Determination of Zirconium in Steels Selenious Acid Method STEPHEN G. SIMPSON WITH WALTER C. SCHUMB, Massachusetts Institute of Technology, Cambridge, Mass. evaporation of the solution and HE determination of airZirconium can be satisfactorily determined in dehydration of the residue. conium by precipitation steels by precipitation f r o m dilute hydrochloric PHOSPHORUS. Phosphoru s with selenious acid was acid solution with selenious acid in the presence would cause precipitation of a t first suggested by Smith and of hydrogen peroxide, and ignition of the preleast part of the zirconium as James (6),and the method has cipitate to zirconium dioxide. The method has zirconium phosphate and remain been applied to the determinain the silica residue, but the tion of zirconium in minerals by been found applicable to steels containing elezirconium would be recovered Simpson and Schumb (5), but ments ordinarily present in zirconium steels. free from phosphate by a sodium the nature and amounts of conThe presence of tungsten m a y cause contaminacarbonate fusion of the residue stituents present in steel are so tion of the final selenite precipitate, and requires and subsequent solution of the different from those in minerals a n additional step in the procedure. residue in acid. that it seemed advisable to deTITANIUM, ALUMINUM, CHROtermine the applicability of the Titanium can be determined-colorimetrically MIUM, V A N A D I U,MC o B A L T selenite method to the determifor small amounts, with cupjerron for larger NICKEL,COPPER, AND URANIUM. nation of zirconium in steels. amounts-in the Jiltrate f r o m the precipitation The precipitation of zirconium SoLuTIoNs USED. In most of zirconium selenite, but the large volume of selenite from acid solution conof the following analyses, 3-gram solution and the presence of selenious acid and taining hydrogen peroxide has samples of a plain carbon steel been shown in the preceding were used, and to each solution hydrogen peroxide, as well as iron and possibly work to cause nearly complete were added definite amounts of vanadium, all of which must be removed, make separation of zirconium from zirconium in the form of a zirit more feasible to .determine titanium on a these constituents by a single conyl chloride solution, as well separate sample, or on a n aliquot portion of the precipitation, and a complete as definite amounts of salts of solution previous to the zirconium precipitation. separation by means of a double other elements, as indicated. precipitation. In this way, solutions of artifiTHORIUM. Thorium, whic'h caused interference with the cia1 steels were prepared containing any desired amounts of selenite method as applied to ores and required additional constituents. ELIMINATION OF INTERFERING CONSTITUENTS. In de- steps in the procedure for its complete removal, is not present vising a tentative method for the determination of zirconium in steels and need not be considered. EFFECT OF ETHER AND ACIDITY. I n applying the proposed in steel by the selenite method, it seemed advisable to follow as closely as possible the selenite method as applied to ores, method given below to the analysis of solutions of steels conmaking only those changes which the entirely different taining added amounts of zirconyl chloride, it was found nature of the sample obviously demands. A method for necessary to use alcohol-free ether in the extraction of iron, Zirconium in steel should allow for the possible presence since ordinary ether has a marked solvent action on zirnot only of those constituents present in a plain carbon steel, conyl chloride. Furthermore, with small amounts of zirbut also of aluminum, titanium, chromium, tungsten, vana- conium it was found that the acid normality of the solution dium, molybdenum, cobalt, nickel, copper, uranium, and from which zirconium selenite is precipitated should be less in certain rare cases possibly of tin, arsenic, columbium, and than that used in the case of ores and should not be much tantalum. The possible effects of these constituents should greater than 0.3 N in hydrochloric acid. therefore be considered before modifications of the selenite PROPOSED METHODFOR DETERMINATIOK OF method are proposed in order to fit the analysis of steels., ZIRCONIUM I N STEEL IRON. In the regular gelenite method for minerals, it was shown that, although iron is precipitated by selenious Dissolve 3 grams of steel in 40 CC. of concentrated hydroacid from neutral solution, it is not so precipitated from chloric acid. When solution is complete or nearly so, add solutions containing mineral acid, and zirconium can there- sufficient concentrated nitric acid to oxidize the iron, Evapofore be precipitated nearly free from iron by a single precipi- rate to dryness on the steam plate, moisten the residue with tation and entirely so by a double precipitation. I n steel, 6 N hydrochloric acid, evaporate to dryness, heat a t 105' C. however, the percentage of iron is so great that it would seem for 30 minutes, and treat with 30 cc. of 6 N hydrochloric advisable to remove at least the greater part of it early in acid and 50 cc. of hot water. After all soluble salts have the analysis. Such removal can be most readily effected dissolved, filter and wash the residue with dilute hydroby shaking the hydrochloric acid solution with ether. chloric acid and finally with hot water. Treat the filtrate MOLYBDENUM. According to Blair (W), molybdenum in and residue separately' as follows: the hexavalent condition is 80 to 90 per cent removed by a FILTRATE. Evaporate the filtrate nearly to dryness, add single extraction with ether from hydrochloric acid solution, 40 cc. of 6 N hydrochloric acid, and extract twice with 40 and is 100 per cent removed if ferric chloride is also present. cc. of alcohol-free ether. Evaporate the aqueous solution The ether extraction used for the partial removal of iron to complete dryness, dissolve in 12 cc. of 12 N hydrochloric should therefore suffice for the removal of all the molybde- acid, dilute to 400 cc., heat nearly to boiling, add 15 cc. of num in the solution. 1 In the presence of much phosphate, most of the zirconium will be found These constituents are in the residue; with little or no phosphate, most of the zirconium will be CARBON, SILICON,AND TUNGSTEN. removed by filtration subsequent to the usual procedure of found in the filtrate.
