SORPTION OF TRACE CONSTITUENTS FROM AQUEOUS …clays.org/journal/archive/volume 31/31-5-321.pdf · INTRODUCTION Uranium is a relatively mobile element in temperate ... high-level

Clays and Clay Minerals, Vol. 31, No. 5, 321-334, 1983.

SORPTION OF TRACE CONSTITUENTS FROM AQUEOUS SOLUTIONS ONTO SECONDARY MINERALS.

I. U R A N I U M

L. L. AMES, J. E. MCGARRAH, AND B. A. WALKER

Battelle, Pacific Northwest Laboratories, P.O. Box 999, Richland, Washington 99352

Abstract--Well-characterized American Petroleum Institute clay standards, source clays from The Clay Minerals Society, and other secondary minerals were used to determine the effects of U concentration, temperature, and solution composition on U-sorption properties. Uranium concentrations ranged from about 1.00 x 10 -4 M to 4.00 x 10 7 M, temperatures from 5 ~ to 65~ and solution compositions containing 0.01 M NaCl and 0.01 M NaHCO3. Silica gel efficiently sorbed uranyl carbonate anion complexes. The higher cation-exchange capacity materials most readily sorbed uranyl ions from the 0.01 M NaCl solution. Temperature increases tended to affect uranyl ion sorption adversely except when the U was present as carbonate complexes. Noncrystalline ferric oxyhydroxides sorbed uranyl ions much more efficiently than any of the secondary crystalline minerals studied. A method for accurately extrapolating U-sorption efficiencies between experimental points based on the Freundlich equation is presented. Key Words--Cation exchange, Clinoptilolite, Freundlich isotherm, Glauconite, lllite, Montmorillonite, Opal, Sorption, Uranium.

INTRODUCTION

Uranium is a relatively mobile element in temperate surface environments; its mobility as controlled by U-mineral solubility equilibria in low temperature waters is well documented (Langmuir, 1978a, 1978b). An additional, relatively unknown factor in U mobility is, however, that of sorption on secondary minerals commonly found on joint surfaces of rocks and in sed- iments normally encountered during aqueous trans- port. Quantitative sorption data are scarce. Goldsztaub and Wey (1955) reported that 7.5 g of U was sorbed from a 1% uranyl nitrate solution onto 100 g of calcined kaolinite. Starik et al. (1958) found that the sorption of trace concentration of U on iron hydroxide was opt imum at about pH 5, and declined above and below this value. Uranium was desorbed with a carbonate solution.

Rancon (1973) studied the sorption of U using four soils described as: (1) a river sediment containing a mixture of quartz, clay, calcite, and organic matter, (2) a river peat, (3) a sediment from Cadarache containing a mixture of quartz, clay, and calcite with no organic matter, and (4) a soil developed on an altered schist from near LaHague containing a mixture of quartz and clay but no calcite or organic matter. The first two soils were equilibrated with their river waters containing 10 ppm U and the last two soils were equilibrated with their respective groundwaters also containing 10 ppm U. The resulting U distribution coefficients are shown in Table 1, which also includes the Kd values on pure quartz, calcite, and illite. The clay minerals in Soils 1, 3, and 4 were not identified, nor were the soils further characterized. Rancon also examined the effects of ini-

Copyright �9 1983, The Clay Minerals Society

tial U concentration on Kd values. Both the U concentration and solution pH changed as U was added to the solution. At 0.1 mg U/liter, the pH was 7.6, for example, and at 1.0 g U/liter, the pH was 3.5. Because the pH changes were a function of U concentration changes, the results are not easily interpreted. In addition, the Kd concept is invalid above the trace U concentration (~ 1.0 mg U/liter). Uranium adsorption data at 1 ppm vs. Kd also were presented. For Soil 4, three peaks were observed: Kd 300 ml/g at about pH 5.5, Kd 2000 ml/g at pH 10, and Kd 270 ml/g at pH 12. Rancon suggested that the adsorption maxima rep- resented by the three peaks also represent electrokinetic potential maxima. Quartz was characterized as inert, calcite as a poor U adsorber, and clays as the best adsorbers of U from solution. Acid, organic-rich soils show much higher U Kd values than the alkaline peat (Soil 2) of Ranron's (1973) study.

Langmuir (1978b) reported several U-enrichment materials based on the work of Schmidt-Collerus (1967) including noncrystalline t i tanium oxide (8 • 104 to 1 X 106), noncrystalline Fe(lII) oxyhydroxides (1.1 X 106 to 2.7 X 106), peat (104 to 106), fine-grained goethite (4 X 103), phosphorites (15), montmoril lonite (6), and kaolinite (2). Giblin (1980) studied U sorption from a simulated groundwater containing 100 ~g U/liter (4.202 X 10 -7 M) onto kaolinite over a pH range of 3.5 to 10. A maximum U distribution of 35,000 ml/g was attained at a pH of 6.5.

Hsi (198 l) examined the sorption of U on hematite, goethite, and noncrystalline ferric oxyhydroxide as affected by pH, U concentration, and carbonate complexing. Tsunaskima et al. (1981) examined the sorp-

321

322 Ames, McGarrah, and Walker Clays and Clay Minerals

Table 1. Uranium Kd Values. ~

Soil Kd (ml/g)

1 --River sediment (clay, CaCO3, organic matter) 39

2--River peat 33 3--Sediment (clay, CaCO3) 16 4--Altered schist (clay) 270 Quartz 0 Calcite 7 Illite 139

From Rancon (1973).

tion of U by Volclay over the concentration range of 1-300 ppm U. The sorption isotherms were reported to follow Langmuir-type curves at higher U-solution concentrations. Giblin et al. (1981) examined the mobility of U as affected by Eh and pH at 25~ Hydrous ferric oxide and kaolinite were used as the solid phases. High mobility in a pH-Eh range where U was ther- modynamically insoluble suggested that U was present in this region as a colloid.

Walton et al. (1981) examined the release of U from two volcanic glass sedimentary sequences in Texas during diagenesis. Uranium was not significantly mobi- lized during the solution of the glass. They reported that once U was effectively trapped by secondary phases, it did not move for about 30 million years. Nash et al. (1981) recently reviewed the few reported field occurrences of U deposition by sorption and concluded that sorption could be an important concentrating step prior to the formation of uranyl or uranous minerals. The lack of rigorous and comparable U-sorption data on characterized geological materials, however, made the role of sorption in U migration difficult to assess.

In addition to the migration and sorption of U and Ra in natural deposits, the subject also is pertinent to high-level radioactive waste disposal where certain clays are under consideration as a portion of the backfill component of the multiple barrier waste package (Wood and Aden, 1982). The primary function of the waste package backfill is to assist in meeting the Nuclear Regulatory Commission criteria that requires a radionuclide release rate of no more than one part in 105 of

the inventory from the engineered barrier system (waste package plus repository) after 1000 years. All other things being equal, radionuclide breakthrough time is a function of the backfill material equilibrium radionuclide distribution coefficient. The present investi- gation was conducted to determine the sorption of uranium on various clays and other secondary minerals as a function of U concentration, temperature, and solution composition.

MATERIALS AND METHODS

Characterization of the secondary minerals

The identification and location of the secondary minerals used in the sorption studies are given in Table 2. The clay minerals were either American Petroleum Institute clay standards (Kerr, 1950) or source clays from The Clay Minerals Society (van Olphen and Fri- plat, 1979). The various size ranges selected for use were obtained by grinding or elutriation. Chemical analyses of these materials for major components were made by Teflon-bomb digestion and inductively cou- pled argon-plasma before sodium solution contact (Ta- ble 3). Thorium analysis was by neutron activation and U, by atomic fluorescence. X-ray powder diffraction results showed that most of the minerals were free of detectable impurities with the exception of the illite and opal samples. The major constituent of the opal was a-cristobalite. Minor quartz contamination was carried over during recovery of the < 2-/~m illite frac- tion.

Cation-exchange capacities (CEC), measured with Cs and a Cs radionuclide (Cs 137) as chlorides at pH 7.0 and 25~ are given in Table 4. The procedure used was similar to that given by Routson et al. (1973). An ethylene glycol-monoethyl ether sorption method (Heilman et al., 1965) was utilized to measure the surface area of the secondary minerals (Table 4). The first number given represents a mean of three values; the following number is a standard deviation.

Following separations, the secondary minerals were contacted three times with 3 M NaC1 solutions, washed with methanol, and centrifugation to remove excess NaC1. Some care had to be taken with the kaolinite to avoid pH values below 5 in the NaC1 solutions.

Table 2. Identification and origin of secondary minerals.

Mineral Location Origin

Illite, <2 um Kaolinite, < 2 ~m Montmorillonite, <2 um

Nontron i t e , < 2 # m Glauconite, 20-50 mesh Clinoptilolite, 50-100 mesh Opal, 20-40 mesh Silica gel, 100-200 mesh, reagent grade

Fithian, Illinois Macon County, Georgia Apache County, Arizona

Garfield, Washington New Jersey coastal plain Death Valley Junction, California Virgin Valley, Nevada Synthetic

A.P.I. Clay Standard 35 A.P.I. Clay Standard 4 The Clay Minerals Society Source Clay

SAz- 1 A.P.I. Clay standard 33A Ward's Natural Science Establishment Anaconda Minerals Company, 1010 A Ward's Natural Science Establishment Fisher Scientific Company

Vol. 31, No. 5, 1983 Sorption of uranium onto clays and clinoptilolite

Table 3. Chemical analyses of the secondary minerals used in the uranium sorption work.

