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1、BRITISH STANDARD CONFIRMED FEBRUARY 1990 BS 6068-2.17: 1986 Water quality Part 2: Physical, chemical and biochemical methods Section 2.17 Methods for determination of total cyanide UDC 556.11 + 614.777 + 628.1/.3 + 663.63:53/54 Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:28:11 GMT+00:0
2、0 2006, Uncontrolled Copy, (c) BSI BS 6068-2.17:1986 This British Standard, having been prepared under the direction of the Environment and Pollution Standards Committee, was published under the authority of the Board of BSI and comes into effect on 28 February 1986 BSI 06-1999 The following BSI ref
3、erences relate to the work on this standard: Committee reference EPC/44 Draft for comment 82/56061 DC ISBN 0580 14987 0 Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:28:11 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6068
4、-2.17:1986 BSI 06-1999i Contents Page Forewordii 0Introduction1 1Scope and field of application1 2Definition2 Subsection 1. Liberation and absorption of hydrogen cyanide 3Principle3 4Reagents3 5Apparatus3 6Sampling and samples3 7Procedure5 Subsection 2. Determination of cyanide ions Photometric meth
5、od with pyridine/barbituric acid 8Applicability6 9Principle6 10Reagents6 11Apparatus6 12Procedure6 13Expression of results7 14Precision7 15Test report7 Subsection 3. Determination of cyanide ions Titrimetric method using the Tyndall effect 16Applicability8 17Principle and reactions8 18Reagents8 19Ap
6、paratus8 20Procedure8 21Expression of results9 22Precision9 23Test report9 Subsection 4. Determination of cyanide ions Titrimetric method using an indicator 24Applicability11 25Principle11 26Reagents11 27Apparatus11 28Procedure11 29Expression of results11 30Test report11 Bibliography13 Figure 1 Appa
7、ratus for separation of hydrogen cyanide by stripping4 Figure 2 Apparatus for determination of cyanide ions using Tyndall effect9 Table 1 Interferences2 Table 2 Precision data (photometric method)7 Table 3 Precision data (titrimetric method)10 Publications referred toInside back cover Licensed Copy:
8、 sheffieldun sheffieldun, na, Tue Dec 05 01:28:11 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6068-2.17:1986 ii BSI 06-1999 Foreword This Section of this British Standard, which has been prepared under the direction of the Environment and Pollution Standards Committee, is based on ISO 6703/1-1984
9、“Water quality Determination of cyanide Part 1: Determination of total cyanide” but is not equivalent in technical content. ISO 6703/1 was prepared by subcommittee 2, Physical, chemical and biochemical methods, of Technical Committee 147, Water quality, of the International Organization for Standard
10、ization (ISO) as a result of discussion in which the UK participated. For ease of publication, the text of ISO 6703/1 has been used as a basis for this Section of this British Standard and a number of amendments have been incorporated. The principal changes now incorporated are that the text has bee
11、n amplified, to improve clarity and avoid misunderstandings in the following clauses: 1, 8, 12.2, 13, 16, 20, 21, 24, and 29. Clause 8 now allows the use of smaller test portions in addition to dilution of absorption solutions with the sodium hydroxide solution. This British Standard is being publis
12、hed in a series of Parts subdivided into Sections that will generally correspond to particular international standards. Sections are being, or will be, published in Parts 1 to 6, which, together with Part 0, are listed below. Part 0: Introduction; Part 1: Glossary; Part 2: Physical, chemical and bio
13、chemical methods; Part 3: Radiological methods; Part 4: Microbiological methods; Part 5: Biological methods; Part 6: Sampling. Terminology and conventions. As a result of using the ISO text some terminology and certain conventions are not identical with those used in British Standards; attention is
14、drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. In British Standards it is current practice to use the symbol “L” for litre (and its submultiples) rather than “I” an
15、d to use the spelling “sulphur” etc., instead of “sulfur”, etc. Additional information. If a high intensity beam of light is passed through a colloidal solution and the solution viewed at a right angle to the incident light, a scattering of light is observed. This is known as the Tyndall effect. A B
16、ritish 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 This document comprises a f
17、ront cover, an inside front cover, pages i and ii, pages 1 to 12, 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. Licensed Copy: sheffieldun s
18、heffieldun, na, Tue Dec 05 01:28:11 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6068-2.17:1986 BSI 06-19991 Attention is drawn to the toxicity of cyanide and to the need to take extreme care when handling cyanides and their solutions. Carry out all operations in a fume cupboard. Avoid contact with
