HWAHAK KONGHAK Vol. 38, No. 5, October, 2000, pp. 753-759(Journal of the Korean Institute of Chemical Engineers)

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(2000� 5� 12� ��, 2000� 8� 1� ��)

Adsorption Characteristics of Eu and Th on Illite and Montmorillonite in Aqueous Solution

Duck Kueon Lee, Hee Taik Kim, Mun Ja Kang*†, Pil Soo Hahn* and Kwan Sik Chun*

Department of Chemical Engineering, Hanyang University*Korea Atomic Energy Research Institute

(Received 12 May 2000; accepted 1 August 2000)

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*+,-. ���� ��� . pH 6�/��0 pH12� 34/5 Ca2+� 67! 8� 9: �;<= �>?� (@A

� B-. CDE pH 6� 8F���0 ��G� HIJ KL/0 pH��DL 4MN5 pH 8����0 ��G� 95%�

��O-. �0 Eu3+� ��� PQ��� ���� RS�� TU� �� V?� WXY-. ��� ��� . pH 3� 5

F��� ��G� HIJ KL/Z pH 5����0 99%��� ��G! +[-. �0 \� Th4+� �� �Q2�� R

S�� TU� ]��-. ^ ��� �� ���� ��� ��. Langmuir ��_;`?� �ab � BO?5 ��_;

`?�cd e� f���G. ���� gh ���� ��� XX 32 109 meq/100 g�OE �� ���� gh

XX 95 128 meq/100 g�O-. CDE MINTEQA2ij� kQ� ������� ��� 2lm. Eu3+, EuOH2+, EuCO3+,

Eu(CO3)2−�OE ��� 2lm. Th4+, Th(OH)2

2+, Th(OH)3+, Th(OH)4�O-.

Abstract − The adsorption characteristics of europium and thorium on clay minerals such as illite and montmorillonite were

investigated by batch experiments. The adsorbed amount of Eu was constant as a function of pH and much affected by a Ca2+

ion at pH below 6. This means the Eu adsorption at low pH is described by ion-exchange reaction. The adsorbed amount was

increased rapidly in the range of pH 6-8, which corresponds to pH edge. The adsorbed Eu was more than 95% of total Eu at pHabove 8. The Eu adsorption at high pH is caused by the surface complexation reaction between Eu3+ or europium carbonates

and minerals. The adsorbed amount of Th was sharply increased in the range of pH 3-5. Th adsorbed Th was more than 99% of

total Th at pH above 5. The Th adsorption is mainly due to the surface complexation of Th4+ or thorium hydroxides. The

adsorption characteristics of Eu and Th on illite and montmorillonite is represented by Langmuir adsorption isotherm. The

maximum adsorbed amount of Eu and Th on illite, resulted from adsorption isotherm, is 32 and 109 meq/100 g, respectively.

The maximum amount of Eu and Th on montmorillonite is 95 and 128 meq/100 g, respectively. The Eu-species calculated by

MINTEQA2 are Eu3+, EuOH2+, EuCO3+ and Eu(CO3)2

− . The Th exists in the species of Th4+, Th(OH)22+, Th(OH)3

+ and

Th(OH)4 in the aqueous phase.

Key words: Europium, Thorium, Illite, Montmorillonite, Adsorption

†E-mail: munkang@kaeri.re.kr

1. � �

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+# ,-./ 0�.� 1!2 !"34� 56# �"7 8�./

(9"� :;�� < =>? @A BC�( 1'. DEF !"

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!"G�� Q�"< S(L TU� VWXY� JK(Z� (9�

!P[\<] 1/H G^ IRO �('. _` abc de�#H

�8& MPf#< ghi M�( 'j k ./ 1<], ()� lm

�B 3n, 3o2p� G^ qr �s� _�t uv"7 w� P

Q� NY( .� 1'. xyH ()� �$z� { |e�� }~"

� ��H ()� �s� �9�2 ��y S(L TU� VW_

�t PQ./�� O'[1].

�(Eu) ��(Th)� ^y�� M$� �#H =�.< ���

M�(r '� ghi M�)� ��(analogue) �8.< a�('.

