Environmental Science Nano - Royal Society of Chemistry
(a-Se) nanospheres with a size ranging from 100 to 200 nm.14,21 To a lesser extent, few studies have also described the formation of biogenic trigonal and monoclinic selenium (t-Se and m-Se).8,22 Ho et al.23 reported the control of organic solvents like DMSO in the transformation of biogenic a-Se nanospheres to 1D t-Se nanostructures (e.g ...
اقرأ أكثرDiffusion behaviour of selenite and hydroselenide in compacted bentonite
The apparent diffusivities (D a) for selenium (Se) in compacted bentonite were obtained at a dry density of 1.6 mg/m 3 as a function of silica sand content and temperature under reducing conditions, in which the dominant species of Se is predicted to be HSe-(hydroselenide) and were compared with D a values obtained under anaerobic conditions, in which the dominant species …
اقرأ أكثرSélénium – SeMineraliser
Excellent antioxydant, il débarrasse aussi l'organisme des métaux lourds toxiques (Cadmium, Plomb, Aluminium, Mercure ). Améliore l'élasticité de la peau et l'état des cheveux. Taches de vieillesse. Mycose, acné (associé à Soufre de préférence). Anti-vieillissement. Puissant antioxydant, il joue un rôle majeur dans l ...
اقرأ أكثر10 méthodes naturelles pour éliminer les métaux lourds - Se …
10 méthodes naturelles pour éliminer les métaux lourds. Voici dix méthodes naturelles pour éliminer les métaux lourds qui nous empoisonnent quotidiennement et qui sont responsables d'un bon nombre de nos maladies autant physiques que psychologiques. Les métaux lourds toxiques tel que l' arsenic, le cadnium, le plomb, le mercure et l ...
اقرأ أكثرDiffusion behavior of selenite in purified bentonite —
Selenium (Se) is an important element for assessing the safety of high-level waste disposal. In this study, the diffusion coefficients of selenite in purified bentonite were investigated. A Japanese purified sodium bentonite, Kunipia-F, which contains approximately 99 wt% montmorillonite, was used in this experiment.
اقرأ أكثرSeparating selenium species by diffusion in Brazilian …
Bentonite was applied in diffusive studies for selenium, an emerging contaminant. The planar source method was used to determine the apparent and effective diffusion coefficients and assess the mobility of the selenium species. A double Gaussian function described the results. Different diffusion coefficients were associated with different mobilities, and …
اقرأ أكثرSorption mechanism of Pu, Am and Se on sodium-bentonite
The experiments were carried out by using the batch method under aerobic conditions for Pu, Am and under anaerobic conditions for Se. The distribution coefficients for Pu and Am were in the range 10 {sup 0} {approximately} 10 {sup 2}m {sup 3}/kg on sodium-bentonite in the above pH range. The sorption of Pu and Am was modeled by ion exchange of ...
اقرأ أكثر(PDF) Experimental and Modeling Study on Diffusion of …
The Da values for Se were between 6.1 × 10-11 and 4.3 × 10-10 m2 · s-1 and showed a tendency to slightly decrease with increasing dry density of bentonite. The dominant Se species in the ...
اقرأ أكثرMigration Behavior of Selenium in the Presence of Iron in …
Selenium (Se) is an important element for assessing the safety of high-level waste disposal. Se is redox-sensitive, and its oxidation state varies from -2 to 6 depending on the redox conditions and pH of the solution. Large quantities of ferrous ions formed in bentonite due to corrosion of carbon steel overpack after the closure of a repository are expected to maintain a …
اقرأ أكثرInfluence of bentonite on trace element kinetics in rats. III. Selenium
Abstract and Figures. Dietary bentonite (2% additive) given to rats for 28 d together with traces of sodium selenite (selenium-75) produced moderate but persistent decreases in the radioselenium ...
اقرأ أكثرcoupe_27.78E | Falaises de craie - CRIANN
Coupe 27.78'E. En cet endroit, la bentonite Lewes arrive au niveau du platier. Le platier devient plus nu, sans gros blocs. On y trouvera des placers recueillant de grosses boules de marcasite dérivant sans doute des niveaux condensés Senneville. Les niveaux les plus élevés du Turonien affleurent bien. Le niveau à silex dispersés ...