19、 the skin and eyes. When pipetting, always use a safety pipette (pipette by bulb). Detoxify samples and solutions containing cyanides or heavy metals in accordance with local official regulations. Other chemicals specified in this Section of this British Standard are also hazardous, for example pyri
20、dine. 0 Introduction Cyanides may be present in water as hydrocyanic acid (prussic acid), as cyanide ions and as complex cyanides. They may be determined as total cyanide or as easily liberatable cyanide, if cyanide compounds are chlorinated, cyanogen chloride (ClCN) is produced, and this compound h
21、as to be determined separately. There are four Sections in BS 6068 for the determination of cyanides in water as follows: BS 6068:2.17:1986, Methods for determination of total cyanide. BS 6068:2.18:1986, Methods for determination of easily liberatable cyanide. BS 6068:2.19:1986, Method for determina
22、tion of cyanogen chloride. BS 6068:2.20:1986, Method for determination of cyanide by diffusion at pH 6. The methods described in Sections 2.17, 2.18 and 2.19 are suitable for controlling the quality of water and for the examination of municipal sewage and industrial effluents. They are appropriate t
23、o the technology available for the destruction of cyanides in treatment plants, and are based on the separation of liberated hydrogen cyanide (or in the case of BS 6068-2.19, of cyanogen chloride) by stripping with a carrier gas. The method specified in BS 6068-2.20, using diffusion separation, is s
24、uitable for the determination of smaller amounts of cyanide, depending on the concentrations of copper and nickel. This Section of this British Standard comprises four subsections. Subsection 1 deals with the liberation and absorption of hydrogen cyanide. The other three subsections deal with altern
25、ative methods for the quantitative determination of cyanide ions, as follows: photometric method with pyridine/barbituric acid (subsection 2); titrimetric method using the Tyndall effect (subsection 3); titrimetric method using an indicator (subsection 4). The specification of three alternative meth
26、ods is necessary because each of the methods has its advantages and disadvantages. None can be quoted as applicable in all cases. The applicability of each method is described in clauses 8, 16 and 24. NOTEDue to the different chemical behaviour of cyanide-containing or cyanide-producing substances,
27、it is not possible to specify only one method for the quantitative determination of cyanide ions. 1 Scope and field of application This Section of this British Standard specifies three methods for the determination of total cyanide (see clause 2) in water. The methods are applicable to water contain
28、ing less than 100 mg of cyanide per litre, but higher concentrations may be determined by suitable dilution of the sample. The methods and corresponding ranges of cyanide contents for which they are suitable are as follows: Photometric method with pyridine/barbituric acid: applicable when the absorp
29、tion solution contains 0,002 to 0,025 mg of cyanide, corresponding to 0,02 to 0,25 mg/l in a 100 ml aliquot portion of the undiluted sample; Titrimetric method using the Tyndall effect: applicable when the absorption solution contains 0,005 mg of cyanide, corresponding to 0,05 mg/l in a 100 ml aliqu
30、ot portion of the undiluted sample; Titrimetric method using an indicator, applicable when the absorption solution contains 0,05 mg of cyanide, corresponding to 0,5 mg/l in a 100 ml aliquot portion of the undiluted sample. A large number of ions and compounds interfere with the determination. These
31、are listed in the Table 1, together with the concentrations below which they do not interfere (the list is not exhaustive). If present singly or in combination, up to the limiting concentrations, they do not interfere with the separation of hydrogen cyanide. The presence of aldehydes, e.g. formaldeh
32、yde, causes low cyanide values because of the formation of cyanohydrin. If any of the limiting concentrations of the interferences is likely to be exceeded, the sample shall be diluted with distilled water before stabilization (see clause 6). Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01
33、:28:11 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6068-2.17:1986 2 BSI 06-1999 Other interference may arise from the presence of fatty acids, which will distil and form soaps during titration of alkaline solution, and from the presence of elementary sulfur. 2 Definition For the purpose of this Se
34、ction of this British Standard the following definition applies. total cyanide simple and complex bound cyanides including organic compounds containing cyanogen groups forming hydrogen cyanide under the conditions of this method. Cyanohydrins are detected in part. CN-groups of compounds defined as s
