foldesova et al 1996 study of physical and thermochemical properties of modified zeolites

7/28/2019 Foldesova Et Al 1996 Study of Physical and Thermochemical Properties of Modified Zeolites

1/7

Journa l o f Thermal Analys is , Vol . 46 (1996) 565-571

S T U D Y O F P H YS IC A L A N D T H E R M O C H E M I C A LP R O P ~ O F M O D IF IE D Z EO LIT ES

M . FOM esov(~, V. Tom kov61, P Lu k66 an d P DiU ingerSlovak Techn ica l Un iver s i ty , 81237 B ra t i sl ava , S lovak Repub l i c1 T e c h n ic a l U n i v e r s i t y o f M i n i n g a n d M e t a ll u rg y , 7 0 83 3 O s t r a v a , C z e c h R e p u b l i c

AbstractT h e t r e a t m e n t o f z e o l i te w i t h a s o l u t i o n o f N a O H a t d i f f e re n t c o n c e n t ra t i o n s c r e a t e s m o d i f i e d

f o r m s o f n a t u r a l z e o l i t e s .T h e s e m o d i f i e d z e o l it e s e x h i b i t a n i n c r e a s e d u p t a k e o f c a e s iu m a n d a s a t i s fa c t o r y u p t a k e o f

c o b a l t . T h e s t r u c tu r a l c h a n g e s i n t h e m o d i f i e d z eo l i te s w e r e s t u d i e d b y X R D a n a l y s i s , w h i c h r e -v e a l s t h e m i n e r a l c o m p o s i t i o n s o f t h e s t u d i e d m a t e r i a l s . T h e t h e r m o d y n a m i c p r o p e r t i e s o f t h em o d i f i e d z e o l i te s w e r e s t u d i e d b y m e a n s o f D T A an d t h e r m o g r a v i m e t r y , an d t h e c h e m i c a l c o m -p o s i t i o n t o o w a s d e t e r m i n e d .K e y w o r d s : s o r p t i o n o f C s a n d C o , t h e r m o e h e m i c a l p r o p e r ti e s , z e o l it e

IntroductionNu c lea r pow er s t a ti ons p rodu ce huge amou nt s o f l i qu id rad ioac ti ve was te s.Th e do m inan t radion ucl ides in these wastes a re 137Cs, 9~ and 6~ O ne pos s i -

b i l it y fo r t he i r imm obi l i za t ion is t he use o f d i f fe ren t ion-exchange rs . Th e i nor -gan i c i on-exchange r o f fe r t he advant ages o f h igh capac i t y , good se l ec t i v i t y ,reproduc ib l e s t o i ch iome t ry , r ad i a t i on re s i s t ance and compa t ib i l i t y wi th g l a s sand cem enta t i on was te fo rms [1] . O ne exce l l en t and re l a ti ve ly cheap i on-ex-changer i s zeol i t e . The bas i s of the zeol i t i c s t ruc ture i s spheres cons i s t ing of2 4 S i O 4 t e tr aede rs j o in ed t oge the r by S i - O -S groups . T he cav i ti e s and chan ne l sin thi s s t ruc ture can ho ld meta l ca t ions (m ost ly a lka li me ta l s and a lka l ine ear thme ta l s ) o r m olecu l e s (e .g . H2 0) . Th e s t ruc ture o f a zeo l it e de t e rm ines its spe -c i f ic phys ica l and c hem ica l proper t ies , such as ion-ex chan ge abi l i ty and a bso rp-t i on , r eve rs ib l e dehy dra t i on and hydra t i on . In S lovak Republ i c, t he re a re r i chdepo s i t e s o f zeo l i ti c ma te r ia l s wh ich con t a in about 70% c l i nopt i lo l i t e [2] .Th e c l i nop t il o l it e con t en t de t e rmines t he sorp t ion ab i li ty o f t he se ma te r i a ls .Th e chem ica l and mo rpholog i ca l p rope r t i e s o f S lovak zeo l i t e [3 ] a re s imi l a r tothose o f the w e l l -know n c l inop t i l o l it e f rom the He c tor o r Cas t l e Creek depos i t sin the U SA . I t exhibi t s an exce l lent sorpt ion uptake of caes ium [1] and, a f te rspec i f i c chemica l t r ea tment , i t ha s a good up t ake of coba l t [5 -7] . Recen t ex-0 3 6 8 - - 4 4 6 6 / 9 6 / $ 5 . O 09 1 9 9 6 A k a d ~ m i a i K i a d 6 , B u d a p e s t