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January 15, 1933
INDUSTRIAL AND ENGINEERING CHEMISTRY
3 per cent hydrogen peroxide and 20 cc. of a 10 per cent solution of selenious acid, and allow to stand until any precipitate has coagulated. Filter, wash with hot water, and unite with the corresponding precipitate obtained from the residue below. RESIDUE.Ignite the siliceous residue in platinum. Treat with sufficient hydrofluoric acid (and two drops of concentrated sulfuric acid) to volatilize the silica. Evaporate to dryness and fuse with sodium carbonate. Extract with hot water, filter, wash with dilute sodium carbonate solution and then with hot water. Ignite the residue and fuse with potassium pyrosulfate. Dissolve in 100 cc. of hot water containing a few drops of sulfuric acid, make ammoniacal, filter, wash with hot water, and dissolve the precipitate in 25 cc. of 6 N hydrochloric acid. Dilute to 400 cc., heat nearly to boiling, add 15 cc. of 3 per cent hydrogen peroxide and 20 cc. of 10 per cent selenious acid solution, and allow to stand until the precipitate has coagulated. Filter, wash with hot water, and unite with the corresponding precipitate obtained from the main filtrate. (The two solutions should not be united prior to the precipitation of zirconium selenite, since the solution from the treatment of the residue may contain phosphate and thus cause zirconium phosphate to Precipitate.) If the zirconium precipitate is large, dissolve it in 25 cc. of hot 6 N hydrochloric acid,2 dilute to 400 cc., add 15 cc. of hydrogen peroxide, and reprecipitate with selenious acid. Ignite the precipitate and weigh as zirconium dioxide.
RESULTS BY PROPOSED METHOD I n the analyses made by the proposed method, 3 grams of a plain carbon steel were dissolved and to the solution were added measured amounts of zirconyl chloride solution corresponding to (a) 0.15 per cent, (b) 0.38 per cent, and (c) 1.92 per cent of zirconium in the original steel. I n addition, 20 mg. each of the other metals in the form of solutions of their salts were added. The results obtained are shown in Table I. TABLEI. ANALYSISOF PLAINCARBON STEELSAMPLES (Sample, 3 grams plain carbon steel)
None ~ i + + + + .41+t+ , T i + ++ +,A1 + ++, U O t + + , VOa Ti++++,Al+++ C .r + + + ,
voa-
T i + +++ A ] + + + , Cr + + + VOa-,' UOZ+*, cot+: &++,Nit+
moc - -
.Gram 47, 0.0046 o.'i5 0.0047 0 . 1 6 0.0048 0.16 0.0048 0.16 0.0042 0 . 1 4 0,0042 0 . 1 4 0.0047 0 . 1 6 0.0046a 0.15
.. Gram 47, .0.0115 0 . 3 8 0.0108 0.36 0.0118 0.39
Uram 47, ,0.0677 1.92 0.0572 1.91 0.0582 1.94
0,0109 0.36
0.0575 1.92 0.0595 1.98 0.0598 1.99
0.0048 0.16
0,0118 0.39
0.0581 1.94
0.0047 0.0047 0.0053 0.0047
0.0115 0 . 3 8 0.0141 0.47 0.0146 0 . 4 9
0.0738 0.0751 0.0747 0.0763 0.0665 0.0572
0.16 0.16 0.18 0.16
MoO4-a Bureau of Standards cast iron No. 74 (0.464 per cent
2.46 2.50 2.49 2.54 2.22 1.91
P).