35、uch may partly or completely form cyanide ions or hydrocyanic acid respectively in water. Mononitriles (R-CN), cyanate and thiocyanate ions and cyanogen chloride are not included Table 1 Interferences Interference Limiting concentration, mg/l Sulfide ions Polysulfide ions Sulfide and polysulfide ion
36、s Sulfide ions Thiosulfate ions Thiocyanate ions Carbonate ions Cyanate ions Nitrate ions Nitrite ions Ammonium ions iron (II) and iron (III) ions Silver ions Mercury ions Chromate ions Propionic acid Phenol Anthracene Naphthalene Anisaldehyde Piperonal Pyrrole Pyridine Chlorine (elemental) Hydrogen
37、 peroxide Perborate ions 1 000 500 1 000 500 1 000 1 000 1 000 1 000 500 500 2 000 5 000 50 50 300 1 000 1 000 100 100 10 10 100 10 250 10 10 Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:28:11 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6068-2.17:1986 BSI 06-19983 Subsection 1. Libera
38、tion and absorption of hydrogen cyanide 3 Principle Heating the sample with hydrochloric acid in the presence of copper(I) ions. Entrainment of the liberated hydrogen cyanide in a current of air into an absorption vessel containing sodium hydroxide solution. NOTE 1Complex cobalt cyanides will not be
39、 determined quantitatively, because, according to their concentrations, they are decomposed to the extent of between 5 and 15 % only, this also applies to some organocyanide compounds. NOTE 2The effect of the specified digestion procedure on cyanohydrine is not fully characterized. 4 Reagents All re
40、agents shall be of recognized analytical grade and the water used shall be distilled or deionized water. 4.1 Hydrochloric acid, solution, A 1,12 g/ml. 4.2 Hydrochloric acid, solution, c(HCl) = 1 mol/l. 4.3 Sodium hydroxide, solution, c(NaOH) = 1 mol/l. 4.4 Sodium hydroxide, solution, c(NaOH) = 5 mol
41、/l. 4.5 Tin(II) chloride, solution1) Dissolve 50 g of tin(II) chloride dihydrate (SnCl2.2H2O) in 40 ml of the hydrochloric acid solution (4.2) and dilute with water to 100 ml. Prepare a fresh solution each week. 4.6 Phenolphthalein, solution, containing chloroform. Dissolve 0,03 g of phenolphthalein
42、 in 90 ml of ethanol and add 10 ml of chloroform. 4.7 Zinc- and cadmium sulfate, solution.1) Dissolve 100 g of zinc sulfate heptahydrate (ZnSO4.7H2O) and 100 g of cadmium sulfate octahydrate (3Cd SO4.8H2O) in water and dilute with water to 1 000 ml. 4.8 Copper(II) sulfate, solution. Dissolve 200 g o
43、f copper(II) sulfate pentahydrate (CuSO4.5H2O) in water and dilute with water to 1 000 ml. 4.9 Cadmium acetate, solution.1) Dissolve 300 g of cadmium acetate dihydrate Cd(CH3COO)2.2H2O in water and dilute with water to 1 000 ml. 4.10 Buffer solution, of pH 5,4. Dissolve 6 g of sodium hydroxide (NaOH
44、) in approximately 50 ml water, add 11,8 g of succinic acid (C4H6O4) and dilute with water to 100 ml. 5 Apparatus Usual laboratory equipment, and 5.1 Apparatus for the separation of hydrogen cyanide by stripping. The apparatus shown in Figure 1, or its equivalent, is recommended and comprises the fo
45、llowing components. 5.1.1 Three-necked distillation flask, of capacity 500 ml, with standard conical joints (centre neck 29/32, side necks 14,5/23). 5.1.2 Reflux condenser (Liebig condenser) 5.1.3 Absorption vessels, protected against return of liquid. 5.1.4 Funnel 5.1.5 Flowmeter 5.1.6 Wash bottle,
46、 of capacity 250 ml, for purification of the air. 5.2 pH meter, with a glass electrode which will fit into the side necks of the distillation flask. 5.3 One-mark volumetric flasks, of capacities 25, 50, 250 and 1 000 ml. 6 Sampling and samples If the sample contains undissolved cyanides, it is neces
47、sary to ensure homogeneous distribution of the undissolved substances in the sample and its dilutions. Immediately after sampling, add 5 ml of the sodium hydroxide solution (4.4), 10 ml of the phenolphthalein solution (4.6) and 5 ml of the tin(II) chloride solution (4.5) to each litre of sample or d
48、iluted sample. Adjust the pH to about 8 by adding the hydrochloric acid solution (4.2), or the sodium hydroxide solution (4.3), drop by drop, until the water turns slightly red. Adjust the pH values of highly coloured samples in the same way after checking with the pH-meter (5.2) or with an indicato
49、r paper. Finally, add 10 ml of the zinc- and cadmium sulfate solution (4.7) to each litre of sample. Analyse the sample as soon as possible. If it is necessary to store it, keep it cool and in the dark. 1) SnCl2 is added as a reducing agent; zinc salt is added to provide stable zinc hexacyanoferrates, cadmium salts are added as sulfide acceptor and because of their bactericidal effect. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:28:11 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6068-2.17:1986 4 BSI 06-1999 Fi