Solvent extraction of thorium(IV)

Jointly published by Elsevier Science S. A., La:tsonne and Akadlmiai Kiad6, Budapest

J. R a d i o a n a l . Nucl. Chem. ,Letters 213 (3) 199-205 (1996)

S O L V E N T E X T R A C T I O N OF T H O R I U M ( I V ) ION W I T H N ,N ,N , N - T E T R A B U T Y L S U C C I N Y L A M I D E FROM NITRIC ACID SOLUTIONS

You-Shao

Institute

Wang, C h a o - H o n g Shen, Y o n g - h u i J i a n - K a n g Zhu, B o - R o n g Bao

Yang,

of N u c l e a r

P.O.

Research, C h i n e s e A c a d e m y Sciences Box 8 0 0 - 2 0 4 S h a n g h a i , China

Received Accepted

26 M a r c h 5 April

of

1996 1996

It was found that N , N , N , N - t e t r a b u t y l s u c c i n y l a m i d e (TBSA) in a d i l u e n t c o m p o s e d of 50% 1 , 2 , 3 - t r i m e t h y l b e n z e n e (TMB) and 50% k e r o s e n e (OK) can e x t r a c t thorium(IV) ion from a n i t r i c acid solution. The r e s u l t s of the e x t r a c t i o n study s u g g e s t e d the formation of a 1:4:1 thorium(IV) ion, n i t r a t e ion and N , N , N , N - t e t r a b u t y l s u c c i n y l a m i d e complex as e x t r a c t e d species. The r e l a t e d therm o d y n a m i c f u n c t i o n s w e r e a l s o calculated.

INTRODUCTION

Substituted have pound

been

alkylamides

reported

contains

ing a b i l i t y

in m a n y

strongly -

\

as e x t r a c t a n t s papers I-3.

polar

for metal

cations

0236-5731/96/US $12.0 Copyrighf 9 1996 Akaddmiai Kiad6, Budapest All rights reserved

199

for a c t i n i d e s

This

C=O groups. is s i m i l a r

k i n d of comTheir

chelat-

to those

of

WANG et al.: SOLVENT EXTRACTION OF Th(IV)

extractants

containing

phosphorus.

contain

no p h o s p h o r u s

produce

new solid w a s t e

cinerable. products

(carboxylic

tractants

[HNO3],

They

discusses

[Th4+],

ing a b i l i t y reaction

[TBSA]

they

considered

dium by T B S A

are not h a r m f u l

of n u c l e a r

systematically

and the r e l a t e d

ex-

fuel.

the e f f e c t s

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

of thorium(Iv)

in-

degradation

as p o t e n t i a l

of T B S k for t h o r i u m ( I V ) .

mechanism

which

they do not

are c o m p l e t e l y

and amines)

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

paper

compounds

and h y d r o l y t i c

acids are

The

are i m p o r t a n t ;

because

The r a d i o l y t i c

to the process.

This

atoms

of

on the e x t r a c t -

The e x t r a c t i o n

from n i t r i c

thermodynamic

acid me-

parameters

are p r e s e n t e d .

EXPERIMENTAL

T B S A was The p u r i t y emental

synthesized

of the d i s t i l l e d

analysis,

of the p r o d u c t procedure which

was

as follows: a certain

shaken with

ing a g i v e n

with

The

composed

was

The p u r i t y

A typical

extraction phase

amount

ion and

of thorium(IV)

of T B S A

a suitable

for

nitric

by of 50%

Samples

immediately

after

phase

thorium(IV)

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

coefficient

98%.

by el-

0.5 ml of the a q u e o u s

and 50% kerosene.

mA spectrophotometric

checked

I ml of the o r g a n i c

concentration

preequilibrated diluent

was

spectroscopy.

than

et al. 4

to S t a n l e y

product

IR and NMR

was h i g h e r

contained

HNO 3 was

according

of both

phase

10 min, acid

containwhich

was

solution.

1,2,3-trimethylbenzene phases

separation.

were

analyzed

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

of

by the c h l o r p h o s p h o n a z o -

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

of thorium(IV)

ion was 200

calculated.


I0

D

1

0,1

2

3

4

5

6

[HN03], mot. Fig.

I. C o r r e l a t i o n b e t w e e n l g D m h 4 + and [HNO 3] at 25 ~ [Th 4+] = 5 . 2 9 x 1 0 - 3 moi/l, [TBSA] = 0.05 m o l / l

RESULTS

AND DISCUSSION

Figure

I shows

the e f f e c t

HNO 3 on the d i s t r i b u t i o n in the two p h a s e s . concentration thorium(IV) the

shows

increases

that there

petition

of the

concentration

coefficient

Accompanied

of HNO3,

concentration

tion

['1

with

of t h o r i u m ( I V ) an i n c r e a s e

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

is a m a x i m u m ,

of t h o r i u m ( I V )

ions

study.

