V O L U M E 19, N O . 6
376 to alumina samples and for helpful suggestions throughout the work.
(7)
LITERATURE CITED
(1) (2) (3)
Abresch, K., Angew. Chem., 48,683-5 (1935). Carruthers, C., IND. E N G . CHEM.,A N A L .ED., 15, 70-1 (1943). Heyrovsk?, J., and Bures, M.,Collection Czechoslov. Chem.
(4)
Kemula, W., and Michalski, M . , Atti X o congr. intern. chim.,
(5) (6)
Komar, N., Zavodskaya Lab., 6 , 1074-8 (1937). Lohuis, D., Meloche, V. IT.. and Juday, C., T r a n s . W i s c o n s i n
C o m m u n . , 8 , 4 4 6 - 5 4 (1936). 3 , 4 1 9 - 2 7 (1939).
Acad. Sei., 31, 285-304(1938).
Lykken, L., Pompeo, D. J., and Weaver, J. R., ISD. EXG. CHEM., ASAL. ED., 17, 724-8 (1945). Majer, V.,Chirnieetzndustrie, 29, 2 1 1 s - 1 4 s (1933). Majer, V.,Z . anal. Chem., 92, 321-51 (1933). Peracchio, E., and Meloche, V., J. Am. Chem. Soc., 60, 1770-5 (1938).
(11)
Schweitzer, H., Acta Brevia h'eerland. Physiol. Pharmacol.
Microbial., 6, 110-12 (1936). (12) Zlotowski, I., and Kolthoff, I. M., IKD. E x . CHEM.,AXAL.ED., 14,473-7 (1942). PRESESTED before the Division of Analytical and Micro Chemistry a t t h e 109th bleeting of the AMERICAX C H E W C A L SOCIETY, Atlantic City, N . J.
Zirconium Determination in Presence of Interfering Elements CHARLES A. KUMINS', Research Laboratories, National Lead Co., T i t a n i u m Division, S o u t h Amboy, N. J .
A specific precipitant for zirconium has been discovered w-hich will separate it quantitatively from titanium, iron, vanadium, aluminum, chromium, thorium, cerium, tin, barium, calcium, copper, bismuth, antimony, and cadmium. The method entails the precipitation of the zirconium with mandelic acid from a hydrochloric acid solution as a zirconium mandelate.
T
HE gravimetric analysis of zirconium-containing compounds
is exceedingly difficult and time-consuming because of the lack of a specific reagent for the element. Those compounds which are employed in the determination of this element may be either inorganic or organic. I n the former group are ammonium acid phosphate and selenic acid (1) and in the latter are included cupferron, henzenearsonic acid, 8-hydroxyquinoline, p-hydroxyphenylarsonic acid, and propylarsonic acid ( 2 ) . Precipitation of the zirconium using the phosphate procedure is open to error on the following grounds ( I ) : 1. dride 2. 3. 4.
Precipitate tends to hydrolyze and lose phosphoric anhyduring washing. Precipitate is slimy and difficult to wash. Separation from thorium requires two precipitations. Cerium must be kept in the trivalent state.
On the other hand the basic selenite precipitate may contain thorium and tin and is subject to a positive ermr if too much iron and titanium are contained in the solution to be analyzed. I n the organic group the following elements interfere with the specific precipitant listed ( 2 ) . Benzenearsonic acid-silicon, tungsten, iron, and titanium. ' Cupferron-cerium, cobalt, iron, silica, titanium, thorium, uranium, rare earths, and most members of the hydrogen sulfide grou 8-f&droxyquinoline-aluminum, chromium, cobalt, copper, iron and nickel, alkalies, hydrochloric, nitric, phosphoric, and sulfuric acids. p-Hydroxyphenylarsonic acid-cerium, phosphates, thorium, tin, and titanium. Propylarsonic acid-antimony, bismuth, and tin. However, as a result of certain investigations in the chemistry of the Group IV elements it was discovered that mandelic acid, C6HsCHOHCOOH, reacted with zirconium salts to yield a white precipitate which was not described in the literature. Accordingly, in view of the complexity of the zirconium analysis, this reaction was investigated in an effort to estimate the utility of the mandelic acid as a specific predipitant for zirconium. As a result of preliminary experiments with solutions of pure zirconyl chloride and zirconyl sulfate in hydrochloric acid it was found that results (Table I) which checked xvith the cupferron address, Interchemical Corp., Research Laboratories, 432 West 45th St., New York 19, N. Y . 1 Present
'
and ammonia precipitation methods could be obtained by the following procedure: A sample containing from 0.050 to 0.3 gram of zirconium oxide in solution was diluted to approximately 20 ml. with concentrated hydrochloric acid. To this were added 50 ml. of 16% mandelic acid and the whole was made up to 100 ml. The temperature was raised slowly to 85" C. and held there for 20 minutes. The resulting precipitate was filtered, washed with a hot solution containing 2% hydrochloric acid and 5% mandelic acid (this wash solution was necessary because the precipitate was sufficiently soluble in pure water to cause low results), and ignited to the OXide. EFFECT OF SULFURIC ACID
Since most commercial solutions of zirconium are made by digesting the ore with concentrated sulfuric acid followed by suitable dilution, it was of interest to determine the effect of free sulfuric acid upon the completeness of the precipitation. The procedure indicated above was followed, u4ng C.P. zirconyl chloride solution (Table 11). Upon examination of the data in Table 11, it is apparent that quantitative results cannot be expected in solutions containing appreciably more than 5% free sulfuric acid. However, that is not so serious as it first appears, since this was equivalent on a sample basis to about 52% free acid-i.e., 5 ml. of zirconium sohtion used = approximately 5 grams plus 5.7 grams of sulfuric acid 3 52y0 free acid.
