Solvent extraction of uranyl (II)

J.Radioanal.Nucl.Chem.,Letters 212 (2) 101-106.(1996)

Jointly published by Elsevier Science S. A., Lausanne and Akad(miai Kiad6, Budapest

SOLVENT EXTRACTION OF URANYL(II) ION WITH N,N,N,N-TETRABUTYLSUCCINYLAMIDE FROM NITRIC 'ACID SOLUTION

You-Shao Wang,

Chao-Hong Shen, Bo-Rong Bao

Jian-Kang

Zhu,

Institute of Nuclear Research, Chinese Academy of Sciences, P.O.Box 800-204, Shanghai, China

Received Accepted

24 October 6 November

1995 1995

N,N,N,N-tetrabutylsuccinylamide(TBSA) in a diluent composed of 50% trimethylbenzene(TMB) and 50% kerosene(OX) can extract uranyl(II) ion from nitric acid solution. The results of extraction study suggested the formation of the 1:2:1 uranyl(II) ion, nitrate ion and N,N,N,N-tetrabutylsuccinylamide complex as extracted species. The values of thermodynamic functions have been calculated.

INTRODUCTION Substituted

alkylamides

have been reported in many contain

as extractants for actinides I-3 papers . These compounds

strongly polar C=O groUps.

ity for metal cations 0236-5731/90/US $12.0 Copyright 9 1996 Akad6miai Kiad6, Budapest All rights reserved

Their chelating

abil-

is similar to those of the exI01

WANG et al.: EXTRACTION OF URANYL(II)

tractants

containing

tain no p h o s p h o r u s new solid waste The r a d i o l y t i c as c a r b o x y l i c process.

phosphorus.

atom are important,

because

degradation

acid and amines)

[HNO3],

[UO~+],[TBSA]

potentially

ability

of T B S A

indicate

systematically

for uranyl(II)

that TBSA is good

ion from nitric uranyl(II)

ion.

to the ex-

fuel.

the effects

of

on the e x t r a c t i n g

The e x t r a c t i n g

for the e x t r a c t i o n

acid medium.

(such

excellent

of n u c l e a r

and t e m p e r a t u r e

con-

incinerable.

products

are not h a r m f u l

for the r e p r o c e s s i n g

This paper d i s c u s s e s

which

they do not p r o d u c e

of being c o m p l e t e l y

and h y d r o l y t i c

They are c o n s i d e r e d

tractants

The c o m p o u n d s

Extraction

ion by T B S A and t h e r m o d y n a m i c

data

uranyl(II)

mechanism

of

parameters

are

presented.

EXPERIMENTAL TBSA was purity

synthesized

of the d i s t i l l e d

analysis,.IR purity

phase,

to S t a n l e y

was c h e c k e d

and NMR

was better

contained

ion and HNO 3, was containing

equilibrated

with

shaken

than

Samples

ately after uranyl(II) photometric

phase

amount

a suitable

by elemental

98%.

amount

A typical

of uranyl(II) I ml of organic

acid solution.

of 50% t r i m e t h y l b e n z e n e

Separation.

ion was d e t e r m i n e d

were

The c o n c e n t r a t i o n

102

immediof

by the a r s e n a z o - I I I

ion was calculated.

The

and 50%

analyzed

m e t h o d 5, and then the d i s t r i b u t i o n

of uranyl(II)

ex-

of TBSA which was pre-

nitric

of both phases

The

0.5 ml of the aqueous

for 10 m i n with

a certain

was c o m p o s e d

kerosene.

a certain

et al. 4. The

spectrometry.

p r o c e d u r e was as follows:

which

diluent

product

spectrometry

of the p r o d u c t

traction

phase

according

spectro-

coefficient


,~, 50 O

,-n 3O

I0 7 5

i

I

I

3

I ,i,L 5 7 10

[HN03] I mot. 1-1

Fig.

I. R e l a t i o n s h i p between i~ D U O S + and Ig[HNO 3] at 20 ~ [UO~ +] =5.00xi0 -j molZl -I; [TBSA]=0.5 tool 1-I

RESULTS

AND D I S C U S S I O N

Figure

I shows the effect of the c o n c e n t r a t i o n

on the d i s t r i b u t i o n two phases.

