1. IST-2008 , Port-Elizabeth 7-10 Oct. 2008, South Africa
RECENT ADVANCES IN TECHNETIUM
ENVIRONMENTALLY FOCUSED
STUDIES
KONSTANTIN E. GERMAN
RUSSIAN ACADEMY OF SCIENCES
A.N. FRUMKIN INSTITUTE OF PHYSICAL
CHEMISTRY AND ELECTROCHEMISTRY
31/4 Leninsky prospect, Moscow , 119991, RUSSIA, Fax: 7-495- 335-17-78

2. 2008 – The Year of Tc
 Plan of presentation
 Tc in the environments – sources,
history and modern trends.
 Tc in acidic and basic HLW.
 Different methods of Tc HLW
treatment (insoluble residues, liquid
wastes discharcges, in-tank
storage, vitrification, plants
decomissioning, transmutation
projects )
 Chemical species of Tc in waste
and environment
 Physico-chemical aspects of Tc
(colloids and nanoparticles)

3. Saying “Tc” here we mean Tc-
99g
 β-emitter (T½ = 2*105 y) accumulating with ~6% yeild by
U, Np or Pu fission = 1kg/t-U
 Tc concentration in reprocessing solutions ~ 5-80 mg/L
 Oxydation states: 0, +1, + 2, +2.5, +3, +4 , +5, +6, +7
 Insoluble ε-phases = Tc metal
 Volatile as:
 Tc2O7, HTcO4 at T>100oC
 TcO2 and Tc-metal (T>350oC+O2);
 MTcO4 for M = Na, K, Cs atT>600oC = vitrification?
 In WATER : Extrimly high migration rate : TcO4-

4. Technetium in the environment
in 1986, NEA_TDB –RARD in 1999
An exceptional issue of “Technetium in the environment” in 1986 although made of
independent parts was a complete presentation of all the pre-Chernobyl ideas and
results [1]. 13 years later an excellent review of NEA-TDB summed up the chemical
thermodynamics of Tc [2]. Time passed being characterized with the controversy of
nuclear industry present and future status, drastic for Tc-99 originating mostly as the
uranium fission product. The definite stop in nuclear development would fix the further
accumulation but now is clearly not the case and we appreciate the authors were
continuing efforts in Tc environmentally focused sciences. Several main directions
could be drawn out: firstly those dealing with already accumulated Tc [3-5], then,
focused on the construction of the migration barriers at the depositories [6-9] and
finally examining the Tc in vitrification. The understanding of Tc interaction with
microbial extremofils was importantly advanced [10-11]. The review is devoted to these
and numerous other results of environmental importance.
“Technetium in the Environment” (Proc. CEC-RPP – SERE CEA Seminar - Cadarache, 1984), Eds.:
G. Desmet and C. Myttenaere, Elsevier Publishers, L&N-Y. (1986).
Rard J.A., Rand M.H., Anderegg G., Wanner H., Chemical thermodynamic of technetium. Eds.
Sandino Amalia M., Osthols E. NEA (1999) Elsiever Publ. Amsterdam.

5. Technogenic sources of Tc to the
environments
 Accumulation of 99Тс in nuclear industry = 8 ton/year
Discharge sources ofTc:
 Explsions in atmosphere 180 TBq (Tera=1012) = 490 kg Тс
Chernobyl accident = 82 kg
 NPP 1МBq /year 1000 МВт (электр.), т.е. :
 В 2000 году все АЭС мира выделили ≈ 350 МБк Тс = 160 г
 Заводы по переработке обл. топлива ≈ 10% от выбросов ЯТЦ
 Завод Селафилд в Ирландское море
 1952-1986 гг : 770 ТБк Тс = 1200 кг Тс
 Завод мыс Аг (Франция) 1966 – 86 гг : 70 ТБк Тс = 100 кг Тс
 Заводы изотопного обогащения U: 90% от выбросов ЯТЦ ≈ 4.1010
Бк Тс/год = 4,5 кг/год Тс
 (Газодиффузионный завод в ОАК РИДЖ: 1975-82 гг. 5-30 Ки Тс =
0.3 - 2 кг Тс/год, 1982-1989 гг. 0.02 – 0.03 кг Тс/год, 1990 – 0.2 кг, 1992
– 1 кг в связи с началом демонтажа оборудования)