Table I.
Cupferron and Ammonia Precipitation
ZrOz Present
Gram 0.1109a 0.1256)
ZrOt Found
Difference
Gram 0,1111 0.1254
Gram +o. 0002
Deviation
% $0.18 -0.16
- 0.0002
Analyzed b y cupferron precipitation from solution of pure zirconyl chloride. b Analyzed b y ammonia precipitation from solution of pure sircony sulfate. a
Table 11. Effect of Sulfuric Acid Volume of Mandeli, Acid MI. 60
30 30 30
Weight of Free H&O,
Grams 18.4 9.2 7.2 5.4
H*SO? in Solution ",OH
% ' 18.4 9.2 7.2 5.4
Gram 0,1255 0.1109 0.1109 0.1109
Mandelic Acid Difference Deviation
Gram 0,1036 0.1042 0,1038 0.1111
Gram -0,0219 -0,0067 -0.0071
$0.0002
% -16.10 - 6.05 - 6.42 $ 0.18
J U N E 1947
377
Severtheless, it was thought of interest to see whether high sulfuric acid concentrations could be neutralized without impairing the results of the analysis.
A standard airconyl chloride solution (cupferron method) containing 0.1109 gram of zirconium oxide was mixed with 5 ml. of concentrated sulfuric acid (9.0 grams) and diluted to 30 ml. with distilled water. Sufficient concentrated sodium hydroxide solution was added to cause a precipitate of zirconium hydroxide which persisted for about 1 to 2 minutes. Fifty milliliters of 16% mandelic acid were then added and the total volume was brought to 100 ml. The following results were obtained: Zirconium oxide Found. pram Actual, gram Difference Deviation,’
rm
EFFECT O F IMPURITIES
Hydrochloric acid solutions containing titanium, aluminum, iron, vanadium, chromium, tin, bismuth, antimony, cerium, calcium, thorium, copper, cadmium, and barium as impurities were mixed with an aliquot sample of a zirconyl chloride solution previously standardized by the cupferron method, and the zirconium content was determined n-ith mandelic acid by the method described. Table I11 lists the weights of the impurities which \yere mixed with the standard aliquot of the zirconyl chloride solution and the results obtained therefrom.
1 0.3300 gram of Fez08 a s ferric 2 0.1320 gram of AhOs (as alumi3 4 5 6
7 8 9 10 11 12 13 14 15 16 17 b
Cupferron
Deviation
% 70.30 70.38 70.26 70.31
2/1000
..
Analyses of Zirconium Mandelate Complex
Element
Actual
Theoretical
% 13.29 55.19 4.31 27.21
13.10 55.20 4.03 27,60
70
APPLICATION TO ANALYSES OF ZIRCONIUM ORES
A sample of zirkite, a zirconium-bearing ore, was dissolved by a borax fusion followed by treatment with dilute (1to 5 ) hydrochloric acid. The solution was treated with 50 ml. of 16% mandelic acid as previously described. The results xere then compared with those obtained by the use of the cupferron method (Table IV). As can readily be seen, they \\-ere in substantial agreement. THEORETICAL
Three separate preparations of the zirconium mandelate complex were prepared by interacting a solutioR of C.P. zirconium oxychloride in 5% hydrochloric acid with 16% mandelic acid. The resulting precipitate was filtered, washed free of water-soluble salts, and dried a t 110” C. for 16 hours. The preparations were then analyzed separately, the zirconium being determined by ignition to the oxide and the carbon and nitrogen by the standard method of Pregl (S).
