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Anion-exchange behaviour of the platinum metals and gold in hydrochloric acid-organic solvent media
Talantn.
1968.
Vol.
15. pp. 339 try 346.
Pcrgamon
Press.
Rmtcd
in Northern
Ireland
ANION-EXCHANGE BEHAVIOUR OF THE PLATINUM METALS AND GOLD IN HYDROCHLORIC ACIDORGANIC SOLVENT MEDIA J. KORKISCN* and H. KLAKL Analytical Institute,
Umverstty of Vtenna IX, WIhringerstrasse
(Recelced 7 AI~W
38, Austria
1967. Accepted 27 October 1967)
Summa~-The amen-exchange characteristrcs of the platmum metals and gold III hydrochlortc acrd medra are descrmed. The drstrrbutton coefficrents of these elements were measured on the strongly baste amon-exchange resm Dowex 1 x 8 in mtxtures of hydrochlorrc actd wrth water and several organic solvents, i.e., dtmethylformamrde, acetone, tetrahydrofuran, droxan, methanol, acettc actd and pyrtdme. Based on these data the condtttons most suttable for quantttattve separation are indicated and drscussed.
DUE to the fact that the platinum metals and gold readily form stable anionic chloride complexes most of these elements are strongly retained by strongly basic anionexchange resins from pure aqueous hydrochloric acid media. The least strongly adsorbed platinum metals are the tervalent ions of iridium and rhodium. Consequently most methods so far reported for the anion-exchange separation of the platinum metals from one another are concerned with separations of iridium and/or rhodium from the rest of the platinum metals.1-9 The strong adsorption of the anionic chloride complex of gold has also been employed for the anion-exchange separation of this element from a number of metal ions.rO-24 For the elution of the adsorbed gold, mixed aqueous-organic solvent solutions containing hydrochloric acid have been used.13 Except for this latter application no attempt has so far been made to investigate systematically the anionexchange behaviour of gold and the platinum metals in hydrochloric acid-organic solvent media. In order to obtain a much more complete picture of the adsorption characteristics and separation possibilities of these elements in organic solvent media, the work presented in this paper was performed, using the most frequently employed anion-exchange resin Dowex 1 in mixtures of 7 organic solvents with hydrochloric acid. For this purpose the effect of increasing concentration of organic solvent and the effect of acidity on the adsorption of the platinum metals and gold were investigated by measuring the distribution coefficients in numerous mixtures of varying composition. From the distribution data thus obtained, the possibilities of separating the elements from one another are indicated and discussed. EXPERIMENTAL Rerqpc”:s ion-ex&ngc resin. The air-dried strongly basic amon-exchanger Dowex 1 x 8 (100-200 mesh, chloride form) was used for the column and batch experiments. Stmdard sofurhs. Weighed amounts of the chlorides of ammonium tetrachloroplatinate(II), hexachloroplatinic acid, palladium(B) chloride, ammonium hexachloropalladate(, ammonium hexachloro-osmate(IV), potassium hexachloroiridate(III), ammonium hexachloroiridate( + Present address: Argonne National Laboratory, Chemistry South Cass Avenue, Argonne, Illinois 60739 U.S.A. 339
Division, Bldg. 200. M121, 9700
J. KORKXSCH and H.
340
KLAKI.
TABLE I-DISTRIBUTION COEFWIENTSOF PLATINUMMETAu AND GOLJJ DOWEX t IN PURE AQUEOUS lWDROCHU)RIC ACID SOLUllONS
Metal ton
WI)
Pt(IV) W(H) W(W) Os(IV) Ir(III) Ir(IV) Ru(III) Ru(IV) Rh(III) Au(II1)
12
9
480 430 32 33 1100 19 700
710 870 50
IS 1500 25 25 1.6 I@
:: 1.6 470
DOWEX
Metal ion
1 IN
3
IO”
22’ 90 70 35i7
COEFRCIENTSOF
1.2
3600 500 350 IO* 7.7 7000 300 420 7 IO’
PLATINUM
METALS
DI~~~~E-~R~H~~C
ACID
13g 1600 10‘ 16 10” 650 820 20 IO‘
AND
GOLD
MIXTURE.5
Final HCI concn., iU, m the presence of dtmethylformamtde (% v/v) 6 (50) 3 (75) 0.0 (100) 9 (25)
R(II) PWV) Pd(I1) Pd(Iv) Os(Iv) k(W)
100 115 II 2::
IrtIV) RUOII)
Isi2
Ru(IV) Rh(II1) Au(II1)
,M
2800 1900 120 80 4800
37;
TABLE II.-D~~TRIBv~oN ON
Fmal HCI concn 6
ON
40 60 IS 15 120
5Y
17 I.3
11 0.9
42202
9k8
30 :: 23 26 20 23 1.1 t2 I.8 7
::: >1500
TABLE III.-DISTRIBUTION COEWICIEN~SOF PLATINUMMETAU AND GOW ON DOW 1 IN ACETONE-HYDROCHLORIC ACXD MIXTURES
~~ Metal ton PtfII) Pt(IV) Pd(I1) Pd(IV) Os(IV) Ir(II1) Ir(IV) Ru(II1) Ru(IV) Rh(II1) Au(II1)
Fmal HCl concn , M, m the presence of acetone (% v/r) 1.2 (90) 9 (25) 6 (50) 3 (75) 250 200 27 26 >500 3’ >5OOt 90 60 3 380
>800 >lOOO 2 >750 30 >8OOt ,700 >800 30 130
>700 >2so 150 150 Xi00 >800 >7oOt >7OO >1800 900 7
>lOOQ >lSoO z! >lOOO >lOOO >1OOOt >I300 >3oGO >lOOO 2
Partial oxrdation of trtdium to tts higher oxzdatron state occurs m this medium. t Partial reductton of irrdium to its lower oxtdatton state occurs m these media. l
I-liial WY
-
hlcral 10n
.- -___
201icn .
M, in the prcscnce of
9 (25)
_.~~._.__.__ 930 700 30 27 1200 3* so0 13OOi 1300t 4 380
Plfll) Pt(IV) Pd(ll) Pd(IV) OS(N) Ir(ll1) II.(IV) RuUlI) Ru(IV) Rh(llI) Au(W)
Ictrali)'drofur,ili ( “,,
6 (50)
3 (:5)
: 500 SO0 60 75 750 30* 400 >500 . 700 ‘2 35
400 600 120 120 : 900 400 ;a400 :-500 ; 1100 260 2
,,I)
1 2 (90) __. -__.-. 1OJ . IOJ 250 : 400 , 800 >lO’
: Go0 6000 -8000 >600 2
* Partial oxcldatton of lrldlum to Its htgher ovldatlon state occurs in these media t In these media dlstrlbutlon coefficients of 60-70 were also measured. TABLE
V-DISTRIBUTION COEFFICIEYTS OF PLATINUM METALS AND ON DouEx 1 1s DIOXAN-HYDROCHLORIC ACID MIXTURES
Metal Ion
Fmal HCI concn., kf, m the presence of dloxan (T; t/l>) 6 (50) 9 (25)
Pt(I1) Pt(IV) Pd (II) Pd(IV) OS(N) Ir(IlI) Ir(IV) RU(IlI) Ru(IV) Rh(T1 I) Au(U) l Parka1 oxldatlon these media t Partial reduction these media.
