Sorption and diffusion behavior of selenium in tuff

Tachi, Yukio; Shibutani, Tomoki; Sato, Haruo; Yui, Mikazu

doi:10.1016/s0169-7722(98)00117-x

Cited by 45 publications

(18 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The distribution coefficients obtained from batch experiments, however, are usually higher than those obtained from diffusion experiments. The difference of specific surface area of crushed and intact rocks contributes to the discrepancy between distribution coefficients (Tachi et al, 1998). Assuming that the mineral composition of surfaces in crushed and intact rocks is similar, the distribution coefficients for the intact rock can be determined by the distribution coefficients obtained from batch experiments by adjusting for the difference between specific surface area of crushed and intact rocks using the following equation:…”

Section: Diffusion Of the Nonreactive Tracer Bromidementioning

confidence: 99%

“…is the distribution coefficient from batch sorption experiments (m 3 g -1 ), SA intact and SA crushed are the specific surface areas for intact and crushed samples (m 2 g -1 ), respectively (Tachi et al, 1998). The corrected distribution coefficients were used to calculate apparent diffusivity and retardation factors.…”

Section: Diffusion Of the Nonreactive Tracer Bromidementioning

confidence: 99%

See 1 more Smart Citation

Evaluation of Cesium, Strontium, and Lead Sorption, Desorption, and Diffusion in Cores from Western Pahute Mesa, Nevada Test Site, based on Macroscopic and Spectroscopic Investigations

Papelis¹,

Um²

2003

View full text Add to dashboard Cite

EXECUTIVE SUMMARYThe interaction of radionuclides and other contaminants with minerals and other aquifer materials controls the rate of migration of these contaminants in groundwater. The stronger these interactions, the more a radionuclide will be retarded. Processes such as sorption and diffusion often control the migration of inorganic compounds in aquifers. These processes are often controlled by the nature of the ions of interest, the nature of the aquifer materials, and the specific geochemical conditions. Parameters describing sorption and diffusion of radionuclides and other inorganic ions on aquifer materials are used in transport codes to predict the potential for migration of these contaminants into the accessible environment. Sorption and diffusion studies can reduce the uncertainty of radionuclide transport modeling on the Nevada Test Site (NTS) and other nuclear testing areas.Equilibrium sorption, desorption, and core diffusion experiments were conducted with five different core samples from Western Pahute Mesa (WPM) on the NTS. These cores included samples PM-1 4823, PM-2 4177, UE18R 2228, UE20c 2855, and UE20c 2908. For three of the samples, PM-1 4823, UE18R 2228, and UE20c 2855, a distinction was made between matrix and fracture sub-samples. The samples were characterized based on mineralogy, specific surface area, morphology, density, and porosity. Sample UE18R 2228, a densely welded tuff, was the only sample that had substantially lower porosity and specific surface area compared to the rest. All samples were mainly composed of feldspars and quartz.Based on sorption data with different solid and metal concentrations, linear sorption isotherms were derived for sorption at pH 8.3, representing a common NTS groundwater pH. Following sorption, desorption experiments were conducted to determine the reversibility of the sorption reactions. Lead was the most reactive metal ion and exhibited strong pH-dependent behavior. Typical K d s for Pb sorption were 1x10 -3 to 5x10 -3 m 3 /g. The sorption of Cs was much less pH-dependent and was overall substantially reduced compared to Pb. Typical K d s for Cs were approximately one order of magnitude less than Pb K d s (1 to 3x10 -4 m 3 /g). Strontium sorption was almost negligible for all solids, especially at lower concentrations. The minimal Sr sorption was caused, at least partly, by the substantial amount of Sr already present in the cores. Under these conditions, therefore, Sr would be very mobile. In all cases, K d s obtained from desorption experiments were higher than the K d s obtained from sorption experiments, typically by a factor of 2 to 10.Diffusion experiments with the entire core were conducted with a nonreactive tracer, bromide, before experiments with the reactive tracers, Pb, Cs, and Sr. Based on the bromide diffusion experiments, effective diffusivities and tortuosities were estimated. The effective diffusivities appeared to be directly correlated to sample porosity. The lowest tortuosity, 8.94, was observed for sample PM-1 4823 Matrix, wh...