J o h n W i l e y & S o n s , L i m i t e dCh i c h e s t e r


2/7

5 66 F O L D E S O V A et al,: P R O P E R T I E S O F M O D I F I E D Z E O L I T E S

p e r im en t s sh o w th a t zeo l i te t r eat ed wi th N aO H wi th s t an d s th e a lk a l in e en v i ro n -m en t in co n c re t e [ 8 ]. Th e r e su l t in g co m p o s i t e h a s ex ce l l en t p h y s ica l an d m e -ch an ica l p ro p e r t i e s th a t w o u ld b e v e ry su i tab le fo r th e so l id i f i ca t io n o f n u c lea rwastes .E x p e r i m e n t a l

Th e zeo l i t i c m a te r i a l u sed in th e se ex p e r im en t s was f ro m th e Ni sHrab o v ec d ep o s i t ( g r a in s i ze f ro m 1 .2 to 2 m m ) . Th e XRD an a ly s i s i n d ica t edth a t t h i s m a te r i a l m o s t ly co n ta in ed c l in o p t i lo l i t e ( th eo re t i ca l f o rm u laNa2.3K1.TCao.sMgo.2A10.2(Si30A16)72.24H20). T h e na tur al ze ol ite w as ch e m ic a ll yt r ea t ed [6 -8 ] b y h ea t in g in 1 M , 4 M o r 6 M so lu t io n s o f Na OH a t 80 ~ fo r 4 h .Af te r h ea t in g , t h e sam p les were wash ed wi th d i s t i l l ed wa te r an d d r i ed . Th i st r ea tm en t y i e ld ed v a r io u s ly m o d i f i ed zeo l i t e s w i th d i f f e r en t co m p o s i t io n s an dp ro p e r t i e s . Th e u p tak es o f Co an d Cs were co n t ro l l ed b y th e m e th o d o f m o d e lr ad io ac t iv e so lu t io n s : 0 .0 5 g sam p les o f zeo l i t e w e re ad d ed to v esse l s co n ta in -ing 10 ml 0 .05 M COC12.6H20 so lu t ion labe l led wi th 6~ or 0 .05 M CsC I so-lu t io n l ab e l l ed wi th 13 7Cs ( th e r ad io ac t iv i ty o f so lu t io n s was m easu red wi th awe l l sc in t i l la t io n d e tec to r) . Af t e r 2 4 h , t h e r ad io ac t iv it i e s o f t h e so lu t io n s w erem easu red an d fu r th e r 0 .0 5 g zeo l i t e sam p les were ad d ed . Th ese s t ep s were r e -p ea ted sev e ra l t im es . Th e m easu rem en t s p e rm i t t ed ca l cu la t io n o f th e so rp t io nco e f f i c ien t s o f Cs an d Co .

Th e ch an g es in th e zeo l i t i c m a te r i a l o n r eac t io n wi th NaOH so lu t io n werech a rac te r i zed b y ch em ica l an a ly si s , XR D an a ly s i s (DR ON 2 ,0 9 ) an d DTA (Q-1500) der iva tograph .

R esu l t s a n d d i s cu s si o nTh e u p tak e o f a r ad io n u c l id e was ch a rac te r i zed b y th e so rp t io n co e f f i c i en t

IX, def ine d a cco rd ing to the fo rm ulacV~ t= - k - -V

w h e re k i s t h e s lo p e o f th e l i n ea r p a r t o f t h e i so th e rm , c is t h e m o la r co n ce n t r a -t io n o f th e so lu t io n , V is t h e v o lu m e o f so lu t io n u sed , an d v i s t h e v a len cy o f th elabe l led ions .Tab le 1 g ives the sorp t ion co ef f ic ien ts (Co , Cs) o f the t rea ted zeo l i te . T he m axi-m u m u p tak e o f caes iu m b y th e zeo l it e t r ea ted wi th 1 M Na OH so lu t io n an d th em ax im u m u p tak e o f co b a l t by th e zeo l i te t r ea ted w i th 4 M N aO H so lu t io n a r es h o w n :