6. Different approaches to handling
the Tc-radwastes
 Dilution in natural waters (only two isotopes β− 3H and
99
Tc) (UK, Russia -hystoric)
 Underground injection HLW, MLW (Tomsk, Krasnoyarsk,
Dimitrovgrad)
 Tank farms storage (military wastes, historic wastes)
 Vitrification of histric wastes, witrification of raffinates
 Metal forms
 New venture forms
 Separation and storage
 Separation ant transmutation

7. The 1995-2005 years were Тс marked by severe
confrontation of Norwegian “greens” with Sellafield
authorities for B205-MAGNOX
discharges into the Irish sea - 180 kg-Тс/year
EARP
Тс-to-sea standard for Sellafield
B211 = 10 HLW tanks
( B205 + EARP-B211 + THORP ) 1050 cub. m each :
– 1995-2000 - 200 ТBq-Тс 5 tanks for “MAC”
– 2000-2003 - 90 ТBk-Тс 2 tanks– sludges
– TPPBr - April 23-24 - 2003 2 tanks - THORP
1 – empty in 2003

8. Pollution of the North sea, caused by
Sellafield, UK)
Тс content
In the samples collected in 1999 - 2001
 water = 0.01- 0.07 Bq/L
 algae = 510 Bq/kg ( ! )
 lobsters = 33 - 42 Бк/кг ( ! )
(acc. to Bellona, Norvege)
Risks of refused distribution of Norvege sea-foods

9. Tc discharges in 2002-2005
The sum of total-beta activity (excluding tritium) from all
nuclear installations has fallen significantly over the
past 15 years. Total emissions are dominated by
discharges from the nuclear fuel plant at
Springfields and to a lesser extent the reprocessing
plant at Sellafield. The two installations together
contribute approximately 98 % of the overall
discharges. The high, but decreasing total-beta
discharges from Sellafield are mainly attributable to
the radionuclide Technetium-99. The reduction of
Sellafield’s total-beta discharges from 2002 to 2005
is a result of the significant reduction in
Technetium-99 discharges, due to the vitrification
process, since 1994 for oxide fuels and 2003, for
magnox fuels. Discharge of Tc-99 to sea (primarily
from treatment of stored Magnox wastes) has been
reduced between 1994 and 2005.
The total beta discharges from Sellafield (2002: 112
TBq, 2003: 83 TBq, 2004: 73 TBq, 2005: 43 TBq)
were previously mainly attributable to the
radionuclide Technetium-99 (2002: 85 TBq, 2003:
37 TBq, 2004 14 TBq, 2005: 6,7 TBq ), for which
abatement technology was installed in 2004. The
reduction of Sellafield’s total beta discharges in
2005 is due to the reduction of Technetium-99
(2004 14 TBq, 2005: 6,7 TBq),

10. Tc releases in Europe
Mayak
Karachay lake
VVER
3*10-2
 For other European facilities the annual
Tc release is negligible

11. Tc behavior during the
underground HLW storage
 Pretreatment : рН +
complexones + . . .
 Ingection into the sandy levels
– collectors
 Migration control
 ………………………………………………………. . .
 Tc sorption at the minerals and
rocks was studied before
 Main conclusions
 Тс(VII) has high migration
Guerman K.E., Kosareva I.M., Peretroukhin V.F., mobility
Savushkina M.K., Egorov N.N., Kudryavtsev E.,
Revenko Yu.A. ICEM'95. V.1. Cross-cutting Issues  Тс(IV) may form both immobile
and management of high-level waste and spent fuel.
(Eds.: S.Slate, Feizollahi, C.Creer), NY, 1995, p. 713 – 722 .
TcO2 and mobile complexes

12. Tc speciation in simulated radioactive wastes conditionned
for the underground injections (1980-88, 1994, 2000)
10
5
4
3
experiment
fit
 TcO4- - is highly migrative
 Radiolyses in presence of
Fourier Transform Magnitude
0
k 3 χ (k)
2
organic components lead to
-5
1
-10
the reduction of Тс(VII) to
0
4 6 8 10 12 14 0 1 2 3 4 5
-1
k (Å ) R + ∆ (Å)
EXAFS ROBL_ESRF Tc(V, IV, III)
 Acetate complexes Тс(V, IV,
III) exist but the data are
scattered and the structure
not systematically studied
 Acetate complexes of Тс(III)
could co-exist withTc(VII) .