323

Montmoril- Clinopti- Detection Constituent Illite Kaolinite Ionite Nontronite Glauconite Iolite Opal Silica gel limit

Main constituents (wt. %) SiO2 57.10 45.10 58.90 45.00 49.20 65.20 88.90 90.7 0.5 AI~O3 18.40 37.80 17.10 6.31 7.46 11.10 0.79 0.14 0.4 Fe203 5.97 0.38 1.58 35.00 20.70 0.79 0.09 -- 0.04 CaO 0.53 0.03 1.08 1.00 1.08 1.55 0.15 0.03 0.01 MgO 1.87 0.27 6.08 0.41 3.55 0.58 0.11 0.03 0.01 Na20 1.40 0.35 3.72 2.50 0.27 2.52 0.10 -- 0.1 K20 5.00 0.25 0.19 0.02 9.40 4.04 0.04 -- 0.01 Loss on ignition 9.05 14.50 11.10 9.60 7.75 14.20 9.80 9.10 0.01

Total 99.84 98.68 99.90 99.84 99.90 99.98 99.98 100.00

Major trace components (ppm) Barium 45 60 267 152 32 340 -- -- 10 Manganese 279 30 720 380 4900 208 -- -- 30 Strontium 101 35 131 44 37 789 -- -- 10 Titanium 5210 9050 1510 512 436 640 -- 172 50 Uranium 1.0 0.5 11.5 -- 1.0 1.5 26.0 -- 0.5 Thorium 16.0 20.0 32.0 3.0 3.0 19.0 -- -- 2.0

-- present below detection limits.

Solutions

Two solut ions con ta in ing four U concen t ra t ions were used wi th the a b o v e minera l s . T h e uranyl concen t r a - t ions are g iven in Tab les 5 -7 wi th the u r a n i u m in 0.01 M NaC1 or 0.01 M NaHCO3. T h e two types o f so lu t ions a l lowed e x a m i n a t i o n o f the effects o f U - c a r b o n a t e c o m p l e x i n g on U so rp t ion a n d its in t e rac t ions wi th t e m p e r a t u r e a n d U concen t r a t i on .

Rad iochemica l l y pure and carr ier - f ree U 233 as uranyl n i t ra te was used to t race U so rp t ion on the minera ls . The use o f U 233 a l lowed accura te sc in t i l la t ion coun t ing o f U in to the pa r t per b i l l ion c o n c e n t r a t i o n range. De- p le ted u rany l n i t ra te (U 23s) was used a long wi th the U 233 to m a k e up the solut ions . T he specific ac t iv i ty o f U 233 was too h igh (9.48 • 10 3 Ci/g) to a l low its pract ical use m u c h a b o v e a so lu t ion c o n c e n t r a t i o n o f 1.0 • 10 -6 M.

Methods

T h r e e a l iquo ts o f each or ig inal so lu t ion before they were con tac t ed wi th the mine ra l s were set as ide for la te r coun t ing wi th the e q u i l i b r i u m so lu t ion al iquots . All so lu t ion a l iquo ts were fi l tered t h r ough 15-]k m e m - branes . Ten mil l i l i ters o f each or iginal so lu t ion was a d d e d for each g r am of minera l . Each so lu t ion-so l id e q u i l i b r i u m e x p e r i m e n t was c o n d u c t e d in t r ip l ica te in sealed, po lyp ropy lene tubes . T h e tubes c o n t a i n i n g the r ad ioac t ive so lu t ions were la ter rap id ly r insed wi th a few mil l i l i ters o f m e t h a n o l to r e m o v e all sol ids a n d r e c o u n t e d to ver i fy t ha t tube so rp t ion was less t h a n 2% of the total act ivi ty , or to a l low cor rec t ions for tube- wall sorp t ion .

T h e slurrys were gently ro ta t ed to assure un i fo rmi ty for a 30-day e q u i l i b r i u m period, A m i n i m u m of 30

days o f m i n e r a l - s o l u t i o n con tac t was r equ i red for the sys tem to a p p r o a c h chemica l equ i l ib r ium. Exper i - m e n t s were c o n d u c t e d at 5 ~ 25 ~ a n d 65~ in e n v i r o n - m e n t a l c h a m b e r s wh ich c o n t a i n e d facili t ies for agi tat- ing the samples a n d con t ro l l ed t e m p e r a t u r e s to wi th in _ 2~

Af te r a 30-day so lu t ion-so l id con tac t per iod, a 15- fi l tered a l iquo t o f each so lu t ion was c o u n t e d a long

wi th in i t ia l so lu t ion samples at the i r respec t ive t empera tures . F r o m the sc in t i l la t ion coun t ing efficiency, the ini t ia l a n d e q u i l i b r i u m so lu t ion counts , a n d the specific ac t iv i t ies o f the rad ionuc l ides , the concen t r a - t ions o f U in the e q u i l i b r i u m so lu t ion a n d on the m i n - eral were calculated. D i s so lved oxygen m e a s u r e m e n t s on final so lu t ions yie lded an average o f 8.3 mg O2/liter, or a c o m p u t e d Eh o f + 6 5 0 mY. Whereas , such solu- t ions were no t s a tu ra t ed in a t m o s p h e r i c 02, the env i - r o n m e n t s were no t sufficiently anox ic to reduce U(VI)

Table 4. Surface areas, ignition losses, and cation-exchange capacities of the based, freeze-dried minerals.

Cesium cation- exchange

900~ capacity ignition (meq/100 g,

Surface area (% wt. pH 7.0, Mineral (mVg _+ 1 s) loss) 25~

Illite 116.1 • 10.1 3.5 25.0 Kaolinite 68.3 • 5.4 14.4 12.2 Montmorillonite 747.0 • 52.8 20.1 120.0 Nontronite 861.0 • 36.0 16.5 95.0 Glauconite 137.3 • 7.9 0.8 16.03 Clinoptilolite 20.0 • 2.2 10.1 140.2 Opal 46.8 • 6.4 3.7 3.18 Silica gel 626.3 • 25.0 10.2 2.79

324 Ames, McGarrah , and Walker Clays and Clay Minerals

Table 5. Exper imenta l mean values for sorpt ion of u ran ium by secondary minerals at 65~ from 0.01 M NaC1 and 0.01 M NaHCO3 solutions.

............................................... 0.01 M NaCI ......................................................................................... 0.01 M NaHCO3 ............................................

Initial U Equilibrium U U on solid Initial U Equilibrium U U on solid Solid (mole/liter) (mole/liter) (mole/g) (mole/liter) (mole/liter) (mole/g)

l l l i te 1.005 X 10 -4 1.585 • 10 -5 9,307 x 10 7 1,004 x 10 4 4.047 x 10 -6 1.059 x 10 -6 1,039 • 10 -5 1.815 x 10 -8 9.428 • 10 -8 1,041 X 10 -5 3,748 X 10 -7 1.104 X 10 -7 1.393 • I0 6 1,754 x 10 -7 1.339 • 10 8 1,353 x 10 6 6.282 • 10 -8 1.418 • 10 s 3,458 x 10 7 4.309 X 10 -8 3,328 x 10 9 3.508 X 10 -7 1,683 • 10 -8 3.672 • 10 -9

Kaol ini te 1.005 X 10 4 3.545 X 10 -6 1.083 • 10 6 1,004 • 10 4 7.130 • 10 -s 2.447 X 10 -7 1,039 X 10- ' 3.775 • 10 -7 1.118 X 10 -7 1.041 X 10 -5 4.478 • 10 -6 6.629 • 10 8 1.393 • 10 -6 5.069 X 10 -8 1,499 • 10 8 1.353 X l0 6 2.433 X 10 -7 1.240 • 10 8 3.458 • 10 7 1.288 X 10 -5 3.720 • 10 9 3,508 • 10 -7 4.143 • 10 -9 3.874 • 10 -9

Montmor i l lon i t e 1,005 • 10 4 5.845 • 10 -6 2.129 • 10 6 1,004 • 10 -4 2.085 • 10 -5 1.790 X 10 -6 1.039 • 10 -5 3.540 • 10 -7 2.258 X 10 7 1,041 • 10 5 1.568 X 10 -6 9.946 • 10 8 1.393 • 10 6 4.787 • 10 -5 3.026 X 10 8 1.353 • 10 -6 2.955 X 10 -7 2.380 • 10 -8 3.458 X 10 -7 1,399 • 10 -8 7,465 X 10 9 3,508 • 10 7 8.764 • 10 -5 5,918 X 10 -9

Nont roni te 1.005 • 10 -4 3,918 X 10 -6 2 . [37 X I0 6 1,004 • 10 4 9.064 X 10 -5 2,159 • 10 -7 1.039 • 10 -5 4.031 • 10 -7 2,209 X 10 -7 1,041 X 10 -5 7.752 X 1.0 -6 5.881 • 10 8 1,393 X 10 6 4,843 X 10 -s 2.975 • 10 -8 1,353 X 10 -6 5.330 X 10 -7 1.770 • 10 -8 3,458 X l0 -7 1.415 • 10 -8 7.336 X 10 9 3,508 • 10 7 6.495 • 10 -8 6.325 X 10 -9

Glauconi te 1.005 • 10 -4 2.982 • 10 -6 1.057 • 10 6 1.004 • 10 4 4.355 X 10 -6 1.041 x 10 6 1.039 x 10 -5 4.783 x 10 -7 1.074 x 10 -7 1.041 X 10 -5 6.887 x 10 -7 1.054 X 10 7 1,393 • 10 -6 6.251 • 10 -5 1.442 x 10 8 1.353 • 10 6 1.003 • 10 -7 1.358 x 10 -8 3.458 • 10 7 1.956 • 10 -8 3.536 • 10 -9 3,508 • l0 -7 2,917 • 10 -8 3.432 • 10 9

Clinopt i lol i te 1.005 x 10 4 4.190 • 10 -6 6,831 X 10 -7 1,004 X 10 -4 7.120 • 10 -5 3,404 X 10 7 1.039 X 10 8 6,440 • 10 -7 1.136 • 10 7 1.041 x 10 -5 7,027 • 10 -6 3.944 X 10 -8 1,393 • 10 -6 6.645 x 10 -8 1,547 x 10 , 1,353 x 10 6 8.489 x 10 -7 5,877 • 10 -9 3.458 x 10 7 1.765 x 10 -8 3.826 X 10 -9 3,508 • 10 -7 3.304 X 10 -7 2.379 X 10 9

Opal 1,005 X 10 -4 4.199 X 10 -6 1.068 X 10 -6 1,004 • 10 -4 5,724 X 10 -5 4.786 • 10 7 1.039 • 10 -5 3.903 • 10 -7 1.109 • 10 7 1.041 • 10 5 4.531 • 10 -6 6.519 • 10 -8 1,393 • 10 -6 6.195 X 10 -8 1.476 X 10 -5 1.353 • 10 6 4.797 X 10 -7 9.684 • 10 -9 3.458 • 10 7 1.789 • 10 -8 3,636 • 10 -9 3,508 X 10 -7 9.214 • 10 -8 2.869 • 10 9

Silica gel 1,005 • 10 4 2.754 • 10 -6 1,075 X 10 -6 1,004 • 10 -4 4.335 X 10 -6 1.057 • 10 6 1.039 • 10 -8 4.414 • 10 -7 1.095 • 10 7 1,041 • 10 5 4.862 • 10 -7 1.092 • 10 -7 1,393 • 10 6 5.237 • 10 -8 1.475 X 10 -8 1,353 • 10 -6 6.861 • 10 -8 1.413 • 10 8 3.458 • 10 -7 1,407 • 10 -8 3,649 • 10 -9 3,508 X 10 7 2,272 x 10 -8 3,610 X 10 -9

t o U( IV) . F i n a l p H m e a s u r e m e n t s s h o w e d l i t t l e c h a n g e

f r o m t h e s t a r t i n g s o l u t i o n p H o f a p p r o x i m a t e l y 7 for

t he NaC1 a n d 8 to 9 fo r t he N a H C O 3 s o l u t i o n .