) . T h e r m a l A n a l . , 4 6 , 1 9 9 6


3/7

FOLDESOV,~ et al.: PROPERTIES OF MODIFIED ZEOLITES 567

Table 1 Sorption coefficients of natural and modified zeolitesSorption coefficient / meq g-lType of zeolite Cs(1) Co(ll)

P * 0.80 0.10modified with 1 M NaOH 1.30 0.28modified with 4 M NaOH 1.02 0.42modified with 6 M NaOH 0.96 0.40*P = natural zeolitic material (Ninny Hrabovec)

Th e ch em ica l co m p o s i t io n s o f t h e n a tu r a l an d m o d i f i ed zeo l i t e s a r e to b efo u n d in Tab le 2 . Th i s Tab le sh o ws th a t t h e co n ten t o f S iO2 is s ig n i f i can t ly d e -c r e a s e d i n t h e z e o l it e s t r ea t e d w i th 4 M o r 6 M N a O H s o l u t io n , w h e r e a s t h eco n ten t s o f A12 03 an d Na2 0 an d th e lo ss o n ig n i t io n a r e in c r eased . T h es e e f f ec t sa r e d u e to th e ch em ica l r eac t io n s o f NaOH, an d m a in ly to th e wash in g -o u t o fth e so lu b le p h ase .Table 2 Chemical compositions of natural and modified zeolites / wt. %

Natural Zeolite modified withComponent zeolite 1 M NaOH 4 M NaOH 6 M NaOH

L.O.I.* 11.45 12.32 23.51 29.28SiO2 68.25 62.83 43.75 36.30

A1203 11.66 12.47 14.44 15.43Fe203 1.17 1.30 1.76 1.87CaO 3.62 3.97 5.05 4.29MgO 1.30 1.77 1.91 1.39Na20 0.70 2.14 7.82 9.54

*L.O.1. = loss on ignition

Fig u re 1 p ro v id es XR D p ic tu re s o f t h e t rea t ed zeo li t e s in co m p ar i so n wi thth a t o f t h e n a tu r a l sam p le , wh i l e F ig . 2 p r e sen ts th e XR D p a t t e rn s o f t h e sam em ater ia l a f te r anne a l ing up to 1000~Tab le 3 g iv es th e lo sse s in m ass o f sam p les ev a lu a ted f ro m th e DTA cu rv es .T h e r e s u lt s s h o w t h a t t h e tr e a t m e n t w i t h 1 M N a O H s o l u t io n c h a n g e d th e

z e o l it e o n l y v e r y w e a k l y. T h e X R D a n a ly s is r e v e a le d th a t t h e d o m i n a n t p h a s eo f n a tu r a l an d m o d i f i ed zeo l i t e (w i th 1 M NaO H so lu t io n ) is c l in o p t i lo l it e ;q u a r t z was a l so id en t i f ied [9 ]. He a t in g o f n a tu r a l z eo l it e an d th a t m o d i f i ed wi th1 M N aO H u p to 1 0 0 0~ was d em o n s t r a t ed b y th e rm a l an a ly s i s t o cau se an in -c r ea se in th e m ass lo ss ( fro m 11 to 1 3 %) .F ig u re 3 p r e sen t s DTA cu rv es fo r a l l t h e se zeo l it i c sam p les . Th e ch an g es a r eseen to b e co n t in u o u s fo r zeo l i t e t r ea ted wi th 1 M Na OH an d fo r n a tu r a l z eo l i t e .

J. Thermal Anal. , 46, 1996


4/7

5 6 8 F O L D E S O V A e t a l. : P R O P E R T I E S O F M O D I F I E D Z E O L I T E S

A p A ]

iA A

I

K

K K

K

K

I

K

6:d

1 I I2 0 @ 1 ~ 2 0

F i g . 1 P h a s e c o m p o s i t i o n o f n a t u r a l a n d m o d i f i e d z e o l i t i e m a t e r i a l s ; K - e l i n o p t i lo l i t e ,Q - q u a r t z , A - a l b i t e , J - j a d e i t e , P - p a r a g o n i t e

