Anion-Exchange Behaviour of a Number of Metal Ions on DEAE-Cellulose in Hydrobromic and Hydriodic Acid Media

R. K u r o d a / T . I sh ida /T . S e k i / K . Oguma

Laboratory for Analytical Chemistry, Faculty of Engineering, University of Chiba, Yayoi-cho, Chiba 260, Japan

Key Words

Thin-layer chromatography Anion-exchange DEAE-cellulose Hydrobromic acid Hydriodic acid

Summary

The adsorption behaviour of 48 metal ions on DEAE- cellulose layers has been investigated in aqueous hydro- bromic and hydriodic acid media. R F values are given as a function of the hydrobromic and hydriodic acid con- centration over the ranges 0 .01- -6mol dm -3 and 0.01-3 mol dm -3, respectively, and are compared with those obtained with Avicel SF. R F spectra are com- paratively simple in both media, reflecting the strong affinity of the bromide and iodide ions to the DEAE- cellulose phase. Pd, Pt, Re, Au and Hg are distributed chromatographically in either system, while most other metal ions exhibit rather ex t reme R F values of near unity or zero. Therefore, the selectivity of the systems is particularly high for Pd, Pt, Re, Au and Hg, providing the possibility of their excellent selective separations.

Introduction

The halide ions react with various metal ions to form halo complexes. This fact has been utilized in the anion-exchange of metal ions. Particularly chloride and fluoride media have been extensively investigated since the pioneer works of Kraus and Nelson [1], and of Faris [2]. So far, not so much information is available about the anion-exchange behaviour of metal ions in bromide and iodide media. Andersen and Knutsen [3] reported distribution coeffi- cients for 15 ions on a strongly basic anion-exchange resin in aqueous hydrobromic acid system. Klakl and Korkisch [4] provided distribution coefficients for 19 elements on D0wex 1 over a limited aqueous hydrobromic acid range of 0.15 to 0.9mol dm -a together with distribution coefficients from hydrobromic acid-organic solvent media. Herber and Irvine [5] studied the anion-exchange behaviour of Zn(II), Cu(II), Ga(III), Co(I1) and Ni(II) on Dowex 1 in hydro- br0mic acid solutions and demonstrated the possibility of

several separations of these ions from each other. W6dkie- wicz and Dybczyfiski [6] measured the distribution co- efficients of more than 30 elements in a weakly basic anion- exchange resin (Amberlite IRA-68) - hydrobromic acid (O.01-12mol dm -3) system. The systematic approach by Marsh et al. [7] revealed the adsorption behaviour of 58 elements from 0.1 to 8.7 mol dm -3 hydrobromic acid and from 0.1 to 7.4 mol dm -3 hydriodic acid onto three strongly basic resins, Bio, Rad AG 1, X4 and X8, and AG MP1. Anionexchange distribution coefficients with Bio-Rad AG 1, X9 were presented for Bi(III), Cd, Pb(II), Zn and In(III) in hydrobromic acid-nitric acid mixtures [8]. Limited information is available on the separation of Cd [9] and Pb [I0, 11] in hydrobromic acid, the separation of Cd in hydriodic acid [12], the separation of Zn from Cd in mixed iodide-sulphate medium [13] the separation of Cu in methanol-hydrobromic acid [14], and the separation of Cd in hydrobromicnitric acid mixtures [15, 16].

The present work was undertaken to reveal the possibility of adsorption of 48 elements from hydrobromic and hydri- odic acid media onto diethylaminoethylcellulose (DEAE- cellulose), a weakly basic cellulosic anion exchanger. The RF data were obtained by thin-layer chromatography. Although Bagliano et al. [17] already reported the R F values of 12 elements on DEAE-paper in hydrobromic acid solutions, this work has been extended to provide a more general aspect of ion-exchange taking place in hydrobromic and hydriodic acid media.

Experimental

Stock Solutions of Metals

Metal stock solutions (0.1 mol dm -a) were prepared as described previously [18]. The used solutions of platinum metals aged for one year after preparation.