اقرأ أكثرCombined use of lime, bentonite, and biochar for immobilization …
Remediation of soil contaminated with cadmium (Cd) that can produce rice enriched with selenium (Se) is highly significant for improving the public health in China. A key issue needing resolution in this regard is the simultaneous immobilization of Cd and mobilization of Se. To explore a potential promising method to remediate median-high Se soil that is …
اقرأ أكثرSelenium speciation in Lower Cambrian Se-enriched
The results for total Se, C org, S, and different iron species contents are presented in Table 1 for the thirty-one samples. Se was mostly enriched in the Ni–Mo–Se sulfide layer (average, 2081 ppm), similar to values of 1000–2000 ppm reported by Orberger et al. (2007), the black shales (84.19 ppm) and K-bentonite (131.18 ppm). There was no obvious difference …
اقرأ أكثرDiffusion behavior of selenite in purified bentonite
Selenium (Se) is an important element for assessing the safety of high-level waste disposal. In this study, the diffusion coefficients of selenite in purified bentonite were investigated. ... One side of the bentonite was spiked with 10 μL of tracer solution containing 0.13 M Na 2 SeO 3 and it was kept at 10, 25, 40, or 55 °C for 1–29 days.
اقرأ أكثرDiffusion behavior of selenite in purified bentonite
In this paper in order to minimize the influence of the impurities, research focused on the diffusion phenomena in purified bentonite. Selenium-79 (79 Se) is one of the key radionuclides for examining the safety of high-level waste disposal. Selenium has also chemical toxicity as known selenosis at higher intake than 0.4 mg d −1 .
اقرأ أكثرBentonite modification with hexadecylpyridinium and aluminum …
Variation in structure after modification was demonstrated by using different characterization techniques. Se removal efficiency of OPBent is investigated by using (75)Se, since selenium (Se) is one of the important long lived fission products found in radioactive waste and has toxic anionic species in an aqueous environment.
اقرأ أكثرMigration Behavior of Selenium in the Presence of Iron in Bentonite ...
Selenium (Se) is an important element for assessing the safety of high-level waste disposal. In this study, the diffusion coefficients of selenite in …
اقرأ أكثرSelenium isotope fractionation during adsorption onto …
Selenium (Se) is a trace element with considerable concerns, since it is an essential micronutrient for organisms at low concentrations, but it becomes toxic at slightly higher concentrations (e.g., Zhu et al., 2008b; Fordyce, 2013; Qin et al., 2013). ... Model results obtained for a sodium bentonite from Wyoming and a calcium bentonite from ...
اقرأ أكثرSelenium - Batch Adsorption Process of Metals and Anions for
Selenium is an essential element. Selenium predominates as selenate and selenite (Fordyce 2007). ... The zeta potential acts as a determining factor in the adsorption of Se( VI) (Lu, Yu, et al. 2017; Dong, Chen, et al. 2016). The higher adsorption capacity of aluminum-based bentonite than sodium-based bentonite was more attributed to the ...
اقرأ أكثرColmater une fuite avec de la "bentonite" - narkive
Discussion: Colmater une fuite avec de la "bentonite". (trop ancien pour répondre) lolo. il y a 18 ans. Bonjour, J'ai une petite source qui sort de terre à côté de mon chalet. Les "anciens" avaient creuser un peu en aval de cette source (2m) et mis plaque pour créer une petite retenue.
اقرأ أكثرStructure of selenium incorporated in pyrite and mackinawite …
This study was aimed at investigating the incorporation of Se (2-) and Se (4+) into pyrite and mackinawite to determine the relevance of iron sulfides to Se retention and the type of structural bonding. The syntheses of pyrite and mackinawite occurred via direct precipitation in batches and also produced coatings on natural pyrite in mixed-flow ...
اقرأ أكثرSorption of Se(IV) on Fe- and Al-modified bentonite
Adsorption of selenium species using other conventional adsorbents such as zeolites, supported magnetite, sand, bentonite, titanium and clays was studied (Lo and Chen 1997;Kuan et al. 1998;Lenz et ...
اقرأ أكثرPotential Selenium Problems in Great Plains Soils
The mining of coal, bentonite, and U in the western USA has increased the potential for Se contamination of soils, surface water, and groundwater. Extremely high Se, As, and Mo values have been reported in areas of U enrichment in Utah, North Dakota, South Dakota, Colorado, Wyoming, New Mexico, and Arizona.
اقرأ أكثرOrigin and distribution of selenium in the upper …
known high selenium concentrations in North Dakota, (2) to delineate areas of potentially high selenium concentrations in North Dakota, (3) to determine the source of selenium and explain the origin of high con centrations in nature, and (4) to identify seleniferous formations and
اقرأ أكثرSeparating selenium species by diffusion in Brazilian bentonite: a ...
Bentonite was applied in diffusive studies for selenium, an emerging contaminant. ... Different diffusion coefficients were associated with different mobilities, and consequently, the coexistence of two selenium species: Se(IV) and Se(VI). Da results were higher for Se(VI), ≈10−10 m2 s−1, while for Se(IV) were ≈10−12 m2 s−1. ...
