JAEA
  • help
  • PC | SP
  • JP | EN
          
Refine your search：     
Report No.
 - 
Clear All
Search Results: Records 1-3 displayed on this page of 3
  • 1

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Natural attenuation of antimony in mine drainage water

Manaka, Mitsuo*; Yanase, Nobuyuki; Sato, Tsutomu*; Fukushi, Keisuke*

Geochemical Journal, 41(1), p.17 - 27, 2007/00

https://doi.org/10.2343/geochemj.41.17
 Times Cited Count：29 Percentile：56.2(Geochemistry & Geophysics)

Natural attenuation was investigated for the antimony in the drainage water of an abandoned mine. Drainage water, waste rocks, and ocherous precipitates collected from the mine were investigated in terms of their mineralogy and chemistry. The chemistry of the drainage water was analyzed by measuring pH, ORP, and EC on site as well as by ICP-MS and ion chromatography. The results of these investigations indicated that Sb, which is generated by the dissolution of stibnite (Sb$$_{2}$$S$$_{3}$$) and secondary formed Sb minerals in waste rocks, was attenuated by iron-bearing ocherous precipitates, especially schwertmannite, that form over time in the drainage water. Bulk distribution coefficients (Kd) for this Sb adsorption to the precipitates ranges up to at least 10$$^{5}$$ L/kg.

JAEA Reports

Raman spectroscopic measurements of porewater in bentonite

Suzuki, Satoru; ; *

JNC TN8400 2000-020, 25 Pages, 2000/04

JNC-TN8400-2000-020.pdf:0.94MB

Nature of porewater in bentonite plays important roles on the mass transport in the compacted bentonite used as a physical and chemical buffer material of the multi-barrier system in the high level radioactive waste manegement Higher activation energies of diffusion in the compacted bentonite than those in the aqueous solution is due probably to change in molecular structure of water in the porewater. The Raman spectroscopy was applied to studying the structure of porewater in bentonite at room temperature. Bentonite (Kunipia F, 98-99wt% of Na-smectite) was mixed with ion-exchanged water by water content of 75, 80, 90, 95 and 98wt% of water or with 0.5M NaCl aqueous solution by 75 and 80wt% of NaCl solution. Intensity maxima of the spectra of ion exchanged water, NaCl solution and their porewater were observed near 3200 to 3250, 3400, 3630cm$$^{-1}$$. These bands can be attributed to water molecules forming stronger hydrogen bond in this manner. Ratio of intensity, 3250cm$$^{-1}$$/3400cm$$^{-1}$$, increased from 0.97 to 1.1 with a decrease in water content of 100wt% (water) to 75wt%. On the other hand, intensity ratio of 3400cm$$^{-1}$$/3250cm$$^{-1}$$ of NaCl aqueous solution, 80wt%and 75wt% were 0.92, 1.2 and 1.3, respectively. Since the Raman scattering near 3250cm$$^{-1}$$ was attributed to water molecule forming the strongest hydrogen bonding in the three bands, those changes in intensity ratio suggests an increase in number of water molecule forming strong hydrogen bond in porewater of the bentonite. The constrained porewater possibly results in the high activation energy of diffusion in the compacted bentonite.

JAEA Reports

Experimental study of pyrite oxidation in compacted sodium bentonite

JNC TN8400 2000-012, 33 Pages, 2000/04

JNC-TN8400-2000-012.pdf:1.04MB

The redox condition of near-field is expected to affect the performance of engineered barrier system. Especially, the oxygen initially existing in the pore space of compacted bentonites strongly affects the redox condition of the near-field. For assessing the influence of the oxygen, the transport parameters of it in the compacted bentonite and consumption process should be known. Therefore, following researches were conducted. In order to understand the diffusion of dissolved oxygen (DO) in compacted bentonite and to predict the effect of DO, the effective diffusion coefficients of DO in compacted sodium bentonite were measured by electrochemistry. As the results, the following relationship between the dry density of compacted sodium bentonite and the effective diffusion coefficient of DO in compacted sodium bentonite was derived: De=1.53$$pm$$0.13$$times$$10$$^{-9}$$exp(-2.15$$pm$$0.24$$times$$10$$^{-3}$$p) where De is the effective diffusion coefficient (m$$^{2}$$s$$^{-1}$$) of DO in compacted sodium bentonite and $$rho$$ is the dry density (kg m$$^{-3}$$) of compacted sodium bentonite. The oxygen concentration in the bentonite is expected to be controlled by oxidation of pyrite as impurity in the bentonite. In order to investigate the above idea, the rates of pyrite oxidation by DO in compacted sodium bentonite were estimated from the experimental data on pyrite-bentonite systems usig the obtained effective diffusion coefficient of DO. The results show that the averages of the rate constants of pyrite oxidation by DO in the bentonite for dry densities of 0.8, 0.9, 1.0, 1.1 and 1.2$$times$$10$$^{3}$$kgm$$^{3}$$ were 1.38$$pm$$0.32$$times$$10$$^{-8}$$, 1.10$$pm$$0.24$$times$$10$$^{-8}$$, 1.16$$pm$$0.35$$times$$10$$^{-8}$$, 9.36$$pm$$2.23$$times$$10$$^{-9}$$ and 7.48$$pm$$1.92$$times$$10$$^{-9}$$ms$$^{-1}$$, respectively. The relationship between the dry density ($$rho$$) and the rate constant (k') was expressed as follows: k'=3.94$$pm$$1.06$$times$$10$$^{-8}$$exp(-1.33$$pm$$0.28$$times$$10$$^{-3}$$$$rho$$) ...

3 (Records 1-3 displayed on this page)
  • 1