R E S U L T S

T a b l e s 5, 6, a n d 7 g i v e t he U s o r p t i o n r e s u l t s a t 65 ~

25 ~ a n d 5~ r e s p e c t i v e l y . T h e e q u i l i b r i u m c o n c e n t r a -

t i o n s o f U in t he s o l u t i o n a n d o n t h e s o l i d ( m i n e r a l )

r e p r e s e n t e x p e r i m e n t a l m e a n s o f t h r e e r e p l i c a t e s . T h e

i n i t i a l U ( t h a t p r e s e n t i n t h e s o l u t i o n b e f o r e t h e ex-

p e r i m e n t b e g a n ) r a n g e d f r o m 1.0 • l 0 -4 M to 3.5 •

l 0 -7 M in c o n c e n t r a t i o n ; h o w e v e r , e q u i l i b r i u m c o n -

c e n t r a t i o n s c o v e r e d a b r o a d e r r a n g e d u e to v a r i e d s o r p -

t i o n o n t h e m i n e r a l s .

T h e s o r p t i o n d a t a o f T a b l e s 5 - 7 fit t h e l i n e a r i z e d

F r e u n d l i c h e q u a t i o n w i d e l y u s e d in t h e s t u d y o f or -

g a n i c s s o r p t i o n o n s o l i d s ( R e i n b o l d et al., 1979) . T h e

F r e u n d l i c h e q u a t i o n ( F r e u n d l i c h , 1922) is ( x / m ) = K C n,

w h e r e ( x / m ) is t h e e q u i l i b r i u m U l o a d on t h e m i n e r a l

i n m o l e / g , C is t he e q u i l i b r i u m s o l u t i o n c o n c e n t r a t i o n ,

a n d K a n d n a re c o n s t a n t s . T h e F r e u n d l i c h s o r p t i o n

i s o t h e r m is g e n e r a l l y u s e f u l u p to a b o u t 5% o f t h e

c a p a c i t y o f t h e so l id . A p l o t o f l n ( x / m ) vs . In C s h o u l d

r e s u l t in a s t r a i g h t l i n e w i t h a s l o p e o f n a n d a Y a x i s

i n t e r c e p t o f K. I l l i t e s o r p t i o n o f u r a n i u m f r o m b o t h

s o l u t i o n s is s h o w n in F i g u r e 1 as a n e x a m p l e o f t h e

F r e u n d l i c h s o r p t i o n i s o t h e r m . T h e F r e u n d l i c h c o n -

s t a n t s g i v e n in T a b l e 8 fo r t h e v a r i o u s e x p e r i m e n t a l

c o n d i t i o n s c a n be u s e d to g e n e r a t e a n e q u i l i b r i u m

r e g r e s s i o n l i n e for t h e r e s p e c t i v e e x p e r i m e n t s . T h e r is

a r e g r e s s i o n coe f f i c i en t t h a t m e a s u r e s h o w w e l l t h e ex-

p e r i m e n t a l d a t a fit t h e r e g r e s s i o n l ine . A p e r f e c t co r -

r e l a t i o n w o u l d be +_ 1 .0000 . S y . x is t he s t a n d a r d de -

v i a t i o n f r o m r e g r e s s i o n a n d is a m e a s u r e o f d i s p e r s i o n ,

s i m i l a r to a s t a n d a r d d e v i a t i o n , a p p l i e d t o d i f f e r e n c e s

b e t w e e n e s t i m a t e d a n d o b s e r v e d v a l u e s o f I n ( x / m ) . U s -

i ng t h e F r e u n d l i c h c o n s t a n t s , a n e q u i l i b r i u m s o l u t i o n

c o n c e n t r a t i o n c a n be g e n e r a t e d for a g i v e n U ( x / m )

v a l u e . F r o m t h e s e d a t a , a d i s t r i b u t i o n coe f f i c i en t (D)

c a n be g e n e r a t e d by ( x / m ) / ( C ) ( 0 . 0 0 1 ) w h i c h h a s t h e

d i m e n s i o n s o f m l / g . T h e d i s t r i b u t i o n coe f f i c i en t s c a n

be c o m p a r e d for m i n e r a l s i n t h e s a m e e x p e r i m e n t a l

e n v i r o n m e n t .

I n a d d i t i o n to t h e s t r a i g h t l i n e r e l a t i o n s h i p g e n e r a t e d

Vol. 31, No. 5, 1983 Sorption of u ran ium onto clays and cl inopt i lol i te 325

Table 6. Exper imenta l mean values for sorpt ion of u ran ium by secondary minerals at 25~ from 0.01 M NaCI and 0.01 M NaHCO3 solutions.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.01 M NaCI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.01 M NaHCO3 ........................................... Initial U Equilibrium U U on solid Initial U Equilibrium U U on solid

Solid (mole/liter) (mole/liter) (mole/g) (mole/g) (mole/liter) (mole/g)

Ill i te 1.004 • 10 4 2.341 • 10 6 1.078 M 10 -6 1.004 • 10 -4 1.792 • 10 5 9.069 M 10 -7 1 . 0 4 4 N 1 0 -s 2 . 6 0 1 • 7 1 . 1 1 9 • 7 1 . 0 4 4 • 5 1 .214X 10 -6 1 . 0 1 4 • -7 1.438 • 10 -6 2.954 • 10 8 1.548 • 10 -8 1.437 • 10 -6 1.400 • 10 7 1.426 • 10 -8 4.379 • 10 7 8.666 • 10 9 4.719 • 10 -9 4.374 • 10 -7 4.738 • 10 8 4.288 • 10 -9

Kaol ini te 1.004 • 10 4 2.445 • 10 6 1.095 • 10 -6 1.004 • 10 -4 8.362 • 10 5 1.875 • 10 7 1.044 • 10 5 2.522 • 10 7 1.139 • 10 7 1.044 • 10 5 5.086 • 10 6 5.982 • 10 -8 1.438 • 10 -6 3.034 • 10 -8 1.573 • 10 8 1.437 • 10 6 1.833 • 10 7 1.401 • 10 8 4 . 3 7 9 • 7 7 . 3 1 4 • 9 4 . 8 1 1 • -9 4 . 3 7 4 • -7 1 .186• 10 8 4 . 7 5 4 • -9

Montmor i l lon i t e 1.004 • 10 4 2.878 • 10 6 1.097 • 10 -6 1.004 X 10 .4 9.300 • 10 5 8.329 • 10 -8 1.044 • 10 -5 1.852 • 10 7 1.153 • 10 7 1.044 • 10 5 9.580 • 10 -6 9.670 • 10 9 1.438 • 10 6 2.981 • 10 g 1.584 • 10 8 1.437 • 10 6 1.273 • 10 -6 1.845 • 10 9 4.379 • 10 7 8.904 • 10 9 4.826 • 10 -9 4.374 • 10 -7 3.780 • 10 7 6.681 • 10 -1~

Nont ron i te 1.004 • 10 4 2.754 • 10 5 8.060 • 10 .7 1.004 • 10 -4 8.693 • 10 5 1.490 • 10 -7 1.044 • 10 -5 1.255 • 10 -6 1.016 • 10 7 1.044 • 10 5 8.698 • 10 -6 1.927 • 10 8 1.438 • 10 6 4.734 • 10 8 1.538 • 10 -8 1.437 • 10 -6 1.121 • 10 6 3.496 • 10 -9 4.379 • 10 -7 1.558 • 10 -8 4.672 • 10 9 4.374 • 10 7 3.182 • 10 .7 1.319 • 10 9

Glauconi te 1.004 • 10 -4 2.878 • 10 -6 1.057 • 10 6 1.004 • 10 4 4.088 • 10 -5 6.452 • 10 7 1 .044• 10 5 3.311 • 10 7 1 .096• 10 -7 1 . 0 4 4 • -8 2 . 4 2 8 • 10 7 8 . 6 8 5 • 10 8 1.438 • 10 -6 9.528 • 10 -~ 1 . 4 5 6 • 8 1 . 4 3 7 • 6 1 . 9 1 1 • 7 1.351 • 10 -8 4.379 • 10 7 3.188 • 10 s 4.401 • 10 -9 4.374 • 10 -7 3.792 • 10 8 4.331 • 10 9

Clinopt i lol i te 1.004 • 10 .4 3.564 • 10 6 7.550 • 10 7 1.004 • 10 4 9.417 • 10 -8 7.264 • 10 -8 1.044 • 10 5 7.143 • 10 -7 1.159 • 10 -7 1.044 • 10 -5 9.936 • 10 6 5.870 • 10 -9 1.438 • 10 6 1.839 • 10 7 1.462 • 10 -8 1.437 • 10 -6 1.374 • 10 6 7.356 • 10 -l~ 4.379 • 10 7 6.535 • 10 8 4.343 • 10 -9 4.374 • 10 7 4.172 • 10 -7 2.354 • 10 to

