Surface complexation modelling of uranyl adsorption onto kaolinite based clay minerals using FITEQL 3.2

2006 ◽  
Vol 94 (12) ◽  
Author(s):  
Deniz Arda ◽  
Julide Hizal ◽  
Resat Apak
Keyword(s):  
Clay Minerals ◽  
Surface Complexation ◽  
Outer Sphere ◽  
Uranyl Ion ◽  
Sphere Surface ◽  
Hexavalent Uranium ◽  
Inner Sphere

The aim of this study is to explain how the kaolinite-based clay minerals adsorb hexavalent uranium (uranyl ion), and to model uranyl adsorption based on inner-sphere surface complexation with the kaolinite edge hydroxyl sites and outer-sphere complexation with the permanent charge sites. The adsorption of UO

Retracted Article: Enhanced adsorption of Eu(iii) on mesoporous Al2O3/expanded graphite composites investigated by macroscopic and microscopic techniques

2012 ◽  
Vol 41 (43) ◽  
pp. 13388-13394 ◽  
Author(s):  
Yubing Sun ◽  
Changlun Chen ◽  
Xiaoli Tan ◽  
Dadong Shao ◽  
Jiaxing Li ◽  
...  
Keyword(s):  
Adsorption Mechanism ◽  
Surface Complexation ◽  
Expanded Graphite ◽  
Outer Sphere ◽  
Sphere Surface ◽  
Inner Sphere ◽  
Retracted Article ◽  
Enhanced Adsorption ◽  
Graphite Composites ◽  
Microscopic Techniques

The adsorption mechanism between Eu(iii) and mesoporous Al2O3/EG composites shifts from outer-sphere to inner-sphere surface complexation with increasing pH.

scholarly journals Waste Brick Dust as Potential Sorbent of Lead and Cesium from Contaminated Water

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1647 ◽  
Author(s):  
Barbora Doušová ◽  
David Koloušek ◽  
Miloslav Lhotka ◽  
Martin Keppert ◽  
Martina Urbanová ◽  
...  
Keyword(s):  
Amorphous Material ◽  
Surface Complexation ◽  
Total Pore Volume ◽  
Zero Point ◽  
Outer Sphere ◽  
Aqueous System ◽  
Sphere Surface ◽  
Adsorption Condition ◽  
Weak Adsorption ◽  
Brick Dust

Adsorption properties of waste brick dust (WBD) were studied by the removing of PbII and CsI from an aqueous system. For adsorption experiments, 0.1 M and 0.5 M aqueous solutions of Cs+ and Pb2+ and two WBD (Libochovice—LB, and Tyn nad Vltavou—TN) in the fraction below 125 µm were used. The structural and surface properties of WBD were characterized by X-ray diffraction (XRD) in combination with solid-state nuclear magnetic resonance (NMR), supplemented by scanning electron microscopy (SEM), specific surface area (SBET), total pore volume and zero point of charge (pHZPC). LB was a more amorphous material showing a better adsorption condition than that of TN. The adsorption process indicated better results for Pb2+, due to the inner-sphere surface complexation in all Pb2+ systems, supported by the formation of insoluble Pb(OH)2 precipitation on the sorbent surface. A weak adsorption of Cs+ on WBD corresponded to the non-Langmuir adsorption run followed by the outer-sphere surface complexation. The leachability of Pb2+ from saturated WBDs varied from 0.001% to 0.3%, while in the case of Cs+, 4% to 12% of the initial amount was leached. Both LB and TN met the standards for PbII adsorption, yet completely failed for any CsI removal from water systems.

Removal of Pb(ii) by nano-titanium oxide investigated by batch, XPS and model techniques

RSC Advances ◽  
2015 ◽  
Vol 5 (107) ◽  
pp. 88520-88528 ◽  
Author(s):  
Zhongxiu Jin ◽  
Huiyi Gao ◽  
Linhua Hu
Keyword(s):  
Ion Exchange ◽  
Titanium Oxide ◽  
Surface Complexation ◽  
Sphere Surface ◽  
Adsorption Mechanisms ◽  
Inner Sphere

The ion exchange and inner-sphere surface complexation were inferred as the adsorption mechanisms of Pb(ii) on nano-TiO2.