TABLE GOLD
GOLD
250 270 40 30 600 10’
390
285 25 20 610 2’ 2OOt 20 19 3 310
80t 3 3 9 ‘40
of lrldlum to Its higher oxldatlon
state occurs m
of lrldmm to its lower oxldatlon
state occurs m
VI -DISTRIBUTION COEFFICIENTS OF PLATINUM METALS AND ON DOWEX 1 IN METHANOL-HYDROCHLORIC ACID MIXTuRES
Metal ion Pt(I1) PUN) Pd(I1) Pd(IV) OS(W) Ir(II1) Ir(IV) Ru(II1) Ru(IV) Rh(III) Au(III)
Final HCl concn., M, m the presence of methanol ( % z/I ) 3 (75) 6 (50) 9 (25) 330 >300 37 40 900 3 >640* 39 4.5 25 >I200
>12DO >llOO 130 110 :2000 15 1600* >900 >llOO 18 850
>1500 >18 500 600 ~6000 430 >7000’ r40OO :-5000 300 500
* Partial reduction of lridlum to its lower oxtdatton state occurs m these media
342
J KORKISCHand H. KL.AKL TABLE VII.-DISTRIBUTION COEFFICIENTS OF PLATINUMMETALSAND GOLD ON DOWEX 1 IN ACETIC ACID-HYDROCHLORIC ACID MIXTURES
Metal Ion Pt(II) Pt(IV) Pd(II) Pd(IV) Os(IV) Ir(II1) Ir(IV) Ru(IlL) Ru(IV) Rh(II1) Au(II1)
Fmal HCl concn., M, in the presence of acetlc acid (% c/u) 9 (25) 3 (75) 6 (50) >2500 >3ooo 36 34 >2000 2 >1200* 3’ 43 3 >lP
103
103 15 75 >2000 14 1500* >600 >550 17 750
>8000 >6000 400 500 >SOOO 200 >7ooo* >3ooo >6OOO 210 400
* Partial reduction of lrldlum to Its lower oxldatlon state occurs in these media. TABLE VIII.--DISTRIBUTION COEFFICIEN-BOF PLATINUMMETALS AND GOLD ON DOWEX 1 IN PYRIDINE-HYDROCHLORIC ACU) MXTURES
Metal Ion
Fmal HCl concn., M, m the presence of pyrldme (% c/u) 9 (25) 6 (50) 3 (75)
Pt(I1) Pt(IV) Pd(I1) Pd(IV) OS(W) Ir(II1) Ir(IV) Ru(II1) Ru(IV) Rh(II1) Au(III)
35 32 11 9 50 1 1 4 2 1 >1oot
2 1 1 rt 5 40 1 1 25 1 1 >50t
1 1 1 <2 5
* Partial reduction of irldlum to Its lower oxldatlon state occurs
in this medium t Gold IS virtually Insoluble m these media. ruthemum(II1) chloride hydrate, ammonium hexachlororuthenate(lV), ammomum hexachlororhodate(III) and tetrachloroaurlc acid were dissolved In 12M hydrochloric acid to give solutions contammg not less than 0 5 mg of element/ml Soluents. The reagent-grade pure orgamc solvents used were dmethylformamlde, acetone, tetrahydrofuran, dloxan, methanol, acetic acid and pyrldme. Determmation of dutnbutlon coejiclents Most of the lstrlbutlon coefficients of the platmum metals and gold were determmed by the column method*s, 1 g of air-dried resm bemg used m each case. Other dlstrlbutlon data were obtamed by the batch method.xa For the detectlon and determmatlon of the platmum metals and gold, sultable colour-formmg reagents have been used.27 RESULTS
AND
DISCUSSION
In Tables I-VIII are shown the distribution coefficients of the platinum metals and gold in the various media that have been investigated. Although the adsorption
343 TABLE ix---SEPAR4TIOY ---___-_
pw,
~.~:x,llJon ______-
Ft;IJ, Pd:lJ) P&l\ j- l’diI1) Pt(lI)-Pd(IV) Pt(I\)-Pd(lV) Pt(Il~-Os(IV~ Pt(IV)-OstJV) Pt(II)-lrflll)
Pt(IV)-IrUIJ)
Pt(JI)-Ru(III) Pt(IV)-Ru(Il1) Pt(II)-RujlV) Pt(:\?-Ru(lV) Pt(II)-Rh(llIJ
PNIV)-Rh(III)
Pt(II)-~LI~JII) Pt(IV)-Au(JI1) Pd:II)-Os(IV) Pd(I\‘!-Os(IV) Pd(II) -Ir(III) Pd(IV)-Ir(lIl) Pd(II)-Ir(IV) Pd(IVklr(IV) PdCII)-Ru(III) Pd(IV)-Ru(IiI) Pd(II)-Ru(IV) PdUV)-RuUV) Pd(Il)-RhUII) PdCIV)-Rh(IIJb Pd(JI)-Au(IIJ) Pd(IV)-Au(II1) Os(IVj-Ir(II1)
OS(w)-IrlIV)
GOLD
Oh
DOWEX
1
____--~.--
-----I_
M&al IOII
I-ACTORS OF PLAT1L.I XX MTTIL5 AND IN HYDROC’~i~~RIC AC 11) -C)LVI 1’3XS
-
l-actors
-
IG(\\). lS(Wj, 12(Dbli-), _ IW)~DblF), 9(A), c 19(A), >3O(THF), i(D), JQJ)), 9thi1, >7O\AX) il(\Y). li(u’), IO(DMb), _ lOOO(DMF), 7(A), , 23(A), 23(THF), 7(D), I?(D). . S(M). --Sj(4A) 13(W), 15(W), 12:DMF). JOcA), : 19(A), 36(THF). 20(D), ND), 8(M), ?3( 4A). 13(W), 16(W), IO(Dhlr), S(A), : 23(A), : 2S(THI‘), 9(D), 15(D), 8(M), Sh(4) 30(P) 20(P) 250(W), 370(W), IXO~W), 1200(W), IOOOCW), 95(DMF), 4l(DMF), l?fI>MF), 83/A,. 3 28(A), 3- 3O(TIJF), IStTHF), 180(D), 23(D), 110(M), __ SO(M), > IZScj(AA), 75CA.4). 35(P). ,“201\t), 580(W), 13OOfW). 900(W). l@OOCW), 83(DMF), 30(DMFJ, SID~JF), 67(A). > 33(A), ,_ 23(THF), 170(THF), 130(D), 25(D), > 100(M), _ :41X1), _ ISUO(AA). %(AA), 3OlP) ‘!-J(v\ ), 28(W), 68(l?Mk :, 55(DMF), 27tDMr). 19(D), S3(D), 8 5(M), SO(A4 t 39(R’). 