753

754 ������������ ����

�� ��i a� ����(Am) �s� �9( ��"7 ��

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VWC� B�'. xyH () �� ��S# �O ��� M�

� JK� VW_�( PQ./�  '[3, 4]. DEL 2-1¡(bi-uni type)

��S# NO ghi ��i a�� VW# NO PQ< w! ¢

� £�('. ¤y(¥(illite)4 ¦§¨ L(¥(montmorillonite)< N©

�ª ��S H �«�Q�� £�¬­(silica sheet) 2®4 ¯«�Q

�� °�(¥­(gibbsite sheet) 1® Q�& 2-1¡>� ±Y Q�

(�/� 1'[5, 6]. () ­� Q�"< Si4 Al( �� Al Mg

9¡²*(isomorphous substitution).« ³e"´ �% .� () ³e

"# �µ.< �(Z( ­ ­�(# ¶·O'. ­¸# ¶·"< �

(Z� '� �(Z# �� (Z¹* lº(ion-exchange reaction)(

BC"'. »� §H�(crystallite edge)#< Si4 Al »¼& ���

4 3���)( ¶·"% .<], ()# ��Ht ©«W lº(sur-

face complexation)� ½"7 �(Z)( VW&'[7-9]. D�� ¤y(

¥< VWC� �¹� ¾�L ¿À�� Á� ¦§¨ L(¥< �(Z

¹*C( Â�r ¿À�( Ã'� ��� 1'[6].

Ä PQ#H< ��i� N©�ª a�ª Eu3+4 ghi a�ª

Th4+� �� Sª ¤y(¥4 ¦§¨ L(¥4� VWlº� Å$

Æ £Ç� ½� ÈÉ~� VW_�� �U� ~�b "Ê'.

2. � �

2-1. ����

£Ç# �8& ¤y(¥4 ¦§¨ L(¥< ËÌ� Source Clay

Mineral Repository#H ÍÎ& Ï('. ¤y(¥< ËÌ ¦ÐLÑ�

Silver Hill( �!(r �(Z¹*C(Cation Exchange Capacity)�

15 meq/100 g(�, ¦§¨ L(¥< ËÌ 4(ÒÓÑ� Crook County

B �!(r �(Z¹*C� 89 meq/100 g('. [f� �s� ���

Table 1# LÐÔÕ'[10, 11]. Eu3+4 Th4+8Ö� Merck�#H ×Í

& Eu(NO3)3Ø4H2O(99.9%)4 Th(NO3)4Ø5H2O(99%)� 1Ù10−2 M

§Ö(stock solution)� �� 2Ú Û ÜU"7 �8"Ê'. D�� 8

Ö� pH�Ý� HClO44 NaOH8Ö� "Ê�r (ZÞt´ �Ý"

� ��H< Junsei Chemical�� NaClO4ØH2O(98%)4 Ca(NO3)2Ø4H2O

(98%)́ �8"Ê'.

2-2. ����

VW£Ç� £Z� N��ß#H Å$Æ� £["Ê<], Eu3+

Th4+ 8Ö# S� àBO Û XáÖ� ¤�[¸ 9| �9"7 lº

[â'. VW[¸# x� £Ç� Eu3+4 Th4+� ãt´ 1Ù10−4 M

"� (ZÞt< 0.01 M NaClO4ª �ß#H S 8Ö� �´ 5 g/

L lº[â� 7¤ 9| Ñ��� [f´ äå"Ê'. pHæ� £Ç

� +^< Eu3+4 Th4+8Ö� ãtB 1Ù10−4 M( .% "� (ZÞ

t< NaClO4 ç< Ca(NO3)2 �� 0.1, 0.01, 0.001 M( .t� �Ý

"r pH< 3#H 9�( æ�[â'. ({ S 8Ö� �< 1 g/L

(� VW[¸� 3¤ "Ê'. ãt´ æ�[è VW�Zé £Ç� (

ZÞtB 0.01 M NaClO4ª �ß#H Eu3+4 Th4+� ãt´ 1Ù10−6

1Ù10−2 M�( æ�[ê £["Ê'. ë¡# tìO 8Ö S

� XáÖ#H ¤�j� [fäå"7 0.45µm í� ^î �ïð(¥

·�� ñò(Corning 21053-25)́ �8"7 S 8Ö� $�"Ê�

$�& YóÖ� Eu3+ Th4+� ãt< ICP-AES(ICPS-1000III, Shimad-

zu)4 ICP-MS(PQ3, VG Elemental)́ (8"7 $U"Ê'. S# V

W& Eu3+4 Th4+� ãt< lºe 8Ö� ãt#H lº Û 8Ö# ô

� 1< ãt� �( ?�"Ê'. lº eÛ 8Ö� pH< combined

�e;(Metrohm 6.0233.100)� �8"7 õ�"Ê'.

