of chloride content 12 Figure 5 Sampling cage: sampling of oleums 21 Figure 6 Dilution apparatus for oleums and liquid sulphur trioxide 22 Tab
11、le 1 Selection of reagent solutions and test portion 12 Table 2 Worked example of the calibration of silver nitrate solution 13 Publications referred to Inside back coverBS 3903:1977 ii BSI 08-1999 Foreword This British Standard has been prepared under the authority of the Chemical Standards Committ
12、ee and includes methods of test for sulphuric acid, oleums and liquid sulphur trioxide of commercial quality and intended for general industrial purposes. The standard, first published in 1965, has been revised in the light of current requirements. Where possible, methods adopted by the Internationa
13、l Organization for Standardization (ISO) have been used and the situation in this respect is summarized as tabulated opposite. This revision also differs from the 1965 publication in the following respects. a) Methods for the determination of density and temperature rise are omitted following the de
14、cision that only the titrimetric method for the determination of sulphuric acid content should be used for referee purposes. b) The methods for the determination of copper and aluminium contents, which are seldom used, are omitted. c) In accordance with current practice, alternative methods for the
15、determination of iron and lead contents by atomic absorption spectrophotometry are included. The original methods in the1965 publication are, however, retained and have undergone no significant change in the course of the revision. WARNING. Concentrated sulphuric acid, oleum and sulphur trioxide are
16、 extremely corrosive and poisonous and should be used with all necessary precautions. Protective clothing, including goggles and gloves, should be worn at all times when handling these materials. A British Standard does not purport to include all the necessary provisions of a contract. Users of Brit
17、ish Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Determination Relationship to ISO method of test Residue on heating Heating temperature is identical with that used in ISO/R913 Sulphur dioxide c
18、ontent Conforms to the method specified in ISO3423 amended to incorporate comments made by the United Kingdom during its development Arsenic content Conforms to the method specified in ISO2590 Ammoniacal nitrogen content Conforms to the method specified in ISO2899 Nitrogen oxides content Conforms to
19、 the method specified in ISO2363 Chloride content Conforms to the method specified in ISO2877 Iron content (spectrophotometricmethod) Is similar in principle to the method specified in ISO/R915 Lead content (spectrophotometricmethod) Conforms to the method specified in ISO2717 Summary of pages This
20、document comprises a front cover, an inside front cover, pages i andii, pages1 to24, 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.BS 3903:19
21、77 BSI 08-1999 1 Section 1. General 1 Scope This British Standard specifies methods of test for commercial sulphuric acid, oleum and liquid sulpur trioxide. Section2 covers tests for acids containing up to100% of H 2SO 4 . Section3 describes methods of test for oleums and liquid sulphur trioxide and
22、 includes a method for their dilution prior to analysis by the methods specified in section2, clauses5 to9. 2 References The titles of the publications referred to in this standard are listed on the inside back cover. Section 2. Methods of test for acids containing up to 100% of H 2 SO 4 3 Determina
23、tion of sulphuric acid content NOTEThis method differs from that specified in ISO/R910 which was disapproved for technical reasons by the United Kingdom. 3.1 Principle. A weighed quantity of the sample is diluted with water and titrated directly with standard volumetric sodium hydroxide solution usi
24、ng screened methyl orange as indicator. 3.2 Reagents. The reagents used shall be of a recognized analytical quality. Water complying with the requirements of BS3978 shall be used throughout. 3.2.1 Sodium hydroxide, N standard volumetric solution. 3.2.2 Screened methyl orange indicator solution, 1g/l
25、, prepared as described in BS4123. 3.3 Apparatus. Ordinary laboratory apparatus and the following are required. 3.3.1 Lunge-Rey pipette, complying with the requirements of BS2058. 3.3.2 Bulb burette, 105ml nominal capacity, complying with the requirements of BS846, having a bulb capacity of80ml and
26、a scale range from80ml to105ml with0.05ml subdivisions. 3.4 Procedure. By means of the Lunge-Rey pipette (3.3.1), transfer a quantity of sample equivalent to4.5g to5g of100% sulphuric acid, weighed to the nearest1mg, to a400ml conical beaker already containing50ml of water. Add a few drops of the sc
27、reened methyl orange indicator solution (3.2.2) and titrate with the N sodium hydroxide solution (3.2.1), contained in the bulb burette (3.3.2), until the first appearance of a green tint. 3.5 Expression of results. Sulphuric acid content, expressed as a percentage by mass of H 2 SO 4 , is given by
28、the formula: where 4 Determination of residue on heating NOTEThis method uses the heating temperature specified in ISO/R913. 4.1 Field of application. The method is applicable to samples in which the residue on heating is equal to or greater than5mg/kg. 4.2 Principle. The sample is evaporated and th
29、e residue is heated at800 50 C. 4.3 Apparatus. Ordinary laboratory apparatus and the following are required. 4.3.1 Platinum basin, flat bottom, capacity about100ml. 4.3.2 Muffle furnace, capable of being controlled at800 50 C. V is the volume of N sodium hydroxide solution used (in ml) M is the mass
30、 of the test portion (in g) 4.904V M -BS 3903:1977 2 BSI 08-1999 4.3.3 Desiccator 4.4 Procedure. Heat the platinum basin (4.3.1) in the muffle furnace (4.3.2) controlled at800 50 C. Cool in the desiccator (4.3.3) and weigh to the nearest0,1mg. Transfer to the basin approximately50g of sample weighed