35(W), 59(DMF), 36fDMF). IS(DMF), 15(D), 90(D), 8(M), 90’ %A) 37(W), 18(W), 77(DMF), 67(DMF), :0(D), SXD). 7(hI), >6O(AA) 29th). 35(W), SP(DhfF), 44tDMF), 15(D), 90(D), ;-7(M), >70tAA) 300W J 440(W), lOOOiW), 730(W), 1000(W), XCDMF), 32(DMF), IEcnkIJ j. 83(A), : 33(A), >2?2(THF), 20(THF), 130(D), 28(D), 130(M), 33(M), ‘30(AA), 6O(AA), 35(P) 27O(Vv ), 54OiWl. 7OO(N’), 530(W), 1000(W), 45(DMTJ, 23(DMF), 67(A), :- 331 A), 2175(THF) 23(THF), 100(D), 30(D), ; 120(M), 40(M1 lW’UA4), 6NAA), 3’f Pj _ !!10;4). Y %OCA), l!(THFj, ;- ZOO(THF), : 5ONTHF), =-25(P). X(h), 3> :30(A), I-;:THF), --300(THF), :- SOOCTHI:), >25(Pj .i’(k 1, Got\\‘). 2! (SMF). SCDMF), >15001DMJ’), ‘-18(A), > 17(A) 40\7HF), 24(D), 15\D), :,24(M), ‘>55(A4), 5tP). 40(P) 33i\V), <~(WJ, :l(J)MF), 7(DMF), :-18(A), ; 17(A), 44(THF), 32(D), 20(D). z Zt(>fb, :-59144) 5(P), -,26(P). 161\%.‘,:?!cWr, 5X%‘), 66(W). 84(W), 9(DMF), ll(DMF), z 15OO(DhIF), 3,A) J(‘,YrlF), 3(D), IZfM), 9thI). 18(AA), 5(AA) l-(111. j;C\\) 35(‘W.X(\\‘), 105(M’J,9(DMFJ, lO(DMF), ll(DMF),g(A), 9,;‘HF). 7(M). l?tTcli, 5(A4), 17CAA) XWI 301\\), lj(DMF), >30OO(DMF), :. 18(A), 17(THF), 8(D), ,>17(h!,, . X(&4). 5(P) 21(W), 3-/(W). JSfDMF), .--19(A), :-18(A), 19(TJ_II=), IO(D), ;16(M), ._ 35th 4) 6(P). 6CDMF), 14[DMF), 16(Dhft), --5OOO(DMF), : 16(A) 6fDhiIF). 13(DMF), ?l(DMF). =16(A). : 9fDMF). > IXOCDMF), lS(4) . 1 l(D\fF), 18(A) 191Y ), 31!Wj, 44(W), ?5(W), 65(W), 5(DMF), 8(DMF), lO(DMF), : 2100(DMFj, 9i4), 7(THF), S(D), 15(M), 7(M). 12(AA), 4(AA), 10(P) 11 f\q 33(W), 30(W), 51&V) SO(W), SCDMF), 8\DMF), 13(DMF), 9(A); 7tTHF). 6(D). 16,&l). 4Ch,l,. II( 4CAA1. 9(P) J4CWj ‘2OCW;. 3S(DMF), G(DMF), >~lOO(l%iF$, 35(A). 200(A), 60(THF), 12% THl-1, I?(D), h(D), ;- J\(M), r28(A), 10(P), ; 50(P) 14(\i), lS:W), 3S(DMF), GCDMI-;. 25(A), 300(A), 60(THF), >?OO(THF), 16(D), S(D), ,--29(M). > Bl(AA), 11(P), > 33(P) 580(H’), 2500(\\). 2100(kb). >lOOO(W), 1000(W). 190(DMF), 90(DMF,, 13CDMF). 3 17(A), - ‘5(A). 4OO(THF), 25(THF), 280(D), 54(D), 3 300tMi = 13@(M), 3=t(‘OO(AAj, > 160(AA), 48(P), 40(P) 39flY
344
J KOKKISCH
and H
KLAKL
TABLE Ix. (Cont.) Metal Ion pairs OS(N)-Ru(II1) OS(N)-Ru(IV) Os(IV)-Rh(II1)
OS(N)-Au(II1) Ir(III)-Ru(II1) Ir(III)-Ru(I\‘) Ir(III)-Au(II1)
Ir(IV)-Ru(II1) Ir(IV)-Ru(IV) Ir(IV)-Rh(II1)
Ir(IV)-Au(II[) Ru(III)-Rh(III) Ru(IV)-Rh(II1) Ru(III)-Au(II1) Ru(IV)-Au(II1) Rh(III)-Au(II1)
Separation factors 100(W), 150(W), 140(DMF), lIO(DMF), ‘4(DMF), 30(D), 200(D), >23(M), >62(AA) 73(W), 150(W), 170(DMF), 14O(DMF), >l?(DMF), 32(D), ZOO(D), >20(M), >46(AA), 24(P), 40(P) 690(W), 2300(W), 1800(W), 1000(W), >lOOO(W), lOO(DMF), 70(DMF), 14(DMF), >17O(A), i29(A), 300tTHF). 34(THF), 200(D), 70(D). 36(M), 71(M), 670(AA), 130(AA), 48(P), 40(P) 87(A), -,500(A). 21(THF), >45O(THF), /4OO(THF) 6(W), 17(W), 39(W), S?(W), 23(A), 17(THF), 13(M), 60(M), 16(AA), 43CAA) 8(W), 17(W), 30(W), 51(W), 37(W), .-27(A), -23(THF), 15(M), ,77(M), ?l(AA), >43(AA) 250(W), 670(W), 1500(W), 1000(W), >lOOO(W), 35O(DMF), 64(DMF), 130(A), 4 3(A), 110(A), >5OO(A), 130(THF), >‘OO(THF), zSOO(THF), 130(D), 22(D), 380(M), 57(M), : 500(AA), 5JL4A). > 100(P), >5O(P) 65(W), 60(W), 94(DMF), 45(DMF), ?l(DMF), 10(D), 27(D). >16CM), 37(AA), 14(P) 47(W), 60(W), l?O(DMF), s-Il(DMF), 10(D), 27(D), 14(M), ,‘8(AA), 28(P) 430(W), 940(W), 960(W), 1000(W), 1000(W), 73\DMF), 28(DMF), 13(DMF), >170(4), >27(A), lX(THF), >18CTHF), 67(D), 9(D), 126(M), 57(M), ;4OO(AA), 90(AA), 57(P). > 100(A), ‘500(A), bll(THF), >2OO(THF), > 3OO(THF), : 50(P) 7(W), 16(W), 33(W), 46(W), 32(W), :-23(4), : 20(THF), ;23(THF), 7(D), 16(M). ‘.- ,2(M), 43(AA), >35(4A) 9(W), 16(W), 26(W), 60(W), 41(W), 20(A), ?O(THF), 27(A), >32(THF), 6(D), 18(M), > 41(M), 53(AA), : 32(AA, 43(W), 40(W), ?SO(DMF), 83(DMF), :-100(A), ;650CA), > 14(THF), 3000(THF), 15(D), 80(D). >250(THF), 31(M). :-31(,44), _ 25(P) 31(W), 40(W), 3’0CDMF), IOOcDMF), r 260( 4). _ 1500(A), _-ZO(THF), >7OO(THF), >- JOOO(THF), 16(D), 80(D), 37(M), : 23(AA), ;.5O(P). 290(W), 625(W), 1300(W), /~lOOO(W), 1000(W), l’)OCDMF), 50(DMF), 130(A), 4 3(A), ;-500(A), 95(THF), 130(1HF). : 300(THF). 100(D), 27(D), >150(M), 17(M), , 125(AA), 21(A4), 21(AA), ilOO( :50(P).