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3-1. �� ��

�8Ö# ¤y(¥L ¦§¨ L(¥´ àBO Û VWlº� �

ö�t´ [¸+# x� 8Ö I# ô� 1< Eu3+� ãt }ªO

» 6[¸ (Û#< ãtB ¤�"% ÷� � 3 1Õ'. () »

´ Fig. 1# LÐÔÕ<] ¤y(¥4 ¦§¨ L(¥# NO ��

VWlº� §ø 1¤( +"« ë¡# ù$` tìk� � 3 1'.

({ VW& �� ¤y(¥� +^< ú �� 98% �t(Õ

� ¦§¨ L(¥� +^< 99.9%(Õ'. 1Ù10−4 M Eu3+8Ö� pH

< 5.94 5.2�(� û(Õ�L ¤y(¥´ àBO Û pH< �� ü

B"7 7.3 7.8�(� û(Õ� ¦§¨ L(¥´ àBO Û pH<

8.1-8.3# tì"Ê'. D�� ��ª ¤y(¥ ç< ¦§¨ L(¥4

Eu3+8Ö� �´ 0.5, 1, 2.5, 5, 10, 25 g/L æ�[ê VW£Ç� £[

O », ¤y(¥� +^< ��4 8Ö� �B 2.5(Y(« VW&

�( ú �� 98% (Y( .Õ'. ¦§¨ L(¥� +^<

��4 8Ö� �B 0.5 B- ¾� +^t VW& �( 99.5%

B .Õ'. () » ýò ��4 8Ö� �B 2.5 g/L (Y(« V

WÛ 8Ö� � ãtB G^ ¾� {þ# VWj ?�[ Ò�B

Ã% d="7 2.5 g/L ~' ¾� �ß( ÿ��"r VW[¸� 1¤(

« ù$` ë¡# tìk� � 3 1Õ'.

¤l�� pH< 38Ö S?«#H� VW�9# IRO ��

� ˲<] (< 2B! ��� ��A 3 1'. � 38Ö#

Table 1. Chemical compositions of illite and montmorillonite[10, 11]

Component (%) SiO2 Al2O3 TiO2 Fe2O3 FeO MgO CaO Na2O K2O H2O+ H2O

−

Illite 55.1 22.0 0.63 5.28 1.34 2.80 0.02 0.08 8.04 6.40 1.00Montmorillonite 62.3 23.5 - 3.35 0.37 1.95 0.31 0.40 0.03 6.45 7.81

Fig. 1. The change of adsorbed Eu and pH as a function of time in theEu adsorption.(Eu3+ conc.=1.00�10−4 M, weights of illite and montmorillonite=5.0 g/L, initial pH=5.9, ionic strength=0.01 M NaClO4)

���� �38� �5� 2000� 10�

����� �� Eu� Th� �� 755

¶·"< JK� pHB æk# xy 8ÖI� 3��(Z(L ��(Z

� W� ¡�"�t O'. 8Ö� pH# xy JK� �s�(

ÿ�% .� (# xy ()� lº�t æ�"7 S©« »¼"

< �Yª VW_�( '�% LÐ '. �� +^< N��ß(r

pH 6("� 38Ö#H< B- |�O ¡>ª Eu3+(Z� Ñ

¶·"r pHæ�# xy 3�� W(L �� W( ¡�.<], ë

¡Y>#H 8Ö# �� 1< �� �s�� §��"« Ný$

pH 6#H EuOH2+4 EuCO3+B =�.� [Á"� pH 8(Y#H Eu

(CO3)2−B |�"'� ~�.� 1'[12, 13]. Ä PQ#Ht *+[��

# NO !�s� ëB ��ª MINTEQA2 � D�[14]� �8"7

pHæ�# x� �� �s� $�´ ?�� ~�� () »´

Fig. 2# LÐÔÕ'. ({ pH 3-10��#H CO2B ¶·"< N��ß

� B�"� �c# �8O 3��W ��W# NO |�tY

3< Table 2# LÐÔÕ'[15]. () »< (Ë ��O þ�� »

[12, 13]4 �"Ê'. , �� pH � 6("#H< Eu3+� 2

¶·"!2 pHB üBk# xy EuOH2+, EuCO3+, Eu(CO3)2

−4 ��

W ¶·k� � 3 1'. D�� � < 8ÖI� 3�(Zãt

# xy S ©«� Á8�� e"B ìy!% .<] (Ï# ��

VW_�( Ã% ìy�'[7, 16]. _` 2-1 ��Sª ¤y(¥4 ¦

§¨ L(¥< ­ ­�(� �Q�ª e"´ � (Z¹* ý$#H

Ñ lº( ¤/L!2 »� §H�# ý$�� �@& Al Si

B 3�./ ¡�& aluminol(AlOH) silanol(SiOH) D ( VWlº

# Ã% �7O'� ���  '. () 3��D # �O �(Z V

W� ©«W� ¡�"< lº('[17, 18].