show abstract

Section: Diffusion Of the Nonreactive Tracer Bromidementioning

confidence: 99%

Section: Diffusion Of the Nonreactive Tracer Bromidementioning

confidence: 99%

Evaluation of Cesium, Strontium, and Lead Sorption, Desorption, and Diffusion in Cores from Western Pahute Mesa, Nevada Test Site, based on Macroscopic and Spectroscopic Investigations

Papelis¹,

Um²

2003

View full text Add to dashboard Cite

show abstract

“…They explained this observation by suggesting that, unlike the smaller fractions, the largest size fraction involved a large number of whole mineral grains. Tachi et al (1998) studied the sorption and diffusion behavior of Se in Tono tuffs in batch experiments (using crushed rock with sample sizes ranging between 0.075 and 0.355 mm) and in throughdiffusion experiments (using samples 30 mm in diameter and 5 mm in thickness). The Kd values from the diffusion experiments were one order of magnitude lower than those from the batch experiments.…”

Section: Measurements Of Kd Valuesmentioning

confidence: 99%

Radionuclide Transport Models Under Ambient Conditions

Moridis¹,

Hu²

2000

View full text Add to dashboard Cite

“…Although a considerable amount of Se sorption data has been obtained under aerobic conditions, [7][8][9][10][11][12][13][14] where selenite and selenate species are dominant, the data obtained under reducing conditions are limited. [12][13][14][15][16] In particular, the sorption data for Se(ÀII) species in alkaline groundwater are scarce.…”

Section: Introductionmentioning

confidence: 99%

Sorption Behavior of Selenium(—II) on Rocks under Reducing Conditions

Iida

Tanaka

Yamaguchi

et al. 2011

Journal of Nuclear Science and Technology

View full text Add to dashboard Cite

The sorption of radionuclides on rocks is an important factor for performance assessment of geologic disposal of radioactive wastes. Batch sorption experiments under reducing conditions were carried out to investigate the sorption behavior of selenium onto granodiorite, sandy mudstone, tuffaceous sandstone, and their major constituent minerals and accessory minerals. Rock cores and groundwater employed in the experiments were sampled with special care to avoid exposing the cores and groundwater to air to minimize their oxidation. Selenium was spiked as HSe À and Se 4 2À in the experimental solutions, and reducing conditions were maintained throughout the sorption periods. Distribution coefficients, K d (m 3 kg À1 ), were obtained in the ranges of 2:2 Â 10 À4 to 4:0 Â 10 À3 m 3 kg À1 for granodiorite, 3:3 Â 10 À2 to 5:6 Â 10 À2 m 3 kg À1 for sandy mudstone, and 2:9 Â 10 À2 to 8:2 Â 10 À2 m 3 kg À1 for tuffaceous sandstone at pHs 8.5 to 11.5. The dominant sorbent minerals for selenium over a neutral to alkaline pH range were determined to be biotite for the granodiorite samples and pyrite for the sandy mudstone and tuffaceous sandstone samples.

show abstract

Sorption and diffusion behavior of selenium in tuff

Cited by 45 publications

References 6 publications

Evaluation of Cesium, Strontium, and Lead Sorption, Desorption, and Diffusion in Cores from Western Pahute Mesa, Nevada Test Site, based on Macroscopic and Spectroscopic Investigations

Evaluation of Cesium, Strontium, and Lead Sorption, Desorption, and Diffusion in Cores from Western Pahute Mesa, Nevada Test Site, based on Macroscopic and Spectroscopic Investigations

Radionuclide Transport Models Under Ambient Conditions

Sorption Behavior of Selenium(—II) on Rocks under Reducing Conditions

Contact Info

Product

Resources

About