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1、INTERNATIONAL STANDARD INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEXLIYHAPOnHAR OPrAHM3ALlMR n0 CTAHLIAPTM3ALWiA-ORGANISATION INTERNATIONALE DE NORMALISATION Aluminium oxide primarily used for the production of aluminium - Determination of sodium content - Flame emission spectrophotometric meth
2、od Ox yde d aluminium principalemen t u tilise pour la production de I aluminium - Dosage du sodium - Me thode par spectrophotome trie de flamme en bmission First edition - 1976-09-15 Ii , I_ F ,a it: : ) , )I 9 $ a,l,ay H,$f, (a l h Ref. No. IS0 1617-1976 (E) . 1 Descriptors : aluminium oxide, chem
3、ical analysis, determination of content, sodium, spectrophotometric analysis. ; Price based on 5 Pages FOREWORD IS0 (the International Organization for Standardization) is a worldwide federation of national standards institutes (IS0 Member Bodies). The work of developing International Standards is c
4、arried out through IS0 Technical Committees. Every Member Body interested in a subject for which a Technical Committee has been set up has the right to be represented on that Committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. D
5、raft International Standards adopted by the Technical Committees are circulated to the Member Bodies for approval before their acceptance as International Standards by the IS0 Council. Prior to 1972, the results of the work of the Technical Committees were published as IS0 Recommendations; these doc
6、uments are now in the process of being transformed into International Standards. As part of this process, Technical Committee ISO/TC 47 has reviewed IS0 Recommendation R 1617 and found it technically suitable for transformation. International Standard IS0 1617 therefore Replaces IS0 Recommendation R
7、 1617-1970 to which it is technically identical. IS0 Recommendation R 1617 was approved by the Member Bodies of the following countries : Australia Austria Belgium Brazil Chile Czechoslovakia Egypt, Arab Rep. France Germany Greece Hungary of India Iran Israel Italy Korea, Rep. of Netherlands New Zea
8、land Norway Peru Poland Portugal Romania South Africa, Rep. of Spain Sweden Switzerland Thailand Turkey United Kingdom U.S.S.R. Yugoslavia No Member Body expressed disapproval of the Recommendation. No Member Body disapproved the transformation of ISO/R 1617 into an International Standard. o Interna
9、tional Organization for Standardization, 1976 l Printed in Switzerland INTERNATIONAL STANDARD IS0 1617-1976 (E) Aluminium oxide primarily used for the production of aluminium - Determination of sodium content - Flame emission spectrophotometric method 1 SCOPE AND FIELD OF APPLICATION This Internatio
10、nal Standard specifies a flame emission spectrophotometric method for the determination of the sodium content of aluminium oxide primarily used for the production of aluminium. The method is applicable to products having a sodium content, expressed as NapO, equal to or greater than 0.05 % (m/m). 2 R
11、EFERENCES IS0 802, Aluminium oxide primarily used for the production of aluminium - Preparation and storage of test samples. IS0 2927, Aluminium oxide primarily used for the production of aluminium - Sampling. 3 PRINCIPLE Fusion, at a controlled temperature, of a test portion of aluminium oxide with
12、 a mixture of lithium carbonate and boron trioxide or, as alternative, a mixture of lithium carbonate and lithium tetraborate. Dissolution of the fused mass in hydrochloric acid. Aspiration of the solution into a flame and determination of the sodium content by measurement of the intensity of the li
13、ght emitted at a wavelength of 589 nm. 4 REAGENTS During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 4.1 Lithium carbonate, anhydrous (Li,COa). 4.2 Boron trioxide (B,Oa), or 4.2.1 Boric acid (HaBOa), or 4.2.2 Lithium tetrabor
14、ate ( Li2B407). NOTE - If crystallized lithium tetraborate pentahydrate (Li26407.5H20) is available, first dehydrate it by gradual heating in a platinum dish. 4.3 Aluminium, 99.99 % pure, in the form of shavings. 4.4 Mercury, extra pure. 4.5 Acetone, p approximately 0,788 g/ml. 4.6 Hydrochloric acid
15、, p approximately I,19 g/ml, about 38 % (m/m) solution. 4.7 Nitric acid, p approximately I,40 g/ml, about 68 % (m/m) solution. 4.8 Sodium, standard solution corresponding to 2,00 g of Na,O per litre. Weigh, to the nearest 0,001 g, 3,774 g of sodium chloride, which has been previously dried for about
16、 12 h at 110 “C and cooled in a desiccator, and dissolve in water. Transfer the solution quantitatively to a 1 000 ml one-mark volumetric flask, dilute to the mark and mix. Transfer the solution to a plastics bottle. 1 ml of this standard solution contains 2.00 mg of Na,O. 4.9 Sodium, standard solut
17、ion corresponding to 0,200 g of Na20 per litre. Take 50,O ml of the standard sodium solution (4.8) place in a 500 ml one-mark volumetric flask, dilute to the mark and mix. 1 ml of this standard solution contains 0,200 mg of Na,O. Prepare this solution just before use and transfer it to a plastics bo