W = water, DMF = dlmethylformam~de, A -- acetone, AA - acetlc acid, P = p)ridme choxan, M = methanol,
THF =- tecrahgdrofuran,
D =
of these elements on strongly basic amon-exchange resms from pure aqueous hjdrochlorlc acid solutions has previously been described bq several 1i1\estlgators,3’-“‘*-31 the adsorption values are recorded m Table I so that thege data can readily be compared with those m Tables II-VIII The datnbutlon coelliclents of the platinum metals recorded m Table I are m good agreement with those that have been measured earlier. In the case of the adsorption of gold, howevel, all values are lower by about one order of magnitude at high hydrochloric acid concentrations In order to avoid a rather lengthy dlscusslon of the separation posslbJltles of the platinum metals and gold m the various media listed m Tables I-VIII, numerous experimentally determined separation factors of many pairs of metal ions m these mixtures are recorded in Table IX From these results It is seen that m the mlxed aqueous-organic solvent systems higher separation factors are found and hence better The separation possibilities exist than m pure aqueous hydrochloric acid systems separation factor of any given pair of ions IS the ratio of the dlstrlbutlon coefficients of the two elements as measured under ldentlcal experimental condlllons. Difficulties m determining the separation factors have been encountered m all
Anron-exchange
of the platinum metals
34s
those systems containing iridium, which when present in the tervalent state is partly oxidized to the quadrivalent form which shows different adsorption characteristics. The same is true when iridium(IV) is present; this is partly reduced to the tervaient state. Therefore separations involving this element cannot readily be carried out. Separations that cannot be performed by the application of pure aqueous hydrochloric acid systems include those of Pt(II)-Os(IV), Pt(IV)-Os(IV), Pt(II)-Au(III), Pt(IV)-Au(III), Pd(I1 jRu(III), Pd(II)-Ru(IV), Pd(IV)-Ru(IV), Os(IV)-Ir(IV), Os(IV~Au(II1) and Ir(IV~Au(II1). These separations can, however, effectively be carried out in the presence of organic solvents (see Table IX). This once more illustrates the usefulness of organic solvents for ion-exchange separations of metal ions. In the case of separations involving the elution of gold with acetone or tetrahydrofuran each containing hydrochloric acid, the combined ion-exchange-solvent extraction (CIESE) principle described earlier32 makes these separations possible. Zu~mmenfas~ng-Das Anionenaustau~hverilalten der P~atlnmetalle und Gold m salzsauren Medken wlrd beschrleben. Die Vertedungskoeffizlenten dleser Elemente wurden an dem stark bastschen Amonenaustauschharz Dowex 1 x 8 m Gemlschen von Salzsaure mlt Wasser und mehreren orgamschen Losungsmltteln wte Dlmethylformamld, Aceton, Tetrah drofuran, D~oxan, Methanol, Esslgsaure und Pyrldm gemessen. Au i! Grund dleser Daten werden die zur quantltatlven Trennung am besten geelgneten ~dIngungen angegcben und diskutlert. R&urn&On d&It, du pomt de vue echange aniontque, les caract&lstlques des m&aux du groupe du platme et de l’or, en milieu aclde chlorhydrlque. Les coefficients de partagc de ces elements ont et6 mesurCs sur la r&me &hangeuse d’amons fortemcnt baslque Dowex 1 x 8 dam des mtlanges d’aclde chlorhydrlque avec I’eau et plusteurs solvants organrques, c’est-&-dire dIm~thyIformam~de, acetone, t&ahydrofuran, dloxane, methanol, aclde ac&que et pyndme. En se basant sur ces don&es, on mdlque les condmons convenant le mieux B la separation quantltatlve et en dlscute. REFERENCES 1. A. G. Marks and F. E. Beamlsh, Anal. Chem., 1958,30,1464. 2. W. M. MacNevin and W. R. Crummett, tbrd., 1953,25,1628; Anal. Chtm. Acta, 1954, IO, 323. 3 S S. Berman and W. A. E McBryde, Can. J. Chem, 1958,36,835. 4. Zdem, rbid., 1958,36,8JS. 5. M. L. Cluett, S. S. Berman and W. A. E. McBryde, Analalyst, 1955,80,204. 6. D. S. Busch, J. M. Prosper0 and K. A. Naumann, Anal Chem., 1959,31,884. 7. Coufalik, F., and M. Svach, 2. Anal. C/tern., 1960,173, 113. 8. E. Blasms and U. Wachtel, 2. Anal. Chem., 1954,142,341. 9. E. Blasius and D. Rexin. IbId.. 1961.179. 105. 10. A. B. Davankov and V. ‘M. L&fer, iaoo>sk. Lab., 1956,22,294. 11. Idem, Zk. Prtkl. Khim., 1956,32,788. 12. S. Sussman, F. C. Nachod and W. Wood, Ind. Erg. Chem., 1945,37,618. 13. A B. Davankov and V. M. Laufer, Zh. Pnkl. Khlm., 1959,32,727. 14. M. V. Darbmyan and E. E. Kapantsyan, Int. Akad, Nauk Arm. SSR, Khim. Nauki, 1965.18,18. 15. S. Hirano, A. Mizuike and K. Yamada, J. Chem. Sot. Japan, Ind. Chem Sect , 1959, 62, 1494, 16 S. Htrano, A. Mizuike and Y. hda, Japan Amlyst, 1960,9,423. 17. D. H. Wdkms and L. E. Htbbs, Anaf. Chim. Acta, 1959,20,273. 18. A. C. Pappas, J. Alstad and G. Lunde, Radjochjm. Acta, 1963.1, 109. D. Brune, K. Sam&l and P. 0. Wester, Afompraxs, 1963,9,368. ;:: D. Brune, K. Samsahl and I?. 0 Wester, Aktreboiaget Atommergl AE-134, Stockholm, Sweden, 1964. 21. P. 0. Wester, D. Brune and K. Samsahl, Intern. J. Appl. Radiation Isotopes, 1964, IS, 59. 22. R. R Brooks, Analyst, 1960,85,745. 23. 3. 0, Da Silva Fdho, A. Abriio and F. W. Lima, Rep. Inst. Energia Atom., Brad, IEA-98,196s.
346 24. 25. 26. 27. 28. 29. 30 31. 32.
