Separation of Scandium from Yttrium, Rare Earths, Thorium, Zirconium, Uranium, and Other Elements by Anion Exchange Chromatography in Ammonium Sulfate Media HlROSHl HAMAGUCHI,' ATSUHIRO OHUCHI, TSUNEO SHIMIZU,' NAOKI ONUMA,' and ROKURO KURODA Department of Chemistry, Tokyo Kyoiku University, Koishikawa, Tokyo
b Sc(l1l) i s adsorbed on a strongly basic anion exchange resin, Dowex 1, X-8 (sulfate form), from 0.1M ( " 4 ) ~ S04-0.025M H2S04 solution. Under these conditions Y(III), rare earths(lll), AI(III), Be(ll), Cd(ll), Co(ll), Cu(ll), G a (Ill), Ge(lV), Mg(ll), Mn(ll), Ni(ll), V(IV), and Zn(l1) are not adsorbed to any great extent, while Mo(VI), Ta(V), Th(lV), Zr(lV), and U(V1) are strongly retained b y the exchanger. Sc(1ll) can be quantitatively separated from macroamounts of any of the cations above. An anion exchange chromatographic procedure for the separation of the rare earths(lll), Sc(lll), Th(lV), Zr(lV), and U(VI) has also been developed, where all five of the metallic ions can be chromatographically separated b y a consecutive elution with (NHJ2S04, HCI, and HC104.
A
LMOST . ~ L Lcolorimetric,
gravimetric, and chelatoinetric reagents for Sc (111) react with many other metal ions and therefore are not specific. Y(III), rare earths(II1): Zr(1V); Tli(IV), and U (VI) are the most troublesome elements, anti usually cause serious interference in both the separation anti the determination of Sc(II1). This study centered on the establishment of an effertive anion exchange separation procedure for Sc(II1) from the elements abore, which would lead to the determination of Sc(II1). The different methods currently used to separate and determine SctIII) have been reviewed in two monographs (6, 7 ) . Since the recent progress in ion exchange separation of Sr(II1) has been reviewed by €lamaguchi et al. (2, s),it will not be discussed here. .\ systematic study of the adsorption of cations on Dowex 1, X-8 in (SHJ2S04 media showed that the differences in 1 Present address, Department of Chemistry, The Universitj of Toklo, Hongo, Tokyo * Presmt address, Gunma Technlcal College, Maebashi, Gunma-ken.
2304
ANALYTICAL CHEMISTRY
eqiiilihrium diatribut ion coefficients between Sc(1II) and a considerable number of metal ions is great enough for a good separation. This fact made it possible to separate Sc(II1) from Y(IIIj, rare earthsUII), Zr(lY)> Th(IV)! and L-(Vl) as well as many other metal ions. Furthermore the procedure described here provides a simple method for separating five metal?---rare earths
(111)orY(III)-Sc(III)-Zr~IT.'~-Th(IV)Ir'(V1)-consecutively using (SHJ2S04 and very common mineral acids. EXPERIMENTAL
Reagents and Apparatus. Analytical reagent, quality chemicals \\-ere used \Thenever possible. St,ock solutions of Sc(III), Y ( I I I ) , and rare eart,hs(III) were prepared by dissolving an appropriate amount of t'he respective oxides (99.970 purity) in a minimum amount of 3.11 H2S04, evaporating to dryness, and diluting to a drfinite volume with water to bring the concentration of each to 2.5 mg. per ml. of H20. Standard solutions of the other ions were prepared by dissolving the sulfates in wat,er or HzSOaof known concentration i o give 10 to 20 nig. of the ion per milliliter of the solvents. ;1 triplicate drtcrmination was made using an appropriate analytical method to standardize each s h c k solution. Ion Exchange Resin. Strong base type anion exchanger, I1owe.u 1! X-8, 100 to 200 mesh, sulfate form was used. Xn appropriate amount of resin (C1 form) was purified by placing it in a large column and backwashing with water to remove fine particler. Then it was washed &h 3.19 H2S04 to convert it to the sulfate form until the effluent gave a negat,ive test with AlgSOa. Finally the resin was washed thoroughly with water until thc effluent gave a negatiw test Xvith IlaCls. The resin vias stored in a large desiccator containing snturat,ed R13r solution. Ion Exchange Columns. Conventional ion escliangc colunini, 9-mm. i.d. and 30 em. long, with gla;s xool and huret t a p a t the hott,orn viere used. The columns were fitted with 200-ml. dropping funnels connected
