The effect of sulphide minerals on uranium oxidation state in in-situ leaching

2017 ◽  
Author(s):  
A. M. Pastukhov ◽  
S. Yu. Skripchenko
Keyword(s):  
Oxidation State ◽  
Sulphide Minerals ◽  
Uranium Oxidation

scholarly journals Selenium– and tellurium–halogen reagents

2018 ◽  
Vol 3 (12) ◽  
Author(s):  
Tristram Chivers ◽  
Risto S. Laitinen
Keyword(s):  
Oxidation State ◽  
Halogen Bond ◽  
The Other ◽  
Oxidation States ◽  
Alkyl Aryl ◽  
Organic Selenium ◽  
Formal Oxidation State ◽  
Wide Range ◽  
Inorganic And Organic

Abstract Selenium and tellurium form binary halides in which the chalcogen can be in formal oxidation states (IV), (II) or (I). They are versatile reagents for the preparation of a wide range of inorganic and organic selenium and tellurium compounds taking advantage of the reactivity of the chalcogen–halogen bond. With the exception of the tetrafluorides, the tetrahalides are either commercially available or readily prepared. On the other hand, the low-valent species, EX2 (E = Se, Te; X = Cl, Br) and E2X2 (E = Se, Te; X = Cl, Br) are unstable with respect to disproportionation and must be used as in situ reagents. Organoselenium and tellurium halides are well-known in oxidation states (IV) and (II), as exemplified by REX3, R2EX2 and REX (R = alkyl, aryl; E = Se, Te; X = F, Cl, Br, I); mixed-valent (IV/II) compounds of the type RTeX2TeR are also known. This chapter surveys the availability and/or preparative methods for these widely used reagents followed by examples of their applications in synthetic inorganic and organic selenium and tellurium chemistry. For both the binary halides and their organic derivatives, the discussion is subdivided according to the formal oxidation state of the chalcogen.

Insights into sulfur poisoning and regeneration of Cu-SSZ-13 catalysts: In situ Cu and S K-edge XAS studies

2021 ◽  
Author(s):  
Vitaly Mesilov ◽  
Sandra Dahlin ◽  
Susanna Liljegren Bergman ◽  
Peter Sams Hammershøi ◽  
Shibo Xi ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Oxidation State ◽  
Absorption Spectroscopy ◽  
Catalytic Reduction ◽  
Sulfur Poisoning ◽  
X Ray ◽  
Scr Catalysts ◽  
X Ray Absorption

In situ Cu and S K-edge X-ray absorption spectroscopy (XAS) was used for the investigation of sulfur-poisoned and regenerated Cu-SSZ-13 selective catalytic reduction (SCR) catalysts. Sulfur in the oxidation state...

scholarly journals Changes in u(VI) SPeciation Upon Sorption onto Montmorillonite from Aqueous and Organic Solutions

1991 ◽  
Vol 257 ◽  
Author(s):  
Catherine Chisholm-Brause ◽  
Steven D. Conradson ◽  
P. Gary Eller ◽  
David E. Morris
Keyword(s):  
Oxidation State ◽  
Aqueous Systems ◽  
X Ray ◽  
Ph Values ◽  
Uranium Oxidation ◽  
Organic Solutions ◽  
X Ray Absorption ◽  
Hydrolysis Of ◽  
Uranium Species ◽  
Lines Of Evidence

ABSTRACTThe speciation of UO22+ and UO22+/ TBP mixtures has been investigated in solution and intercalated with the reference smectite clay SAz-1 using x-ray absorption, Raman, andluminescence spectroscopies. Neither aquated UO22+ nor its TBP complex undergoes any detectable changes in uranium oxidation state on intercalation. Further, at the pH values employed in this work, there is no evidence for hydrolysis of the uranium species to generate dimeric or higher order uranium oligomers. However, we do find indications that the structures of the solution complexes are altered on intercalation, particularly for the UO22+TBP system and for more dilute UO22+/aqueous systems. In addition, several lines of evidence suggest that, at the loading levels used in this study, the uranyl species is interacting with two or more spectroscopically distinguishable sites on SAz-1.

scholarly journals In situ XAS study of the local structure and oxidation state evolution of palladium in a reduced graphene oxide supported Pd(ii) carbene complex during an undirected C–H acetoxylation reaction

2019 ◽  
Vol 9 (8) ◽  
pp. 2025-2031 ◽  
Author(s):  
Ning Yuan ◽  
Maitham H. Majeed ◽  
Éva G. Bajnóczi ◽  
Axel R. Persson ◽  
L. Reine Wallenberg ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Oxidation State ◽  
Local Structure ◽  
Carbene Complex ◽  
In Situ Xas ◽  
Reduced Graphene ◽  
State Evolution ◽  
Supported Pd

In situ XAS is used to reveal the evolution of palladium species during an undirected C–H acetoxylation reaction.