13. Russians experience of Tc separation and
conversion (decl. avail.for CEA France 1994-1997)
Spitsyn V.I., Kuzina A.F., Prokopchuk Yu. Z., Chepurkov G.Ya. , German K.E.,
Oblova A.A.,Kryuchcov S.V. Preparation of technetium metal by thermal
decomposition of tetrabutylammonium pertechnetate in inert gas atmosphere.
Report IPCAS, N-P-2907, 1983.
Spitsyn V.I., Kuzina A.F., Prokopchuk Yu.Z., Chepurkov G.Ya., German K.E., Oblova
A.A., Kryuchcov S.V., Dzekun E.G., Sokhina L.P. Precipitation technology for
technetium separation from radioactive wastes. Report Mayak/IPCAS- 1984.
Spitsyn V.I., Kuzina A.F., Prokopchuk Yu.Z., Chepurkov G.Ya., German K.E., Oblova
A.A., Kryuchcov S.V., Tzarenko A.F., Akopov G.A., Krinitsyn A., Kapitonov V.I.,
Galkin A.,Maksimenko A., Berezuk N., Mezentsev V.I. Technology of technetium
recovery from radwastes.Report Mayak /IPCAS/ Khlopin Radievy.Inst.,1985, N P-
3171. 32 p.
Spitsyn V.I., Kuzina A.F., Prokopchuk Yu.Z., Chepurkov G.Ya., Guerman K.E.,
Oblova A.A.,Kryuchcov S.V., Kapitonov V.I., Mezentsev V.I. Improuvment of
anion exchange technetium recovery from radwastes using TBP as eluent.
Report Mayak -IPC AS. 1985, N P-3066 , 82 P.
German K.E., Kuzina A.F., Spitsyn V.I. Patent: Method of technetium carbide
preparation. USSR. Patent No 1258016, 1986.2

14. Russian approach to Tc separation in PUREX included (1980-1986):
extraction at the first extraction stage, back extraction at the U-Pu
separation stage, anion-exchange separation at QuatPhosBase AER,
purification at VP-1AP-AER, denitrification with formic acid or H 2O-SH,
precipitation of KTcO4 or R4NTcO4 and its conversion to metal Tc
Association
MTcO4 Solubility in Density constant in  Conversion to metal:
M= water at 25°C g/ml water, L/M  Search for the
Me4N+ 0.135 ± 0.005 1,67 - conditions (Ar-6%H2, gaz
0.096 [8]
(2.5 ± 0.7) x 10-2
product evaquation,
Et4N+ 1,34 -
1.24 x 10-2 at 20°C
(8.7 ±0.2) x 10 -3
 Products - volatile and
Pr4N+ 7.8 x 10-3 [8] 1,26 2,6 ± 0,4 solid,
(4.3 ± 0.20) x 10-3
Bu4N+
4.2 x 10-3 at 20°C
1,17 15 ± 3  Russ.Inorg. Chem-2002
Pent4N+ (7.9 ± 0.2) x 10-4 1,12 27 ± 5
-47-No5
Hex4N+ (7.1 ± 0.5) x 10-5 1,07 40 ± 5
Hept4N+ (8.8 ± 0.8) x 10-6 1,03 52 ± 5
p[(C4H9)4N]OH (aqueouse) ↔ [(C4H9)4NOH]p (aqueouse) (8)
[(C4H9)4N] (aqueouse) + TcO4 (aqueouse) ↔ [(C4H9)4N]TcO4 (solide)
+ -
(9)
[(C4H9)4NOH]p (aqueouse) + TcO4 (aqueouse) ↔ [(C4H9)4NOH]p-1TcO4 (aqueouse) + OH (10)
- -
HTcO4 ↔ H+ +TcO4- (TcKa)
Tc
Ka/( TcKa + [H+]) = [TcO4-] /([TcO4-]+ [HTcO4]) = [TcO4-] /[Tc]tot
The TcKa was found equl to 4.02 M which is in very good agreement with [ [i]]
[i]
Ashley K.R., Ball J. R. Solvent extraction and ion exchange, 1994, 12(2), p.239-259.