It is seen that the proposed method for zirconium gives satisfactory results except in cases where tungsten is present. The presence of that element tends to give variable values which are especially high in the case of mixtures containing 1 Occasionally with larger amounts of zirconium the precipitate does not dissolve completely in the acid, but leaves a small white residue which usually does not yield even to concentrated acid. This residue ignites to zirconium dioxide and is probably normal zirconium selenite, which, in contrast to the basic selenite, is insoluble in acid. It should therefore be allowed to remain in suapension and be included with the second precipitate of selenite.
41
considerable amounts of zirconium, and in such cases the final precipitate on examination showed the presence of large amounts of tungsten but no appreciable amounts of other contaminants. It would seem, therefore, that the usual method of removing tungsten with silica by evaporation to dryness is not quantitative when much zirconium is present, and the unremoved tungsten is brought down by the subsequent selenite precipitate. Since no method was found for satisfactorily breaking up what are undoubtedly one or more complex tungsten-zirconium compounds, it seemed most feasible to correct for the tungsten brought down by the final zirconium selenite precipitate. To do this, the ignited precipitate was fused with sodium carbonate, leached with hot water, filtered, washed with hot water, and the residue ignited to zirconium dioxide, the tungsten being removed in the filtrate as sodium tungstate. Table I1 shows the results of analyses of samples containing tungsten by the proposed selenite method with this additional step introduced. TABLE11. ANALYSES OF SAMPLES CONTAINING TUNQSTEN Zr FOUND WEENZr PRESENT
Zr FOUND WEEN Zr PREsENT
=
Zr FOUND
WE~N Zr
PRESENT
3
CONSTITUENTS ADDED 0.0046 GRAM, 0.0115 GRAM, 0.0576 GRAM, (20 MG. OF EACHMETAL) 0.15% 0.38% 1.92% Gram % Gram % Gram % T i + + + + ,wOa-0.0046 0.15 0.0113 0.38 0.0580 1.93 0.0572 1 . 9 1 T i + + + +WO1-- Mood-- 0.0047 0 . 1 6 0.0112 0 . 3 7 T i + + + + WOa--: : &fool--, vos 0.0045 0.15 0.0113 0 . 3 8 Ti++++WO - - MoOl-V03-,'A1+:++:U0z++ ' 0.0047 0.16 0.0113 0.38
DETERMINATION OF TITANIUM As has been pointed out by Lundell and Knowles (4, it is advantageous in a sample of zirconium alloy to determine the percentage of titanium and zirconium in a single sample of material, although few methods for zirconium in steel make provision for such determination of titanium. I n the case of the selenite method for zirconium, any titanium is in the filtrate from the zirconium precipitate, and the solution also contains iron, hydrogen peroxide, a large amount of excess selenious acid, and any vanadium, chromium, and other acid-soluble metals that may have been present in the original alloy, so that a quick isolation or determination of titanium in this solution is a matter of some difficulty. Several possible methods of determining titanium were considered, as follows: Titanium precipitates as selenite from neutral solution with selenious acid in the absence of hydrogen peroxide, but it was found that the precipitation is not quantitative in the presence of even the small amount of free acid necessary to prevent the precipitation of iron. Brown and Madden (3) have shown that titanium can be quantitatively precipitated as phosphate from the filtrate of a zirconium phosphate precipitation after the removal of any hydrogen peroxide by boiling. Unfortunately, when this method is applied t o samples containing very small amounts of titanium such as would likely be present in a zirconium steel, the titanium is very slow in precipitating and is sometimes not formed after several days. Recently, Beans and Mossman (1) have shown the possibility of precipitating titanium as titanium iodate from strong nitric acid solution, but the amounts of iron and vanadium present in the zirconium filtrate in the case of steels would have to be removed previously. This would likewise be true of the cupferron method. The colorimetric determination of titanium with hydrogen peroxide is especially convenient with small amounts of titanium, but to apply this to the zirconium selenite filtrate necessitates the evaporation of a large volume of solution
ANALYTICAL' EDITION
42
nearly to dryness. In doing so, it was found that free selenium tends ,to separate out in a colloidal form difficult to filter, and also tends to give a color to the solution. I n addition, the iron and vanadium present must be eliminated or corrected for. A few colorimetric determinations of titanium were attempted in various zirconium selenite filtrates, using 50-cc. Nessler tubes for comparison with standards. With 4.0 mg. of titanium originally present, the estimated amount of titanium in three determinations was between 3.5 and 5.0 mg., but the time spent in the determinations makes the method impracticable for ordinary use. It would be preferable to determine the titanium independently on an
Vol. 5, No. 1
aliquot portion of the solution prior to the precipitation of zirconium selenite. LITERATURE CITED (1) Beans, I€. T., and Mossman, D. R.,J. Am. Chem. Soc., 54. 1905 (1932). (2) Blair, A. A., Ibid., 30, 1229 (1908). (3) Brown, J., and Madden, H. T., Ibid., 42, 36 (1920). (4) , . , Lundell, G. E. F.. and Knowles, H. B., IND.ENQ.C H E M .14, 1136 (1922). (5) Simpson, S. G., and Schumb, W. C., J. Am. Chem. Soc., 53, 921 (1931). (6) Smith, M. M., and James, C., Ibid., 42, 1764 (1920). RECEIVED August 6, 1932
Determination of Small Amounts of Invert Sugar in the Presence of Sucrose Revised Procedures A. H. EDWARDS AND S. J. OSBORN, Great Western Sugar Company, Denver, Colo.