J . Thermal A na l . , 46 , 1996


5/7

F O L D E S O V A e t a l. : P R O P E R T I E S O F M O D I F IE D Z E O L I T E S 5 69

N

N'

N N

N

N

h

= f

N N.N

N

AA Ci i

4M

..... 1 ..... I

F i g . 2 P h a s e c o m p o s i t i o n o f n a t ur a l a n d m o d i f i e d z e o l it e s a f t e r a n n e a l i n g u p to t h e t e m p e r a -t u r e 1 0 0 0 ~ Q - q u a r t z , A - a l b i t e , C - c r i s t o b a l i t e , N - n e p h e l i n e

J. Thermal Anal., 46, 1996


6/7

570 F()LDESOVA et al.: PROPERTIES OF MODIFIED ZEOL1TES

Table 3 Thermogravimetrie data on zeolites used

Type of zeoliteLoss First loss in Second loss in Maximu m of

in mass / mass/temp erature/ endo therm, effect/% %1~ %/~ ~CP* 11.0 10.4/450 0.6/740

1 M** 13.3 13.3/740 -4 M** 24.6 22.4/460 2.2/7606 M** 30.4 28.21320 2.41790

800810

*P = natural zeolitic material** natural zeolitic material modi fied by treatment with 1 M, 4 M or 6 M NaOH

JS

i2 0 2 0 0

J

r/k) z I

4 0 0 6 O 0 8 0 0 1 0 o 0T /~Fig. 3 DTA curves of natural and modifie d zeolites; P - natural zeolit e, 1 M - zeolit e modi -fied with 1 M NaOH solution, 4 M - zeolite modified with 4 M - zeolite modified

with 4 M NaOH solution, 6 M - zeolite modif ied with 6 M NaOH solution

L~

4M

6 ~

Fo r b o th m a te r i a ls , t h e lo ss in m ass i s ev id en t o n ly u p to 7 5 0 ~ Th e DTAcu rv es fo r b o th m a te r i a l s sh o w o n ly a b ro ad ex p re ss io n le ss en d o th e rm ic e ff ec t.Tab le 4 l is ts t h e p h ase co m p o s i t io n s o f th e sam p les b e fo re an d a f t e r an n ea l -in g u p to th e 1 00 0~ Th e p h ase co m p o s i t io n s o f t h e sam p les af t e r an n ea l in g u p

to 1 0 00 ~ a r e v e ry s im i l a r acco rd in g to th e XR D an a ly s is .I t m ay b e a ssu m ed th a t t h e h ig h - t em p era tu r e s t ab le fo rm o f S iO2 ( c r i s to -

b a l i t e ) p e r s i s t s t o g e th e r w i th a v e ry sm a l l am o u n t o f q u a r t z an d a lb i t e(NaAISi3 Os). Th e p a t t e rn in d ica te s a s ig n i fi can t am o u n t o f th e a m o rp h o u sf o r m .J. Thermal Anal., 46, 1996


7/7

FOLDE SOV, ~. et al.: P R OP ER TIES OF MO DIF IED ZEOL ITES 571

T a bl e 4 P ha s e co mpo s i t i o ns o f na tura l a nd t rea ted zeo l i t e sT y p e o f

z e o l i t e b e f o r e a n n e a l in gP* e l inop t i lo l i te , quartz

1 M * * e l i n o p t i l o l i t e , q u a r t z4 M * * a l b i te , q u a r t z6 M * * a l b i te , q u a r t z , paragoni te , jadei te

* P = natural zeo l i te

C o m p o s i t io n o f z e o l i t ea f ter a nnea l i ng up to 1 0 0 0 ~quartz , (er i stobal ite) , a lbite , am orp ho us partquartz , (er i stobal ite) , a lbite , am orp ho us partn e p h e l i n e , a m o r p h o u s p ar tn e p h e l i n e , a m o r p h o u s p a rt ....

* * natural zeol i t ic ma terial mo dified by treatm ent with i M, 4 M or 6 M N a O H

T h e c h e m i c a l t r e a tm e n t o f n a t ur a l z e o l i t e w i t h m o r e c o n c e n t r at e d s o l u t io n so f N a O H ( 4 M o r 6 M ) c a u s e d m o r e m a r k e d c h a n g e s . T h e r m o g r a v i m e t r i c c a l -c u l a t io n s r e v e a le d l o s s e s i n m a s s o f 2 5 - 3 0 % .