15. Co-precipitation of Tc(VII) with Bu4NReO4
from 100 ml 1.0 M NaOH, [ TcO4-] = 5*10-4 M, [ Bu4N+]
= 0.005 - 0.02 M, reagent = 0.1M NH4ReO4
Tc fraction
remained
in the solution 0,02M Bu4N
1 0,01M Bu4N
0.005M Bu4N
0.8
0.6
∆ V= +3%
0.4
0.2
0
100 102 104 106 108 110
Total volume, %

16. Tc oxides
Parameters for inner
electrons (Tc3d3/2,5/2) Tc2O5- decomposition of
Tc Oxide E(Tc) Half-width Tc2O5*nH2O at 100oC
Tc2O5*nH2O – gamma in
NaOH
1 Tc2O5 256,6 1,8
Tc4O5*14H2O hydrolisis
2 Tc2O5*nH2O 256,0 1,7 of K3Tc2Cl8
Tc4O5 - thermolisis
3 TcO2 255,2 1,8
4 TcO2*1.6H2O 255,4 2
5 Tc4O5*14H2O 255,9 1,8
6 Tc4O5 255,0 (0,4) 3.5
253,6 (0,4)
(I1:I2=1:1.3)
7 Tc2O7 - volatile

17. Tc under HAW vitrification conditions
 No stable Tc silicates were found before – but now we
know about Tc sodalite although losing in structure
stability to cancrinite in presence of common nitrate
 Pertechnetates are volatile at temp. > 600oC
Reduced Tc valence forms –
 Tc(IV) no interaction with silicates
 Tc(0) no interaction with silicates
Tc separation before HAW vitrification is preferable

18. Methods for Tc separation from alkaline and
neutral solutions
Not a problem compared to acidic, quite efficient
are several methods used in Russia in 1980-85
EXTRACTION Chromatography
Ketones : Aceton, QuatPhosBase(KHL-Rad-
Methyl-ethyl-ketone,) Inst) +VP-1АP(IPCERAS)
ТPPBr/ТPAsBr/CCl4 (= RAILEX) for technology
Polyglicoles HPLC - DIONEX-AS11 (for
anallyt separation from
MoO4/I/Br/ClO4/TcO4)
solidex TPPBr (developed for HLW B205-MAGNOX)
- Not easy when Tc species is different from Tc(VII)
(Schroeder, 1996 - Hanford: treatment with S2O8 etc.

19. Properties of different reagents for Tc
separation by (co-) crystallization or solidex
technology
Table 4.1 Aqueous solubilities of technetium salts  Тетрафениларсоний бромид
Pertechnetate cations Solubility at 25ºC, M (Трибалат, Кузина)
Cesium 1.60x10-2  Нитрон (Кузина)
Thallium 3.1x10-3
Tetrapropylammonium (8.7± 0.2)x10-3
 Тетрафенилфосфоний
бромид (BNFL) (совместимы с
Tetrabutylammonium (4.3 ±0.2)x10-3 фосфатными стеклами)
4.2x10-3 at 20° C
-4  Тетраалкиламмоний бромид /
Tetrapentylammonium (7.9 ±0.2)x10
перренат (осадки совместимы с
Tetrahexylammonium (7.1 ±0.5)x10-5 боратными стеклами, метод
Tetraheptylammonium (8.8 ±0.8)x10-6 опробован в 1982-85 совм. с ПО
Triphenylguanidinium (3.9 ±0.3)x10-3 Маяк, в 1995-97 определены
Tetraphenylarsonium (4.0 ±0.2)x10-4 оптимальные осадители,
которые рекомендованы КАЭ
Франции и ДЭ США)
Some of these regents were also used for
•Tc-Ion-selective electrode construction
•Fiber sorbents production