J. Kotucrsc~
and H. KLAKL
A. Mizuike, Y. hda, K. Yamada and S. Hirano, Anal. Chrm. Acta, 1965, 32,428. J. Korkrsch and I. Hazan. Anal. Chem.. 1965.37.707. J. Korkisch and S. S. Ahiuwaha, Talania, 1967, i4, 155. E. B. Sandell, Colonmetric Determmatron of Traces of Metals, 3rd Ed., Intersctence, New York, 1959. K. A. Kraus, F. Nelson and G. W. Smith, J. Phys. Chem., 1954,58,11. A. A. Korobkm and I. N. Plaksin, Izv. Vysshlkh Uchebn. Zavedemr, Tsvetn. Met., 1958, 5, 90, Nauchn. Dokl. Vyssher Shkoly, Met., 1, 14 (1959) J. W. Morgan, Anal. Chum. Acta, 1965.32,s. K. A. Kraus and F. Nelson, J. Am. Chem. Sot , 1954,76,984 J. Korkisch, Separatron Scrence, 1966, 1, 159
1968.
Vol.
15. pp. 339 try 346.
Pcrgamon
Press.
Rmtcd
in Northern
Ireland
ANION-EXCHANGE BEHAVIOUR OF THE PLATINUM METALS AND GOLD IN HYDROCHLORIC ACIDORGANIC SOLVENT MEDIA J. KORKISCN* and H. KLAKL Analytical Institute,
Umverstty of Vtenna IX, WIhringerstrasse
(Recelced 7 AI~W
38, Austria
1967. Accepted 27 October 1967)
Summa~-The amen-exchange characteristrcs of the platmum metals and gold III hydrochlortc acrd medra are descrmed. The drstrrbutton coefficrents of these elements were measured on the strongly baste amon-exchange resm Dowex 1 x 8 in mtxtures of hydrochlorrc actd wrth water and several organic solvents, i.e., dtmethylformamrde, acetone, tetrahydrofuran, droxan, methanol, acettc actd and pyrtdme. Based on these data the condtttons most suttable for quantttattve separation are indicated and drscussed.
DUE to the fact that the platinum metals and gold readily form stable anionic chloride complexes most of these elements are strongly retained by strongly basic anionexchange resins from pure aqueous hydrochloric acid media. The least strongly adsorbed platinum metals are the tervalent ions of iridium and rhodium. Consequently most methods so far reported for the anion-exchange separation of the platinum metals from one another are concerned with separations of iridium and/or rhodium from the rest of the platinum metals.1-9 The strong adsorption of the anionic chloride complex of gold has also been employed for the anion-exchange separation of this element from a number of metal ions.rO-24 For the elution of the adsorbed gold, mixed aqueous-organic solvent solutions containing hydrochloric acid have been used.13 Except for this latter application no attempt has so far been made to investigate systematically the anionexchange behaviour of gold and the platinum metals in hydrochloric acid-organic solvent media. In order to obtain a much more complete picture of the adsorption characteristics and separation possibilities of these elements in organic solvent media, the work presented in this paper was performed, using the most frequently employed anion-exchange resin Dowex 1 in mixtures of 7 organic solvents with hydrochloric acid. For this purpose the effect of increasing concentration of organic solvent and the effect of acidity on the adsorption of the platinum metals and gold were investigated by measuring the distribution coefficients in numerous mixtures of varying composition. From the distribution data thus obtained, the possibilities of separating the elements from one another are indicated and discussed. EXPERIMENTAL Rerqpc”:s ion-ex&ngc resin. The air-dried strongly basic amon-exchanger Dowex 1 x 8 (100-200 mesh, chloride form) was used for the column and batch experiments. Stmdard sofurhs. Weighed amounts of the chlorides of ammonium tetrachloroplatinate(II), hexachloroplatinic acid, palladium(B) chloride, ammonium hexachloropalladate(, ammonium hexachloro-osmate(IV), potassium hexachloroiridate(III), ammonium hexachloroiridate( + Present address: Argonne National Laboratory, Chemistry South Cass Avenue, Argonne, Illinois 60739 U.S.A. 339
Division, Bldg. 200. M121, 9700
J. KORKXSCH and H.
340
KLAKI.
TABLE I-DISTRIBUTION COEFWIENTSOF PLATINUMMETAu AND GOLJJ DOWEX t IN PURE AQUEOUS lWDROCHU)RIC ACID SOLUllONS
Metal ton
WI)
Pt(IV) W(H) W(W) Os(IV) Ir(III) Ir(IV) Ru(III) Ru(IV) Rh(III) Au(II1)
12
9
480 430 32 33 1100 19 700
710 870 50
IS 1500 25 25 1.6 I@
:: 1.6 470
DOWEX
Metal ion
1 IN
3
IO”
22’ 90 70 35i7
COEFRCIENTSOF
1.2
3600 500 350 IO* 7.7 7000 300 420 7 IO’
PLATINUM
METALS
DI~~~~E-~R~H~~C
ACID
13g 1600 10‘ 16 10” 650 820 20 IO‘
AND
GOLD
MIXTURE.5
Final HCI concn., iU, m the presence of dtmethylformamtde (% v/v) 6 (50) 3 (75) 0.0 (100) 9 (25)
R(II) PWV) Pd(I1) Pd(Iv) Os(Iv) k(W)
100 115 II 2::
IrtIV) RUOII)
Isi2
Ru(IV) Rh(II1) Au(II1)
,M
2800 1900 120 80 4800
37;
TABLE II.-D~~TRIBv~oN ON
Fmal HCI concn 6
ON
40 60 IS 15 120
5Y
17 I.3
11 0.9
42202
9k8
30 :: 23 26 20 23 1.1 t2 I.8 7
::: >1500
TABLE III.-DISTRIBUTION COEWICIEN~SOF PLATINUMMETAU AND GOW ON DOW 1 IN ACETONE-HYDROCHLORIC ACXD MIXTURES
~~ Metal ton PtfII) Pt(IV) Pd(I1) Pd(IV) Os(IV) Ir(II1) Ir(IV) Ru(II1) Ru(IV) Rh(II1) Au(II1)
Fmal HCl concn , M, m the presence of acetone (% v/r) 1.2 (90) 9 (25) 6 (50) 3 (75) 250 200 27 26 >500 3’ >5OOt 90 60 3 380
>800 >lOOO 2 >750 30 >8OOt ,700 >800 30 130
>700 >2so 150 150 Xi00 >800 >7oOt >7OO >1800 900 7
>lOOQ >lSoO z! >lOOO >lOOO >1OOOt >I300 >3oGO >lOOO 2
Partial oxrdation of trtdium to tts higher oxzdatron state occurs m this medium. t Partial reductton of irrdium to its lower oxtdatton state occurs m these media. l
I-liial WY
-
hlcral 10n
.- -___
201icn .
M, in the prcscnce of
9 (25)
_.~~._.__.__ 930 700 30 27 1200 3* so0 13OOi 1300t 4 380
Plfll) Pt(IV) Pd(ll) Pd(IV) OS(N) Ir(ll1) II.(IV) RuUlI) Ru(IV) Rh(llI) Au(W)
Ictrali)'drofur,ili ( “,,
6 (50)
3 (:5)
: 500 SO0 60 75 750 30* 400 >500 . 700 ‘2 35
400 600 120 120 : 900 400 ;a400 :-500 ; 1100 260 2
,,I)
1 2 (90) __. -__.-. 1OJ . IOJ 250 : 400 , 800 >lO’
: Go0 6000 -8000 >600 2
* Partial oxcldatton of lrldlum to Its htgher ovldatlon state occurs in these media t In these media dlstrlbutlon coefficients of 60-70 were also measured. TABLE
V-DISTRIBUTION COEFFICIEYTS OF PLATINUM METALS AND ON DouEx 1 1s DIOXAN-HYDROCHLORIC ACID MIXTURES
Metal Ion
Fmal HCI concn., kf, m the presence of dloxan (T; t/l>) 6 (50) 9 (25)
Pt(I1) Pt(IV) Pd (II) Pd(IV) OS(N) Ir(IlI) Ir(IV) RU(IlI) Ru(IV) Rh(T1 I) Au(U) l Parka1 oxldatlon these media t Partial reduction these media.
