Über den Mechanismus der Bildung von Polyanionen in wäßriger Lösung. Zum Bildungsmechanismus eines Polytetramolybdations [Mo4O144-]n / On the Mechanism of Formation of Polyanions in Aqueous Solution. Concerning the Mechanism of Formation of a Polytetramolybdate Ion [Mo4O144-]n

1976 ◽  
Vol 31 (6) ◽  
pp. 737-748 ◽  
Author(s):  
Karl-Heinz Tytko
Keyword(s):  
Aqueous Solution ◽  
Coordination Sphere ◽  
Analytical Formula ◽  
Reaction Pathways ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Theoretical Considerations

Possible structures and the pertinent reaction pathways for the polymetalate ion present in a slightly soluble polymetalate having the analytical formula A2O · 2 MOs have been derived on the basis of theoretical considerations. Structure and kind of combination of the tetrameric units of one of the possibilities are in agreement with the results of X-ray structure analyses. First the previously proposed planar tetrametalate ion [M4O12(OH)4]4--is formed by stepwise aggregation according to an addition mechanism. This species undergoes a rearrangement of the coordination sphere of two of the M atoms and is then subject to a polycondensation resulting in a polytetrametalate chain, [M4O144-]n.

scholarly journals EXAFS analysis of uranium(IV) and thorium(IV) complexes in concentrated CaCl2 solutions

2011 ◽  
Vol 1 (1) ◽  
pp. 161-165
Author(s):  
A. Uehara ◽  
T. Fujii ◽  
H. Matsuura ◽  
N. Sato ◽  
T. Nagai ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Fine Structure ◽  
Coordination Number ◽  
Coordination Sphere ◽  
Perchloric Acid ◽  
Hydration Number ◽  
Bond Distance ◽  
X Ray ◽  
Acid Aqueous Solution ◽  
X Ray Absorption

Abstract The coordination of U4+ and Th4+ in concentrated CaCl2 solutions is studied by U and Th L III edge extended X-ray absorption fine structure (EXAFS) spectroscopy. With the decrease of concentration of CaCl2 from 6.9 to 4 M, the Cl− ion coordination number N Cl in the U4+ coordination sphere decreases from 3.4 to 1.3, while the hydration number N O increases from 4.5 to 6.7. The combined coordination number N O+NCl of U4+ in concentrated Cl− solution (8.0), is lower than that in 1.5 M perchloric acid aqueous solution (9.0). For Th4+, the decrease of concentration from 6.9 to 4 M CaCl2, the coordination number N Cl in the Th4+ coordination sphere decreased slightly from 1.9 to 1.5, while coordination number N O increased from 7.6 to 8.8. The N O+NCl of Th4+ in concentrated Cl− solution (9.0), is similar to that in 1.5 M perchloric acid. The bond distance of U–Cl (2.67 Å), is shorter than that of Th–Cl (2.76 Å), because of low coordination number N O to U4+. By adding HCl into the system, the U4+ and Th4+ coordination sphere is unchanged. The coordination structures of U4+ and Th4+ in concentrated LiCl is also discussed.

MECHANISM OF SILICA NANO-PLATE FORMATION FROM LUCENTITE

2007 ◽  
Vol 14 (02) ◽  
pp. 235-239 ◽  
Author(s):  
N. H. TRAN ◽  
M. A. WILSON ◽  
A. S. MILEV ◽  
G. R. DENNIS ◽  
G. S. K. KANNANGARA
Keyword(s):  
Aqueous Solution ◽  
Fourier Transform ◽  
Fine Structure ◽  
Acrylic Acid ◽  
Surface Defects ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Plate Formation ◽  
Clay Intercalation ◽  
Poly Acrylic Acid

The mechanism of formation of silica nano-plates by exfoliation of a phyllosilicate magnesium containing clay, Lucentite, in an aqueous solution of poly(acrylic acid) has been studied. Fourier transform infrared spectroscopy and Mg K -edge near edge X-ray adsorption fine structure (NEXAFS) analysis shows that non-surface (bulk) Mg ions were not chemically involved in the poly(acrylic acid)/clay intercalation, but were substantially involved in the exfoliation resulting in the silica nano-plates. During intercalation, O K -edge NEXAFS shows that surface defects were formed which represent additional structural branches on the surface. During exfoliation, these increased significantly. Si L3,2-edge NEXAFS measurements shows that this occurred by migration of SiO 4 groups within the exfoliated silica plates.

Structural Study of a new Compound Based on Acid 1,4-Cyclohexanedicarboxylic (1,4-CDC)

2010 ◽  
Vol 6 (1) ◽  
pp. 891-896
Author(s):  
Manel Halouani ◽  
M. Dammak ◽  
N. Audebrand ◽  
L. Ktari
Keyword(s):  
Aqueous Solution ◽  
Water Molecules ◽  
Carboxyl Group ◽  
X Ray Diffraction ◽  
Compound I ◽  
Unit Cell Parameters ◽  
Monoclinic System ◽  
X Ray ◽  
Cell Parameters ◽  
Cyclohexanedicarboxylic Acid

One nickel 1,4-cyclohexanedicarboxylate coordination polymers, Ni2 [(O10C6H4)(COO)2].2H2O  (I), was hydrothermally synthesized from an aqueous solution of Ni (NO3)2.6H2O, (1,4-CDC) (1,4-CDC = 1,4-cyclohexanedicarboxylic acid) and tetramethylammonium nitrate. Compound (I) crystallizes in the monoclinic system with the C2/m space group. The unit cell parameters are a = 20.1160 (16) Å, b = 9.9387 (10) Å, c = 6.3672 (6) Å, β = 97.007 (3) (°), V= 1263.5 (2) (Å3) and Dx= 1.751g/cm3. The refinement converged into R= 0.036 and RW = 0.092. The structure, determined by single crystal X-ray diffraction, consists of two nickel atoms Ni (1) and Ni (2). Lots of ways of which is surrounded by six oxygen atoms, a carboxyl group and two water molecules.