In Situ X-Ray Diffraction and In Situ X-Ray Absorption Spectroscopy for Investigation of Intercalation Batteries: Application to the Alkaline H+/γ-MnO2 system.

1990 ◽  
Vol 210 ◽  
Author(s):  
C. Lévy-Clèment ◽  
C. Mondoloni ◽  
C. Godart ◽  
R. Cortès
Keyword(s):  
Charge Transfer ◽  
Oxidation State ◽  
Absorption Spectroscopy ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
Alkaline Batteries ◽  
X Ray ◽  
In Situ Techniques ◽  
X Ray Absorption

AbstractThis paper presents applications of in situ X-ray diffraction and absorption techniques to the study of H+/MnO2 alkaline batteries. The two complementary in situ techniques are described. Investigation of the electrochemical insertion and deinsertion of H+ has been made through its influence on the evolution of the crystallographic structure of γ-MnO2, while investigation of the transfer of e has been undertaken through the variation of the oxidation state of the manganese during the discharging and charging process of a battery. New insights in the understanding of the mechanisms of proton insertion and charge transfer into γ-MnO2 are discussed.

Uranium oxidation kinetics monitored by in-situ X-ray diffraction

2017 ◽  
Vol 485 ◽  
pp. 202-206 ◽  
Author(s):  
S. Zalkind ◽  
G. Rafailov ◽  
I. Halevy ◽  
T. Livneh ◽  
A. Rubin ◽  
...  
Keyword(s):  
Oxidation Kinetics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Uranium Oxidation

scholarly journals A Continuous Flow System for In-Situ XANES Measurements of Change in Oxidation State of Ce (III) to Ce (IV)

2005 ◽  
Vol 6 (1) ◽  
pp. 65-67 ◽  
Author(s):  
Toshihiko Ohnuki ◽  
Takahiro Yoshida ◽  
Takuya Nankawa ◽  
Takuo Ozaki ◽  
Naofumi Kozai ◽  
...  
Keyword(s):  
Oxidation State ◽  
Continuous Flow ◽  
Flow System ◽  
Continuous Flow System ◽  
In Situ Xanes

scholarly journals A compact furnace for in situ X-ray absorption spectroscopy: design, fabrication and study of cationic oxidation states in Pr6O11 and NiO

2021 ◽  
Vol 28 (2) ◽  
pp. 455-460
Author(s):  
Suchinda Sattayaporn ◽  
Somboonsup Rodporn ◽  
Pinit Kidkhunthod ◽  
Narong Chanlek ◽  
Chutarat Yonchai ◽  
...  
Keyword(s):  
Oxidation State ◽  
Absorption Spectroscopy ◽  
Heating Temperature ◽  
Reduction Process ◽  
Oxidation States ◽  
Quartz Tube ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

A well designed compact furnace has been designed for in situ X-ray absorption spectroscopy (XAS). It enables various heat ramps from 300 K to 1473 K. The furnace consists of heaters, a quartz tube, a circulated refrigerator and a power controller. It can generate ohmic heating via an induction process with tantalum filaments. The maximum heating rate exceeds 20 K min−1. A quartz tube with gas feedthroughs allows the mixing of gases and adjustment of the flow rate. The use of this compact furnace allows in situ XAS investigations to be carried out in transmission or fluorescence modes under controlled temperature and atmosphere. Moreover, the furnace is compact, light and well compatible to XAS. The furnace was used to study cationic oxidation states in Pr6O11 and NiO compounds under elevated temperature and reduced atmosphere using the in situ X-ray absorption near-edge structure (XANES) technique at beamline 5.2 SUT-NANOTEC-SLRI of the Synchrotron Light Research Institute, Thailand. At room temperature, Pr6O11 contains a mixture of Pr3+ and Pr4+ cations, resulting in an average oxidation state of +3.67. In situ XANES spectra of Pr (L 3-edge) show that the oxidation state of Pr4+ cations was totally reduced to +3.00 at 1273 K under H2 atmosphere. Considering NiO, Ni2+ species were present under ambient conditions. At 573 K, the reduction process of Ni2+ occurred. The Ni0/Ni2+ ratio increased linearly with respect to the heating temperature. Finally, the reduction process of Ni2+ was completely finished at 770 K.

Stabilisation of tri-valent ions with a vacant coordination site at a corrole–metal interface

2020 ◽  
Vol 56 (76) ◽  
pp. 11219-11222
Author(s):  
P. S. Deimel ◽  
P. Casado Aguilar ◽  
M. Paszkiewicz ◽  
D. A. Duncan ◽  
J. V. Barth ◽  
...  
Keyword(s):  
Oxidation State ◽  
Metal Interface ◽  
Coordination Site

We show that a tri-valent oxidation state is retained in in situ metallated V and Ti corroles in contact with a Ag(111) surface.

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