TABLE GOLD
GOLD
250 270 40 30 600 10’
390
285 25 20 610 2’ 2OOt 20 19 3 310
80t 3 3 9 ‘40
of lrldlum to Its higher oxldatlon
state occurs m
of lrldmm to its lower oxldatlon
state occurs m
VI -DISTRIBUTION COEFFICIENTS OF PLATINUM METALS AND ON DOWEX 1 IN METHANOL-HYDROCHLORIC ACID MIXTuRES
Metal ion Pt(I1) PUN) Pd(I1) Pd(IV) OS(W) Ir(II1) Ir(IV) Ru(II1) Ru(IV) Rh(III) Au(III)
Final HCl concn., M, m the presence of methanol ( % z/I ) 3 (75) 6 (50) 9 (25) 330 >300 37 40 900 3 >640* 39 4.5 25 >I200
>12DO >llOO 130 110 :2000 15 1600* >900 >llOO 18 850
>1500 >18 500 600 ~6000 430 >7000’ r40OO :-5000 300 500
* Partial reduction of lridlum to its lower oxtdatton state occurs m these media
342
J KORKISCHand H. KL.AKL TABLE VII.-DISTRIBUTION COEFFICIENTS OF PLATINUMMETALSAND GOLD ON DOWEX 1 IN ACETIC ACID-HYDROCHLORIC ACID MIXTURES
Metal Ion Pt(II) Pt(IV) Pd(II) Pd(IV) Os(IV) Ir(II1) Ir(IV) Ru(IlL) Ru(IV) Rh(II1) Au(II1)
Fmal HCl concn., M, in the presence of acetlc acid (% c/u) 9 (25) 3 (75) 6 (50) >2500 >3ooo 36 34 >2000 2 >1200* 3’ 43 3 >lP
103
103 15 75 >2000 14 1500* >600 >550 17 750
>8000 >6000 400 500 >SOOO 200 >7ooo* >3ooo >6OOO 210 400
* Partial reduction of lrldlum to Its lower oxldatlon state occurs in these media. TABLE VIII.--DISTRIBUTION COEFFICIEN-BOF PLATINUMMETALS AND GOLD ON DOWEX 1 IN PYRIDINE-HYDROCHLORIC ACU) MXTURES
Metal Ion
Fmal HCl concn., M, m the presence of pyrldme (% c/u) 9 (25) 6 (50) 3 (75)
Pt(I1) Pt(IV) Pd(I1) Pd(IV) OS(W) Ir(II1) Ir(IV) Ru(II1) Ru(IV) Rh(II1) Au(III)
35 32 11 9 50 1 1 4 2 1 >1oot
2 1 1 rt 5 40 1 1 25 1 1 >50t
1 1 1 <2 5
* Partial reduction of irldlum to Its lower oxldatlon state occurs
in this medium t Gold IS virtually Insoluble m these media. ruthemum(II1) chloride hydrate, ammonium hexachlororuthenate(lV), ammomum hexachlororhodate(III) and tetrachloroaurlc acid were dissolved In 12M hydrochloric acid to give solutions contammg not less than 0 5 mg of element/ml Soluents. The reagent-grade pure orgamc solvents used were dmethylformamlde, acetone, tetrahydrofuran, dloxan, methanol, acetic acid and pyrldme. Determmation of dutnbutlon coejiclents Most of the lstrlbutlon coefficients of the platmum metals and gold were determmed by the column method*s, 1 g of air-dried resm bemg used m each case. Other dlstrlbutlon data were obtamed by the batch method.xa For the detectlon and determmatlon of the platmum metals and gold, sultable colour-formmg reagents have been used.27 RESULTS
AND
DISCUSSION
In Tables I-VIII are shown the distribution coefficients of the platinum metals and gold in the various media that have been investigated. Although the adsorption
343 TABLE ix---SEPAR4TIOY ---___-_
pw,
~.~:x,llJon ______-
Ft;IJ, Pd:lJ) P&l\ j- l’diI1) Pt(lI)-Pd(IV) Pt(I\)-Pd(lV) Pt(Il~-Os(IV~ Pt(IV)-OstJV) Pt(II)-lrflll)
Pt(IV)-IrUIJ)
Pt(JI)-Ru(III) Pt(IV)-Ru(Il1) Pt(II)-RujlV) Pt(:\?-Ru(lV) Pt(II)-Rh(llIJ
PNIV)-Rh(III)
Pt(II)-~LI~JII) Pt(IV)-Au(JI1) Pd:II)-Os(IV) Pd(I\‘!-Os(IV) Pd(II) -Ir(III) Pd(IV)-Ir(lIl) Pd(II)-Ir(IV) Pd(IVklr(IV) PdCII)-Ru(III) Pd(IV)-Ru(IiI) Pd(II)-Ru(IV) PdUV)-RuUV) Pd(Il)-RhUII) PdCIV)-Rh(IIJb Pd(JI)-Au(IIJ) Pd(IV)-Au(II1) Os(IVj-Ir(II1)
OS(w)-IrlIV)
GOLD
Oh
DOWEX
1
____--~.--
-----I_
M&al IOII
I-ACTORS OF PLAT1L.I XX MTTIL5 AND IN HYDROC’~i~~RIC AC 11) -C)LVI 1’3XS
-
l-actors
-
IG(\\). lS(Wj, 12(Dbli-), _ IW)~DblF), 9(A), c 19(A), >3O(THF), i(D), JQJ)), 9thi1, >7O\AX) il(\Y). li(u’), IO(DMb), _ lOOO(DMF), 7(A), , 23(A), 23(THF), 7(D), I?(D). . S(M). --Sj(4A) 13(W), 15(W), 12:DMF). JOcA), : 19(A), 36(THF). 20(D), ND), 8(M), ?3( 4A). 13(W), 16(W), IO(Dhlr), S(A), : 23(A), : 2S(THI‘), 9(D), 15(D), 8(M), Sh(4) 30(P) 20(P) 250(W), 370(W), IXO~W), 1200(W), IOOOCW), 95(DMF), 4l(DMF), l?fI>MF), 83/A,. 3 28(A), 3- 3O(TIJF), IStTHF), 180(D), 23(D), 110(M), __ SO(M), > IZScj(AA), 75CA.4). 35(P). ,“201\t), 580(W), 13OOfW). 900(W). l@OOCW), 83(DMF), 30(DMFJ, SID~JF), 67(A). > 33(A), ,_ 23(THF), 170(THF), 130(D), 25(D), > 100(M), _ :41X1), _ ISUO(AA). %(AA), 3OlP) ‘!-J(v\ ), 28(W), 68(l?Mk :, 55(DMF), 27tDMr). 19(D), S3(D), 8 5(M), SO(A4 t 39(R’). 