T h e D T A c u r v e s o f t h e s e m o d i f i e d z e o l i te s d e m o n s t r a te an e n d o t h e r m i cp r o c e s s a t a b o u t 1 0 0 ~ a n d a n e x o t h e r m i c p r o c e s s f r o m 7 5 0 u p t o 8 0 0 ~ o b -v i o u s l y r e l a t i n g t o a p r o c e s s i n t h e s o l i d s ta t e .

X R D a n a l y s i s p o i n t s t o c h a n g e s c a u s e d b y h e a t i n g u p t o 1 0 00 ~ t h e o r i g i n a lz e o l i t e m o d i f i e d w i t h 4 M N a O H d i s p la y s v e r y l o w c r y s t a l li n it y : o n l y a l b i te a n dq u a r t z . A n n e a l i n g c h a n g e s i t t o a u n i q u e c r y s t a ll in e p h a s e , n e p h e l i n e ( N a A 1 -S i O 4 ), t o g e t h e r w i t h a n a m o r p h o u s p a r t.

T h e s a m p l e m o d i f ie d w i th 6 M N a O H c o n ta in s a m i x tu r e o f c r y s ta l li n ef o r m s : a l b i te , q u a r t z , j a d e i t e ( N a A I S i 2 0 6 ) a n d p r o b a b l y a l s o p a r a g o n i t e{ N a A I 2 ( A I S i3 O I 0 ) (O H ) 2 }. O n a n n e a l i n g a t 1 0 0 0 ~ t h e s t r u c tu r e o f t h i s s a m p l ec h a n g e s t o n e p h e l i n e ( a s i n t h e c a s e o f z e o l i te tr e at ed w i t h 4 M N a O H ) , a n ds o m e a m o r p h o u s m a t er ia l is p r o b a b ly a l s o fo r m e d .

A l l t h e r e s u l t s s h o w t h a t t h e e f f e c t s o f N a O H o n n a t u r a l z e o l i t e l e a d t oc h a n g e s i n p h a s e c o m p o s i t io n a n d m i c r os t ru c t u re w h i c h r e s u lt i n i n c r e a s ed C sa n d C o u p t a k e s ( f r o m a q u e o u s s o l u t i o n ) .

T h i s e x p e r i e n c e c o u l d b e u s e f u l i n th e i m m o b i l iz a t i o n o f r a d i o n u c l id e s p r e s -e n t i n w a s t e w a t e r s fr o m n u c l e a r p o w e r p l a n t s.R e f e r e n c e s

1 A . D y e r a n d E H . K a d h i m , J. Radioanal . Nucl . C h e m . , 1 3 1 ( 1 9 8 9 ) 1 6 1 .2 J . K oza6 , D. O~enfi~ , D . R u s n hk a n d J . H o f f m a n , M i n e r S l o v a e a , 1 4 ( 1 9 8 2 ) 1 2 4 .3 A. Sopkov~l and J . Bubanee, Chem. Prf imys l , 38 (1988) 11 .4 L . L . A m e s , A m e r . M i n e r a l . , 45 (1960) 689 .5 P . H l o ~ e k , M . F f l d e s o v f i a n d P . L u k e , , J . Radioanal . Nuel . C h e m . , L e t t . , 1 6 5 ( 1 9 9 2 ) 1 7 5 .6 P. Lukfi~, P. H l o ~ e k a n d M . F f l d e s o v f i , G eo l o g i ea C a rpa t i ea - Ser i e s C l a y , 2 (1992) 125 .7 P. Luk,5.6 and M . F61desov~., J . Radioanal . Nuel . C h e m . , L e t t . , 1 8 8 ( 1 9 9 4 ) 4 2 7 .8 V . Tomkovf i , P . Luke 6 , M. F 61de sov f i a nd J . Ma j l i ng , S l ova k P a te n t. A p p l .: P V 0 0 0 5 - 95 ,B ra t i s l a va , 1995 .9 Se lecte d Pow der Di f fra ct ion Data for M inerals , Phi ladelphia , 1974 .

J. Thermal Anal., 46, 1996

foldesova et al 1996 study of physical and thermochemical properties of modified zeolites

Documents