Effect of Impurities
( Z r O t present i n sample, 0.1109 gram) Impurity ZrO; F o u n d Difference Deviation ammonium sulfate
Analyses of Zirkite Ore
Table V.
C 0 H (by difference)
Since such a sample would contain 64.5% free sulfuric acid, an amount that is rarely encountered, this deviation would not appear to be too serious. Neutralization with ammonium hydroxide produced results which were 4.24T0 less than the actual quantity.
Table 111.
% 70.50 70.40 70.44 Av. 70.45
Zr
0,1096 0,1109 0,0013 1.7
~
Table IV. hlandelic Acid
Gram
Gram
0,1109
0.00
0.1107 n u m sulfate) -0 0002 0.1420 gram of Ti02 (as T i C h 0.1107 solution) -0 0002 0.1420 g r a m of Ti02 0.1107 - 0 0002 0.1320gram of A h 0 1 0.0221a 0.3300 gram of Fer03 0 0 0.1420 gram of Ti02 0.1320 gram of Ah03 Same a s 5 plus 0.0010 gram of vanadium as ammonium vana0.0500b - 0.0002 date 0.1114 0.663gram of SnOz a s SnCla +0.0005 0,1113 0.736gram of BixOs a s BiOClz +0.0004 0.1113 0.640 g r a m of SbzOr a s SbOCh +0.0004 0,1109 1.88 grams of BaO as B a C h 0.0 0,1109 0.953gram of CaO a s C a C h 0.0 0.681 gram of T h o * a s thorium. nitrate 0.1111 +o. 0002 0.530 gram of CuO a s CuSOd 0.1108 -0.0001 0.720 gram of CrnOa a s CrClr 0.1108 -0.0001 0.3 gram of CaO as C a C h 0.1111 t o . 0002 0.1112 0.2gram of CeOn a s ceric sulfate f 0,0003 Mixtures of 7 to 16 0.1120 +0.0011 Sample contained 0.0221 gram of zirconium oxide. Sample contained 0.0502 gram of zirconium oxide.
70 0.0 -0.18
The individual results checked closely enough to indicate the formation of a definite compound which corresponded to the following probable formula, as can be seen by comparing the average of the three determinations x i t h the theoretical composijtion of the tetramandelate.
-‘O. 18 -0.18 0.0
-0.4 +0.45
+O. 36 +0.36 0.0 0.0
+o. 18
0.09 -0.09 +0.18 +0.27 1.0
The zirconium mandelate dissolves in dilute sodium hydroxide, followed by the immediate precipitation of zirconium hydroxide. When ammonium hydroxide is employed no precipitate of zirconium hydroxide is observed, indicating the formation of a probable complex ammonium zirconium mandelate. This was not investigated further but it was evident that this was the cause of the low results obtained when the excess sulfuric acid was neutralized with ammonium hydroxide. ACKNOWLEDGMENT
In spite of the high molar ratio of oxide impurities to zirconia, which ranged from about 6:l to 15:1, good checks were obtained. Where the unstable salts of thorium, antimony, tin, and bismuth are the contaminants, results are slightly higher, though not sufficiently high to impair the method. This may be due to the hydrolysis of the basic chlorides when the solution is heated to 85 O C. after addition of the mandelic acid. In practice it is extremely doubtful that s;ch large quantities of impurities will be present as indicated in Table 111. Nevertheless, should such an eventuality occur it would be easy to heat the hydrochloric acid solution containing the zirconium and other elements to boiling and filter off the hydrolyzed salts. The filtrate may then be cooled and the analysis continued as previously indicated.
The author wishes to express his appreciation to J. L. Turner, director of research, to the late W. W. Plechner assistant director of research, and to A. E. Jacobsen of the National Lead Company, Titanium Division, for their interest and encouragement in this project, and to Gloria Greening and the Interchemical Corporation for assistance in preparing this paper. LITERATURE CITED
(1) Hillebrand and Lundell, “Applied Inorganic Analysis,” New York, John W l e y & Sons, 1929.
(2) Milan, “Organic Reagents in Inorganic AnaIysis,” Philadelphia,
P. Blakiston’sSons & Co., 1941. (3) Roth and Dan, “Qualitative Organic Microanalysis of Fritz Pregl,” Philadelphia, P. Blakiston’sSons & Co., 1937.