35(W), 59(DMF), 36fDMF). IS(DMF), 15(D), 90(D), 8(M), 90’ %A) 37(W), 18(W), 77(DMF), 67(DMF), :0(D), SXD). 7(hI), >6O(AA) 29th). 35(W), SP(DhfF), 44tDMF), 15(D), 90(D), ;-7(M), >70tAA) 300W J 440(W), lOOOiW), 730(W), 1000(W), XCDMF), 32(DMF), IEcnkIJ j. 83(A), : 33(A), >2?2(THF), 20(THF), 130(D), 28(D), 130(M), 33(M), ‘30(AA), 6O(AA), 35(P) 27O(Vv ), 54OiWl. 7OO(N’), 530(W), 1000(W), 45(DMTJ, 23(DMF), 67(A), :- 331 A), 2175(THF) 23(THF), 100(D), 30(D), ; 120(M), 40(M1 lW’UA4), 6NAA), 3’f Pj _ !!10;4). Y %OCA), l!(THFj, ;- ZOO(THF), : 5ONTHF), =-25(P). X(h), 3> :30(A), I-;:THF), --300(THF), :- SOOCTHI:), >25(Pj .i’(k 1, Got\\‘). 2! (SMF). SCDMF), >15001DMJ’), ‘-18(A), > 17(A) 40\7HF), 24(D), 15\D), :,24(M), ‘>55(A4), 5tP). 40(P) 33i\V), <~(WJ, :l(J)MF), 7(DMF), :-18(A), ; 17(A), 44(THF), 32(D), 20(D). z Zt(>fb, :-59144) 5(P), -,26(P). 161\%.‘,:?!cWr, 5X%‘), 66(W). 84(W), 9(DMF), ll(DMF), z 15OO(DhIF), 3,A) J(‘,YrlF), 3(D), IZfM), 9thI). 18(AA), 5(AA) l-(111. j;C\\) 35(‘W.X(\\‘), 105(M’J,9(DMFJ, lO(DMF), ll(DMF),g(A), 9,;‘HF). 7(M). l?tTcli, 5(A4), 17CAA) XWI 301\\), lj(DMF), >30OO(DMF), :. 18(A), 17(THF), 8(D), ,>17(h!,, . X(&4). 5(P) 21(W), 3-/(W). JSfDMF), .--19(A), :-18(A), 19(TJ_II=), IO(D), ;16(M), ._ 35th 4) 6(P). 6CDMF), 14[DMF), 16(Dhft), --5OOO(DMF), : 16(A) 6fDhiIF). 13(DMF), ?l(DMF). =16(A). : 9fDMF). > IXOCDMF), lS(4) . 1 l(D\fF), 18(A) 191Y ), 31!Wj, 44(W), ?5(W), 65(W), 5(DMF), 8(DMF), lO(DMF), : 2100(DMFj, 9i4), 7(THF), S(D), 15(M), 7(M). 12(AA), 4(AA), 10(P) 11 f\q 33(W), 30(W), 51&V) SO(W), SCDMF), 8\DMF), 13(DMF), 9(A); 7tTHF). 6(D). 16,&l). 4Ch,l,. II( 4CAA1. 9(P) J4CWj ‘2OCW;. 3S(DMF), G(DMF), >~lOO(l%iF$, 35(A). 200(A), 60(THF), 12% THl-1, I?(D), h(D), ;- J\(M), r28(A), 10(P), ; 50(P) 14(\i), lS:W), 3S(DMF), GCDMI-;. 25(A), 300(A), 60(THF), >?OO(THF), 16(D), S(D), ,--29(M). > Bl(AA), 11(P), > 33(P) 580(H’), 2500(\\). 2100(kb). >lOOO(W), 1000(W). 190(DMF), 90(DMF,, 13CDMF). 3 17(A), - ‘5(A). 4OO(THF), 25(THF), 280(D), 54(D), 3 300tMi = 13@(M), 3=t(‘OO(AAj, > 160(AA), 48(P), 40(P) 39flY
344
J KOKKISCH
and H
KLAKL
TABLE Ix. (Cont.) Metal Ion pairs OS(N)-Ru(II1) OS(N)-Ru(IV) Os(IV)-Rh(II1)
OS(N)-Au(II1) Ir(III)-Ru(II1) Ir(III)-Ru(I\‘) Ir(III)-Au(II1)
Ir(IV)-Ru(II1) Ir(IV)-Ru(IV) Ir(IV)-Rh(II1)
Ir(IV)-Au(II[) Ru(III)-Rh(III) Ru(IV)-Rh(II1) Ru(III)-Au(II1) Ru(IV)-Au(II1) Rh(III)-Au(II1)
Separation factors 100(W), 150(W), 140(DMF), lIO(DMF), ‘4(DMF), 30(D), 200(D), >23(M), >62(AA) 73(W), 150(W), 170(DMF), 14O(DMF), >l?(DMF), 32(D), ZOO(D), >20(M), >46(AA), 24(P), 40(P) 690(W), 2300(W), 1800(W), 1000(W), >lOOO(W), lOO(DMF), 70(DMF), 14(DMF), >17O(A), i29(A), 300tTHF). 34(THF), 200(D), 70(D). 36(M), 71(M), 670(AA), 130(AA), 48(P), 40(P) 87(A), -,500(A). 21(THF), >45O(THF), /4OO(THF) 6(W), 17(W), 39(W), S?(W), 23(A), 17(THF), 13(M), 60(M), 16(AA), 43CAA) 8(W), 17(W), 30(W), 51(W), 37(W), .-27(A), -23(THF), 15(M), ,77(M), ?l(AA), >43(AA) 250(W), 670(W), 1500(W), 1000(W), >lOOO(W), 35O(DMF), 64(DMF), 130(A), 4 3(A), 110(A), >5OO(A), 130(THF), >‘OO(THF), zSOO(THF), 130(D), 22(D), 380(M), 57(M), : 500(AA), 5JL4A). > 100(P), >5O(P) 65(W), 60(W), 94(DMF), 45(DMF), ?l(DMF), 10(D), 27(D). >16CM), 37(AA), 14(P) 47(W), 60(W), l?O(DMF), s-Il(DMF), 10(D), 27(D), 14(M), ,‘8(AA), 28(P) 430(W), 940(W), 960(W), 1000(W), 1000(W), 73\DMF), 28(DMF), 13(DMF), >170(4), >27(A), lX(THF), >18CTHF), 67(D), 9(D), 126(M), 57(M), ;4OO(AA), 90(AA), 57(P). > 100(A), ‘500(A), bll(THF), >2OO(THF), > 3OO(THF), : 50(P) 7(W), 16(W), 33(W), 46(W), 32(W), :-23(4), : 20(THF), ;23(THF), 7(D), 16(M). ‘.- ,2(M), 43(AA), >35(4A) 9(W), 16(W), 26(W), 60(W), 41(W), 20(A), ?O(THF), 27(A), >32(THF), 6(D), 18(M), > 41(M), 53(AA), : 32(AA, 43(W), 40(W), ?SO(DMF), 83(DMF), :-100(A), ;650CA), > 14(THF), 3000(THF), 15(D), 80(D). >250(THF), 31(M). :-31(,44), _ 25(P) 31(W), 40(W), 3’0CDMF), IOOcDMF), r 260( 4). _ 1500(A), _-ZO(THF), >7OO(THF), >- JOOO(THF), 16(D), 80(D), 37(M), : 23(AA), ;.5O(P). 290(W), 625(W), 1300(W), /~lOOO(W), 1000(W), l’)OCDMF), 50(DMF), 130(A), 4 3(A), ;-500(A), 95(THF), 130(1HF). : 300(THF). 100(D), 27(D), >150(M), 17(M), , 125(AA), 21(A4), 21(AA), ilOO( :50(P).