18、ttle. 4.10 Sodium, standard solution corresponding to 0,080 g of NaaO per litre. Take 40,O ml of the standard sodium solution (4.8), place in a 1 000 ml one-mark volumetric flask, dilute to the mark and mix. 1 ml of this standard solution contains 0,080 mg of Na,O. Prepare this solution just before
19、use and transfer it to a plastics bottle. 1 IS0 1617-1976 (E) 5 APPARATUS Ordinary laboratory apparatus and 5.1 Platinum crucible, of upper diameter approximately 50 mm, lower diameter approximately 35 mm and height approximately 40 mm, fitted with a platinum lid, or 5.1 .I Platinum-gold alloy cruci
20、ble (Au 5 %), having the same dimensions, or 5.1.2 Graphite crucible, of suitable quality and having about the same dimensions as the platinum crucible (5.1). NOTE - Using a sample of Al203 of known Na20 content, a test should be carried out in order to check that the purity and density of the graph
21、ite are such as to cause no variation of the NaaO content. A density of graphite complying with such requirements is equal to or greater than 1.7. 5.2 Open electric furnace, capable of being controlled at 500 + 20 “C. 5.3 Electric furnace, capable of being controlled at 1 100 f 50 “c. 5.4 Borosilica
22、te glass beaker, of capacity approximately 400 ml. 5.5 Borosilicate glass beaker, of capacity approximately 600 ml. 5.6 Flame spectrophotometer, provided with an atomizer burner suitably fed to excite the emission of the 589 nm sodium line. 6 PROCEDURE 6.1 Test portion Weigh, to the nearest 0,001 g,
23、 1 g of the test sample, dried at 300 “C (see 3.3 of IS0 802). 6.2 Preparation of the calibration graph 6.2.1 Preparation of the base solutions 6.2.1.1 PREPARATION OF AN ALUMINIUM CHLOR IDE SOLUTION CORRESPONDING TO log OF A1203 PER LITRE Clean about 6 g of the aluminium (4.3) by dipping into a litt
24、le of the nitric acid solution (4.7). Wash in water and dry with the acetone (4.5). Weigh, to the nearest 0,001 g, 5,294 g of the clean dry metal; place in the beaker (5.5) and add approximately 100 ml of water and 95 ml of the hydrochloric acid solution (4.6). introduce 1 drop of the mercury (4.4)
25、to facilitate the dissolution. When the reaction subsides, place the beaker on a sand bath and maintain a gentle heat until all the aluminium has dissolved. Allow to cool and transfer the solution to a 1 000 ml one- mark volumetric flask. Wash the beaker and collect the washings in the same flask, d
26、ilute to the mark and mix. Transfer the solution to a plastics bottle. 6.2.1.2 PREPARATION OF A HYDROCHLORIC ACID SOLUTION OF THE FLUX Place in the beaker (5.4) - 14 g of the lithium carbonate (4.1) and 17,5 g of the boron trioxide (4.2) or 31 g of the boric acid (4.2.1) or - 7.5 g of the lithium ca
27、rbonate (4.1) and 21 g of the lithium tetraborate (4.2.2). Add approximately 50 ml of water and, in small portions, 30 ml of the hydrochloric acid solution (4.6). After the liberation of gas has ceased, place the beaker on a sand bath and stir from time to time with a glass rod until the boric acid
28、is completely dissolved. Dilute to approximately 200 ml with hot water, allow to cool and then transfer to a 250 ml one-mark volumetric flask. Wash the beaker and collect the washings in the same flask, dilute to the mark and mix. Transfer the solution to a plastics bottle. 6.2.2 Preparation of the
29、standard matching solutions (see 8.1) Into a series of eight 100 ml one-mark volumetric flasks, place, in order, 40 ml of the aluminium solution (6.2.1), 10 ml of the flux solution (6.2.1.2) and then the volumes of standard sodium solution (4.9) shown in the following table : Standard sodium Corresp
30、onding mass Mass of Na20 referred solution (4.9) of Nap0 to 100 g of A1203 ml w g 0” 0 0 5.0 1 ,oo 0.25 10.0 2.00 0.50 12.5 2,50 0.625 15.0 3.00 0.75 17,5 3.50 0.875 20.0 4.00 1 ,oo 25.0 5.00 1.25 * Blank test on reagents for the calibration graph, Then dilute to the mark and transfer the solutions
31、to plastics bottles. Use only freshly prepared standard matching solutions. 6.2.3 Spectrophotometric measurements Switch on the spectrophotometer (5.6) a sufficient time in advance to ensure stabilization. Adjust the sensitivity of the apparatus and the slit aperture in accordance with the character
32、istics of the apparatus used, ensuring a band width of 6 nm at the most, centred on the emission maximum (theoretical value 589 nm). 2 -,-,- IS0 1617-1976 (E) Aspirate the series of standard matching solutions (6.2.2) into the flame and measure the intensity of the emission. Ensure that the rate of
33、aspiration of the solutions into the flame is kept constant during the preparation of the calibration graph. 6.2.4 Plotting the calibration graph Plot a graph having, for example, the masses, in milligrams, of Na,O contained in 100 ml of the standard matching solutions as abscissae and the correspon