Opal 1.004 • 10 4 3.451 • 10 6 1.075 • 10 -6 1.004 • 10 -4 9.209 • 10 5 9.213 • 10 8 1.044 • 10 5 4.178 • 10 7 1.111 • 10 -7 1.044 • i 0 5 9.498 • 10 -6 1.044 • 10 ~ 1.438 • 10 -6 5.270 • 10 -8 1.536 • 10 ~ 1.437 • 10 6 1.295 • 10 -6 1.579 • 10 9 4.379 • 10 7 2.051 • 10 -8 4.629 • 10 -9 4.374 • 10 -7 3.806 • 10 7 6.303 • 10 -~~

Silica gel 1.004 • 10 4 1.959 • 10 -6 1.083 • 10 -6 1.004 • 10 .4 1.876 • 10 6 1.084 • 10 -6 1.044 • 10 8 2.345 • 10 -7 1.123 • 10 7 1.044 • 10 -5 1.809 • 10 7 1.129 • 10 -7 1.438 • 10 6 2.981 • 10 8 1.549 • 10 -8 1.437 • 10 .6 2.972 • 10 8 1.548 • 10 -8 4.379 • 10 -7 1.550 • 10 8 4.657 • 10 -9 4.374 • 10 7 7.393 • 10 -9 4.731 • 10 9

fo r t h e s e s o r p t i o n d a t a by t h e l i n e a r i z e d F r e u n d l i c h

e q u a t i o n , a F r e u n d l i c h - l i k e g r o u p o f c o n s t a n t s c a n a l s o

be g e n e r a t e d b y t he l i n e a r i z e d e q u a t i o n , l n ( x / m ) = In

L + p i n CI, w h e r e Ct is t he i n i t i a l U c o n c e n t r a t i o n in

s o l u t i o n a n d L a n d m a r e c o n s t a n t s . T h e s e c o n s t a n t s

a r e g i v e n in T a b l e 9 a l o n g w i t h t h e i r r e s p e c t i v e cor -

r e l a t i o n coe f f i c i en t (r) a n d s t a n d a r d d e v i a t i o n f r o m

r e g r e s s i o n (Sy. x) v a l u e s . T h e y a r e p o t e n t i a l l y m o r e use -

ful t h a n t h e a c t u a l F r e u n d l i c h c o n s t a n t s o f T a b l e 8

b e c a u s e t h e y c a n be u s e d to d e t e r m i n e a U l o a d i n g o n

a g i v e n s e c o n d a r y m i n e r a l w h e n o n l y t he i n i t i a l s o l u -

t i o n c o n c e n t r a t i o n (CI) is k n o w n .

D I S C U S S I O N

T h e F r e u n d l i c h s o r p t i o n i s o t h e r m h a s b e e n w i d e l y

u s e d to fit s o r p t i o n o f v a r i o u s s u b s t a n c e s o n t o so i l s

( H a m a k e r a n d T h o m p s o n , 1972; R e i n b o l d et al., 1979),

a n d i t s u se h e r e is n o t u n i q u e . H a l s e y (1952 ) a n d A d -

a m s o n ( 1 9 7 6 ) s h o w e d t h e o r e t i c a l l y t h a t t he K a n d n

c o n s t a n t s i n t h e F r e u n d l i c h e q u a t i o n d e p e n d on t h e

e n e r g y a n d e n t r o p y o f s o r p t i o n a n d o n t he e n e r g y o f

i n t e r a c t i o n b e t w e e n t h e s o r p t i o n s i tes . T h e e q u a t i o n

d e s c r i b e s a s o r p t i o n i s o t h e r m f r o m a n i d e a l s o l u t i o n

by an e n e r g e t i c a l l y h e t e r o g e n e o u s se t o f s o r p t i o n s i tes ,

w i t h t h e s o r p t i o n e n e r g y v a r y i n g e x p o n e n t i a l l y . T h e

o r i g i n a l F r e u n d l i c h e q u a t i o n , h o w e v e r , for w h i c h t h e

s o r p t i o n i s o t h e r m w a s n a m e d , w a s p u r e l y e m p i r i c a l .

T h e i n s t a n c e i n w h i c h Ct is u s e d in t h i s w o r k r a t h e r

t h a n C is m e r e l y a u s e f u l v a r i a t i o n on F r e u n d l i c h ' s

o r i g i n a l s o r p t i o n i s o t h e r m .

O n e o f t he m o r e p r a c t i c a l m e a s u r e s o f t h e e f f i c i ency

o f a s o l i d in s o r b i n g a d i s s o l v e d s u b s t a n c e f r o m so lu -

t i o n is t h e d i s t r i b u t i o n coef f i c ien t , D. I f D v a l u e s a r e

o b t a i n e d a t s o l u t i o n - m i n e r a l e q u i l i b r i u m a n d u n d e r

c o m p a r a b l e e x p e r i m e n t a l c o n d i t i o n s , t h e y a l l o w a

c o m p a r i s o n to be m a d e o f t h e e f f i c i ency o f s e v e r a l

m i n e r a l s i n s o r b i n g a d i s s o l v e d c o m p o n e n t f r o m t h e

s a m e s o l u t i o n . A D v a l u e is d e f i n e d as t he e q u i l i b r i u m

c o n c e n t r a t i o n o f U o n t he m i n e r a l in m o l e / g d i v i d e d

by t he e q u i l i b r i u m s o l u t i o n c o n c e n t r a t i o n in m o l e / m l

a n d h a s the d i m e n s i o n s o f m l / g .

U s e o f t he s a m e C v a l u e t o c o m p u t e U d i s t r i b u t i o n

coe f f i c i en t s a l s o a l l o w s a s o r p t i o n c o m p a r i s o n b e t w e e n

m i n e r a l s . T h i s u se is s o m e w h a t a r t i f i c i a l b e c a u s e d i f -

3 2 6 A m e s , M c G a r r a h , a n d W a l k e r Clays and Clay Minerals

-19 I ' I ' L ' ' I ' I '

-20 5 ~ 1 7 6 o / / 25 C 65oC

2-

= -23

-24

-25, -27 -26 -25 -24 -23 -22 -21 -20 -19

InC, M

F i g u r e 1. F r e u n d l i c h e q u a t i o n p l o t s o f t he n a t u r a l l o g a r i t h m o f t he e q u i l i b r i u m U c o n c e n t r a t i o n in s o l u t i o n (C) vs. t he n a t u r a l l o g a r i t h m o f e q u i l i b r i u m U l o a d i n g o n il l i te (x /m) .

f e r e n t C t v a l u e s f o r e a c h m i n e r a l a r e r e q u i r e d t o p r o -

d u c e t h e s a m e C . A b e t t e r c o m p a r i s o n c a n b e m a d e b y

u s i n g t h e s a m e CI v a l u e f o r a l l m i n e r a l s .

F i t h i a n i l l i t e i s u s e d h e r e t o i l l u s t r a t e t h e s o r p t i o n

d a t a . T h e e x p e r i m e n t a l s o r p t i o n v a l u e s a n d t h e r e -

s u i t i n g r e g r e s s i o n l i n e s ( s h o w n i n F i g u r e 1 f o r i l l i t e ) a r e

n o r m a l F r e u n d l i c h s o r p t i o n i s o t h e r m s o f I n ( x / m ) p l o t -

t e d v s . In C a t e q u i l i b r i u m .

C o m p a r i n g D v a l u e s b e t w e e n m i n e r a l s e x p o s e d t o

t h e s a m e i n i t i a l U s o l u t i o n i s p o s s i b l e b y u s e o f t h e

d a t a i n T a b l e s 8 a n d 9 . T h e D v a l u e d a t a w e r e g e n e r a t e d

b y a s s u m i n g a n i n i t i a l U c o n c e n t r a t i o n , d e t e r m i n i n g

t h e ( x / m ) v a l u e w i t h t h e F r e u n d l i c h - l i k e c o n s t a n t s g i v -

e n i n T a b l e 9 a n d u s i n g t h e ( x / m ) v a l u e t o c o m p u t e a

C v a l u e w i t h t h e F r e u n d l i c h c o n s t a n t s g i v e n i n T a b l e

8. W i t h i l l i t e a s a n e x a m p l e , D v a l u e s d e c r e a s e w i t h

i n c r e a s i n g t e m p e r a t u r e s i n N a C 1 s o l u t i o n , w h e r e a s t h e y

i n c r e a s e w i t h i n c r e a s i n g t e m p e r a t u r e f r o m a N a H C O 3

s o l u t i o n d u e t o t h e h e a t s e n s i t i v i t y o f t h e u r a n y l c a r -

b o n a t e c o m p l e x ( L a n g m u i r , 1 9 7 8 a ) . F u r t h e r , D v a l u e s

T a b l e 7. E x p e r i m e n t a l m e a n v a l u e s fo r s o r p t i o n o f u r a n i u m b y s e c o n d a r y m i n e r a l s a t 5~ f r o m 0.01 M NaC1 a n d 0 .01 M N a H C O 3 s o l u t i o n s .