Preparation of Thin-Layer Plates

DEAE-cellulose (Serva, Heidelberg, FRG, for TLC)was used as the adsorbent. For comparison, the microcrystalline cellulose Avicel SF (F.M.C., Marcus Hook, Pa., USA) was also used as an adsorbent. Both DEAE-cellulose (chloride form) and Avicel SF plates were prepared as described previously [19].

Chromatographia Vol. 15 No. 4, April 1982 Originals 223

0009-5893/82/4 0223-04 $ 02.00/0 �9 1982 Friedr. Vieweg & Sohn Verlagsgesellschaft mbH

Development

Metal ions (0.5mm 3) were applied to the plate 2cm from one edge, with micropipettes. After air-drying for 15 min, the plate was developed in a rectangular glass tank. When hydriodic acid was used as the developer, the developing tank was wrapped with a black paper to prevent photo- oxydation of hydriodic acid during development. The solvent front was allowed to rise t5 cm high from the start. The following solvent systems were tested: 0.010, 0.030, 0.10, 0.30, 1.0, 3.0 and 6.0mol dm -3 hydrobromic acid and 0.010, 0.030, 0.10, 0.30, 1.0 and 3.0mol dm -3 hydriodic acid. After the development, the plate was dried under an IR lamp. In the case of the hydriodic acid system, the plate was dried in a nitrogen gas stream. Metal ions were then detected in almost the same way as described pre- viously [18]. For detection of Fe(III), Co(II), Ni(II), Cu(II), AGO), Hg(II), TI(I), Pb(II) and Bi(III) in hydriodic acid media, dilute sodium sulphide solution and then dilute sodium sulphite solution were sprayed on the plates, in order to prevent the oxydation of sulphide to sulphate by iodine, which was generated from iodide by photo- oxydation. The R F values reported represent the averages of duplicate or triplicate determinations.

Results and Discussion

Adsorption of Metal Ions

Figs. 1 and 2 plot the Rr values of 48 metal ions on DEAE- cellulose ( C I - ) , as a function of the hydrobromic and hydriodic acid concentrations respectively; for the purpose of comparison, the RF values on Avicel SF are also given.

Adsorption in Hydrobromic Acid

As can be seen in Fig. 1, a group of metal ions show marked difference in their RF values between DEAE-cellulose and Avicel SF. Differences are particularly noticed in lower con- centration range of hydrobromic acid. This group of ions includes Se, Mo, Ru, Rh, Pd, Cd, Te, Re, Ir, Pt, Au, Hg and Bi. They are among those which are adsorbed on Dowex 1 from 0 .01-12mol dm -3 hydrobromic acid, but comprise only a fraction of elements exhibiting strong adsorption on Dowex 1 from hydrobromic acid solution [7]. Actually, the DEAE-cellulose acts as a more selective adsorbent than the strongly basic resinous exchanger in hydrobromic acid media. It is worth noting that a weakly basic anion-exchange resin, Amberlite IRA-68 (Br-), which is a polyacriylic-type resin having a -N(R2) functional group, behaves rather similarly to DEAE-cellulose in hydrobromic acid solutions in accordance with its basicity. In the Amberlite IRA-68- hydrobromic acid system [6] elements showing the strong adsorption are rather limited as is the case for DEAE- cellulose, and a group of elements including Pt(IV), Hg(II), Ag(I), Au(III), TI(III), Re(VII), Ir(IV), Mo(hydrolysis)and W(hydrolysis) are those which exhibit the highest adsorp- tion. They exactly coincide with the elements which show great differences in RF values between DEAE-cellulose and

Avicel SF in our system. Their adsorption trends on Amber. lite IRA-68 are much the same as those on DEAE-cellulose, the distribution coefficients (Kd) decreasing with increasing hydrobromic acid concentration. These trends appear to be caused by the competition of bromide ions and the already formed very stable bromo complexes for the ion-exchange sites.