Heterogeneous Fenton Catalytic Removal of Organic Pollutant in Aqueous Solution by using Coal Gangue as a Catalyst

2019 ◽  
Vol 12 (4) ◽  
pp. 312-325
Author(s):  
Jiwei Zhang ◽  
Jingjing Xu ◽  
Shuaixia Liu ◽  
Baoxiang Gu ◽  
Feng Chen ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Removal Rate ◽  
Organic Pollutant ◽  
Coal Gangue ◽  
Ion Leakage ◽  
Heterogeneous Fenton ◽  
Solution Ph ◽  
X Ray

Background: Coal gangue was used as a catalyst in heterogeneous Fenton process for the degradation of azo dye and phenol. The influencing factors, such as solution pH gangue concentration and hydrogen peroxide dosage were investigated, and the reaction mechanism between coal gangue and hydrogen peroxide was also discussed. Methods: Experimental results showed that coal gangue has the ability to activate hydrogen peroxide to degrade environmental pollutants in aqueous solution. Under optimal conditions, after 60 minutes of treatment, more than 90.57% of reactive red dye was removed, and the removal efficiency of Chemical Oxygen Demand (COD) up to 72.83%. Results: Both hydroxyl radical and superoxide radical anion participated in the degradation of organic pollutant but hydroxyl radical predominated. Stability tests for coal gangue were also carried out via the continuous degradation experiment and ion leakage analysis. After five times continuous degradation, dye removal rate decreased slightly and the leached Fe was still at very low level (2.24-3.02 mg L-1). The results of Scanning Electron Microscope (SEM), energy dispersive X-Ray Spectrometer (EDS) and X-Ray Powder Diffraction (XRD) indicated that coal gangue catalyst is stable after five times continuous reuse. Conclusion: The progress in this research suggested that coal gangue is a potential nature catalyst for the efficient degradation of organic pollutant in water and wastewater via the Fenton reaction.

The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

1961 ◽  
Vol 5 ◽  
pp. 276-284
Author(s):  
E. L. Moore ◽  
J. S. Metcalf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Temperature Form ◽  
High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

scholarly journals Novel Hybrid Compounds Containing Benzofuroxan and Aminothiazole Scaffolds: Synthesis and Evaluation of Their Anticancer Activity

2021 ◽  
Vol 22 (14) ◽  
pp. 7497
Author(s):  
Elena Chugunova ◽  
Gabriele Micheletti ◽  
Dario Telese ◽  
Carla Boga ◽  
Daut Islamov ◽  
...  
Keyword(s):  
Anticancer Agents ◽  
Normal Liver ◽  
Mitochondrial Pathway ◽  
Reaction Pathways ◽  
Aromatic Nucleophilic Substitution ◽  
X Ray ◽  
Hybrid Compounds ◽  
Aromatic Nucleophilic Substitution Reaction ◽  
Further Development

A series of novel hybrid compounds containing benzofuroxan and 2-aminothiazole moieties are synthesized via aromatic nucleophilic substitution reaction. Possible reaction pathways have been considered quantum-chemically, which allowed us to suggest the most probable products. The quantum chemical results have been proved by X-ray data on one compound belonging to the synthesized series. It was shown that the introduction of substituents to both the thiazole and amine moieties of the compounds under study strongly influences their UV/Vis spectra. Initial substances and obtained hybrid compounds have been tested in vitro as anticancer agents. Target compounds showed selectivity towards M-HeLa tumor cell lines and were found to be more active than starting benzofuroxan and aminothiazoles. Furthermore, they are considerably less toxic to normal liver cells compared to Тamoxifen. The mechanism of action of the studied compounds can be associated with the induction of apoptosis, which proceeds along the mitochondrial pathway. Thus, new hybrids of benzofuroxan are promising candidates for further development as anticancer agents.

scholarly journals Removal of Phenol from Aqueous Solution Using Internal Microelectrolysis with Fe-Cu: Optimization and Application on Real Coking Wastewater

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 720
Author(s):  
Do Tra Huong ◽  
Nguyen Van Tu ◽  
Duong Thi Tu Anh ◽  
Nguyen Anh Tien ◽  
Tran Thi Kim Ngan ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Ph Value ◽  
Reaction Rate Constant ◽  
Phenol Concentration ◽  
Treated Wastewater ◽  
Coking Wastewater ◽  
X Ray ◽  
Chemical Plating ◽  
Internal Electrolysis ◽  
Phenol Decomposition

Fe-Cu materials were synthesized using the chemical plating method from Fe powder and CuSO4 5% solution and then characterized for surface morphology, composition and structure by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The as-synthesized Fe-Cu material was used for removal of phenol from aqueous solution by internal microelectrolysis. The internal electrolysis-induced phenol decomposition was then studied with respect to various parameters such as pH, time, Fe-Cu material weight, phenol concentration and shaking speed. The optimal phenol decomposition (92.7%) was achieved under the conditions of (1) a pH value of phenol solution of 3, (2) 12 h of shaking at the speed of 200 rpm, (3) Fe-Cu material weight of 10 g/L, (4) initial phenol concentration of 100.98 mg/L and (5) at room temperature (25 ± 0.5 °C). The degradation of phenol using Fe-Cu materials obeyed the second-order apparent kinetics equation with a reaction rate constant of k of 0.009 h−1L mg−1. The optimal process was then tested against real coking wastewater samples, resulting in treated wastewater with favorable water indicators. Current findings justify the use of Fe-Cu materials in practical internal electrolysis processes.

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