..................................... 0.01 M NaCI ........................................................................................ 0.01 M NaHCOs ........................................... Initial U Equilibrium U U on solid Initial U Equilibrium U U on solid

Solid (mole/liter) (mole/liter) (mole/g) (mole/g) (mole/liter) (mole/g)

Il l i te 1 .005 X 10 -4 7 . 6 6 8 • I0 7 1 .097 • 10 -6 1 .005 X 10 -4 6 . 1 8 4 • 10 -5 4 . 2 5 1 X 10 -7 1 .038 • 10 -5 8 . 3 9 2 X 10 8 1 .133 X 10 7 1 .045 • 10 5 4 . 7 7 8 X 10 6 6 . 2 3 6 X 10 8 1 .403 • 10 -6 4 . 9 8 7 • 10 9 1 .537 • 10 -s 1 .434 • 10 6 4 . 4 7 5 X 10 -7 1 .085 X 10 -8 3 . 9 2 8 • 10 -7 1 .382 X 10 -9 4 . 3 0 3 • 10 9 4 . 3 8 8 X 10 -7 1 .248 • 10 7 3 . 4 5 2 X 10 9

K a o l i n i t e 1 .005 • 10 -4 7 . 9 5 8 • 10 -6 1.401 X 10 -6 1 .005 X 10 -4 8 .081 • 10 -s 2 . 2 0 0 X 10 7 1 . 0 3 8 • -6 4 . 4 5 4 • 7 1 . 1 1 0 • 7 1 . 0 4 5 X 1 0 5 5 . 8 2 0 • 6 5 . 1 7 3 X I 0 s 1 .403 • 10 -6 1 .745 • 10 -s 1 .549 • 10 -s 1 .434 • 10 6 1 .882 X 10 -7 1 .392 • 10 s 3 . 9 2 8 X 10 -7 2 . 1 4 6 X 10 9 4 . 3 6 5 • 10 -9 4 . 3 8 8 X 10 -7 1 .860 X 10 -8 4 . 6 9 5 X 10 -9

M o n t m o r i l l o n i t e 1 .005 X 10 -4 9 . 6 7 9 X 10 .6 2 . 0 4 3 N 10 -6 1 .005 X 10 -4 9 . 5 0 9 X 10 -5 1 .218 • 10 7 1 .038 X 10 -5 8 . 5 8 5 X 10 7 2 . 1 4 2 X 10 7 1 .045 • 10 5 9 . 9 7 2 X 10 -6 1 .075 • 10 -8 1 .403 X 10 -6 8 . 8 3 8 X 10 -8 2 . 9 5 8 • l 0 8 1 .434 X 10 6 1 .351 • 10 7 1 .874 X 10 -9 3 . 9 2 8 X 10 -7 1 .987 • 10 -8 8 . 3 8 9 • 10 -9 4 . 3 8 8 X 10 .7 4 . 0 5 4 X 10 -7 7 . 5 1 2 • 10 ,0

N o n t r o n i t e 1 .005 • 10 -4 6 . 1 8 5 • 10 -6 2 . 0 8 6 X 10 -6 1 .005 X 10 -4 9 . 1 2 3 • 10 s 2 .051 X l 0 7

1 .038 X 10 -5 7 . 7 8 9 • 10 7 2 . 1 2 4 • 10 7 1 .045 X 10 -5 8 . 2 9 4 X 10 -6 2 . 3 8 5 • 10 -8 1 .403 • 10 -6 5 . 2 9 2 X 10 s 2 . 9 8 7 • 10 s 1 .434 • 10 6 1 .217 • 10 6 4 . 8 0 8 • 10 9 3 . 9 2 8 X 10 -7 8 . 6 6 5 • 10 -9 4 . 2 4 9 • 10 -9 4 . 3 8 8 X 10 -7 3 . 5 3 7 X 10 -7 1 .882 X 10 9

G l a u c o n i t e 1 .005 • 10 -4 2 . 5 3 9 • 10 6 1 .062 • 10 -6 1 .005 • 10 4 4 . 1 4 5 • 10 5 6 .401 • 10 -7 1 .038 • 10 -5 3 . 5 1 9 • 10 -7 1 .092 • 10 7 1 .045 x 10 -s 3 . 4 3 9 X 10 -6 7 . 6 0 0 x 10 -8 1 .403 • 10 -6 4 . 4 6 1 • 10 -8 1 .472 X 10 8 1 .434 • 10 6 3 . 3 3 2 • 10 7 1 . 1 9 4 • 10 9 3 . 9 2 8 x 10 -7 2 . 5 6 8 • 10 8 3 . 9 7 9 X 10 9 4 . 3 8 8 x 10 .7 6 . 9 1 6 X 10 s 4 . 0 0 7 x I 0 - t~

C l i n o p t i l o l i t e 1 .005 • 10 -4 8 . 2 1 5 x 10 5 2 . 1 3 9 X 10 7 1 .005 N 10 -4 9 . 5 6 8 X 10 -5 5 . 6 1 3 • 10 8 1 .038 X 10 -5 8 . 1 0 8 • 10 6 2 . 6 4 9 X 10 -8 1 .045 X 10 5 1 .004 X 10 5 4 . 7 4 9 X 10 -9 1 .403 X 10 -6 9 . 7 9 4 X 10 -7 4 . 9 3 8 X 10 9 1 .434 • 10 -6 1 .378 X 10 6 6 . 5 5 6 • 10 to 3 . 9 2 8 • 10 -7 2 . 6 3 1 • 10 7 1 .512 • 10 -9 4 . 3 8 8 X 10 -7 4 . 1 8 5 X 10 -7 2 . 3 6 3 X 10 10

O p a l 1 .005 X 10 -4 7 . 4 8 0 X 10 6 1.031 • 10 -6 1 .005 X 10 -4 9 . 1 2 5 X 10 -5 1 .026 • 10 7 1 .038 X 10 -s 6 . 6 2 7 • 10 7 1 .078 • 10 -7 1 .045 X 10 -5 8 . 9 7 2 X 10 6 1 .639 X 10 -8 1 .403 X 10 -6 7 . 0 6 5 • 10 -8 1 .477 • 10 8 1 .434 X 10 -6 t . 2 0 8 X 10 -6 2 . 5 0 6 X 10 9 3 . 9 2 8 • 10 -7 2 . 2 5 0 • 10 8 4 . 1 0 6 • 10 9 4 . 3 8 8 X 10 _7 3 . 7 4 8 X 10 .7 7 . 0 9 6 X 10 t0

Si l ica gel 1 .005 • 10 -4 1 .653 • 10 6 1 .087 • 10 6 1 .005 • 10 -4 8 . 2 2 5 X 10 -7 1 .097 • 10 6 1 .038 x 10 -5 t . 2 0 5 x 10 7 1 .129 X 10 7 1 .045 X 10 _5 9 . 2 5 9 X 10 -8 1 . 1 4 0 X 10 7 1 .403 X 10 -6 1 .108 • 10 8 1.531 • 10 -8 1 .434 X 10 -6 7 .621 X 10 9 1 . 5 6 9 x 10 -8 3 . 9 2 8 • 10 -7 3 . 3 6 5 • 10 -9 4 . 2 8 4 • 10 -9 4 . 3 8 8 x 10 7 3 . 1 8 0 • 10 9 4 . 7 9 2 x 10 -9

Vol. 31, No. 5, 1983 Sorption of uranium onto clays and clinoptilolite

Table 8. Freundlich constants for the uranium sorption isotherms of Tables 5-7,

327

Temperature Sy.x Solid (~ Solution K p r (In unils)

Illite 5 NaC1 0.1515 0.8502 0.9969 _+0.2323 5 NaHCO3 7.409 • 10 4 0.7673 0.9995 _+0.0849

25 NaCI 0.2748 0.9642 0.9996 _+0.0799 25 NaHCO3 0.01731 0.8938 0.9984 + 0.1611 65 NaCI 0.0274 0.9390 0.9989 _+0.1432 65 NaHCO3 0.4696 1.0413 0.9992 _+ 0.1206

Kaolinite 5 NaCI 3.849 • 10 -3 0.6931 0.9954 _+ 0.2947 5 NaHCOs 1.359 • 10 5 0.4483 0.9975 _+0.1450

25 NaCI 0.1867 0.9371 0.9994 +0.1007 25 NaHCOs 9.478 • 10 6 0.4175 0.9998 _+0.0364 65 NaCI 0.3405 1.0089 1.0000 +0.0090 65 NaHCOs 5.460 • 10 ~ 0.5558 0.9978 _+0.1480

Montmorillonite 5 NaCI 0.05634 0.8890 0.9998 _+0.0625 5 NaHCO3 6.102 • 10 4 0.9338 0.9974 _+0.1964

25 NaC1 0.2094 0.9443 0.9979 _+0.1890 25 NaHCO3 2.597 • 10 4 0.8733 0.9994 _+0.0921 65 NaCI 0.1828 0.9313 0.9970 _+ 0.2322 65 NaHCO3 0.1114 1.0297 0.9987 _+0.1525

Nontronite 5 NaCI 0.1054 0.9133 0.9967 _+ 0.2642 5 NaHCO3 5.191 • 10 -4 0.8478 0.9995 _+0.0644

25 NaC1 4.871 • 10 -4 0.6158 0.9995 +0.1042 25 NaHCO3 3.823 • 10 4 0.8442 0.9996 +0.0691 65 NaCI 0.6858 1.0123 0.9996 _+0.0858 65 NaHCO3 1.681 • 10 -5 0.4830 0.9995 +0.0606

Glauconite 5 NaCI 3.1205 1.1539 0.9935 _+0.3388 5 NaHCO3 1.837 x 10 s 0.7959 0.9992 _+0.1118

25 NaCI 8.7606 1.2397 0.9961 _+0.2592 25 NaHCO3 9.214 • 10 4 0.7183 1.0000 _+0.0187 65 NaCI 1.4554 1.1175 0.9990 + 0.1477 65 NaHCO3 1.1591 1.1340 0.9994 _+ 0.1059

Clinoptilolite 5 NaC1 6.441 • 10 -4 0.8549 0.9996 _+0.0720 5 NaHCO3 5.958 • 10 4 1.0108 0.9990 _+0.1343

25 NaCI 11.4636 1.3127 0.9985 _+0.1643 25 NaHCO3 1.282 • 10 3 1.0608 0.9996 _+0.0904 65 NaC1 0.07412 0.9365 0.9995 _+ 0.0841 65 NaHCO3 2.225 x 10 3 0.9205 1.0000 _+0.0233

Opal 5 NaCI 0.06827 0.9388 0.9993 _+0.1066 5 NaHCO3 4.921 x 10 .4 0.9002 0.9980 _+0.1670

25 NaCI 0.5441 1.0450 0.9992 +0.1168 25 NaHCO3 4.417 • 10 -4 0.9173 0.9991 _+0.1128 65 NaC1 0.4060 1.0323 0.9994 _+0.1037 65 NaHCOs 1.214 • 10 -3 0.8020 0.9997 +0.0618

Silica gel 5 NaC1 0.1391 0.8812 0.9992 _+ 0.1150 5 NaHCO3 0.5784 0.9442 0.9973 -+0.213 l

25 NaCI 1.1580 1.0556 0.9988 + 0.1449 25 NaHCO3 0.5415 0.9949 0.9993 + 0.1125 65 NaC1 0.7515 1.0611 0.9982 _+0.1813 65 NaHCO3 0.6236 1.0727 0.9995 _+0.0978

increase as U concen t ra t ions decrease in NaCI solu- t i ons . In NaHCO3 solut ions, D values also increase with t empera tu re at 5~ but at 25 ~ and 65~ they decrease with increasing tempera ture . In general,

N a H C O s solut ion D values are less than those f rom NaC1 solut ions for the ca t ion-exchange mater ia ls (illite,

kaolinite, smecti tes , zeolites, and opal) due to carbonate eomplex ing o f the U. The effects o f t empera ture ,

solut ion compos i t ion , and initial solut ion concent ra- t ion o f U on U sorp t ion on illite are more easily seen

graphically in Figures 2 and 3. The D values represent a response to complex in terac t ions be tween carbona te complexing, the exo the rmic nature o f the sorp t ion , the type o f sorpt ion sites on the minera l and t empera tu re effects on the aqueous species.

