Aqueous Complexes for Efficient Size-based Separation of Americium from Curium

2014 ◽  
Vol 53 (12) ◽  
pp. 6003-6012 ◽  
Author(s):  
Mark P. Jensen ◽  
Renato Chiarizia ◽  
Ilya A. Shkrob ◽  
Joseph S. Ulicki ◽  
Brian D. Spindler ◽  
...  
Keyword(s):  
Size Based Separation ◽  
Aqueous Complexes

Th-MOF showing six-fold imide-sealed pockets for middle-size-separation of propane from nature gas

2021 ◽  
Author(s):  
Feng Luo ◽  
Li Wang ◽  
Lele Gong ◽  
Wansheng Jia ◽  
Rajamani Krishna ◽  
...  
Keyword(s):  
Selective Adsorption ◽  
Supramolecular Interactions ◽  
Separation Mechanism ◽  
Ideal Solution ◽  
Light Alkanes ◽  
Size Separation ◽  
Direct Separation ◽  
Nature Gas ◽  
Breakthrough Experiments ◽  
Size Based Separation

Abstract Separation of propane from nature gas is of great importance to industry. However, in light of size-based separation, there still lacks effective method to directly separate propane from nature gas, due to the comparable physical properties for these light alkanes (C1-C4) and the middle size of propane. In this work, we found that a new Th-MOF could be an ideal solution for this issue. The Th-MOF takes UiO-66-type structure, but with the pocket sealed by six-fold imide groups; this not only precisely reduces the size of pocket to exactly match propane, but also enhances the host-guest interactions through multiple supramolecular interactions. As a result, highly selective adsorption of propane over methane, ethane, and butane was observed, implying unique middle-size separation. The actual separation was confirmed by breakthrough experiments, and it is found that both relatively smaller molecules (methane and ethane) and relatively bigger molecules (butane) break through the Th-MOF column within 10 min/g, whereas propane with middle size can maintain very long retention time up to 80 min/g, strongly suggesting middle-size separation and its superior application in direct separation of propane from nature gas. The separation mechanism, as unveiled by both theoretical calculation and comparative experiments, is due to the six-fold imide-sealed pockets that could effectively distinguish propane from other light alkanes through both size effect and host-guest interactions.

Factors affecting bromate removal capacity of zerovalent iron packed columns

2006 ◽  
Vol 6 (6) ◽  
pp. 119-130 ◽  
Author(s):  
C. Fan ◽  
C.H. Chan ◽  
L. Xie ◽  
C. Shang
Keyword(s):  
Zerovalent Iron ◽  
Minor Role ◽  
Sulfate Concentration ◽  
Quality Factors ◽  
Bicarbonate Concentration ◽  
Factors Affecting ◽  
Weight Percentage ◽  
Removal Capacity ◽  
A Minor ◽  
Aqueous Complexes

In a series of column experiments lasting for approximately 1500 pore volume, the effects of operational factors (flow rates, sand admixtures) and water quality factors (concentrations of DO, sulfate, phosphate and bicarbonate) on bromate removal capacity of zerovalent iron were investigated. The bromate removal capacity, obtained from migration of concentration profiles, was observed to decrease with increases in flow rate. In the case that 20 wt-% iron was replaced by sands, the bromate removal capacity increased, but, on the contrary, the bromate removal capacity inevitably decreased when the weight percentage was increased by two times. Dissolved oxygen played a minor role in decreasing the bromate removal capacity, this decreasing effect only prevailed near the proximal end of depassivating irons. The bromate removal capacity increased in the presence of 100 mg/L sulfate concentration but decreased when the sulfate concentration further increased. When comparing the effect on removal capacity for phosphate and sulfate, the inhibiting effect of phosphate on the bromate removal capacity was larger. Lastly, the removal capacity increased with increasing bicarbonate concentration, which may due to the formation of aqueous complexes.

Thermodynamic parameters for the complexation of Tc(IV) with bromide under aqueous conditions

2020 ◽  
Vol 108 (5) ◽  
pp. 409-414
Author(s):  
Cecilia Eiroa-Lledo ◽  
Donald E. Wall ◽  
Nathalie A. Wall
Keyword(s):  
Working Conditions ◽  
Equilibrium Constants ◽  
Liquid Extraction ◽  
Complexation Reaction ◽  
Hydrolysis Constant ◽  
Carboxylate Ligands ◽  
Liquid Liquid Extraction ◽  
Varied Temperature ◽  
Aqueous Conditions ◽  
Aqueous Complexes

AbstractTechnetium-99 is a long-lived fission product present in nuclear wastes, found mainly as Tc(VII) and Tc(IV) in the environment. The quantification of the equilibrium constants for the formation of Tc(IV) aqueous complexes has been limited to carboxylate ligands and interactions with the halides is mostly unknown. This work reports equilibrium constants of the formation of the TcO(OH)+ complexes with Br−, in a 3 M NaClO4 solution of pcH 2 and varied temperature, using a liquid-liquid extraction system. Neutron activation confirmed the suitability of the extraction technique for this work. Under the working conditions, Br− forms a weak exothermic TcO(OH)Br complex, with a Gibbs free energy (ΔGr) of 3 ± 3 kJ · mol−1 at a temperature of 273.15 K. The values for ΔHr (−32 ± 3 kJ · mol−1) and ΔSr (106 ± 9 J · mol−1 · K−1) of the complexation reaction were quantified using a van’t Hoff analysis. This work also showed that bromide addition does not displace the hydroxide from TcO(OH)+, as the equilibrium constant of bromide addition is much weaker than the first hydrolysis constant of the metal.

Size-based separation and collection of mouse pancreatic islets for functional analysis

2010 ◽  
Vol 12 (5) ◽  
pp. 865-874 ◽  
Author(s):  
Ki-Hwan Nam ◽  
Wang Yong ◽  
Tricia Harvat ◽  
Adeola Adewola ◽  
Shesun Wang ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Pancreatic Islets ◽  
Mouse Pancreatic Islets ◽  
Size Based Separation

scholarly journals The investigations of bioactive copper(II) complexes with reduced low-molar dextran

2008 ◽  
Vol 22 (2-3) ◽  
pp. 177-185 ◽  
Author(s):  
Milorad Cakić ◽  
Žarko Mitić ◽  
Goran S. Nikolić ◽  
Ljubomir Ilić ◽  
Goran M. Nikolić
Keyword(s):  
Fourier Transform ◽  
Complex Formation ◽  
Room Temperature ◽  
Molar Mass ◽  
Reaction Conditions ◽  
Average Molar Mass ◽  
Square Planar ◽  
Physicochemical Methods ◽  
Fourier Transform Ir ◽  
Aqueous Complexes

The optimization of the reaction conditions (pH,T,t) to obtain stable copper(II) ion complexes with dextran derivatives were investigated in this paper. A complete synthesis of stable aqueous complexes can be realized with reduced low-molar polysaccharides, at an average molar mass 5000 g mol–1and pH 7.5–8. Fourier-transform IR spectra of polysaccharide dextran and its compounds with copper(II) ion, recorded at room temperature, were analyzed in order to obtain the information about the structure and the conformation of these polymer compounds. The ESR parameters of the spectra indicate the square-planar coordination of Cu(II) ion with four O atoms. Copper(II) complex formation with dextran and its derivatives were analyzed by physicochemical methods. Synthesized complexes of Cu(II) ion with reduced low-molar dextran in comparison with commercial preparations showed the considerably lower acute toxicity (LD501705).

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