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The analysis of beet sugar factory products more attention than it has refactory p r o d u c t s i n d v e d on the Part of sugar involves the determination of small amounts of chemists, although their method volves the determination invert sugar in the presence of relatively large has been adopted by the Assoof small amounts of invert sugar in the presence of relatively large W?RXUU% Of Sucrose. With the exception of ciation of Official Agricultural amounts of sucrose, Present the Herzfeld method, which is directly applicable Chemists (1) for the determionly to the analysis of raw sugar and to which nation of reducing sugars in methods do not have tables that plants. The Quisumbing and are suitably worked out for rathere are certain objections, present Thomas tables, however, are tios of sucrose and invert sugar are nod well adapted to the determination of not sufficiently comprehensive in the variety of products encountered, and the reduction invert sugar in beet sugar factory products, to cover the ratios of sucrose and invert sugar usually enprocedure is open to various obincluding molasses. jections. The Herzfeld method Preliminary investigations covered various countered in beet p r o d u c t s . (5, 9)1 which has internsdetails and in particular conjrmed the necessity many These features, authors devised i n v e s t i ga anew ted tional usage, is applicable only of improvement in the usual methods of preparing heating procedure for the reto raw sugar and cannot be Fehling solutions. A Procedure WPlicable LO duction, and were the first to used for molasses without serious error. Analysts also complain all beet sugar factory products is described, and insist on the preparation of of the difficulty of securing two methods of carrying out the copper reductions Fehling solutions by a method are recommended, ~ d and ~ ~which insures ~ exact proportions. t ~ check results by the Herzfeld P r e l i m i n a r y to adapting the which is a t t r i b u t e d tageS Of the [WO methods are discussed, and Quisumbing and Thomas method by Pick (12) to local overheating of the solution caused by ComPlete tables for the use Of both d h o d s are to the purpose in question, the influence of some details of prothe a p p l i c a t i o n of i n t e n s e given. heat. cedure was investigated. I n order to make the methods applicable to all beet sugar INVESTIGATIONS factory products of widely varying concentration and purity, One thing which had to be decided was the amount of dry the following simple procedure is employed: The calculated amount of the test sample is weighed out which will yield substance which should be used for the determination. It exactly a desired and definite amount of dry substance (5 or was found difficult to filter and wash the precipitate from a 2.5 grams) in the 50 ml. of solution used to reduce the Fehling molasses solution containing 10 grams of dry substance (in solution. This calculation is abridged by the use of tables, 50 ml.), even when the amount of invert sugar present was and, in place of true dry substance, refractometer or Brix low. A test solution containing 5 grams of dry substance values may be used if desired. By constructing copper gave sufficient material for accurate results, was easy to tables, in which the reducing effect of various amounts of handle, and yielded a precipitate of good color. Good results sucrose (5,2.5, and 1.5grams) is taken into account, the invert were also obtained with 2.5 grams of dry substance, but the value may be obtained lrom knowledge of the approximate accidental error increases with decreasing concentration. purity of the product under examination. The invert values The authors therefore recommend the use ordinarily of 5 in the copper tables are expressed as percentages on dry grams of dry substance, and of 2.5 grams when the percentage substance, which is often the basis desired in recording data of invert sugar is fairly high-i. e., above 1.5 per cent. Some or comparing the amount of invert sugar in a series of different typical results obtained with different amounts of dry substance are shown in Table I. The percentage of invert products. The Quisumbing and Thomas ( I S ) investigation deserves sugar found tends to increase slightly with decreasing conHE analysis of beet sugar