The compar i son be tween opal and silica gel sorp t ion

o f U is o f interest because o f the pr ior work by Zielinski (1980) on u ran ium in secondary silica. He found that dr ied silica gel con ta ined f rom 400 to 1000 t imes the U concen t ra t ion in solution. Ziel inski uti l ized a some-

328

Table 9. In CI.

Ames, McGarrah, and Walker Clays and Clay Minerals

Freundlich-like constants for the uranium sorption isotherms of Tables 5-7 for the equation In(x/m) = In K + p.

Temperature Sy.x Solid (~ Solution K p r (In units)

Illite 5 NaC1 0.01097 1.0000 1.0000 _+ 0.0016 5 NaHCO3 0.001492 0.8826 0.9997 _+0.0643

25 NaCI 0.01065 0.9993 1.0000 _+ 0.0020 25 NaHCO3 0.009354 0.9923 0.9980 _+0.1801 65 NaC1 0.008432 0.9912 1.0000 + 0.0229 65 NaHCO3 0.01076 1.0018 1.0000 _+0.0055

Kaolinite 5 NaC1 0.01845 1.0377 0.9995 _+0.0989 5 NaHCO3 1.432 X 10 .4 0.6964 0.9974 _+0.1470

25 NaC1 0.01076 0.9987 1.0000 _+ 0.0020 25 NaHCO3 1.141 • 10 4 0.6740 0.9857 • 65 NaC1 0.01080 1.0003 1.0000 _+0.0004 65 NaHCO3 2.4836 • 10 .4 0.7364 0.9957 +0.2077

Montmorillonite 5 NaC1 0.01866 0.9909 1.0000 +0.0026 5 NaHCO3 6.093 • 10 4 0.9381 0.9977 _+0.1866

25 NaC1 0.01081 0.9986 1.0000 _+0.0900 25 NaHCO3 3 . 2 1 6 • l 0 4 0.8936 0.9996 _+0.0690 65 NaCt 0.02069 0.9967 1.0000 _+0.0112 65 NaHCO3 0.01199 0.9818 0.9925 _+0.3650

Nontronite 5 NaC1 0.05374 1.0909 0.9958 _+0.2983 5 NaHCO3 5.299 x 10 4 0.8615 0.9990 •

25 NaCI 5.036 • 10 .3 0.9461 0.9998 _+0.0494 25 NaHCO3 4.377 • 10 4 0.8707 0.9998 +0.0492 65 NaC1 0.02565 1.0136 1.0000 +0.0272 65 NaHCO 3 6.608 • 10 5 0.6162 0.9983 _+0.1800

Glauconite 5 NaC1 0.01127 1.0063 1.0000 _+0.0145 5 NaHCO3 3.463 X 10 .3 0.9342 1.0000 _+0.0116

25 NaCI 0.01155 1.0094 1.0000 _+0.0107 25 NaHCO3 3.187 • 10 3 0.9205 0.9999 _+0.0465 65 NaC1 0.01092 1.0043 1.0000 +0.0052 65 NaHCO3 0.01131 1.0095 1.0000 +0.0067

Clinoptilolite 5 NaCI 7.372 • I0 4 0.8872 0.9998 _+0.05 I2 5 NaHCO3 5.779 • 10 .4 1.0116 0.9991 +0.1273

25 NaCI 5.487 • 10 3 0.9544 0.9984 _+0.2619 25 NaHCO3 1.415 • 10 -3 1.0675 0.9991 +0.1309 65 NaCI 3.565 • 10 3 0.9177 0.9983 _+0.1627 65 NaHCO3 1.136 • 10 3 0.8894 0.9982 _+0.1637

Opal 5 NaCI 9.907 • 10 3 0.9960 1.0000 +0.0064 5 NaHCO3 3.305 • 10 -4 0.8723 0.9991 _+0.2141

25 NaC1 0.01088 1.0018 1.0000 _+ 0.0048 25 NaHCO3 4.420 X 10 .4 0.9254 0.9993 _+0.0997 65 NaC1 0.01084 1.0018 1.0000 _+0.0054 65 NaHCO3 2.075 • 10 3 0.9073 0.9999 _+0.0348

Silica gel 5 NaCI 0.01066 0.9983 1.0000 -+ 0.0017 5 NaHCO3 0.01096 1.0000 1.0000 -+ 0.0039

25 NaC1 0.01098 1.0018 1.0000 _+0.0056 25 NaHCO3 0.01079 0.9999 1.0000 _+0.0025 65 NaCI 0.01087 1.0021 1.0000 _+0.0051 65 NaHCO3 0.01092 1.0037 1.0000 _+ 0.0057

wha t different me thodo logy in that his silica gel was prec ip i ta ted in the U-con ta in ing solut ion f rom a Na- s tabi l ized silica sol. The silica gel used in the present s tudy was added to the solut ion as a 100 to 200 mesh solid originally conta in ing 9.1 wt. % water. It was also a high surface area (626.3 _+_ 25.0 mVg), low cat ion- exchange capaci ty (1.28 meq /100 g) material . The D values p lo t ted vs. In C~ for opal and silica gel are given

in Figures 4-7 . Note that opal behaves much like illite in its response to t empera tu re dur ing U sorpt ion. Ura-

n ium D values were not very large f rom sod ium bi- ca rbona te solut ions, but the order o f magn i tude o f D was reversed with t empera tu re as c o m p a r e d to NaC1 solutions. Silica gel, on the o ther hand, showed the

same order and type o f U sorp t ion wi th changing t em- perature. Uran ium sorpt ion was somewha t greater when complex ing b icarbonate was present with D values o f about 1800 ml /g at the lower end o f the concen t ra t ion range studied. Illite, however , a t ta ined D values > 3000 ml/g in 0.01 M NaC1 solutions. An i m p o r t a n t aspect

Vol. 31, No. 5, 1983 Sorption of uranium onto clays and clinoptilolite 329

3500 ' I ' I ' I ' I ' I ' I '

3000

2500

1000 5 ~

500 25 ~

65 ~ /

0 , I , I , I t , I L I , I , -15 -14 -13 -12 -11 -10 -9 -8

InC[, M

Figure 2. Natural logarithm of the initial U concentration in the solution (CO vs. the U equilibrium distribution coefficient (D) for illite in 0.01 M NaCI.

2O00

1500

of silica gel is that it is able to sorb both uranyl cations to some extent and anionic carbonate complexes from solution. This also is true for glauconite at the lower U concentrat ions, but to a lesser extent.

350_ , 1 ' I ' I ' I ' I 2'5oC I '

300 "--

-g"= 2o0

1 5 0 1 ~

100

50

0 -15

0.01 M NaCI

, I , I L I J I J I J I , -14 -13 -12 -11 -10 -9 -8

InCI, M

Natural logarithm of the initial U concentration Figure 4. in solution (CI) vs. the U equilibrium distribution coefficient (D) for opal in 0.01 M NaC1.

Gal loway and Kaiser (1980) reported in a study o f u ran ium deposits o f the Catahoula Fo rma t ion on the Texas coastal plain that groundwaters were more closely associated with the U minera l iza t ion plot on mont -

300 ' ] ' I ' I ' I ' I ' I '

~ . . . . ~ . ~ ' ~ ' ~ 5 ~

250 J

200 0.01 M NaHC03

15o a"

100

5 0 1 5oc

OF , I , I ; I i I i I , I , -15 -14 -13 -12 -11 -10 -9 -8

InCI, M

Figure 3. Natural logarithm of the initial U concentration in the solution (CO vs. the U equilibrium distribution coefficient (D) for illite in 0.01 M NaHCO3.

..=

0

30

25

20

151

10!

03

-15 -14 -13 -12 -11 -10 -9 -8 In C[, M

Figure 5. Natural logarithm of the initial U concentration (C,) vs. the U equilibrium distribution coefficient (D) for opal in 0.01 M NaHCQ.


1500 _ ' I ' I ' I ' I ' I ~ I '

1250

500 " ' - ' ' ' " ~ 2 5 ~ C

. , . . . , . . . . . - - , - -

65oc 250

, l L ] , I , I , l , I , -15 -14 -13 -12 -11 -10 -9 -8

InC[ , M

Figure 6. Natural logarithm of the initial U concentration in solution (C0 vs. the U equilibrium distribution coefficient (D) for silica gel in 0.01 M NaC1.

1000

O3

-~ 750

d

morillonite-clinoptilolite activity diagrams deepest into the montmoril lonite field. Implied was an important role for montmoril lonite in U concentration and an unimportant role for clinoptilolite. Assuming that ini-

1750

1500

125C

10001 O~

E

75C

500

25(?

0.01 MNaHCO3

25oC

65oc . ._ . , . , . . . - . - . . - - -

0 , ! I I , I ~ L i l ~ P z -15 -14 -13 -12 -11 -10 -9 -8

In CI, M

Figure 7. Natural logarithm of the initial U concentration in solution (CO vs. the U equilibrium distribution coefficients (D) for silica gel in 0.01 M NaHCO3.

250

200

150

~ 1 o o

50

- a _ _ L _ _ L _ 2 I I ' I I ' I /

0 ' I 5.C [ , I , I , I , 1 [ {3

-17 -16 -15 -14 -13 -12 -11 -10 -9

InCI, M

Figure 8. Natural logarithm of the initial U concentration in solution (C]) vs. the U equilibrium distribution coefficient (D) for clinoptilolite in 0.01 M NaC1.

tial U concentration was by sorption, an examination of the comparative U-sorption efficiencies of montmorillonite and clinoptilolite should confirm the above suggested U-montmori l l ini te association.