'�O (ZÞt �ß#H pHæ�# x� �� VW�t´ Fig.

3 4# LÐÔÕ'. Fig. 3� ¤y(¥# NO VW£Ç » pH 6

("#H ¤y(¥# VW& �( ú f�� 40%("Ê� pH

8(Y#H 95%(Y( VW.Õ'. D�� pH 6 8�(#H< VW&

�� �( pHB üBk# xy Î0` üB"< pH§H�(pH

edge)́ ~7Ñ� 1'. ¦§¨ L(¥# NO VW_�� Fig. 4#H

~< ÿ4 ��], pH 6("#H< 60%�tB VW.� pH 6 8

�(#H< VWj( üB"r pH 8(Y#H< �� 95%(Y(

VW&'. ¦§¨ L(¥#Ht pH 6 8�(#H pH §H�B !"

&'. D�� () pH§H�< 8Ö� (ZÞtB Â��3� #$"

% LÐô� � 3 1Õ'. ¤y(¥4 ¦§¨ L(¥# NO �

� VW[ Na+4 Ca2+(Z� ��� Fig. 3 4#H �¹� ~«, Na+

(Z� (ZÞt´ �ÝO +^~' Ca2+(Z� �ÝO +^ V

W& �� �( �³� � 3 1'. D�� Na+4 Ca2+(Z�

+^ §ø ãtB Â� +^B VW& �( �³� � 3 1'.

�� VWj( �/!< Ï� pH 6("#H #$"% LÐL� ¤

y(¥~'< ¦§¨ L(¥B %& Ã% ��� '³� � 3 1'.

��S#H< (Z¹* ý$ SiOH4 AlOH¡>� §H� ý$

(edge site)( H '� �¬�(� VWlº( �ö.< Ï� �

��  '[8]. Fig. 3 4� VW»#Ht ) 3 1*( pH§H� (

"� pH�+#H< VWj� pHæ�# ,!"% ¤�"r '� �(

Z� ��� '³� � 3 1'. D�� �� ãt� Na+~' Ca2+

B ¶·- { VWj( m�"F �� VW� �e�� ªc

!? 1³� ~7 .'. ¾� pH#H ��S# NO ��

3W� ­¸� (Z¹* lº# �� ¤/ô� � 3 1� ({ VW

Fig. 2. Calculated distribution of Eu-species in the aqueous phase equil-ibrated with atmospheric CO2.

Table 2. Stability constants used for modeling of Eu-species[15]

Reactions log K

Eu3++H2O=EuOH2++H+ 0−7.8Eu3++2H2O=Eu(OH)2

+ +2H+ −16.4Eu3++3H2O=Eu(OH)3+3H+ −25.2Eu3++CO3

2− =EuCO3+ 0-7.9

Eu3++2CO32− =Eu(CO3)2

− -12.9

Fig. 3. The adsorbed Eu on illite as a function of pH at different ionicstrength.(Eu3+ conc.=1.00�10−4 M, weight of illite=1.0 g/L)

Fig. 4. The adsorbed Eu on montmorillonite as a function of pH at dif-ferent ionic strength.(Eu3+ conc.=1.00�10−4 M, weight of montmorillonite=1.0 g/L)

HWAHAK KONGHAK Vol. 38, No. 5, October, 2000

756 ������������ ����

j� �¹� �'[19]. (< ­¸# (Ë ¶·"< �(Z( Eu3+

¹*.< Ï� 8ÖI� Na+L Ca2+�� '� �(Z) H +

/�� lº� ¤�ê Eu3+� VW� ��"< Ï� =�&'. D

�� 8Ö� pHB üB"«H ��S� §H� ý$� Á8�)�

³e"´ �% .� () ³e"� ©« � �s�� ©« W

� ¡�"<], pH 6-7�(#H� Î0O VWj� üB< �

�s� () ©« Á8�� Wlº# �ªO Ï� ~ª'[19].