W = water, DMF = dlmethylformam~de, A -- acetone, AA - acetlc acid, P = p)ridme choxan, M = methanol,
THF =- tecrahgdrofuran,
D =
of these elements on strongly basic amon-exchange resms from pure aqueous hjdrochlorlc acid solutions has previously been described bq several 1i1\estlgators,3’-“‘*-31 the adsorption values are recorded m Table I so that thege data can readily be compared with those m Tables II-VIII The datnbutlon coelliclents of the platinum metals recorded m Table I are m good agreement with those that have been measured earlier. In the case of the adsorption of gold, howevel, all values are lower by about one order of magnitude at high hydrochloric acid concentrations In order to avoid a rather lengthy dlscusslon of the separation posslbJltles of the platinum metals and gold m the various media listed m Tables I-VIII, numerous experimentally determined separation factors of many pairs of metal ions m these mixtures are recorded in Table IX From these results It is seen that m the mlxed aqueous-organic solvent systems higher separation factors are found and hence better The separation possibilities exist than m pure aqueous hydrochloric acid systems separation factor of any given pair of ions IS the ratio of the dlstrlbutlon coefficients of the two elements as measured under ldentlcal experimental condlllons. Difficulties m determining the separation factors have been encountered m all
Anron-exchange
of the platinum metals
34s
those systems containing iridium, which when present in the tervalent state is partly oxidized to the quadrivalent form which shows different adsorption characteristics. The same is true when iridium(IV) is present; this is partly reduced to the tervaient state. Therefore separations involving this element cannot readily be carried out. Separations that cannot be performed by the application of pure aqueous hydrochloric acid systems include those of Pt(II)-Os(IV), Pt(IV)-Os(IV), Pt(II)-Au(III), Pt(IV)-Au(III), Pd(I1 jRu(III), Pd(II)-Ru(IV), Pd(IV)-Ru(IV), Os(IV)-Ir(IV), Os(IV~Au(II1) and Ir(IV~Au(II1). These separations can, however, effectively be carried out in the presence of organic solvents (see Table IX). This once more illustrates the usefulness of organic solvents for ion-exchange separations of metal ions. In the case of separations involving the elution of gold with acetone or tetrahydrofuran each containing hydrochloric acid, the combined ion-exchange-solvent extraction (CIESE) principle described earlier32 makes these separations possible. Zu~mmenfas~ng-Das Anionenaustau~hverilalten der P~atlnmetalle und Gold m salzsauren Medken wlrd beschrleben. Die Vertedungskoeffizlenten dleser Elemente wurden an dem stark bastschen Amonenaustauschharz Dowex 1 x 8 m Gemlschen von Salzsaure mlt Wasser und mehreren orgamschen Losungsmltteln wte Dlmethylformamld, Aceton, Tetrah drofuran, D~oxan, Methanol, Esslgsaure und Pyrldm gemessen. Au i! Grund dleser Daten werden die zur quantltatlven Trennung am besten geelgneten ~dIngungen angegcben und diskutlert. R&urn&On d&It, du pomt de vue echange aniontque, les caract&lstlques des m&aux du groupe du platme et de l’or, en milieu aclde chlorhydrlque. Les coefficients de partagc de ces elements ont et6 mesurCs sur la r&me &hangeuse d’amons fortemcnt baslque Dowex 1 x 8 dam des mtlanges d’aclde chlorhydrlque avec I’eau et plusteurs solvants organrques, c’est-&-dire dIm~thyIformam~de, acetone, t&ahydrofuran, dloxane, methanol, aclde ac&que et pyndme. En se basant sur ces don&es, on mdlque les condmons convenant le mieux B la separation quantltatlve et en dlscute. REFERENCES 1. A. G. Marks and F. E. Beamlsh, Anal. Chem., 1958,30,1464. 2. W. M. MacNevin and W. R. Crummett, tbrd., 1953,25,1628; Anal. Chtm. Acta, 1954, IO, 323. 3 S S. Berman and W. A. E McBryde, Can. J. Chem, 1958,36,835. 4. Zdem, rbid., 1958,36,8JS. 5. M. L. Cluett, S. S. Berman and W. A. E. McBryde, Analalyst, 1955,80,204. 6. D. S. Busch, J. M. Prosper0 and K. A. Naumann, Anal Chem., 1959,31,884. 7. Coufalik, F., and M. Svach, 2. Anal. C/tern., 1960,173, 113. 8. E. Blasms and U. Wachtel, 2. Anal. Chem., 1954,142,341. 9. E. Blasius and D. Rexin. IbId.. 1961.179. 105. 10. A. B. Davankov and V. ‘M. L&fer, iaoo>sk. Lab., 1956,22,294. 11. Idem, Zk. Prtkl. Khim., 1956,32,788. 12. S. Sussman, F. C. Nachod and W. Wood, Ind. Erg. Chem., 1945,37,618. 13. A B. Davankov and V. M. Laufer, Zh. Pnkl. Khlm., 1959,32,727. 14. M. V. Darbmyan and E. E. Kapantsyan, Int. Akad, Nauk Arm. SSR, Khim. Nauki, 1965.18,18. 15. S. Hirano, A. Mizuike and K. Yamada, J. Chem. Sot. Japan, Ind. Chem Sect , 1959, 62, 1494, 16 S. Htrano, A. Mizuike and Y. hda, Japan Amlyst, 1960,9,423. 17. D. H. Wdkms and L. E. Htbbs, Anaf. Chim. Acta, 1959,20,273. 18. A. C. Pappas, J. Alstad and G. Lunde, Radjochjm. Acta, 1963.1, 109. D. Brune, K. Sam&l and P. 0. Wester, Afompraxs, 1963,9,368. ;:: D. Brune, K. Samsahl and I?. 0 Wester, Aktreboiaget Atommergl AE-134, Stockholm, Sweden, 1964. 21. P. 0. Wester, D. Brune and K. Samsahl, Intern. J. Appl. Radiation Isotopes, 1964, IS, 59. 22. R. R Brooks, Analyst, 1960,85,745. 23. 3. 0, Da Silva Fdho, A. Abriio and F. W. Lima, Rep. Inst. Energia Atom., Brad, IEA-98,196s.
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