20. The SRS waste volumes (Table 2.4 of "Integrated Database Report - 1993: S.Spent
Fuel and Radioactive Waste Inventories, Projections, and Characteristics,”] Tc-99
quantities (Table 2.11), and Tc-99 concentrations calculated from these data
Isolation Valve
Capped
Tank Equipment Risers (typ) Service Line (e.g. steam, air)
(e.g. slurry pump)
Grout fill
Formwork
2000# grout (typ)
Underground
line
(valve closed) Diversion Box
CLSM
Underground line
(line capped)
Reducing Grout
SRS TYPE IV HIGH LEVEL WASTE TANK
Volume, Tc-99, Ci [Tc-99], [Tc], 10 6 Kd
liters Ci/liter g/liter
total
Liquid 61.4 1.68E+04 2.74E-03 0.162 -
Sludge 13.9 1.14E+04 8.20E-03 0.483 3
Salt Cake 53.8 2.78E+03 5.17E-04 0.0305 0.2
Overall waste 129.1 3.098E+04 2.40E-03 0.141 -
Question to be answered : Which components absorb Tc with Kd
higher than 3 and are resistant to leaching?

21. Tc concentrations found in
99
various tank sludges at SRS
[Tc-99],
The discovery of relatively Tank mCi/g dried Reference
high 99 Tc concentrations Number solids
in inorganic mineral 17 0.462 d'Entremont et
sludge heels taken from al. 1997
some tanks at the US- 20, white 0.34 d'Entremont and
DOE Savannah River Site solids Hester 1996
(SRS) has prompted 20, brown 0.94 d'Entremont and
investigations of Tc solids Hester 1996
uptake from alkaline 42 0.22 Hay 1999
highly active waste (HAW)
51 0.21 Hay 1999
by solid adsorbents
8 0.22 Hay 1999
11 0.34 Hay 1999

22. Sludge components as carriers
for Tc(VII) and Tc(IV)
S O L ID S L U D G E C O M P O N E N T S
W H IT E S O L ID S B R O W N S O L ID S
A L U M IN O S IL IC A T E S M E T A L H Y D R O X ID E S
C A N C R IN IT E (F e , C r, M n )(O )(O H )
S O D A L IT E
. C R Y O L IT E . . P L A T IN U M G R O U P .
N a 3 A lF 6 M E T A L S
R h , R u , P d
. S O D IU M O X A L A T E .
N a 2 C 2 O 4
TiO2 was also tested

23. Study of Tc uptake with Aluminosilicates
under oxidizing conditions at 70-130oC
 Literature data have demonstrated the possibility of
ClO4- and MnO4- co-crystallisaton with aluminosilicates :
purple Na8[AlSiO4]6(MnO4)2 (Weller,1999 etc.)
OUR EXPERIMENTS on TcO4- (reaction: NaAlO2+Na2SiO3+NaOH)
Solution Formed solid Kd
 TcO4- is too large
10-3-10-5M Tc and therefore it is
0.2-5M NaOH Cancrinite less 1
0.5-5 M NaNO3
excluded from the
aluminosilicate
10-3-10-5M Tc structure in both
0.2-5M NaOH Sodalite less 1
NaNO3 free
cancrinite and
sodalite

24. Case of Aluminosilicates formed
in concentrated Tc(VII) solution
 [Tc] = 0.2 M Fig. 1. NMR-99Tc spectrum of the aluminosilicate containing
 in NaNO3 solutions - cancrinite 57 mg-Tc/kg. Tc spectrum presents evidence for -30 ppm shift
characteristic of coordinated pertechnetate
 in NaNO3-free solutions - sodalite
 Although NMR spectrum presented
shift typical for coordinated Tc(VII)
its concentration is very low
 Dissolution in NaHF2 and LSC has
shown : [Tc] in solid cancrinite was
57 mg/kg ~ 100 times less than in
initial solution
 Tc is excluded from the
aluminosilicate structure

25. Study of Tc uptake with Aluminosilicates under
reducing conditions
(0.2M N2H5Cl, 1M NaNO3, T = 800С, t = 3 d)
Precipitation of Leaching conditions:
cancrinite↓
Leaching T, Leaching yield , Tc, %
NaOH Tc yield, agent: o
C
3 1 day 10 days
M %
hour
2.0 18.9 1M NaOH 20 0.8 1 3.7
4.0 32 2M NaOH 20 0.8 1.2 2.0
2.0 25.2 0.1M NaOH + 60 25 26.9 27
0.25 M H2O2
2.0 18.9 0.1M NaOH + 18 4 6.9 7
0.5 H2O2
4.0 32 0.1M NaOH + 18 6.5 6.9 11
0.5 H2O2
Under reducing conditions Tc uptake is important
Tc(IV) in aluminosilicates is resistant to leaching

