Fundamental Study on the Solidification of Radionuclides with Hydrous TiIV Oxide Modified with Either Si or Zr

1994 ◽  
Vol 353 ◽  
Author(s):  
Hiromichi Yamazaki ◽  
Yasushi Inoue
Keyword(s):  
Metal Ions ◽  
Sorption Capacity ◽  
Liquid Waste ◽  
Transition Metal Ions ◽  
Distribution Coefficients ◽  
Radioactive Liquid Waste ◽  
Titanium Silicate ◽  
Fundamental Study ◽  
Acidic Solutions ◽  
Exchange Site

AbstractThe potentiality of hydrous TiIV-Si oxide (TS) and hydrous TiIV-Zr oxide (TZ) for the selective sorption and immobilization of radioactive Co2+, Eu3+, Th4+ and UO22+ ions has been studied experimentally: The distribution coefficients and sorption capacity for these ions at various conditions in solutions, the structure and the composition of the exchangers in relevant ionic forms at high temperatures, and the leaching rates from the calcined exchangers into water and 0.01M HNO3 solution at room temperature. These results were discussed together with the results previously obtained for Cs+ and St2+, in order to evaluate the performance of TS and TZ as solidification media for radioactive liquid waste. TS takes up these cations more than TZ does in acidic solutions due to the higher acidity of the exchange site. In TZ, transition metal ions show high affinity despite the small distribution coefficients for representative metal ions. The dissolution of Co2+, Eu3+, and Th4+ is very slow from both calcined exchangers due to the crystallization of titanates of these cations. The leaching rates of Cs+, St2+ and UO22+ from calcined TS are much slower than those from TZ, indicating the formation of titanium silicate containing these cations. Based on these results, TS is considered to be superior to TZ in the sorption capacity and fixation capability of various kinds of radionuclides and is considered as a promising material for the solidification of radwaste.

Selective exchange of divalent transition metal ions in cryptomelane-type manganic acid with tunnel structure

1993 ◽  
Vol 8 (3) ◽  
pp. 611-616 ◽  
Author(s):  
Masamichi Tsuji ◽  
Sridhar Komarneni
Keyword(s):  
Ion Exchange ◽  
Transition Metal ◽  
Metal Ions ◽  
Adsorption Process ◽  
Tap Water ◽  
Transition Metal Ions ◽  
Distribution Coefficients ◽  
Tunnel Structure ◽  
Linear Relationships ◽  
Exchange Selectivity

The ion-exchange selectivity of divalent transition metal ions on cryptomelane-type manganic acid (CMA) with tunnel structure has been studied using the distribution coefficients (Kd) at a small fractional exchange in nitrate media. All metal ions studied showed linear relationships with a slope of −2 on the log-log plot of Kd vs [HNO3] which clearly indicated that the adsorption process is an “ideal” ion-exchange. The selectivity increased in the following order: Pb ≫ Mn > Co > Cu > Hg > Cd > Zn > Ni. The high selectivity of the manganic acid was successfully utilized in the removal of Co2+ from seawater and tap water.

scholarly journals Electrolysis of Natural Waters Contaminated with Transition-Metal Ions: Identification of A Metastable FePb-Based Oxygen-Evolution Catalyst Operating in Weakly Acidic Solutions

ChemPlusChem ◽  
2018 ◽  
Vol 83 (7) ◽  
pp. 704-710 ◽  
Author(s):  
Shannon A. Bonke ◽  
Ken L. Abel ◽  
Dijon A. Hoogeveen ◽  
Manjunath Chatti ◽  
Thomas Gengenbach ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Oxygen Evolution ◽  
Natural Waters ◽  
Transition Metal Ions ◽  
Acidic Solutions

Use of Selective Sorbents for Liquid Wastes Treatment

1997 ◽  
Vol 506 ◽  
Author(s):  
I.M. El-Naggar ◽  
N. Belacy ◽  
M.M. Abou-Mesalam ◽  
H.F. Aly
Keyword(s):  
Citric Acid ◽  
Liquid Waste ◽  
Distribution Coefficients ◽  
Infrared Spectrometry ◽  
Ferric Nitrate ◽  
X Ray Diffraction ◽  
Radioactive Liquid Waste ◽  
Acid Media ◽  
Quantitative Separation ◽  
Diffraction Patterns

ABSTRACTAcidic salts of polyvalent metal antimonates(M-antimonates(M-Sb); M=Cerium, Tin, Titanium and Silicon) have been synthesized under different conditions( 1,2). The products were characterized by powdered X-ray diffraction patterns, Differential Thermal Analysis(DTA) and infrared spectrometry. Chemical stability of the product materials were studied by mixing 50 mg of the prepared materials with 50 ml of the desired medium(H20, HNO3 and HCI) with determination for the concentration of the metalions dissolved(Sb, Ce, Sn, Ti and Si) which showed high chemical stabilities in water and acid media up to I OM HNO 3 and 6M HCI.The data of the distribution coefficients showed that the selectivity decrease in the order; Eu3+> Co2+> Sr2+> Cs+ for cerium(IV) antimonate(CeSb), tin(IV) antimonate(SnSb) and silicon(IV) antimonate(SiSb), while the selectivity decrease in the order UO22+>Th4+ for titanium(IV) antimonate(TiSb). Besides, the effect of EDTA, citric acid, ferric nitrate and sodium nitrate as interfering ions in solution on the distribution coefficient of the studied cations for CeSb and SnSb were studied under certain conditions. The results showed that, the Kj values of CS+, Co2+ and Eu3+ are decreases with increasing the concentrations of ferric and sodium nitrates in the feed solutions for both materials and also Kd values are effected to some extent in case of EDTA and citric acid. Based on the obtained results, practical separation experiments on column were performed(3).The following figures represents the break-through curves for CeSb and SnSb columns for some radionuclides 60Co (10-3M ) as example. From the above studies we conclude that, CeSb and SnSb have been successfully used for the quantitative separation of cesium which suggests its use in the treatment of radioactive liquid waste.

