BS 1728-14-1965 Methods for the analysis of aluminium and aluminium alloys - Determination of nickel (gravimetric method)《铝与铝合金的分析方法 第14部分 镍的测定(重量法)》.pdf

1、BRITISH STANDARD BS1728-14: 1965 Method for the determination of Nickel In aluminium Part2: Magnesium; Part3: Zinc (mercuric potassium thiocyanate method); Part4: Zinc (polarographic method); Part5: Copper (absorptiometric method); Part6: Iron (volumetric-titanous chloride method); Part7: Zinc (zinc

2、 oxide method); Part8: Iron (absorptiometric1:10 phenanthroline method); Part9: Manganese (volumetric-arsenite/nitrite method); Part10: Manganese (absorptiometric method); Part11: Silicon (perchloric acid method); Part12: Silicon (absorptiometric-molybdenum blue method); Part13: Titanium (absorptiom

3、etric-chromotropic acid method). The preparation of this series of methods has been authorized by the Non-Ferrous Metals Industry Standards Committee as part of a general programme for the standardization of methods for the sampling and analysis of non-ferrous metals. The methods have been found to

4、give reliable and reproducible results and, while in some instances they may appear to be lengthy, it should be appreciated that they are primarily intended as “referee” methods to be used in cases of dispute. A British Standard does not purport to include all the necessary provisions of a contract.

5、 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 front cover, an inside front cover, pagesi andii, pages1 and2 and a back cover. This sta

6、ndard 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.BS1728-14:1965 BSI 10-1999 1 Introduction a) Principle. The alloy is dissolved in hydrochloric and nitric acids. Heavy metals are precipitated

7、 with sodium hydroxide and copper is removed by electrolysis. The nickel is then precipitated with dimethylglyoxime and determined gravimetrically. b) Range. The method is recommended for nickel contents from0.2per cent to3per cent. c) Reproducibility. Experiments have been carried out independently

8、 by a number of analysts using this method. The degree of reproducibility that can be expected is shown by the following results obtained: Apparatus a) Class A volumetric glassware complying with the relevant British Standards shall be used throughout. b) Platinum-gauze electrodes of stationary type

9、 and of suitable size. c) Electrodeposition apparatus fitted with stirrer or means of agitation, pressed air, and capable of providing a direct current of3amperes. Solutions required All reagents shall be of the highest purity obtainable, and distilled water shall be used throughout. Citric acid (20

10、per cent w/v). Dissolve200g of citric acid (C 6 H 8 O 7 .H 2 O) in water, dilute to1litre and mix. Dimethylglyoxime (1per cent w/v). Dissolve10g ofdimethylglyoxime in potassium hydroxide solution(3per cent w/v) dilute to1litre with the potassium hydroxide solution and mix. Hydrazine hydrochloride (1

11、0per cent w/v). Dissolve100g of hydrazine hydrochloride in water, dilute to1litre and mix. Hydrochloric acid (50per cent v/v). Dilute500ml of hydrochloric acid (sp. gr.1.16 to1.18) to1litre and mix. Nitric acid (50per cent v/v). Dilute500ml of nitric acid (sp. gr.1.42) to1litre and mix. Sodium hydro

12、xide (0.5per cent w/v). Dissolve5g of sodium hydroxide in water, dilute to1litre and mix. Sulphuric acid (50per cent v/v). To400ml of water add cautiously500ml of sulphuric acid (sp. gr.1.84) mix, cool, dilute to1litre and mix. Sulphurous acid. Pass sulphur dioxide gas into100ml of water until a sat

13、urated solution is obtained. Procedure Adjust the weight of sample and quantities of reagents as follows: Weigh the appropriate quantity of sample, transfer to a250ml beaker and add the appropriate quantity of hydrochloric acid (50per cent). When the reaction subsides add5ml of nitric acid (50per ce

14、nt), boil for5minutes and dilute to100ml. Filter off the insoluble matter on a paper pulp pad or a medium texture filter paper 1)and wash with hot water. Reserve the filtrate and washings. Transfer the pad or paper and the precipitate to a platinum vessel of suitable size, dry, and ignite at550650 C

15、 for30minutes. Cool, add5ml of hydrofluoric acid 2) , then add nitric acid (50per cent) dropwise to oxidize the silicon until a clear solution is obtained. Add a few drops of sulphuric acid(50per cent) and evaporate to dryness. Take up the residue with a few ml of water containing a few drops of sul

16、phuric acid(50per cent) and add this solution to the main filtrate. Adjust the volume to about200ml. Weigh the appropriate quantity of sodium hydroxide, transfer to a600ml beaker and dissolve in100ml of water. Add5ml of hydrazine hydrochloride solution(10per cent), mix, then transfer to this the sam

17、ple solution with continuous stirring. Heat to boiling. Continue boiling for12minutes, then allow the residue to settle, filter through a hardened medium texture filter paper 3)or paper pulp pad and wash well with hot sodium hydroxide solution(0.5per cent). Nickel content Standard deviation per cent

18、 0.24 0.53 0.67 2.50 0.010 0.010 0.013 0.032 Nickel content Sample weight Hydrochloric acid (50per cent) Sodium hydroxide per cent less than1 over1 g 2 1 ml 50 25 g 30 20 1) Whatman No.40 is suitable. 2) This refers to the usual analytical reagent of40per cent w/w. 3) Whatman No.540 is suitable.BS17

19、28-14:1965 2 BSI 10-1999 Dissolve the residue with hot nitric acid (50per cent) adding a little sulphurous acid if manganese is present. Wash with hot water, add10ml of sulphuric acid(50per cent) and evaporate to dense white fumes. Cool, add100ml of water and heat until soluble salts are dissolved.

20、Filter off the silica on a medium texture filter paper 4)and wash with hot water (Note1). Adjust the volume to150ml and add5ml of nitric acid(50per cent). Insert a pair of platinum electrodes in the solution and electrolyse with stirring at about3amp for20minutes. Check for completeness of depositio

21、n of copper by adding a little water and continue the electrolysis; no further copper should be deposited on the newly immersed portion of the cathode. When deposition is complete, without interrupting the current, remove the beaker containing the electrolyte and wash down the electrodes into the sa

22、me beaker. Adjust the volume of the solution to200ml, add10ml of citric acid solution(20per cent) andneutralize with ammonia solution (sp. gr.0.880.91). Heat to about90 C and add, with stirring,20ml of dimethylglyoxime solution(1per cent) for up to20mg of nickel and5ml for each additional10mg of nic

23、kel. Allow to stand without further heating for30minutes (Note2), cool to room temperature, filter through a weighed sintered glass crucible (porosity3) and wash with cold water. Dry the crucible and precipitate at110120 C for two hours, cool and weigh. Calculation NOTE 1If the copper content is kno

24、wn to be lessthan0.1percent omit the electrolysis and continue from paragraph8 of the procedure. NOTE 2Allow the solution to stand for2hours for nickel contents below0.5per cent. 4) Whatman No.40 is suitable. where A = weight (g) of nickel, glyoxime, W = weight (g) of sample taken. Nickel per cent A

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