26. Study of Tc(VII) sorption
by crystalline TiO2
under oxidizing conditions
 Tc(VII) was sorbed by TiO2
from neutral solution
with Kd = 30 ml/g.
 However, the Kd at pH=10
was only 3.3 ml/g  Among the
 No affinity to Tc(VII) was minerals tested for
noted for TiO2 at pH=12 Tc(VII) uptake,
and higher . high-density TiO2
MST and was the most
Silicotitanates yet not efficient

27. Study of Tc uptake with
Na oxalate under
oxidizing and reducing conditions
NaOH + H2C2O4 = Na2C2O4
X-ray diffraction tests :
the precipitate is
sodium oxalate Na2C2O4
(PDF#20-1149)
 Tc(VII) is excluded from the Na oxalate structure
under oxidizing conditions (Kd = 1-2)
 Under reducing conditions Tc(IV) forms a separate
TcO2*1.6H2O phase - no interaction between Tc
hydroxide and Na oxalate were detected
 Tc precipitate is not resistant to leaching with 0.1 N
NaNO2

28. Study of Tc uptake with
Cryolite Na3AlF6 under
oxidizing and reducing conditions
6F-+NaAlO2+Na2CO3
X-ray diffraction tests :
the precipitate is cryolite Na 3 AlF 6
 Reduced Tc :  Oxidizing
conditions:
 17-35% of Tc(IV) as
TcCl62- is co-  Kd is less 1
precipitated with
cryolite  Tc(VII) is excluded
 N2H5NO3 inhibits co- from cryolite
structure
precipitation

29. Study of Tc(IV) uptake
with Cryolite Na3AlF6
under reducing conditions
[NH4F] [Na2CO3] in [N2H5NO3], in Tc(IV)
No initial, final solution, final solution, uptake,
M M M %
1 2,0 0,6 - 20
2 2.5 0.6 - 23
3 3.0 0,6 - 26
4 4,0 0.6 - 28
5 6,0 0,6 - 35
8 2,0 0,4 - 25
9 2,0 0,8 - 17
10 2,0 0,6 0,1 0
• Tc(IV) is added as Na 2 TcCl 6 to ( NH4F+NaAlO2)
solution
• No additional reducing agent in exp. No 1-9
• Leaching test were impossible to quantify

30. Study of Tc(IV) uptake with
FeOOH under reducing conditions
 Reducing agent: 0.02M FeSO4, T = 600С, time = 3 h
 Precipitate : FeOOH/Fe2O3
Precipitation test: Leaching test (t=18 oC, d = days):
NaOH Tc in solid Leaching Leaching yield ,Tc, %
M phase, % agent: 1 d 10 d 29 d 105d
0.6 97 0.1M NaOH 1.0 9.8 14.9 24
2.0 88.0 1M NaOH 2.9 16.5 40.2 58
4.0 90 2M NaOH 0.8 2 3 8.2
Though Tc adsorbed better on iron hydroxides from 0.5–2.0 M NaOH
than from 3.0-4.0 M NaOH, the precipitates formed at lower NaOH
concentration were more easily leached by the NaOH leachant
Tc leaching with H2O2 was 20 % and with Na2S2O8 was70-100% in 100
days

31. Study of Tc(IV) uptake with
MnOOH under reducing conditions
 Reaction NaOH + Na2MnO4+ N2H5OH= MnOOH
X-ray diffraction tests : the freshly precipitated
solid was Mn2O3 , the aged precipitate was
manganite MnOOH (PDF#18-805)
MnOOH precipitation MnOOH leaching to 0.1 NaOH (1,3,4) and Na2S2O8(2)
12
1) Mn/Al=1/10
90 2) Mn/Al=1/40
10
3)Mn/Al=1/10
75
Tc uptake by precipitate, %
8 4) Mn/Al=1/40
Leached Tc, %
60
Mn/Al=1/10 6
45
30 Mn/Al=1/40 4
15 2
0
0
0 5 10 15 20 25 30
0 2 4 6 8 10 12
Time,d Time. d
 Manganese(III) oxides were effective Tc carriers and
underwent chemical transformations on ageing that increased
leaching resistance to most agents.