Growing of bromo complexes, as indicated by increasing K4 values with increasing hydrobromic acid concentration, is noted for some of the first transition metals, i.e., V, Cr. Mn, Fe, Co, Cu and In, etc. for the Amberlite IRA-68 system. This is very slightly reflected on the trend in the RF values in DEAE-cellulose system, elongated spots only being form- ed at the highest hydrobromic acid concentration tested. RF minima found for Zn, Cd and Pb on DEAE-cellulose at 3.0, 1.0 and 1.0mol dm -3, respectively, appear as Kd maxima on Amberlite IRA-68 at approximately the same concentrations. In this way, the adsorption behaviour of metal ions on DEAE-cellulose is quite similar to those on the weakly basic resinous exchanger although the adsorp. tion on DEAE-cellulose is again more moderate than on the resinous exchanger. Owing to the moderate adsorption capability of DEAE-cellulose, it is rather suited as a suitable ion-exchange adsorbent in thin-layer chromatography, but not in column chromatography except for several metals showing the highest adsorption, such as Pt and Hg.

Thin-layer chromatography of 12 ions on amines and sub. stituted ammonium salts has been investigated by Brinkman [20] in hydrobromic acid media (0 .5 -8mol dm-3). RF curves for A1, Mn, Co and Ni on Amberlite LA-I, an un. saturated secondary amine, hardly differed from the curves given in the present paper, but more stronger adsorption took place on LA-1 for Fe~ Cu, Zn, Sb, Bi, Cd and Hg. Tertiary amines even allow Mn and Co to adsorb much tightly within the same hydrobromic acid concentration range as used in our present work. Again, DEAE-cellulose is more moderate than weakly basic liquid exchangers in ad- sorption strength toward metal ions. Naturally the R r spectra of 12 inorganic ions on DEAE-paper in the 0.5 to 6mol dm -3 hydrobromic acid range [17] are analogous to those given in Fig. 1.

As a whole, the adsorption behaviour of metal ions on DEAE-cellulose is rather extreme; there are many elements showing RF values near unity over the hydrobromic acid concentration range tested. This is probably because of the strong affinity of bromide ions to the DEAE-cellulose phase. The general selectivity sequence to the ion-exchanger: C1- < Br- < I - results in rather simple RF spectra in hydro- bromic acid (and also hydriodic acid) media. However, chromatographic distribution of several ions such as Re, the platinum metals, Au, Hg, etc. provides a very favourable, selective means for the separation of these ions.

Adsorption in Hydriodic Acid

Again simple RF spectra are obtained for most metal ions in hydriodic acid media. In accordance with the selectivity sequence for the anion exchanger: I - > Br-, the number of metal ions showing adsorption on DEAE-cellulose in this media is small as compared to hydrobromic acid media.

224 Chromatographia Vot. 15 No. 4, April 1982 Originals

Be(l l )

Cr(lll)

Ga(lll)

Mg (II)

Ii-+--i Mn(ll)

t.i+i.o+i Ge(IV) t,+,o,++...

Nb(V) Mo(Vl)

lir r ii!T+II Sb(lll) Te (IV)

, ",'11#++'+.+I t+~il++ I~t .... t l Jr{IV) Pt (IV)

;"+'i'" I"" t++'+

~++.. i l+++++m,

AI(III)

Fe(lll)

f.-.-i+i As(m)

,i g g .~ .~,~ "~

+ , , + ,

Ru(lll)

Ba(ll) ~o.ogg ] -+++#

Au (111)

il+++,++?

1.0

RF

0 . 5

�9 +o +~

i ~ . + . -

i i ~ i i i i

O.O1 0,03 0.10 O,30 I.O 3,0 6,0

Hydrobromic acid mot dm "3

Rh(lll) Pd(ll)

rii' 'II+ + ++ I! !++:! La(lll) Sm(lll)

'iiiiii 7 Hg(l l ) T [ ( I )

' tli i

Ca(ll)

t+++711 Co(lit

Se(IV)

A.q(I)

Yb(lll)

Pb(ll)

Sc(lll)

Ni(I1)

Sr(l l) !e*~ r176 ~,

Cd(II)

T i (IV)

Cu(ll)

Y(m)

In(lll)

v(w)

Hf (IV) W (Vl)

tr77T~ Bi( l I I ) Th(IV)

tl...;;, l++I ++~-+ + + + 1 111 . . . . .