31、 to the nearest0.01g. Evaporate the acid carefully on a sand bath inside a fume cupboard and heat the basin containing the residue to dryness. Transfer the basin containing the residue to the muffle furnace controlled at800 50 C and heat for about15min. Remove the basin from the furnace, place in a
32、desiccator, cool and weigh to the nearest0.1mg. Repeat the operations of heating, cooling and weighing until the difference between successive weighings does not exceed0.5mg. 4.5 Expression of results. The residue on heating, expressed as milligrams per kilogram, is given by the formula: where 5 Det
33、ermination of sulphur dioxide content NOTEThis method conforms to that specified in ISO3423 as amended to incorporate the comments made by the UnitedKingdom during its development. 5.1 Field of application. The method is applicable to products with sulphur dioxide content equal to or greater than2mg
34、/kg. 5.2 Principle. Sulphur dioxide is removed from the sample by means of a current of nitrogen and absorbed into a known volume of iodine solution. The excess iodine is titrated against standard volumetric sodium thiosulphate solution. 5.3 Reagents. The reagents used shall be of a recognized analy
35、tical quality. Water complying with the requirements of BS3978 shall be used throughout. 5.3.1 Hydrazinium sulphate 5.3.2 Iodine, approximately 0.1N, 0.05N or 0.01N solution, as required (see5.5.3). Prepare this solution at the time of use. 5.3.3 Sodium thiosulphate, 0.1N, 0.05N or 0.01N standard vo
36、lumetric solution, as required (see5.5.4). Prepare this solution at the time of use. 5.3.4 Starch, 5g/l solution. 5.3.5 Nitrogen, pure, containing less than0.001% of oxygen. It is recommended that the reduction valve from the nitrogen cylinder be connected to a gas-washing bottle containing a150g/l
37、solution of titanium (III) chloride. 5.3.6 Crushed ice, prepared from water complying with the requirements of BS3978. 5.4 Apparatus. Ordinary laboratory apparatus and the following are required. 5.4.1 Glass apparatus, with ground glass joints, as shown inFigure 1, comprising the following: a) 3-nec
38、ked flask (A), 500ml or250ml capacity; b) cylindrical dropping funnel (B) fitting into one of the two side-necks of the flask; c) tube, fitted with a stopcock (C), fitting into the central neck of the flask and terminating in a fritted disc at a level of about10mm above the bottom of the flask; d) t
39、hree gas-washing bottles (D 1 ), (D 2 ), (D 3 ), Dreschel type,100ml or125ml capacity, with the inlet tubes terminating in fritted discs complying with the requirements of BS1752 (grade no.4, pore diameter54m to154m) to disperse the gas. NOTEThe corresponding ISO method uses fritted discs of grade P
40、16, pore diameter44m to164m. 5.4.2 Glass flask, with a ground glass stopper. 5.4.3 Flowmeter or bubble-counter, for use in the range5l/h to50l/h. M 1 is the mass of the residue (in g) M 2 is the mass of the test portion (in g) M 1 10 6 M 2 -BS 3903:1977 BSI 08-1999 3 5.5 Procedure 5.5.1 Test portion
41、. Fill the flask (5.4.2) with the test sample and take, weighing by difference to the nearest0.05g, a test portion of approximately200g. If the density of the sample exceeds1.70g/ml, slowly pour the test portion, cooling so that the temperature remains below10 C, onto sufficient of the crushed ice (
42、5.3.6) to give a solution of density approximately1.70g/ml. 5.5.2 Blank test. At the same time as the determination, carry out a blank test following the same procedure and using the same quantities of all reagents as used in the determination. 5.5.3 Preparation of the apparatus. Place50ml of the ap
43、propriate iodine solution (5.3.2) in the first gas-washing bottle (D 1 ). Divide25ml of the corresponding standard volumetric sodium thiosulphate solution(5.3.3) between the second and third gas-washing bottles (D 2 , D 3 ), if necessary adding a little water to ensure sufficient scrubbing of the ga
44、s. NOTEThe two bottles (D 2 ) and (D 3 ) are intended to retain any entrained iodine. Place the bottle (D 1 ) in a cooling bath and ensure that during all subsequent operations the temperature of its contents does not rise above10 C and that the bottle is not exposed to a bright light. If the sample
45、 contains nitrite or nitrate ions, place an excess of the hydrazinium sulphate solution(5.3.1)inthe flask (A) in relation to the nitrite and nitrate contents in the test portion. Connect up the apparatus (5.4.1) and displace the air by means of a rapid current of the nitrogen (5.3.5). 5.5.4 Determin
46、ation. Run the test portion (5.5.1) into the flask (A) through the dropping funnel (B) and pass a current of the nitrogen (5.3.5) at a rate, measured by the flowmeter or bubble-counter (5.4.3), of about20l/h for3h. At the end of this time there should still be an excess of iodine in the gas-washing
47、bottle (D 1 ). Figure 1 Apparatus for determination of sulphur dioxide content Expected sulphur dioxide content Strength of iodine solution mg/kg N (approximate) 2 to 30 0.01 30 to 150 0.05 150 0.1BS 3903:1977 4 BSI 08-1999 Disconnect the three gas-washing bottles (D 1 ), (D 2 ) and (D 3 ) and trans
48、fer their contents quantitatively into a beaker. Rinse the bottles with a few millilitres of water, collecting the washings in the beaker. Titrate the excess of iodine with the appropriate standard volumetric sodium thiosulphate solution (5.3.3) in the presence of the starch solution (5.3.4). 5.6 Ex
49、pression of results. The sulphur dioxide content, expressed as milligrams of sulphur dioxide (SO 2 ) per kilogram, is given by the formula: where 6 Determination of arsenic content NOTEThis method conforms to that specified in ISO2590, which corresponds to BS4404. 6.1 Field of application. The method is applicable to the determination of arsenic in the range1mg to10mg of arsenic per kilogram. 6.2 Principle. The arsenic in the sample is reduced with zinc, the arsine evolved is absorbed in a solut