34、ding values of intensity of emission decreased by the measured value on the blank on the reagents for the calibration graph, on a logarithmic scale, for example, as ordinates. 6.3 Determination 6.3.1 Preparation of test solution Weigh into the crucible (5.1, 5.1 .I or 5.1.2) - 1.40 g of the lithium
35、carbonate (4.1) and - 1.75 g of the boron trioxide (4.2) or 3,lO g of the boric acid (4.2.1) ; or - 0,75 g of the lithium carbonate (4.1) and - 2,lO g of the lithium tetraborate (4.2.2). Mix carefully, add the test portion (6.1) and mix the whole quantity carefully, preferably with a platinum spatul
36、a. Cover the crucible with its lid and place in the open electric furnace (5.2). controlled at 500 + 20 “C, and maintain this temperature until melting of the flux occurs. Transfer the covered crucible to the electric furnace (5.3), controlled at 1 100 + 50 “c, without allowing the temperature to ex
37、ceed 1 150 “C, and maintain this temperature until fusion of the aluminium oxide is complete (approximately 90 min). NOTE - Preliminary grinding of the test portion facilitates melting at a lower temperature. If grinding is carried out, use a corundum mortar (see 3.3 of IS0 802). Remove the crucible
38、 from the furnace and allow to cool in air. Heat it again over the flame of a Bunsen burner and then quickly immerse the base of the crucible in a bath of cold water so as to crack the vitrified mass. Detach the pieces of the fused mass with the aid of a platinum rod, if necessary tapping the walls
39、of the crucible lightly with a spatula, and collect them in the beaker (5.4). Add 7.5 ml of the hydrochloric acid solution (4.6) into the beaker, and 5 ml into the crucible. Heat the crucible gently on a sand bath until the residue is completely dissolved. Transfer the solution to the beaker; rinse
40、the crucible several times with hot water, collecting the washings in the beaker. Cover the beaker with a watch-glass and place it on the sand bath. Simmer gently until the fused mass is completely dissolved. Then remove the beaker from the sand bath and allow to cool. Transfer the solution to a 250
41、 ml one-mark volumetric flask, carefully wash the beaker, collecting the washing water in the same flask, dilute to the mark and mix. Transfer the solution to a plastics bottle. 6.3.2 Spectrophotometric measurements 6.3.2.1 PRELIMINARV MEASUREMENT Carry out a preliminary measurement as specified in
42、6.2.3 at the same time as the spectrophotometric measurements on the standard matching solutions (6.2.2). 6.3.2.2 BRACKETING MEASUREMENT Carry out a second measurement on the test solution by bracketing it between two standard matching solutions which differ by only 0,05 g of Na,O (referred to 100 g
43、 of AI,O,). Prepare these standard matching solutions using the volumes of the two base solutions (6.2.1 .I and 6.2.1.2) specified in 6.2.2 with the addition of the appropriate volumes of the standard sodium solution (4.10). These quantities shall not differ by more than 2,5 ml. 6.4 Blank test 6.4.1
44、 Preparation of the solution In the beaker (5.4), place the same quantities of the flux as used for the preparation of the test solution (see 6.3.1). Add approximately 50 ml of water and 3 ml of the hydro- chloric acid solution (4.6). Place the beaker on a hot-plate and stir from time to time until
45、dissolution is complete. Continue the heating and stirring in order to eliminate carbon dioxide. Cool and transfer the solution to a 250 ml one-mark volumetric flask, which already contains 100 ml of the aluminium solution (6.2.1.1). Wash out the beaker carefully, collect the washings in the same fl
46、ask, dilute to the mark and mix. Transfer the solution to a plastics bottle. 6.4.2 Spectrophotometric measurements Carry out the measurements as specified in 6.2.3 in conjunction with the measurements of the test solution and the standard matching solution specified in 6.3.2.1 and 6.3.2.2. 7 EXPRESS
47、ION OF RESULTS The concentration C, expressed in grams per litre, of the solution actually submitted to the spectrophotometer, is given by the formula c= E-E, +(C,-C,)- IC ED-E, f, -El - c,+tc,-C,)- E, -Es 1 where C, is the concentration, in grams per litre, of the weaker standard matching solution
48、used in the deter- mination; 3 -,-,- IS0 1617-1976 (E) El is the value of the corresponding measurement; C2 is the concentration, in grams per litre, of the stronger standard matching solution used in the deter- mination; E, is the value of the corresponding measurement; E is the value of the measur
49、ement corresponding to the determination; Ca is the concentration, in grams per litre. of the weaker standard matching solution used in the blank test; E, is the value of the corresponding measurement; Cd is the concentration, in grams per litre, of the stronger standard matching solution used in the blank test; E4 is the value of the corresponding measurement; E. is the value of the measurement corresponding to the blank test. The sodium content, expressed as a percentage by mass of sodium