4 mol/l,

which

ion

in the

coefficient

in the r e g i o n of our

of HNO 3 s u r p a s s e s

of

of

When

the c u r v e

is due to the com-

and HNO 3 for the c o o r d i n a -

sites of TBSA.

Figure

2 illustrates

concentration rium(IV)

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

ion b e t w e e n

coefficient

the e f f e c t of t h o r i u m ( I V )

the two phases.

an i n c r e a s e

ion until

a concentration 3 indicates

on the e x t r a c t i o n values

increase

of tho-

The d i s t r i b u t i o n

of Th 4+ is an a l m o s t h o r i z o n t a l

line w i t h

Figure

coefficient

ion

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

straight of t h o r i u m ( I V )

of 8x]0 -3 m o l / l .

the e f f e c t

of t h o r i u m ( I V }

linearly with 201

of T B S A ion.

The

concentration igDTh4+

the i n c r e a s i n g

concentra-


D6

94

I

I

1

Fig.

I

!

3

~

I

I

I

5

7

[Th4+],x

10 -3 mot. [-1

10

2. C o r r e l a t i o n b e t w e e n i g D T h 4 + and ig [Th 4+] at 25 ~ [TBSA] = 0.5 m o l / l ; [ H N 0 3 ] : 3.5 m o l / l

10 D

11

t

t

I

03

,

I

05

i

i

07

1.0

[TBSA],mo[[ -I Fig.

3. C o r r e l a t i o n b e t w e e n igDTh4+ and ig [TBSA] at 25 ~ [Th4+] : 5 . 0 0 x i 0 - 3 mol/l; [HNO3] : 3.5 mol/l

tion of

TBSA,

and the

slope

that

the b i n d i n g

ratio

1:1.

The r e s u l t s

illustrate

is 1.1.

This

of T B S A with

HNO 3 and T B S A are the m a i n

that

th0rium(IV)

shows ion is

the c o n c e n t r a t i o n s

factors 202

result

which

can a f f e c t

of the


D6 5

/

-j _

I

I

I

30

3.1

3.2

I 3.3

3.4 I

T,xl0 Fig.

-3

4. C o r r e l a t i o n b e t w e e n igDTh4+ and ~ . [Th 4+] = 5.00xi0 -3 mol/l: [TBSA] = 0.5 mol/l; [HNO 3] = 3.5 mol/l

distribution

coefficient

t r a c t i o n data extraction

indicate

of thorium(IV)

ion. The ex-

that T B S A is e q u a l l y g o o d

thorium(IV)

for the

ion from nitric acid m e d i u m w h e n

c o m p a r e d with TBP and N , N - d i a l k y l a m i d e 6. Figure

4 illustrates

distribution

coefficient

values

increase

result

shows

from the a q u e o u s

ion. The igDTh4+ I This l i n e a r l y with the i n c r e a s e of T" phase

of thorium(IV)

to the o r g a n i c phase

ion

is an exo-

and the e n t h a l p y of Th 4+ e x t r a c t i o n

is

kJ/mol.

In th~se e x t r a c t i o n p h a s e was

studies,

in a large excess

ion in the a q u e o u s phase. 1:4:1

on the

of thorium(IV)

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

thermic process -17.56

the e f f e c t of t e m p e r a t u r e

c o m p a r e d with thorium(IV)

The r e s u l t s

c o m p l e x of thorium(Iv)

tracted

The:q)+

4NO3(aq)+

s u g g e s t that a

ion, NO 3- and T B S A was ex-

into the o r g a n i c phase.

r e a c t i o n of the p r e s e n t Eq. (I)

T B S A in the o r g a n i c

Thus,

the e x t r a c t i o n

system can be e x p r e s s e d

TBSA(org)= 203

by

Th(NO3)4.TBSA(org )

(I)


Then,

the e x t r a c t i o n

constant

(Kex)

can be defined

as

K

ex =

- - I_ [ N O ~ ]o aq - -a 4 [ T B S A ] _ _ -or I q g

[Th(NO3)4.TBSA]org[Th4+]

and Eq.

(2) can be r e a r r a n g e d

(2)

as

4[T~SA]o~ g

Kex: D T h [ N O 3 ] a q

(3)

or igDTh = igKex*

According mol/17;

to gq.

was e v a l u a t e d consisted

of

[TBSA]

3), the v a l u e

to be 0.081

The suggested

+ ig[TBSA]org

(4) ([HNO 3] = 3.5 mol/l,

the c o n d i t i o n s

ing Kex see Fig.

4lg[NO3]aq

[NO3 ] = 3.26

and [Th 4+] for calculat-

of Kex

(50% TMB + 50% OK)

• 0.006.

structure

of Th 4+ , NO

of the 1:4:1

complex

and T B S A can be e x p r e s s e d

lows: ,,-•

~ 4~. c.-"

(4)

" ~ , c . "~

%o o// .0-. ~ / . . - 0 - .

o -.~o.;Z