There was a close

distribution

coefficient

concentration

of HNO3.

in the aqueous traction

ions slope

relationship

of uranyl(II)

is about

I-6 mol

ion.

which

of HNO 3

ion in the

between

the

ion and the of HNO 3

1 -I for the ex-

There was c o m p e t i t i v e

b e t w e e n NO 3- and uranyl(II)

a maximum

ion.

is due to c o m p e t i t i o n

and HNO 3 for_ the c o o r d i n a t i o n

The curve of uranyl(II)

sites of TBSA,

the

of ig DUO

is n e a r l y centration ficient

2+ against ig [ HNO 3] w i t h i n 6 mol 1 -I 2 2. Figure 2 i l l u s t r a t e s the effect of the conof uranyl(II)

ion on the d i s t r i b u t i o n

coef-

of uranyl(II)

distribution with

phase

of uranyl(II)

The best c o n c e n t r a t i o n

of the uranyl(II)

extraction shows

coefficient

ion b e t w e e n the two phases, the 2+ c o e f f i c i e n t of UO 2 increases linearly

an increase

in the c o n c e n t r a t i o n 103

of uranyl(II)

ion.


~+~ 30 0

I

I

f

I

3

I

I

5

I

i

7

10

ot,t-' Fig. 2. Relationship between ig Dr~n2~-and ig[UO 2+]at 20 ~ [TBSA]=0~ tool I-I.~2[HNO3]=3.5 mol 1 -I

I0

5 3

I

0.1

Fig. 3 .

I

0.3

t

I

i

I

t

t

0.5 0.7 [TBSA.l,moI-{ -1

Relationship between i~ DUO2+ and Ig[TBSA] at 20 ~ [UO~+]=5.00xl0 -j mo121 -I ; [HN03]=3.5 mol 1 -I

Figure 3 indicates the effect of the concentration of TBSA on the extraction of uranyl(II) ion, the ig DUO 2+ 2 va 1 ues increase linearly with increasing concentration of TBSA, with a slope of unity. This results show the binding ratio of TBSA with uranyl(II) 104

ion to be 1:1.

WANGeta].: EXTRACTIONOF URANYL(II) ~

10

o s

5

3

3.0

3.2

3,4

y1, x10-3 Fig.

! [uo2+] = 4. Relationship between ig DUO2+ and ~ 1 [HN03]= 5.00xi0 -3 tool i -1 ; [TBSA]=0,"5 mol 3.5 tool 1 -I

Figure

4 illustrates

the effect of temperature

on the

distribution coefficient of uranyl(II) ion. Thel ig DUO22 + values increase linearly with the increase of ~ . Thus the extraction

of uranyl(II)

ion from the aqueous to the

organic phase is an exothermic of UO22+

extraction

process, and the enthalpy is -18.63 kJ mol -I "

In these extraction

studies,

TBSA in the organic phase

was present in a large excess compared with uranyl(II) ion in the aqueous phase.

The results in Figs 1 and 3

suggest that the 1:2:1 complex of uranyl(II) and TBSA was extracted extraction

into the organic phase.

reaction of the present

pressed as Eq.

ion, NO 3Thus, the

system can be ex-

(I).

U022+ (aq) + 2N03 (aq) + TBSA(org) = U02 (NO3)2"TBSA(org)

Then,

the extraction

constant

Kex = [UO2 (NO3)2 "TBSA]o--+ r [UO~ ~

105

(I)

(Kex) be defined as ] aq [-IrNO-~-2 3j aq ~ iTBSA~-Ijorg

(2)


and Eq.

(2) can be r e a r r a n g e d as follows:

Kex = Du[NO~ ]-2 [TBSA]-I

(3)

ig D u = ig Kex + 2 ig[NO3Jaq + ig[TBSA]org

(4)

aq

org

or

A c c o r d i n g to Eq. (4) (for the [HNO3], [TBSA] and U 022+ ] to c a l c u l a t e Kex see Fig. 3). The value for Kex(50%TMB+50%OK)

was e v a l u a t e d to be I .22+-0.06.

The suggested

structure of the I : 2 :I complex w h i c h

2+ , NO 3 and TBSA can be e x p r e s s e d as folc o n s i s t e d of UO 2 lows 6 : 0~

N."E~O~ 0i A~O""~.N ~ ' 0

ti

C

o

II

C

X = N(C4H9) 2 REFERENCES I. C. Musikas, 1211.

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