Comparable D curves for clinoptilolite are shown in Figures 8 and 9 for 0.01 M NaCl and 0.01 M NHCO3 solutions, respectively, and for montmoril lonite in Fig- ures l0 and 11 for the same solutions. As usual, the presence of anionic uranyl carbonate complexes in the 0.01 M NaHCO3 solution greatly diminished uranyl sorption by the clinoptilolite and montmorillonite, both of which are cation-exchange materials. At 65~ U sorption was greatest due to uranyl carbonate complex heat sensitivity and a resulting higher uncomplexed uranyl ion concentration. Montmorillonite is obvious- ly a much more efficient U sorbent than clinoptilolite over the initial U concentration shown in Figures 8 - 11. Hence, the laboratory results here tend to support

10

d

' I ' I ' I ' I ' 1 ' I ' I

-,----___._ 65oc

0 , I , I { I -17 -16 -15 -14 -13

InCl , M

25 ~ 5oc

-12 -11 -10 -9

Figure 9. Natural logarithm of initial U concentration in solution (C~) vs. the U equilibrium distribution coefficient (D) for clinoptilolite in 0.01 M NaHCO3.


700

600

500

400

300

2O0

100

0 i 17

I ~ , ~ ' I ' I ' I ' I ' I ' _

25~

I , I J l J I , I J I ~ I , -16 -15 -14 -13 -12 -11 -10 -9

In CI, M

Figure 10. Natural logarithm of the initial U concentration in solution (C,) vs. the U equilibrium distribution coefficient (D) for montmorillonite in 0.01 M NaC1.

the field o b s e r v a t i o n s o f Ga l loway a n d Kaise r (1980) conce rn ing the U m o n t m o r i l l o n i t e assoc ia t ion in Ca- t ahou l a F o r m a t i o n U deposi ts .

G ib l in (1980) repor ted some ra ther large (up to 35,000 ml /g at p H 6.5) U d i s t r i bu t i on coefficients on a kaol ini te , whereas L a n g m u i r (1978a, 1978b) r epor t ed some very low d i s t r i bu t i on coefficients (as low as 2 m l / g). D curves at 5 ~ 25 ~ a n d 65~ for 0.01 M NaC1 a n d kao l in i t e are s h o w n in Figure 12. T he cu rve at 25~ a n d Ct o f a b o u t 4.2 X 10 _7 M U ( - 1 4 . 6 8 3 ) a n d ap- p rox ima te ly p H 7 shou ld be close to G i b l i n ' s 35 ,000 ml /g U d i s t r i b u t i o n coefficient, bu t it is not . T h e rea- sons for the d ive rgence be tween the a b o v e two repor ted d i s t r i bu t i on coefficients a n d those r epor ted in Figure 12 are u n k n o w n , bu t m a y be due to any o f several expe r imen t a l factors, no t all o f wh ich can be deduced

10o

5c

0 17

' I ' I , I ' I T ] ' I ' I '

25oC 5~ / /

I ~1 , ~ 1 , l , I L 1 , J , I , -16 -15 -14 -13 -12 -11 -10

InCl , M

- 9

Figure 11. Natural logarithm of the initial U concentration in solution (CO vs. the U equilibrium distribution coefficient (D) for montmorillonite in 0.01 M NaHCO3.

2000 o~

~ 15oo

3000 f ' X ' r ' I ' I ' I " I ' I ' _ _

I k 2500f

1ooo --

500 65 ~

D "-17 -16 -15 -14 -13 -12 -11 -10 -9

In CI, M

Figure 12. Natural logarithm of the initial U concentration in solution (C,) vs. the U equilibrium distribution coefficient (D) for kaolinite in 0.01 M NaC1.

f rom the G i b l i n a n d L a n g m u i r reports . Fo r example , U tube-wal l so rp t ion cor rec t ions were f o u n d to be re- qu i r ed in some cases. Fa i lure to do so resu l ted in dis- t r i bu t i on coefficients t ha t were too low w h e n the tube- wall so rp t ion occur red in the or iginal so lu t ion samples a n d too high w h e n it occur red on the equ i l ib ra t ing so lu t ion-so l id s ample tubes.

Near ly all s econdary clay mine ra l s show surficial coat ings o f nonc rys t a l l i ne Fe, Mn , A1, a n d Si oxyhy- d rox ides t ha t can po ten t ia l ly resul t in con t ro l o f sorp- t ion o f some d i s so lved subs tances , inc lud ing U. O f the a b o v e nonc rys t a l l i ne surficial coat ings, ferric oxyhy- d rox ide p r o b a b l y has the m o s t po ten t i a l for increas ing U so rp t ion a b o v e t h a t o f the seconda ry clay m i n e r a l itself.

As m e n t i o n e d above , no a t t e m p t was m a d e to re- m o v e the smal l quan t i t i e s o f nonc rys t a l l i ne oxyhy- d rox ides o f F e , Mn, A1, a n d Si tha t are usual ly present , even on reference or source clays. Fo r example , A n - de r son a n d J e n n e (1970) r epo r t ed tha t the A.P.I . ka-

Table 10. Experimental mean values for sorption of uranium by ferric oxyhydroxide at 60~ from the solution composition given in Table 11.

U on ferric Initial U Equilibrium U oxyhydroxide

(mole/liter) (mole/liter) (mole/g)

1.005 X 10 -4 4.113 X 10 -6 3.452 X 10 -4 1.051 X 10 -s 1.724 X 10 -7 3.702 X 10 -s 1.513 X 10 _6 1.805 X 10 -8 5.353 X l0 -6 5.041 X l0 -7 6.756 X 10 -9 1.781 • l0 -6


-7 ' I ' [ ' I ' I

-9

o~ O

E. -11 E

-13

-15 , I J I J I , I I -20 -18 -16 -14 -12 -10

In C, M

Figure 13. Naturallogarithmofthe equilibrium U concentration in the solution (C) vs. the natural logarithm of equilibrium U loading on ferric oxyhydroxide (x/m).

olinite 4 used in the present study contained 0.01 wt. % Fe203 and 0.001 wt. % MnO2. The most important noncrystalline sorbent of uranium was ferric oxyhydroxide with distribution coefficients in excess of 2 • 106 ml/g. It always produced U isothermal sorption data that fit the Dubinin-Radushkevich sorption isotherm (Ames et aL, 1983). A ferric oxyhydroxide-coat- ed dioctahedral smectite (0.68 wt. % Fe) produced Du- binin-Radushkevich sorption isotherms. Removal of the ferric oxyhydroxide coating and reoxidation of the dioctahedral smectite not only reduced U sorption by an order of magnitude, but the sorption data then fit a Freundlich sorption isotherm (Ames et al., 1982). Hence, if ferric oxyhydroxide U sorption comprises a substantial portion of the total clay plus ferric oxyhydroxide U sorption, the data fit a Dubinin-Radush- kevich sorption isotherm. If ferric oxyhydroxide made a minimal contribution to total U sorption, the data fit a Freundlich sorption isotherm. Because all of the U-sorption data for the minerals in the present study fit the Freundlich sorption isotherm, U-sorption on ferric oxyhydroxide was considered to be minimal.

Table 11. Solution composition used in the ferric oxyhydroxide experiments.

Concentration Concentration Compound (mg/liter) Constituent (mg/liter)

NaHCO3 112.2 Na + 30.7 KzSO4 20.1 K + 9.0 CaClz. 2H20 23.8 Ca 2+ 6.5 MgCI:. 6H20 8.4 Mg z+ 1.0 SiO2 (noncrystalline) 22.5 HCO3- 81.5

SO42 11.1 C1- 14.4

pH = 8.0; ionic strength = 0.002132.

An example of the efficiency of ferric oxyhydroxide for sorption of U is given in Table 10. One milliliter of 0.1 M FeC13 solution was added to 40 ml of distilled water and titrated to pH 7 in 50-ml polypropylene centrifuge tubes. The X-ray amorphous precipitate was washed three times with the solution composition given in Table 11. Uranium was added to the solution, and the ferric oxyhydroxide and solution were contacted with agitation for seven days. These sorption data yielded a straight line with the Dubinin-Radushkevich sorption isotherm (Dubinin and Radushkevich, 1974), but are presented as Freundlich sorption isotherms in Figure 13. The relationship between the Freundlich and Dubinin-Radushkevich sorption isotherms was given by Sokolowska and Szczypa (1980). The D values for ferric oxyhydroxide varied from 85,000 ml/g at a C~ value of 1.005 • 10 _4 M U to 300,000 ml/g at a C~ of 5.041 • 10 -7 M U, about two orders of magnitude above comparable D values for the most efficient U-sorbing secondary minerals in a similar environment. Uranium sorption on crystalline secondary minerals probably should not be considered as a process leading directly to the formation of U ore deposits. Although sorption may contribute to other U concentrating processes leading to ore deposits, instances of sorption on crystalline secondary minerals as the prin- cipal U concentration process would be rare.

A C K N O W L E D G M E N T

The authors are grateful to the U.S. Department of Energy for sponsoring this work.

REFERENCES

Adamson, A.W. ( 1976) Physical Chemistry of Surfaces, 3rd ed., Wiley, New York, 389 pp.

Ames, L. L., McGarrah, J. E., Walker, B. A., and Salter, P. F. (1982) Sorption of uranium and cesium by basalts and an associated secondary smectite: Chem. Geol. 35, 205- 225.

Ames, L. L., McGarrah, J. E., Walker, B. A., and Salter, P. F. (1983) Uranium and radium sorption on amorphous ferric oxyhydroxide: Chem. Geol. (in press)

Anderson, B. J. and Jenne, E.A. (1970) Free-iron and manganese oxide content of reference clays: Soil Sci. 109, 163- 169.

Dubinin, M. M. and Radushkevich, L. W. (1974) Equation of the characteristic curve of activated charcoal: Proc. Acad. Sci. U.S.S.R., Phys. Chem. Sec., 55, 331-333.

Freundlich, H. (1922) Colloid and Capillary Chemistry: London, Methion and Co., 172-179.