Fig. 1 R F values of inorganic species on DEAE-cellulose (CI-) and on Avicel SF, in hydrobromic acid media.

Zn( l l )

Zr ( IV)

tl+l++ l+t! Sn(IV)

Re(VII)

t::::"I u(vi)

. i .~ , +~ ~ .l.+.t

0, DEAE-cellulose, I , Avicel SF. For convenience, the R F values on Avicel SF have been arbitrari ly displaced toward the left along the abscissa.

~q$,~.~ A~(,,,)

Cr (I11) Mn (11) Fe(lll)

Coa(lll) Ge(IV) As(Ill)

Nb(V) Mo(VI) Ru (1111

Sb(ltl) Te (IV) Ba(ll

lr(IV) Pt (IV) Au(lll)

t++";; tT+++T+Tt , , ~ * ~ . , ^ * &

1 . 0

RF

0 . 5

t iii il Ti(Iv) V(IV)

Cu(ll) Zn(ll

7r' l ++'+

Ca(ll) Sc(lll)

'~ t ..... ...... Co(ll Ni( l l )

tI t Se(IV) Sr[ll)

:TIT;t+I tliiiiii Acj(i) Cd(tl)

,~ .o @ ,,0. �9

Yb(lll Hf (IV)

Pb(ll) Bi(ll]) J+~ ~ o o+ +1

i r++L? +) [io ~, + + +

Y(III Zr(IV)

F 0 r i + i i

OOI 0 0 3 O10 0-30 1.O 3 0

Hydriodic acid mo[ dm -3

Rh(lll) Pd(ll) In(NI Sn(IV)

! tliiii ! +tftttt+t+ La(lll S m ( t l l ) W (Vt) Re(VII)

C f 2 tT+ll l +l " " Hq (TI) TI(I ) Th(IV) U(Vl)

o o o v

t+o++;o;i ti7[17 tTi"7, Fig. 2 R F values of inorganic species on DEAE-cellulose (CI-) and on Avicel SF, in hydriodic acid media.

0, DEAE-cellulose, i , Avicel SF. For convenience, the R F values on Avicel SF have been arbitrari ly displaced toward the left along the abscissa.

Chromatographia Vo l . 15 No. 4, A p r i 1 1 9 8 2 Or ig inals 225

1.0

RF

Mn

0.5 Re

Pt

Re

i �84 .5;;

Zr

.=,_.

(c)

Ga

Sn

Sb Sb

(d)

Ni Ni - '-..,' Ni Re

i

~:~ ~ ~ Hg Pd i ~i Cd Cd ~-

Fig. 3

Separations of some inorganic ions on DEAE-cellulose (Cl-) layers, in hydriodic acid media.

Developers: (a) 0.1M HI (b) 0.3M HI (c) 1.0M H I (d) 3.0M H I

Nb, Mo(tailing), Rh, Pd, Cd, Re, Ir, Pt, Au, Hg and Bi are among those which exhibit ion-exchange adsorption on DEAE-ceUutose; therefore, there are great differences in the RF values between DEAE-cellulose and Avicel SF parti- cularly in the lower concentration range of hydfiodic acid. It is interesting to see that the adsorption trends of Mo, Rh, Pd, Re, Ir, Pt, Au, Hg and Bi, just cited above, are much the same as found in hydriodic acid - Dowex 1 media [7], as far as the same acid concentration (up to 3 mol dm -a) is concerned. Their adsorption strength is decreasing with in- creasing hydriodic acid concentration, both for DEAE- cellulose and Dowex 1. This reflects the high affinity of iodide ion to the DEAE~:ellulose phase as well as to Dowex 1, so that there may be a competition between iodide and the already formed iodo complexes. Growing of iodo com- plexes leading to higher adsorption with increasing hydri- odic acid concentration is not reflected at all in the trend of the R F values; this metal group shows R F values o f near unity, as seen for Co, Zn and As: (see ref. [7] for their Kd values on Dowex 1 in hydriodic acid media).

