Photo-catalytic Degradation and Sorption of Radio-cobalt from EDTA-Co Complexes Using Manganese Oxide Materials - 12220

Conference · Sun Jul 01 00:00:00 EDT 2012

OSTI ID:22293512

Koivula, Risto; Harjula, Risto ^[1]; Tusa, Esko ^[2]

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1. University of Helsinki, P.O.Box 55, FI-00014 Helsinki (Finland)
2. Fortum Power and Heat Oy P.O.Box 100, 00048 FORTUM (Finland)

The synthesised cryptomelane-type α-MnO{sub 2} was tested for its Co-57 uptake properties in UV-photo-reactor filled with 10 μM Co-EDTA solution with a background of 10 mM NaNO{sub 3}. High cobalt uptake of 96% was observed after 1 hour of UV irradiation. As for comparison, a well-known TiO{sub 2} (Degussa P25) was tested as reference material that showed about 92% cobalt uptake after six hours of irradiation in identical experiment conditions. It was also noted that the cobalt uptake on cryptomelane with out UV irradiation was modest, only about 10%. Decreasing the pH of the Co-EDTA solution had severe effects on the cobalt uptake mainly due to the rather high point of zero charge of the MnO{sub 2} surface (pzc at pH ∼4.5). Modifying the synthesis procedure we were able to produce a material that functioned well even in solution of pH 3 giving cobalt uptake of almost 99%. The known properties, catalytic and ion exchange, of manganese oxides were simultaneously used for the separation of EDTA complexed Co-57. Tunnel structured cryptomelane -type showed very fast and efficient Co uptake properties outperforming the well known and widely used Degussa P25 TiO{sub 2} in both counts. The layered structured manganese oxide, birnessite, reached also as high Co removal level as the reference material Degussa did but the reaction rate was considerably faster. Since the decontamination solutions are typically slightly acidic and the point of zero charge of the manganese oxides are rather high > pH 4.5 the material had to be modified. This modified material had tolerance to acidic solutions and it's Co uptake performance remained high in the solutions of lower pH (pH 3). Increasing the ion concentration of test solutions, background concentration, didn't affect the final Co uptake level; however, some changes in the uptake kinetics could be seen. The increase in EDTA/MoMO ratio was clearly reflected in the Co uptake curves. The obtained results of manganese oxide were very promising for the treatment of EDTA complexed Co solutions. The better performance values and cheaper production cost of manganese oxide, compared to titanium dioxide, is so big driving force that further studies on the material are evident. The possibilities for continuous treatment, instead of the fluidized bed -type batch experiment are investigated and the effects of other compounds affecting the de-complexation of Co-EDTA are further studied. (authors)

• Research Organization: WM Symposia, 1628 E. Southern Avenue, Suite 9-332, Tempe, AZ 85282 (United States)
• OSTI ID: 22293512
• Report Number(s): INIS-US-14-WM-12220; TRN: US14V1167115036
• Resource Relation: Conference: WM2012: Waste Management 2012 conference on improving the future in waste management, Phoenix, AZ (United States), 26 Feb - 1 Mar 2012; Other Information: Country of input: France; 13 refs.
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
COBALT
COBALT 57
DECONTAMINATION
EDTA
IRRADIATION
MANGANESE OXIDES
REACTION KINETICS
REMOVAL
SOLUTIONS
SORPTION
SYNTHESIS
TITANIUM OXIDES
UPTAKE