by one-hole rubber stoppers. The columns were loaded with 10.0 grams of resin slurried with water. The resulting resin bed was 21 cm. long. Procedure. DISTRIBUTION CoE F F I C I E X T 1 I m s n i w m x , r . One milliliter of the stock solut,ion of each metal was transferred to a 50-ml. toppered Erlenmeyer flask and evaporat,ed to dryness. Thirty milliliters of (SH4)*SOasolution of varying concentration with or without free sulfuric acid, and 1 gram of the dried resin were then added to the flask. The flask was stoppered and shaken for 20 hours mechanically at room temperature. The resin was removed by filtration and an aliquot of the filtrate was analyzed for cation hy an appropriate method ar described later. The distribution coefficient, Rdr mas calculat8ed by the following relationship:
K,j
=
amount of metal ionigram of dry resin amount of metal ion,;ml. of solution COLVMS SEPARATiOX. Before starting the elution the column should be
solution, by passing several column volumes of eluent t8hrough the column. .\dd to t,he coliimn 10 to 20 ml. of a mixt,ure of Sc(I1I) and the other met'al ions. The sample solution should be approxiiiiatmely0.1.11 in (S&)?SOI and 0.023.11 in H,SO,. The efl'ect of the concentration of frer acid is critical; thus, excess sulfuric acid should be ai-oided. Kash the column with 60 ml. of 0.131 (T\",)2S04-0.025AU H2SO4 and collect the effluent. This fraction cont~ains I'(II1) and rare earths(II1) a' nP11 a$ man) other ions including .ll(III), LktII). CdtII), Co(II), Cu(II), G a l I I I ) , Ge(IT'), 1 I g i I I ) , \In(II) Ni (11). 17(It7),and Zn(I1) Then elute SclIII) 111th 50 ml. of 1.U HCI or 60 ml. of'0.5 11 HzS04; collect the effluent and titiate with EDTA a$ outlined in Table I When lIo(V1) ii accoiniianied by Sc(III), elute Sc(II1) first n i t h about 200 ml. of 0 1-19 (SH4)2Q04-0.025X H2S041then lIo(V1) with 90 ml. of 0.5-11 SaOH-0.5X SaCI. If Th(I1') and T-(T'I) are prrsent, uash the column
s
I n 0.1;1.&SO4 1 media the distribution coefficients of Sc(II1) are approximately 4 over the concentration range of 0.03 to 2M ("&SO4. When the free acid concentration increases to 0.5M H2S04,
i
Table I.
Cation A.l(III), Ga(III), V(1V) 1 0.01
0.1
1 .o
Be(I1)
Concn. of (NHWO4 M
Figure 1 . Distribution coefficients of Sc(lll), Th(lV), Zr(lV), and U(VI) as funcconcentration tion of ("&SO4 Free acid concentrotion i s kept constant a t 0.025M HoS04. Resin, Dowex 1 X-8
Cd(II), Mg(II), Zn(I1) Co(II), Cu(II), Ni(I1) Fe(II1) Ge(1V) La(III), Lu(III), Sc(III), Sm(III), Th(IV), Y(II1) Mn(I1)
first with 0 1;M (~H4)~SO4-0.025~?1 Mo(V1) H2S04solution to iemove rare earths (111) and the other nonadsorbable ions above. Sc(I11) 16 recovered in the 100to 200-nd fraction of the same eluent, while Th(IV) and C(V1) remain strongly adsorbed on the column. Elute Th(IT/) n i t h 40 ml. of 451 HC1, then V(T-1) with 30 ml. of 1M l-IC104. Determine Th(1T') and V(V1) in the effluents, respectibely, a$ ouilined in Table I. If the sample solution contains rare earthi(II1) or Y(IIT), Sc(III), Th(lV), Zr(IV), and L7(VIi, elute first rare earths(II1) or Y(II1) and Sc(II1) chromatographically with 200 ml of 0.1.11 (SH,)2S04-0.025X HzS04 then Th(1V) mith 60 ml. of 1M (KH4)?SO40.02531 HzS04, Zr(1V) with 50 ml of 4JI HC1; and finally, U(V1) n i t h 30 ml. of lJ1 HC104.