اقرأ أكثرSelenium in Soils - USDA
the selenium content of the soil on which it grows. Table 4 gives data on this variation. Vegetation from several irrigation projects was found to have a relatively low selenium content as compared with the vegetation on adjacent unirrigated soil of similar selenium content. Hurd-Karrer (174) found that sulphates inhibit the selenium ab-
اقرأ أكثرmarne_Lewes | Falaises de craie - CRIANN
La bentonite Lewes. La bentonite Lewes se présente généralement comme une encoche décimétrique très apparente dans la falaise. Elle équivaut à la marne West Tofts. Angleterre. Cette marne contient d'abondants Micraster leskei et …
اقرأ أكثرEvaluation of Se(IV) removal from aqueous solution by GMZ Na-bentonite …
Binary sorption system [Se(IV)/Na-bentonite] Se(IV) sorption kinetics. The sorption of Se(IV) ions on GMZ Na-bentonite as a function of contact time at pH 3.50 ± 0.15 and initial Se(IV) concentration of 1.46 × 10 −5 mol/L is shown in Fig. 1a. It can be seen that the sorption steady state was reached within 40 h, which is consistent with the reported work on …
اقرأ أكثرPierre Sélénite - Vertus des pierres - France Minéraux
La sélénite est une pierre qui émet des énergies positives et apaise l'environnement. Si vous la gardez près de votre lit, elle vous aidera à dormir plus facilement et plus profondément, sans trouble du sommeil et sans cauchemar. En plus de posséder des vertus apaisantes, la pierre sélénite vous protège en éloignant les énergies négatives.
اقرأ أكثرExperimental and Modeling Study on Diffusion of Selenium …
Effective diffusion coefficients of selenium through bentonite/sand mixtures were obtained by the through-diffusion method under reducing conditions where selenium was dissolved as HSe and Se 4 2. Experiments were carried out under variable bentonite content and porewater salinity. Bentonite contents in bentonite/sand mixtures varied from 20 ...
اقرأ أكثرCombined use of lime, bentonite, and biochar for
To explore a potential promising method to remediate median-high Se soil that is contaminated by Cd, a potted experiment was conducted, and seven combined amendments (0.03-0.12% lime, 0.03-0.18% bentonite, and 0.3-1.2% biochar of the dry soil weight) were used to immobilize Cd in three paddy soils, in which the concentrations of Cd and Se are 0 ...
اقرأ أكثرTowards an understanding of the sorption of U(VI) and Se(IV) on …
The sorption behaviour of uranium(VI) and selenium(IV) on a purified bentonite sample has been investigated and the results compared with those for sorption onto the unpurified material and goethite. Batch sorption data for U(VI) on purified bentonite show strong sorption in the pH range 5 to 8 ( R d >10 4 cm 3 g −1 ).
اقرأ أكثرNET.06.2012.010 ESTIMATION OF THE BEHAVIORS OF …
of selenium was analyzed using inductively coupled plasma-mass spectrometry (ICP-MS, Perkin-Elmer, Elan 6100), and the activity of Se-75 in the solution was measured by using γ-spectrometry (GEM-30185-P, EG&G, ORTEC). The amount of selenium sorbed onto solid (iron, iron compounds or bentonite) was calculated from the concen-
اقرأ أكثرMigration Behavior of Selenium in the Presence of Iron in …
Results indicated that Se was strongly retained by the processes such as precipitation reaction with ferrous ions in bentonite. Se K-edge X-ray absorption near-edge structure (XANES) measurements were performed at the BL-11 beamline at SAGA Light Source, and the results revealed that the oxidation state of Se in the bentonite remained Se(IV).
اقرأ أكثرBentonite modification with hexadecylpyridinium and …
Variation in structure after modification was demonstrated by using different characterization techniques. Se removal efficiency of OPBent is investigated by using (75)Se, since selenium (Se) is one of the important long lived fission products found in radioactive waste and has toxic anionic species in an aqueous environment.
اقرأ أكثرSelenite: Meaning, Properties and Powers - The Complete Guide
The name 'Selenite' derives from the Greek goddess Selene, the goddess of the moon. It's also called the Satin Spar, Maria Glass, or Desert Rose. But that is only the literal meaning of Selenite – there exist important spiritual meanings, too. The spiritual meaning of Selenite is rejuvenation and divine feminine energy.
اقرأ أكثر(PDF) Experimental and Modeling Study on Diffusion of Selenium …
The Da values for Se were between 6.1 × 10-11 and 4.3 × 10-10 m2 · s-1 and showed a tendency to slightly decrease with increasing dry density of bentonite. The dominant Se species in the ...
اقرأ أكثرDiffusion behavior of selenite in purified bentonite - ScienceDirect
Selenium (Se) is an important element for assessing the safety of high-level waste disposal. In this study, the diffusion coefficients of selenite in …
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