O0, Fig. 2#H< Eu3+B � ��W æ�"< pH��B 6

7�(1� ) 3 1<] (< � VW� Î0O üB4 ¤²"�

1'. () �£ ýò ¾� pH#H (Z¹*# 27"< �s��

Eu3+1� � 3 1'. D�� � pH#H< Eu3+L � ��W

( ©«Wlº# �� VW÷� � 3 1'. DEL '� PQ »

#H< 8ÖI� �� pHB üBk# xy 3e( &'< �£(

}ª.Õ<], pH 6.2(Y#H< EuOHCO3(s)B =�&'< ~�[20]

B 1Õ� pH 7.0(Y#H� 3e� Eu(OH)3(s) 4õO ~�[21]t

1Õ'. Fig. 3#H ) 3 1< pH 6(Y#H� Î0O VWj� üB

< �� 3e# �O Ϥ BC�t 1'.

¤y(¥4 ¦§¨ L(¥� ãt´ ¤�"% "� Eu3+� ãt´

æ�[\«H £[O £Ç»´ ë¡Y>#H 8Ö# ¶·"< Eu3+ã

t# NO S# VW& Eu3+ãt Fig. 5# LÐÔÕ'. ({

� 8Ö� pH< 5.54 9.3�(� û(Õ'. D5� ÈÉ~« ��

ãtB ¾� +^< 8Ö� ë¡ãtB üB-3� VW& ãtB �

6� 1� �é¡>(unit log slope) üB"'B �ãtB Â�

+^< VW& ãtB �6� 0� ¤�O û(zero slope)� ÷� �

3 1'. () »< Langmuir ¡>� VW�Zé� ��A 3 1

'[22]. D�� ¦§¨ L(¥4< ì� ¤y(¥� +^< Â�

�ãt#H �6� 0� �é#H 7/L VW& ãtB �¸ üBk�

~7Ñ� 1'. (< � 8Ö� ãtB Â� { 8Ö� pHB Y

N�� ¾�� (Z¹* lº( ¤ý �7"< Ï� ��A 3 1

'. D�� �� ãtB Â� ��#H< 3e( ¤/8 BC�(

Â�], (EO �£� �6� 0� �+(Û#H VW& ãtB Î0`

üB"< �£ ýò }ª- 3 1<][22], Fig. 5#H< ©«# 3e

( ¤/ Ï� }ª.! ¢�'. ¤y(¥� +^ VW& Eu3+�

�Nãt< 9.2Ù10−5 mol/g(� ¦§¨ L(¥� +^ VW& Eu3+�

�Nãt< 3.3Ù10−4 mol/g(Õ'. () »´ Lagmuir VW�Zé

¡> Fig. 6# LÐÔÕ'. Langmuir Æ�

LÐ9 3 1<], 7�H C< ë¡Y>� 8Ö#H Eu3+� ãt

(mg/L)(� X< VW× 1 gµ VW& Eu3+� �(mg/g)(r Xm� V

W×# VW& Eu3+� �Nj(mg/g)(� k< »¼#:!# !?& Y

3('[23]. Fig. 6# LÐ; £Çû� ýò ¤y(¥4 ¦§¨ L

(¥# NO �� VW� Langmuir VW�Zé# < 2ik�

� 3 1�,»�& Y3< ¤y(¥ +̂ # k=0.05,Y!?3(r2)=0.995

(� ¦§¨ L(¥ +^# k=0.17, Y!?3(r2)=0.988('. Fig. 6

#H é¡ �6�� +3 ýò �N VWj� Q- 3 1<] ¤y

(¥ +^< 16 mg/g(Õ� ¦§¨ L(¥< 48 mg/g(Õ'.

3-2. � ��

¤y(¥4 ¦§¨ L(¥# NO ��� VW( �ö.< Ï� È

É~� �� VW[¸# x� VW& ��� �� Fig. 7# LÐÔÕ

'. lº 3[¸ Û# [fäå´ "Ê<] ({ ¤y(¥4 ¦§¨ L

(¥# VW& ��� ú ��ãt� 97%# �µ.Õ� D (Û#t

( ãtB !./ ë¡# tìk� � 3 1Õ'. 1Ù10−4M ��

8Ö� pH< 3.8�tÊ�L ¤y(¥´ àBO Û pH< Î0` üB

"7 6.9# (�EH ¤��=�r ¦§¨ L(¥´ àBO Û#< l

º 18[¸(Û# 9.0� ¤��='. ¤y(¥ ç< ¦§¨ L(¥4

Th4+8Ö� �´ 0.5#H 25 g/L>! üB[ê VW£Ç� £[O »,CX---- 1

kXm

---------- 1Xm

-------C+=

Fig. 5. The adsorbed Eu concentration as a function of equilibrium Euconcentration at 1.0 g/L of illite and montmorillonite.