U(VI) Zr(1V)
Sc(II1) Th(1V) U(V1)
the distribution coefficient of Sc(II1) becomes practically zero regardless of the concentration of ammonium sulfate. Results of separations of Sc(II1) in which a high ratio of other metal ions
Analytical Methods Used
Method Titration with EDTA using a mixture of 1-(2pyridylazo)-2-naphthol and its Cu salt as indicator Colorimetrically with p-nitrobenzene-azo-orcinol as reagent) Titration with EDTA using Eriochrome Black T Titration with EDTA using Murexide as indicator Titration with EDTA using Variamine Blue B, hydrochloride as indicator Colorimetrically with phenylfluorone as reagent Titration with EDTA using Xylenol Orange as indicator Titration with EDTA4using Pyrocatechol Violet as indicator Back-titration with CuSO4 in excess of EDTA using 1-(2-pyridylazo)-2-naphthol as indicator Colorimetrically with hydrogen peroxide as reagent Back-titration with Bi(SO3)3 in excess of EDTA using Xylenol Orange as indicator
Table II. Distribution Coefficients [(NH,)2S04medium in absence of free HBO,] (SHa)$O,, M 0 01 0 03 0 1 0 3 1 0 90 76 56 28 10 225 276 161 68 34 ... ... 1000 820 548
2 0 6 21 246
3 0 ... ...
201
~
RESULTS A N D DISCUSSION
In Figure 1 the val.ues for the distribution coefficients of Sc(III), Th(IV), Zr(IV), and U(V1) in sulfate media are given as a function of (NH&SOa concentration. The concentration of free acid is kept constant at 0.025M HZSO4. The figure indicates the possibility of separating Sc(1II) from C(VI), Zr(1V) , and Th(1V) as well as consecutive chromatographic separation of the four metals. Most metal ions show no or only slight adsorption on the strongly basic anion exchanger from the sulfate or sulfuric acid media ( I , 4 , 5 ) . Therefore the anion exchange-sulfate system seems to provide a basis for a specific separation of Sc(I11) from many other ions. I t must be noted here that the distribution coeffici'ents of the metal ions depend markedly on the free sulfuric acid concentration. The distribution coefficients of Sc(III), Th(IV), and U(V1) in ammonium sulfate system in the absence of the free acid are shown in Table 11.
Table 111.
Separation of Sc(lll) from Foreign Metals in (NH4)&04 Medium
Sc, mg. Added 2.56
0.930
2.56
2 56
Found 2.80 2.60 2.65 2.59 2.48 2.50 2.60 2.59 0.931 0,934
Al(II1) Be(I1) CdlII'I co(11 j Cu(I1) Ga(II1) Ga(II1) Ge(1V) La(II1) La( 111)
Foreign ions, mg. Added 44.8 20.0 47.6 42,3 49.4 40.2 10.0 20.0 10.6 96.5
Found 44.7 20.4 49.1 42.8 49.0 39.8 10.2 20.3 10.6 97.3
jV(V1)'
50.0
49 I
2.55 2.35 2.58 2.51
hl e( I1 hG(11j Mo(V1) Ni(I1)
59.6 44.4 10.0 50.0
59.6 44.0 10.0
2 53 2 59 2 62
V( IV) Zr(1V) Zn(I1)
40 0 38 9 50 1
39 5 38 9 52 0
50.7
VOL. 36, NO. 12, NOVEMBER 1964
2305
to Sc(II1) is used are presented in Table 111. The separation of Sc(II1) from large amounts of foreign metals is quantitative. La(”, Sm(III), and Lu(1II) are selected as typical rare earth metals. I3ecause Y(III), rare earths(III), Zr(IV), and Th(1V) do not shoiv noticeable adsorption on the anion exchanger from HC1 media, the procedure described seems to be useful for their separation. In addition, rare earths(III), Th(IV),and U(T’1) fractions are recovered sharlily from the column without any troublesome tailing. However, when large amounts of Th(IV), Zr(IV), or TJ(V1) (or all of them) are present, the Sc(II1) breakthrough tends to appear in a slightly earlier fraction of effluent, but the separation is still good.
The flow rate of eluent does not affect the chromatographic separation of Sc (111); a range of the flow rate from 0.5 to 1.5 ml. per minute can be used without disturbing the elution patterns of Sc(111) or the other metals. .imong the metals tested qualitatively, Ta(V) and W(V1) showed strong adsorption on the resin from the sulfate media, 0.1M (SHa)zS04-0.025Jl HzS04, while Fe(1lI) a,nd In(II1) were weakly adsorbed. h t the lower acid concentration employed here [0.025.11 HzS04-0.1V(XH&SOa], Ti( IV) is seriously hydrolyzed, partly passing through the column and partly being adsorbed strongly on the resin. Ti(IV) does not show any adsorption from the 0.5X HzSO~-O.lM (NH&SO4 medium.
