ORNL-TM-1480

Contract No. W-7^05-eng-26

ISOTOPES DEVELOPMENT CENTER

THE EXTRACTION OF TRIVALENT GOLD FROM HYDROCHLORIC ACIDSOLUTIONS INTO ISOPROPYL ETHER, BIS-(p-CHLOROETHYL)

ETHER, ETHYL ACETATE, AMYL ACETATE, AND METHYL ISOBUTYL KETONE

J. J. Pinajian

Isotopes Division

APRIL 1966

OAK RIDGE NATIONAL LABORATORY

Oak Ridge, Tennessee

operated byUNION CARBIDE CORPORATION

for the

U.S. ATOMIC ENERGY COMMISSION

OAK RIDGE NATIONAL LABORATORY LIBRARIES

3 ^st ostTmH t

Ill

CONTENTS

Page

Abstract !

Introduction 1

Procedure 2

Results 5

THE EXTRACTION OF TRIVALENT GOLD FROM HYDROCHLORIC ACIDSOLUTIONS INTO ISOPROPYL ETHER, BIS-(p-CHLOROETHYL)

ETHER, ETHYL ACETATE, AMYL ACETATE, AND METHYL ISOBUTYL KETONE

J. J. Pinajian

ABSTRACT

The extraction of trivalent gold by isopropyl ether,bis-(p-chloroethyl) ether, ethyl acetate, amyl acetate,and methyl isobutyl ketone from hydrochloric acid solutions was studied as a function of acid concentration.The distribution coefficients were found to decrease inthe order: amyl acetate < isopropyl ether < ethylacetate < bis-(p-chloroethyl) ether < methyl isobutylketone. Isopropyl ether and ethyl acetate were foundto be soluble in higher concentrations of hydrochloricacid solutions. Bis-(p-chloroethyl) ether has a distribution coefficient reaching a maximum of 495 at 6 MHC1. Methyl isobutyl ketone has a distribution coefficient of IO98 at 6 M HC1 which increases to ~6000 at1 M HC1. The distribution coefficient of platinum was

found to be ~10~2 at 6 M HC1 and factors for separationfrom gold were estimated to be 5 x 104, 5 x 103, and6 x 105 for isopropyl ether, bis-(p-chloroethyl) ether,and methyl isobutyl ketone, respectively.

INTRODUCTION

Solvent extraction procedures offer a convenient method for the separa

tion of micro-to-macro quantities of metals in comparatively simple steps.

Thus, the problem of separating carrier-free 195Au or 199Au from a platinum

target, for example, may be carried out efficiently using solvent extrac

tion, provided that the distribution coefficient of gold is sufficiently

greater than that of platinum. By judicious choice of an organic solvent/

aqueous system, carrier-free 195Au or 199Au may be prepared in a solids-free

state.

Since the literature offered little in the way of detailed information

on the extraction behavior of trivalent gold, we initiated a study of the

extraction of gold(lll) chloride in the hydrochloric acid system using

isopropyl ether, bis-(p-chloroethyl) ether, ethyl acetate, amyl acetate,

and methyl isobutyl ketone. Ethyl ether was not investigated because of

its volatility and flammability. The hydrochloric acid system was used

because it is more convenient to handle and has fewer undesirable features

for medical and biological applications and for the preparation of sources

for gamma-spectroscopy measurements.

PROCEDURE

The organic solvents used were standard stock reagents• No purifica

tion was undertaken since the procedures were designed for routine labora

tory operations.

Isopropyl ether, purified, Baker and Adamson, GeneralChemical Division, Allied Chemical Corporation

Bis-(p-chloroethyl) ether, Chemicals Division, UnionCarbide Corporation

Ethyl acetate, purified 95-93$> Baker and Adamson,General Chemical Division, Allied Chemical Corporation

Amyl acetate, purified, Baker and Adamson, GeneralChemical Division, Allied Chemical Corporation

Methyl isobutyl ketone (4-methyl-2-pentanone), B.P. ll4-ll6°C,Matheson, Coleman, and Bell, Division of MathesonCompany, Inc.

All aqueous solutions were prepared with demineralized water

(l-l x 106-ohm resistance).

In each case the solution of gold activity was evaporated down to

incipient dryness and then taken up in the desired acid concentration.

Care was taken not to use prolong heating while the gold activity was

at incipient dryness, since nitric acid would then be required to remove

the activity from the glass.

The gold activity used as the radioindicator was either 64.8-hr

198AuCl3, 1 M in HC1 and HN03, or 183-day l95AuCl3, 1 M in HC1. The

198Au activity was obtained from the Isotopes Sales Department, Oak Ridge

National Laboratory, and had a specific activity of 38.4 mc/mg gold. The

carrier-free l95Au activity was prepared by the proton irradiation of

platinum in the ORNL 86-Inch Cyclotron.1 Approximately 200 uc of activity

was used in each experiment.