Galloway, W. E. and Kaiser, W. R. (1980) Catahoula For- mation of the Texas coastal plain: origin, geochemical evo- lution and characteristics of uranium deposits: Texas Bur. Econ. Geol., Rept. Invest. 100, 81 pp.

Giblin, A. M. (1980) The role of clay adsorption in genesis of uranium ores: in Uranium in the Pine Creek Geosyncline, J. Ferguson and A. B. Goleby, eds., Intern. Atomic Energy Agency, Vienna, 521-529.

Gibtin, A. M., Batts, B. D., and Swaine, D. J. (1981) Lab- oratory simulation studies of uranium mobility in natural waters: Geochem. Cosmochim. Acta 45, 699-709.


Gotdsztaub, S. and Wey, R. (1955) Adsorption of uranyl ions by clays: Bull. Soc. Franc. Mineral. Crist. 78, 242- 253.

Halsey, G. D. (1952) The role of surface heterogeneity in adsorption: Adv. Catal. 4, 259-269.

Hamaker, J. W. and Thompson, J. M. (1972) Organic Chemicals in the Soil Environment, Vol. I: Ch. 2 Marcel Dekker, Inc., New York, 49-143.

Heilman, M. D., Carter, D. L., and Gonzalez, C. L. (1965) The ethylene glycol monoethyl ether technique for deter- mining soil-surface area: Soil Science 100, 409-413.

Hsi, C. D. (1981) Sorption of uranium(VI) by iron oxides: Ph.D. thesis, Colorado School of Mines, Golden, Colorado, 154 pp.

Kerr, P. F., director (1950) American Petroleum Institute Project 49, Clay Mineral Standards, Analytical Data on Reference Clay' Materials. Columbia University Press, New York, 160 pp.

Langmuir, D. (1978a) Uranium solution-mineral equilibria at low temperatures with applications to sedimentary ore deposits: Geochim. Cosmochim. Acta 42, 547-569.

Langmuir, D. (1978b) Uraniumsolution-mineralequilibria at low temperatures with applications to sedimentary ore deposits: in Uranium Deposits, Their Mineralogy and Or- igin, Mineralogical Association of Canada, Short Course Handbook 3, Univ. Toronto Press, Toronto, Canada 17- 56.

Nash, J. T., Granger, H. C., and Adams, S.S. ( 198 l) Geology and concepts of genesis of important types of uranium deposits: Econ. Geol. 75th Ann&. Vol. I, 63-116.

Rancon, D. (1973) The behavior of underground environments of uranium and thorium discharged by the nuclear industry: in Environmental Behavior of Radionuclides Re- leased in the Nuclear Industry, IAEA-SM-172/55, Intern. Atomic Energ. Comm., Vienna, Austria, 333-346.

Reinbold, K. A., Hassett, J. J., Means, J. C., and Banwart, W . L . (1979) Adsorption of energy-related organic pol-

lutants: a literature review: Env. Prot. Agency Rept. EPA- 600/3-79-086, National Tech. Inform. Serv. PB80-105117, 11-60.

Routson, R. C., Wildung, R. E., and Serne, R.J . (1973) A column cation-exchange capacity procedure for low exchange-capacity soils: Soil Sci. 115, 107-112.

Schmidt-Collerus, J. J. (1967) Research in uranium geo- chemistry-investigations of the relationship between organic matter and uranium deposits: U.S. Atom. Energy Comm. Open File Rept. GJO-933-1 and GJO-933-2, U.S. Atomic Energy Commission, Grand Junction, Colorado, 141 pp. and 192 pp., respectively.

Sokolowska, Z. andSzczypa, J. (1980) Adsorption isotherms for weak acid anions in soils: Geoderma 24, 349-361.

Starik, I. Ye., Starik, F. Ye., and Apollonova, A. N. (1958) Adsorption of traces of uranium on iron hydroxide and its desorption by the carbonate method: Zh. Neorgan. Khimii, 3, p. 1.

Tsunaskima, A., Brindley, G. W., and Bastovanov, M. ( 198 l) Adsorption of uranium from solutions by montmorillonite; compositions, and properties of uranyl montmorillonites: Clays & Clay Minerals, 29, 10-16.

van Olphen, H. and Fripiat, J.J. (1979) Data Handbook for Clay Materials and Other Non-metallic Minerals: Perga- mon Press, London, 346 pp.

Walton, A. W., Galloway, W. E., and Henry, C. D. (1981) Release of uranium from volcanic glass in sedimentary sequences: an analysis of two systems: Econ. Geol. 76, 69- 88.

Wood, M. I. and Aden, G.D. (1982) Evaluation of sodium bentonite and crushed basalt as waste package backfill materials: U.S. Dept. Energy Doc. RHO-BWI-ST-21, Rock- well Hanford Operations, Richland, Washington, 62 pp.

Zielinski, R. A. (1980) Uranium in secondary silica: a pos- sible exploration guide: Econ. Geol. 75, 592-602.

(Received t October 1982; accepted 1 April 1983)

Pe31oMe---Xopouao cxapaKTeptl3OBaHHbIe o6pa3tlbl CTaH~apTHblX r~14n H3 AMepnKancKoro HeqbTmioro I/IHcTtlTyTa, o6pa311OBhlC r31IIHh! 143 OOuleCTBa no FJndHIfCTblM MHHepaJIaM 14 ~pyrne BTOptlqHbIe Mn14epa31bl 14cno~b3oBarlncb ~IJDI onpe]Ie~enns BaHsnnn KOHLIeHTpat114n ypaaa, TeMrlepaTypbl 14 COCTasa pacTBopa na CBOfiCTBa copfRn14 ypaHa. KonResTpatlrln ypana naxo~4~14Cb B ~nanasone OT OKO~O 1,00 • 10 -4 M ~o 4,00 • 10 -7 M, TeunepaTypbi n3uenn~nc~, OT 5 ~ ~Io 65~ ri pacTaOpbI co;aep;~a3n 0,01 M NaCI n 0,01 M NaHCO3. KpeMne3eMnhxfi renb xqbdpercTnnno cop6apoaa.a annonnbie KOM- nneKcbt ypannaoBoro Kap6onara. M14nepam, l c noabltuennofi KaTnono-o6Mennofi cnoco6~tOCTbrO nan6o~ee OXOTnO cop6npoBann ypannnoab~e nonbi nx 0,01 M pacTBopa NaCI. YBe~14qe14ne TeMne- paTypbI BJIn~l~O o6paTHOnponopllnoHa~bHO na cop6ttnro ypa8n.rloBbxx HOHOB, 3a ncrJnoqeHneM c~yqan, Korea U npncyTcTaoaa~ B B14jle gap6onaTHhlX KoMn3eKcom HeKpncTa~anqecKne ~<eae314bxe r14;IpooKnc14 cop6npoBa~14 ypaHriaOBbIe 14OHbl 60ace 3qbqbeKTnB140, aeM Bce riBB3e~oaanHh~e BTOpt'lqHhIe KpncTa~n- qecrdte Mnnepam+ Flpe~acTaa~ea, pa3pa60TanHbifi na OCHORe ypaaHennfl qbpefiu~nxa, MeTo~ ~a3z TOqHOfi 3~cTpano~mtn14 3dpqbeKTnaHOCT14 cop6Un14 U Me:m4Iy 3KcnepnMeHTam, HblMn ToqKaM14. [E.G.]

Resiimee--Gut bestimmte Tonstandards des American Petroleum Institute und der Clay Minerals Society sowie andere sekund~ire Minerale wurden verwendet, um die Auswirkungen der U-Konzentration, der Temperatur und der L6sungszusammensetzung auf die U-Adsorption zu bestimmen. Die U-Konzentra- tionen reichten von etwa 1,00 • l0 -4 M bis 4,00 • 10 -7 M, die Temperatur von 5 ~ bis 65~ Die L6- sungszusammensetzung war 0,01 M NaC1 und 0,01 M NaHCO 3. Silikagel adsorbierte Uranylkarbona- tanionenkomplexe sehr gut. Die Substanzen mit h6herer Kationenaustauschkapazit~t adsorbierten sehr leicht Uranylionen aus der 0,01 M NaC1-LOsung. Ein Temperaturanstieg zeigte einen negativen Effekt aufdie Uranyladsorption, aut3er das U war in Form eines Karbonatkomplexes vorhanden. Nichtkristalline Eisenoxyhydroxide adsorbierten Uranylionen vie1 wirksamer als alle andere untersuchte sekund~ire kristal- line Minerale. Es wird eine Methode zur genauen Extrapolation zwischen experimentell bestimmten Punkten der U-Adsorptionseffizienz angegeben, die auf der Freundlich-Gleichung beruht. [U.W.]


R~sum~--Des standards d'argile bien caracteris6s de l'American Petroleum Institute, des argiles de source du Clay Minerals Society, et d'autres min6raux secondaires ont 6t6 employ6s pour d6terminer les effets de la concentration d'U, de la temp6rature, et de la composition de la solution sur les propri6t6s de la sorption d'U. Les concentrations d'uranium s'6tageaient d'~t peu pr6s 1,00 • 10 4/~ 4,00 X 10 7 M, les temp6ratures de 5~ ~ 65~ et les compositions des solutions contenant 0,01 M NaCI et 0,001 M NaHCO3. Le gel de silice a sorb6 de mani6re efficace les complexes anion de carbonate uranyl. Les mat6riaux ayant la capacit6 d'6change de cations la plus elev6e ont sorb6 le plus facilement les ions uranyls de la solution 0,01 M NaCI. Des augmentations de temp6rature tendaient ~ affecter advers6ment la sorption de l'ion uranyl, sauf lorsque I'U 6tait pr6sent en tant que complexes carbonates. Des oxyhydrides ferriques non- cristallins ont sorb6 les ions uranyls de mani6re beaucoup plus efficace qu'aucun des min6raux cristalline secondaires 6tudies. Une m6thode est pr6sent6e pour extrapoler pr6cisement les efficacit6s de sorption d 'U entre des points exp6rimentaux bas6e sur l'6quation de Freundlich. [D.J.]

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SORPTION OF TRACE CONSTITUENTS FROM AQUEOUS …clays.org/journal/archive/volume 31/31-5-321.pdf · INTRODUCTION Uranium is a relatively mobile element in temperate ... high-level