Reductive properties of hydriodic acid as well as the forma- tion of insoluble iodides complicate the trend of the R F values for some ions. Cu(II) is reduced by iodide to form insoluble Cu2I: and Au(IlI) is reduced to metal. Pd(II), Ag(I), TI(I) and Pb(II) are known to react with iodide to form insoluble iodides, which will be converted in an excess of iodide to iodo complexes. Se(IV) and Te(IV) may be partially reduced to metallic states. These reactions lead to a complex trend of the RF values; particularly the solubility of a precipitate appears to affect appreciably the form of the RF curves. Formation of an insoluble precipitate is characterized by the RF curve which traces a pronounced minimum on Avicel SF, as found for Pd, Ag (see upward trailing at 0 .01mol dm -a I - ) , Cu, T1 and Pb. For these metals the formation of soluble iodo complexes may be evident from the trend of the RF values on DEAE-cellulose, which increases with increasing hydriodic acid concentration.

Separa t ions

Investigation of the RE values of the metals chromatogra- phed on DEAE-cellulose in hydrobromic and hydri0dir acid media permits the analyst to carry out a number of separations. Several chromatograms obtained in hydri0dic acid media are illustrated in Fig. 3. The selective separation of ions showing a RE distribution may also be feasible using either hydrobromic or hydfiodic acid as the developer.

R e f e r e n c e s

[1] K . A . Kraus, F. Nelson, Proc. Intern. Conf. Peaceful Uses Atomic Energy 7,113 (1956).

[2] J.P. Faris, Anal. Chem. 32, 520 (1960). [3] T. Andersen, A. B. Knutsen, Acta Chem. Scand. 16,849

(1962). [4] E. Klakl, J. Korkisch, Talanta 16, 1177 (1969). [5] R. H. Herber, Jr. IV. lrvine, Jr., J. Am. Chem. Soc. 76,987

(1954). [6] L. W6dkiewicz, R. Dybczy~ski, J. Chromatogr. 102,277

(1974). [7] S. F. Marsh, J. E. Alarid, C. F. Hammond, 114. J. McLeod.

F. R. Roensch, J. E. Rein, "Anion-Exchange of 58 Elements in Hydrobromic Acid and in Hydriodic Acid", Los Alam0~ Scientific Laboratory Report UC-4 (February 1978).

[8] F. W. E. Strelow, Anal. Chem. 50, 1359 (1978). [9] F. IV. E. Strelow, W. J. Louw, C. H. S. W. Weinert, Anal.

Chem. 40, 2021 (1968). [10] F. W. E. Strelow, F. yon S. Toerien, Anal. Chem. 38,545

(1966). [11] J. Korkisch, H. Gross. Mikrochim. Acta 1975 II,413. [12] S. Kallmann, H. Oberthin, R. Liu, Anal. Chem. 30, 1846

(1958). [13] E.R. Baggott, R. G. If. Willcocks, Analyst 80, 53 (1955). [14] J. Korkisch, L Steffan, H. Gross, Mikrochim. Acta 197511,

569. [15] F. W. E. Strelow, Anal. Chim. Acta 97, 87 (1978). [16] F. W. E. Strelow, Anal. Chim. Acta 100, 577 (1978). [17] G. Bagliano, G. Grassini, M. Lederer, L. Ossicini, J. Clare

matogr. 14,238 (1964). [18] R. Kuroda, K. Oguma, M. Otani, J. Chromatogr. 96,223

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togr. 139,355 (1977). [20] U. A. Th. Brinkman, G. De Vries, E. Van Dalen, J. Chrc,

matogr. 23,287 (1966). Received: Nov. 23, 1981 Accepted: Dec. 3I, I981 A

226 C h r o m a t o g r a p h i a Vo l . 15 No. 4, Ap r i l 1982 Originals