The distribution data were obtained by contacting equal volumes (20 ml]

of the organic phase with the hydrochloric acid solutions containing the

l95Au- or l98Au-labeled gold. In each case, the organic was equilibrated,

prior to use, with the same concentration of hydrochloric acid used in

the study. Extractions were made at room temperature (22°C). Preliminary

experiments established the equilibrium time at <30 seconds. After con

tacting the two phases for O.5-I min, the phases were separated and centri-

fuged, and 1.00-ml aliquots taken for analysis- The analysis for the

l98Au was made by counting the 0.4l2-Mev photopeak, and for the 195Au, the

0.099-Mev photopeak, using a 3- by 3-in. Nal(Tl) gamma spectrometer.

Distribution data were also obtained in the same fashion for 3-4 mM

and 8.3 mM platinum, labeled with 3.0-day 191Pt.

RESULTS

The results of the distribution study are shown in the following

table. Figure 1 shows the distribution coefficient* of trivalent gold

in various organic solvents as a function of the hydrochloric acid con

centration.

*The distribution coefficient, KD, is defined as:

gold activity in the organic phaseD ~ gold activity in the aqueous phase

Table 1. Distribution Coefficients of Au3+ BetweenOrganic Solvents and Hydrochloric Acid Solutions

Au3+,mM

Distribution coefficients

Hydrochloric acid coneentration

Organic solvent 1 M 2 M 4 M 6 M 8 M 10 M

Isopropyl ether 0.0125 0-7 1-3 3-4 5.8 8.3b 0.3813

Bis-(p-chloroethyl)ether 0.0125 -- 279 4ll 495 408 4o6

Ethyl acetate CFa -- 46.2 23-8 9-1 — —

Amyl acetate CFa --0.43 0-37 0.33 — —

Methyl isobutyl ketone 0.0125 6038 3715 833 IO98 -- --

Carrier-free.

Organic solvent dissolves in aqueous phase•

Using the standard deviation of the ratios of the respective counting

rates (with their respective standard deviations) as an index of the reli

ability of the distribution data, then the following generalizations can be

made regarding the accuracy of the KD:

Range of Kp Estimated limit of error in data, jo

io3-io4 +100 -50

ic^-io3 +100 -50

101-102 +20 -10

1 -10 +10 -5

10_1-1 +10 -5

10~2-10-1 +20 -10

io"3-io-2 +100 -50

The increase in the extraction efficiency of bis-(p-chloroethyl) ether

over isopropyl ether follows the trend in the extraction behavior predicted

by Kuznetsov2 in his paper on the extraction of iron chloride into organic

10*ORNL-DWG 66-3117

103

<02

*D

10<

10°

-110

J98Au, 12.5x10~3 mMMETHYL ISOBUTYL KETONE

J98Au, 12.5X10"3 n\M/>/5-(/3-CHL0R0ETHYL) ETHER

J95Au, CARRIER-FREEETHYL ACETATE

i?5Au, CARRIER-FREEAMYL ACETATE

-498Au, 1.27x10-3 m/l/ISOPROPYL ETHER

6

HCI (M)

8 40

Fig. 1. The Distribution Coefficient of Trivalent Gold inVarious Organic Solvents as a Function of the Hydrochloric AcidConcentration.

12

solvents. The marked increase (by an order of magnitude) of the distri

bution coefficient with methyl isobutyl ketone again follows the trend

suggested by Kuznetsov. On the other hand, extraction with amyl acetate

is a factor of 100 less efficient than extraction with ethyl acetate.

There appears to be no question that bis-k(p-chloroethyl) ether and

methyl isobutyl ketone are far superior to the other solvents examined

for the extraction of gold(lll) chloride. The solubility of both isopropyl

ether and ethyl acetate in the acid solution restricts their effectiveness

as an extractant for gold.

These results also indicate that the distribution coefficient of

methyl isobutyl ketone increases markedly with a decrease in acid con

centration. The extraction of gold(lll) chloride with bis-(f3-chloroethyl)

ether, on the other hand, reaches a maximum at ~6 M HCl and then decreases

with a decrease in acid concentration.

The distribution coefficient for platinum was found to be ~10-2 for

bis-(p-chloroethyl) ether, ethyl acetate, and methyl isobutyl ketone.

Hence, factors for the separation of gold from platinum are 5 x 104,

5 x 103, and 6 x 105 for bis(p-chloroethyl)ether, ethyl acetate, and

methyl isobutyl ketone, respectively.