Fig. 6. Langmuir adsorption isotherm of Eu adsorption on illite andmontmorillonite.

Fig. 7. The change of adsorbed Th and pH as a function of time in theTh adsorption.(Th�+ conc.=1.00�10−4 M, weights of illite and montmorillonite=5.0 g/L, initial pH=3.8, ionic strength=0.01 M NaClO4)

���� �38� �5� 2000� 10�

����� �� Eu� Th� �� 757

¤y(¥� +^< 2.5 g/L(Y#H D�� ¦§¨ L(¥� +^<

0.5(Y� û#H VW& ��( 99.9%B .Õ'.

��� ¾� pH� 38Ö#H< Th4+(Z ¡> ¶·"L pHB

üBk# xy 3��(Z ��(Z# �� W( ¡�&'. B3$

�2 ��"7 �s�� ?�O ~�# �"«[24, 25] pH 3.5>!<

Th4+ 2 ¶·"'B pHB üBk# xy ThOH3+, Th(OH)22+, Th

(OH)3+� 3�� W( ¡�&'. D�� � pH 5(Y#H< 8ÖY

� Th(OH)42 ¡�./ ¶·O'. (����´ ¤�"% ![è £

Ç» ýò ?�O �s�� pH 3.5#H 5.5�(#H< Th(OH)3+

4 Th(OH)4� 3�� W( Ñ ¶·"'B pH 5.5 (Y#H< Th

(OH)3CO3−4 Th(CO3)5

6−� �� W( Ñ ¶·O'< ~�t 1

Õ'[26]. () »´ 2� "7 MINTEQA2 � D�� �8"7

pHæ�# x� Th4+(Z� �s� $�´ ?�� ~�'. ({ pHB

2-9ª ��#H CO2B ¶·"< N��ß� B�"Ê� �c# �8&

3��W ��W# NO |�tY3< Table 3# LÐÔÕ'[27].

?/� »´ Fig. 8# LÐÔÕ<] pH 3.5("# Th4+(Z� !@

�� ¶·"r pHB üBk# xy B3$�B ¤/L Th(OH)22+,

Th(OH)3+, Th(OH)4�� 3�( ¶·k� � 3 1'. ��W�

¡�� ËËO Ï� LÐA'.

Table 3. Stability constants used for modeling of Th-species [27]

Reactions log K

Th4++H2O=ThOH3++H+ −3.2Th4++2H2O=Th(OH)2

2+ +2H+ −6.9Th4++3H2O=Th(OH)3

+ +3H+ −9.1Th4++4H2O=Th(OH)4+4H+ −13.90Th4++CO3

2− =ThCO32+ 11.0

Fig. 8. Calculated distribution of Th-species in the aqueous phaseequilibrated with atmospheric CO2.

Fig. 9. The adsorbed Th on illite as a function of pH at different ionicstrength.(Th4+ conc.=1.00�10−4 M, weight of illite=1.0 g/L)

Fig. 10. The adsorbed Th on montmorillonite as a function of pH atdifferent ionic strength.(Th4+ conc. =1.00�10−4 M, weight of montmorillonite=1.0 g/L)

Fig. 12. Langmuir adsorption isotherm of Th adsorption on illite andmontmorillonite.

Fig. 11. The adsorbed Th concentration as a function of equilibriumTh concentration at 1.0 g/L of illite and montmorillonite.

HWAHAK KONGHAK Vol. 38, No. 5, October, 2000

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Table 4. Maximum adsorbed amount of Eu and Th on illite and montmorillonite

Minerals Illite Montmorillonite

Cation exchange capacity by the literature[10, 11] 15 meq/100g 89 meq/100gCations Eu3+ Th4+ Eu3+ Th4+

Maximum adsorbed concentration by Fig. 5 and 11 9.2�10−2 mmol/g 2.5�10−1 mmol/g 3.3�10−1 mmol/g 4.0�10−1 mmol/g(28 meq/100 g) (100 meq/100 g) (99 meq/100 g) (160 meq/100 g)

Maximum adsorbed amount by adsorption isotherm 16 mg/g 63 mg/g 48 mg/g 74 mg/g(32 meq/100 g) (109 meq/100 g) (95 meq/100 g) (128 meq/100 g)

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HWAHAK KONGHAK Vol. 38, No. 5, October, 2000