32. Boehmite sorbs perrhenate and pertechnetate
By Peng-Chu Zhang*, James L. Krumhansl and Patrick V. Brady
Sandia National Laboratories, Albuquerque, USA
Radiochim. Acta 88, 3692373 (2000)
(a) Al(OH)3 - Aluminum hydroxide - gibbsite ;
(b) Boehmite [AlO(OH)] -aluminum oxyhydroxide
(c) Al2O3 aluminum oxide - corund
Boehmite and Al-oxyhydroxide gels sorb ReO4 a non-radioactive
analogue of TcO4 from NaNO3 solutions.Sorption appears to be
substantially electrostatic (though there appears to be a specific
preference for ReO4 over NO3 and is most effective at pH , 8.
Measured Kd’s lie between 5 and 105 ml g-1, depending on the solid,
pH, and ionic strength. ReO4 and TcO4 are both partially removed
from high pH Hanford-type acid waste simulants upon neutralization
and formation of Al-rich sludges. It was proposed that sequestration of
Tc by boehmite limits dissolved Tc levels in the near and sub-surface
environment and for that purpose boehmite might be relied on as a
backfill, or reactive barrier, to limit environmental transport of Tc.
How Mo-Tc generators could do work being made of Al oxide - oxyhydroxide ???

33. Tc(VII) + S2-
Kinetics of the reaction of pertechnetate with sulfide
in 0.3M Na S solution at 22oC
2
1.0
0.9
0.8
0.7
Convertion degree
0.6
0.5
[Tc], *104M
0.4
Tc2.66
0.3 Tc1.9
Tc1.52
0.2
Tc1.14
Tc0.57
0.1
0.0
0 2 4 6 8 10 12 14 16 18 20 22 24
Time, min

34. Separation of Tc2S7 colloides from Na2S solution by
Microfilterfuge (RAININ Instr. Co) with ultrafiltration
membranes - 30000 NMWL
Tc2S7 ultrafiltration
[Na2S]
 Formation of colloides Tc2S7
0.0007
0.46M is complète in 50 hours
0.0006
0.0005
0.33M under these conditions
0.2M
C(Tc), M/L
0.0004
0.13M
0.0003
0.0002
0.066M  [Tc] in the solutions at
0.0001
0.033M
times from 50 to 150 hours
0.02M
0
0 25 50 75 100 125 150 175 200
corresponds to true
TIME, H solubility of Tc2S7
Solubility Tc2S7 in Na2S solutions
0.00035
0.0003
C(Tc) = -9E-05Ln[Na2S] - 2E-05
0.00025 R2 = 0.9917
C(Tc), M/L
0.0002
0.00015
0.0001
0.00005
0
0 0.1 0.2 0.3 0.4 0.5
[Na2S], M/L

35. The reduction of Tc(VII) to Tc(V,IV,III ) by
abiotic and biotic processes
The reduction of Tc(VII) to Tc(IV) by abiotic and biotic processes has recently
been the subject of extensive studies because it has a significant effect on
the mobility of technetium in waste streams, vadose zones, sediments, and
groundwater. These reaction processes are the basis for certain
remediationtechnologies such as permeable barriers composed of zero-
valent iron particles (i.e., as metallic iron) or sodium-dithionite reduced soils,
which are being tested for immobilization of groundwater contaminants.

36. Microbial reduction of Tc(VII)
Microbial reduction of Tc(VII) has been suggested as a potential mechanism
for removing technetium from contaminated groundwaters and waste
streams (e.g., Lovley 1993, 1995, Lyalikova,German et all. 1994).
Certain dissimilatory metal reducing bacteria and sulfate reducing bacteria
have been determined to be capable of coupling the oxidation of organic
carbon or hydrogen to the reduction of Tc(VII) to Tc(IV)
(Lyakikova,German,Khizhnyak Peretrukhin 1994 , 1998, Gavrilov –German
2007 and Lloyd and Macaskie 1996; Lloyd et al. 1997, 1998, 1999, 2000a,b;
Wildung et al. 2000; Fredrickson et al. 2000).

37. Transmutation
Tc-Ru acidic and pyrochemical
solubilization problem
N. Schroeder approach : homogeneous transmutation