LITERATURE CITED
(1) Bunney, I,. R., Ballou, S . E., Pascual, J., Foti, 8., ASAI,. CHEM.31, 324 (1959). ( 2 ) Hamaguchi, H., Kishi, RI., Onuma, X., Kuroda, R., Talanta 11, 495 (1964). (3) Harnaguchi, H., Kurodn, R., Aoki, K., Sugisita, It., Onurna, N., Ibid., IO, 153 (1963). (4) Kagle, R. A , , Murthy, T. K. S., Analyst 84, 37 (1959). ( 5 ) Sekine, T., Saito, S . ,A-ature 181, 1464 (1958). (6) Stevenson, P. C., Nervik, W. E., C. S. At,. Ehergy Cornm. K e p t . NAS-NS 3020, 1961. ( 7 ) Vickery, R. C., “The Chemistry of Yttrium and Scandium,” Perganion Press, Sew York, 1960. RECEIVEDfor review April 3, 1964. Accepted June 16, 1964.
Cation Exchange Separation of Titanium and Zirconium Using Perchloric Acid Application to the Analysis of PZT Ceramics R. G. DOSCH and F. J. CONRAD Organization 1 1
74,Sandia laboratory, Albuquerque, N. M .
b A
description is given of a cation exchange procedure for a quantitative separation of zirconium and titanium from lead and bismuth, and from each other, using HCIOd-NHJ mixtures and HClOd as eluents. This procedure has been applied to the analysis of highfired lead oxide-zirconium oxidetitanium oxide ceramic material (PZT).
H E USEFUL PIEZOCLIXTRIC propT e r r i e s of ceramic 13aTi03 has stimulated a search for other ferroelectrics suitable for fabricating piezoelectric ceramics. Shirane, Suzuki, and Takeda ( 1 4 ) and others (13) described the properties of solid solutions of PbTiOs and I’b%r03 and Jaffe, Koth, and Narzullo (6! 2 studied piezoelectric propertirs of lead zirconatelead titanate (WT) solid-solution ceramics. Small com1)ositional changes can produce marked changes in final piezoelectric properties. These variations can be minimized by close control of the constituents a t all stages of processing. To date, the composition of 1’ZT ceramics usually are determined empirically by memuring their physical and electrical 1)roperties. Knowledge of the composition during processing, and particularly in the finished ccramic, could be more easily obtained if the dis-
2306
ANALYTICAL CHEMISTRY
solution procedure and the method for separating Ti and Zr from the resulting solution, and from each other, were simplified. Brown and Rieman (3) used ion exchange techniques employing an HCIcit,ric acid eluent and I3elya Alimarin, and Kolosova ( 2 ) used 1X HCl in an ion exchange procedure for the separation of Ti from Zr. However, because either relatively large effluent volumes are required or pH control is critical, use of these methods has been limited. Other investigators ( I f , 12) have ut,ilized anion exchange techniques and HzS04-Sa2S04and HCI media, respectively, to separate Zr from a number of elements, including Ti. Use of the chloride ion i F undesirable in cases where cations form either insoluble chlorides or unknown complexes. Thus, many current ion eschange procedures suffer from one of three disadvantages: use of relatively large effluent volumes, critical control of eluent pH, or the presence of an undesirable anion. I n an investigation of the behavior of titanium( IV) in HClO,, 13eukenkamp and Herrington ( 2 ) reported the possibility of titanium(1V’i-perchlorate complexes forming at HC104 concentrations From their work in above 2.11. separating vanadium from titanium and other cations, Fritz and Abbink
(6) proposed that Ti(1V) could be separated from other tri- or quadrivalent metal ions using HC1O4-H2O2 eluent systems. This paper describes a cation exchange procedure for a quantitative separation of zirconium and titanium from each other, using an HCIOd eluent system. The method as applied to the analysis of PZT ceramics is briefly described. Solutions containing titanium and zirconium in amounts between 10 to 100 mg. of each element have been separated from each other. EXPERIMENTAL
Column Preparation. The borosilicate glass ion exchange columns were 30 X 1.0 cm. (i.d.) and 10 x 1.0 cm. (i.d.). The resin used was I>owex AG-5OWX8, 100- to 200-mesh, hydrogen form. Twenty-seven grams of resin, dry weight, were used in t,he larger columns, and 9 grams, dry weight, were used in the smaller columns. The resin was washed several times with distilled water, and the finest particles were decanted after each washing. The resin then was washed with 1.1- IICI, followed by distilled water until a negative chloride test was obtained. Reagents. TITANIUMELUENT. ; isolution of 257, HCIO, was prepared by diluting 178 ml. of 707, HC104 to 500 ml. with distilled water.