ACKNOWLEDGEMENTS

The author would like to thank A. P. Callahan for conducting these

experiments.

REFERENCES

1. J. J. Pinajian, The cyclotron preparation of carrier-free l95Au by

the l95Pt(p,n)l95Au + l96Pt(p,2n)l95Au reactions, to be published.

2. V. I. Kuznetsov, Ob izvlechenii organicheskimii rastvoritelyami

khlornogo zheleze iz solyanokislykh rastvorov, Zh. Obshch. Khim.

17: 175-80 (1947), [see S. J. Rimshaw and J. J. Pinajian, The

extraction of iron chloride from hydrochloric acid solutions by

organic solvents, USAEC Translation ORNL-tr-1199, Oak Ridge

National Laboratory (March 1966)].

•J

1.

2.

3<4-6.

1-8.

9-10.

11.

12.

13.14.

15.

56.57-58.59-60.

61.

62.

63.64.

65-67.68.

69.70.

71-

72.

73.74.75.

76.77-78.79-80.

81.

82.

83.84.

85.86,

87.

90.

91-92.

93.94-108.

P. S. Baker

E . E. Beauchamp

G. E. BoydT. A. Butler

F. N. Case

L. T. Corbin

J. A. Cox

J. H. Gillette

C P. Keim

M. T. Kelley

E. H. Kobisk

E. Lamb

L. 0. Love

/^

INTERNAL DISTRIBUTION

16. W. S. Lyon17. H. G. MacPherson

18-42. J. J. Pinajian43. M. E. Ramsey44. R. A. Robinson

45. A. F. Rupp46. F. G. Seeley47. A. M. Weinberg48. J. C White49. Laboratory Records — RC

5O-51. Central Research Library52-54. Laboratory Records

55. Document Reference Section

EXTERNAL DISTRIBUTION

Argonne National Laboratory, Argonne, Illinois0. M. Bizzell, Div. of Isotopes Development, AEC, Washington, D. CJ. L. Bloom, Div. of Isotopes Development, AEC, Washington, D. CR. E. Bowman, Div. of Technical Information, AEC, Washington, D. CE. J. Brunenkant, Div. of Technical Information, AEC, Washington, D. CH. D. Bruner, Div. of Biology and Medicine, AEC, Washington, D. CL. P. Bupp, General Electric Co., HAPO, Richland, WashingtonJ. T. Cristy, AEC-R00, Richland, WashingtonD. C Davis, Research and Development Div., AEC-ORO, Oak Ridge, Tenn.E. E. Fowler, Div. of Isotopes Development, AEC, Washington, D. C.R. N. Goslin, Dept. of Physics, Oglethorpe Univ., Atlanta, Ga.W. J. Haubach, Mound Laboratory, Miamisburg, OhioJ. W. Hitch, Div. of Isotopes Development, AEC, Washington, D. C1. A. Hobbs, AEC-SR00, Aiken, S. CJ. W. Irvine, 6-426, MIT, Cambridge 39, Mass.T. R. Jones, Div. of Research, AEC, Washington, D. C.B. F. Judson, General Electric Co., HAPO, Richland, WashingtonW. K. Kern, Div. of Isotopes Development, AEC, Washington, D. CG. A. Kolstad, Div. of Research, AEC, Washington, D. C.P. W. McDaniel, Div. of Research, AEC, Washington, D. C.J. E. Machurek, Div- of Isotopes Development, AEC, Washington, D. CB. Manowitz, Brookhaven National Lab., Upton, L. I., N. Y.R. B. Martin, Research and Development Div., AEC-ORO, Oak Ridge, Tenn.J. W. Morris, Savannah River Lab., E. I. duPont, Aiken, S. C.Mound Laboratory, Miamisburg, OhioF. K. Pittman, Div. of Reactor Development, AEC, Washington, D. CJ. A. Powers, Div. of Isotopes Development, AEC, Washington, D. C.G. L. Rogosa, Div. of Research, AEC, Washington, D. CG. J. Rotariu, Div- of Isotopes Development, AEC, Washington, D. CH. M. Roth, Research and Development Div., AEC-ORO, Oak Ridge, Tenn-L. G. Stang, Hot Lab. Div-, Brookhaven National Lab., Upton, L. I., N.Y.V. R. Thayer, Atomic Energy Division, E. I. duPont, Wilmington, Del.J. Vanderryn, Office of the General Manager, AEC, Washington, D. CLibrary, Brookhaven National Laboratory, Upton, L. I., N. Y.Library, Hanford Atomic Products Operation, Richland, WashingtonLibrary, Savannah River Laboratory, Aiken, S. C.DTIE, AEC