Surface Interactions of Actinide Ions with Geologic Materials Studied by XAFS

1999 ◽  
Vol 590 ◽  
Author(s):  
E. R. Sylwester ◽  
E. A. Hudson ◽  
P. G. Allen
Keyword(s):  
Complex Structure ◽  
Outer Sphere ◽  
Equatorial Region ◽  
Uranyl Ion ◽  
Ambient Atmosphere ◽  
Solution Ph ◽  
Aquo Complex ◽  
Inner Sphere ◽  
Silica Alumina ◽  
Sphere Mechanism

ABSTRACTWe have investigated the interaction of the actinyl ion, , with silica, alumina, and montmorillonite surfaces under ambient atmosphere and aqueous conditions using x-ray Absorption Fine Structure (XAFS) Spectroscopy. In acid solution (pH ∼ 3.5), the uranyl ion shows a strong interaction with the silica and alumina surfaces, and a relatively weak association with the montmorillonite surface. The extent of direct surface interaction is determined by comparing structural distortions in the equatorial bonding environment of the uranyl ion relative to the structure of a “free” uranyl aquo complex. Based on this formalism, surface complexation on silica and alumina occurs through an inner-sphere mechanism with surface oxygen atoms binding directly to the equatorial region of the uranyl ion. In contrast, sorption on montmorillonite occurs by an outer sphere mechanism in which the uranyl ion retains the simple aquo complex structure and binds to the surface via ion-exchange. In near-neutral solutions (pH ∼ 6), sorption on all of the materials is dominated by an inner-sphere mechanism. The formation of surface oligomeric species is also observed on silica and alumina.

Protonation effects on dynamic flux properties of aqueous metal complexes

2009 ◽  
Vol 74 (10) ◽  
pp. 1543-1557 ◽  
Author(s):  
Herman P. Van Leeuwen ◽  
Raewyn M. Town
Keyword(s):  
Complex Formation ◽  
Metal Ion ◽  
Good Description ◽  
Minor Component ◽  
Outer Sphere ◽  
Metal Species ◽  
Central Metal ◽  
Inner Sphere ◽  
A Minor ◽  
Protonated Ligand

The degree of (de)protonation of aqueous metal species has significant consequences for the kinetics of complex formation/dissociation. All protonated forms of both the ligand and the hydrated central metal ion contribute to the rate of complex formation to an extent weighted by the pertaining outer-sphere stabilities. Likewise, the lifetime of the uncomplexed metal is determined by all the various protonated ligand species. Therefore, the interfacial reaction layer thickness, μ, and the ensuing kinetic flux, Jkin, are more involved than in the conventional case. All inner-sphere complexes contribute to the overall rate of dissociation, as weighted by their respective rate constants for dissociation, kd. The presence of inner-sphere deprotonated H2O, or of outer-sphere protonated ligand, generally has a great impact on kd of the inner-sphere complex. Consequently, the overall flux can be dominated by a species that is a minor component of the bulk speciation. The concepts are shown to provide a good description of experimental stripping chronopotentiometric data for several protonated metal–ligand systems.

scholarly journals RuIII(edta) complexes as molecular redox catalysts in chemical and electrochemical reduction of dioxygen and hydrogen peroxide: inner-sphere versus outer-sphere mechanism

RSC Advances ◽  
2021 ◽  
Vol 11 (35) ◽  
pp. 21359-21366
Author(s):  
Debabrata Chatterjee ◽  
Marta Chrzanowska ◽  
Anna Katafias ◽  
Maria Oszajca ◽  
Rudi van Eldik
Keyword(s):  
Hydrogen Peroxide ◽  
Electron Transfer ◽  
Electrochemical Reduction ◽  
Molecular Oxygen ◽  
Outer Sphere ◽  
Transfer Processes ◽  
Edta Complexes ◽  
Inner Sphere ◽  
Electron Transfer Processes ◽  
Sphere Mechanism

[RuII(edta)(L)]2–, where edta4– =ethylenediaminetetraacetate; L = pyrazine (pz) and H2O, can reduce molecular oxygen sequentially to hydrogen peroxide and further to water by involving both outer-sphere and inner-sphere electron transfer processes.

Features of the formation of zinc(II) and cadmium(II) complexes with the inner-sphere and outer-sphere position of the decahydro-closo-decaborate anion in the presence of azaheterocyclic ligands

2021 ◽  
Vol 520 ◽  
pp. 120315
Author(s):  
Svetlana E. Korolenko ◽  
Aleksey S. Kubasov ◽  
Lyudmila V. Goeva ◽  
Varvara V. Avdeeva ◽  
Elena A. Malinina ◽  
...  
Keyword(s):  
Outer Sphere ◽  
Inner Sphere ◽  
Closo Decaborate Anion
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