HREM Study of electron-induced surface radiation damage in ReO3

1991 ◽  
Vol 49 ◽  
pp. 636-637
Author(s):  
R. Ai ◽  
H.-J. Fan ◽  
L. D. Marks
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Carbon Film ◽  
Transition Metal Ions ◽  
Surface Radiation ◽  
Valence Transition ◽  
Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

Synthesis, Spectral and Antimicrobial Investigation of 2-(Naphthalenel-ylamino)-2- Phenylacetonitrile and 1, 10-Phenanthroline with Five Divalent Transition Metal Ions

2019 ◽  
Vol 10 (01) ◽  
Author(s):  
Mohammed Al-Amery1 ◽  
Ashraf Saad Rasheed ◽  
Dina A. Najeeb
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Transition Metal Ions ◽  
Molar Conductance ◽  
Octahedral Geometry ◽  
Mixed Ligand ◽  
Gram Negative Bacteria ◽  
Magnetic Studies ◽  
Gram Positive Bacteria

Five new mixed ligand metal complexes have been synthesized by the reaction of divalent transition metal ions (Hg, Ni, Zn, Cu and Cd) with 2-(naphthalen-l-ylamino)-2-phenylacetonitrile (L1 ) and 1,10-phenanthroline (L2). The coordination likelihood of the two ligands toward metal ions has been suggested in the light of elemental analysis, UV-Vis spectra, FTIR, 1H-NMR, flam atomic absorption, molar conductance and magnetic studies. Results data suggest that the octahedral geometry for all the prepared complexes. Antibacterial examination of synthesized complexes in vitro was performed against four bacterias. Firstly, Gram-negative bacteria namely, Pseudomonas aerugin and Escherichia. Secondly, Gram-positive bacteria namely, Bacillus subtilis, Staphylococcuaurouss. Results data exhibit that the synthesized complexes exhibited more biological activity than tetracycline pharmaceutical.

Amentoflavone: A Bifunctional Metal Chelator that Controls the Formation of Neurotoxic Soluble Aβ42 Oligomers

2020 ◽  
Author(s):  
Liang Sun ◽  
Anuj K. Sharma ◽  
Byung-Hee Han ◽  
Liviu M. Mirica
Keyword(s):  
Reactive Oxygen Species ◽  
Metal Ions ◽  
Antioxidant Properties ◽  
Reactive Oxygen ◽  
Amyloid Plaques ◽  
Transition Metal Ions ◽  
Oxygen Species ◽  
High Affinity ◽  
Amyloid Aβ ◽  
Β Amyloid

<p>Alzheimer's disease (AD) is the most common neurodegenerative disorder, yet the cause and progression of this disorder are not completely understood. While the main hallmark of AD is the deposition of amyloid plaques consisting of the β-amyloid (Aβ) peptide, transition metal ions are also known to play a significant role in disease pathology by expediting the formation of neurotoxic soluble β-amyloid (Aβ) oligomers, reactive oxygen species (ROS), and oxidative stress. Thus, bifunctional metal chelators that can control these deleterious properties are highly desirable. Herein, we show that amentoflavone (AMF) – a natural biflavonoid compound, exhibits good metal-chelating properties, especially for chelating Cu<sup>2+</sup> with very high affinity (pCu<sub>7.4</sub> = 10.44). In addition, AMF binds to Aβ fibrils with a high affinity (<i>K<sub>i</sub></i> = 287 ± 20 nM) – as revealed by a competition thioflavin T (ThT) assay, and specifically labels the amyloid plaques <i>ex vivo</i> in the brain sections of transgenic AD mice – as confirmed via immunostaining with an Ab antibody. The effect of AMF on Aβ<sub>42</sub> aggregation and disaggregation of Aβ<sub>42</sub> fibrils was also investigated, to reveal that AMF can control the formation of neurotoxic soluble Aβ<sub>42</sub> oligomers, both in absence and presence of metal ions, and as confirmed via cell toxicity studies. Furthermore, an ascorbate consumption assay shows that AMF exhibits potent antioxidant properties and can chelate Cu<sup>2+</sup> and significantly diminish the Cu<sup>2+</sup>-ascorbate redox cycling and reactive oxygen species (ROS) formation. Overall, these studies strongly suggest that AMF acts as a bifunctional chelator that can interact with various Aβ aggregates and reduce their neurotoxicity, can also bind Cu<sup>2+</sup> and mediate its deleterious redox properties, and thus AMF has the potential to be a lead compound for further therapeutic agent development for AD. </p>

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