Radiation crosslinking of carboxymethylcellulose of various degree of substitution at high concentration in aqueous solutions of natural pH

2003 ◽  
Vol 68 (5) ◽  
pp. 771-779 ◽  
Author(s):  
Radoslaw A Wach ◽  
Hiroshi Mitomo ◽  
Naotsugu Nagasawa ◽  
Fumio Yoshii
Keyword(s):  
Aqueous Solutions ◽  
Degree Of Substitution ◽  
High Concentration ◽  
Radiation Crosslinking

scholarly journals Pyromorphite formation from montmorillonite adsorbed lead

Mineralogia ◽  
2011 ◽  
Vol 42 (2-3) ◽  
pp. 75-91 ◽  
Author(s):  
Tomasz Bajda ◽  
Tomasz Marchlewski ◽  
Maciej Manecki
Keyword(s):  
Ion Exchange ◽  
Aqueous Solutions ◽  
Phosphate Concentration ◽  
High Concentration ◽  
Exchange Effect ◽  
System A ◽  
New Phase

Pyromorphite formation from montmorillonite adsorbed lead The reaction of Pb-adsorbed montmorillonite with aqueous solutions of PO4 and Cl ions results in the decrease in phosphate concentration associated with the formation of a new phase - pyromorphite Pb5(PO4)3Cl. Pyromorphite crystals range in size from hundreds of nm to several tens of μm, depending on the PO4, K, and Ca concentrations in the reacting system. A strong ion-exchange effect of K+ and Ca2+ cations on desorption of Pb2+ from Pb-adsorbed montmorillonite was observed. Also, a high concentration of cations leads to a rapid desorption of Pb and the formation of fine pyromorphite crystals. In contrast, low PO4, K and Ca concentrations result in the formation of relatively large euhedral crystals. Final Pb concentrations are much lower in experimental sets than in control experiments with no phosphate present.

Chemistry of rhenium as an analogue of technetium: Experimental studies of the dissolution of rhenium oxides in aqueous solutions

2003 ◽  
Vol 91 (4) ◽  
Author(s):  
E. Kim ◽  
J. Boulègue
Keyword(s):  
Aqueous Solutions ◽  
Thermodynamic Data ◽  
Experimental Studies ◽  
Experimental Results ◽  
Radioactive Element ◽  
Oxidation States ◽  
Dissolution Behavior ◽  
High Concentration ◽  
Very High ◽  
Chemical Analogue

SummaryThe migration of fissiogenic Tc into the environment can be predicted by studying the dissolution behavior of Re, a chemical analogue of Tc, avoiding the use of a radioactive element at high concentration. We developed a series of experimental studies of the solubility of Re oxides under various oxidation states (+VII, +IV, and +III), in oxidizing and anoxic media, so as to verify the validity of the available thermodynamic data concerning Re. The experimental results confirm that the predictable solubility of Re, under the conditions found in radioactive wastes storage, is very high when in the form of {ReO

Heat capacities and volumes of NaCl, MgCl2, CaCl2, and NiCl2 up to 6 molal in water

1981 ◽  
Vol 59 (21) ◽  
pp. 3049-3054 ◽  
Author(s):  
Gèrald Perron ◽  
Alain Roux ◽  
Jacques E. Desnoyers
Keyword(s):  
Aqueous Solutions ◽  
Long Range ◽  
Higher Order ◽  
Heat Capacities ◽  
Range Order ◽  
Long Range Order ◽  
High Concentration ◽  
Concentration Region ◽  
Partial Molar Heat Capacities ◽  
High Concentrations

It has been claimed by Enderby and co-workers that changes in long-range order occur in NiCl2 aqueous solutions at high concentrations. To investigate the possibility of a transition, the partial molar heat capacities and volumes of NiCl2, CaCl2, MgCl2, and NaCl were measured and compared in water at 25 °C up to 6 mol kg−1. In the case of NaCl, data were also measured at 5 and 45 °C. A slight change in slope of [Formula: see text] is observed for NiCl2 around 4 mol kg−1 which may suggest a third or higher order transition. However, the change is too small to support unambiguously any particular model for the high concentration region.

scholarly journals Determination of the average molecular weight of sodium polystyrenesulphonate from viscosity measurement

2012 ◽  
Vol 10 (10) ◽  
pp. 17-19 ◽  
Author(s):  
Ajaya Bhattarai
Keyword(s):  
Molecular Weight ◽  
Sodium Chloride ◽  
Aqueous Solutions ◽  
Average Molecular Weight ◽  
Viscosity Measurement ◽  
Degree Of Substitution ◽  
Chemical Company ◽  
Scientific World ◽  
Aldrich Chemical Company

Precise measurements on the viscosity of aqueous solutions of sodium polystyrenesulphonate and in presence 0.1 N sodium chloride at 308.15 K were reported. The degree of substitution of sodium polystyrenesulphonate used was one. The sodium polystyrenesulphonate (NaPSS) used in these investigations was purchased from Aldrich Chemical Company, Inc. whose  viscosity average molecular weight  was 70,000.  The experimental viscosity average molecular weight of polystyrenesulphonate was found 70,186.15. Scientific World, Vol. 10, No. 10, July 2012 p17-19 DOI: http://dx.doi.org/10.3126/sw.v10i10.6855

Long-term preservation of α-amylase activity in highly concentrated aqueous solutions of imidazolium ionic liquid

2018 ◽  
Vol 7 (2) ◽  
pp. 106-113 ◽  
Author(s):  
Konstantza Tonova
Keyword(s):  
Ionic Liquid ◽  
Aqueous Solutions ◽  
Free Water ◽  
Potassium Acetate ◽  
Acetate Anion ◽  
High Concentration ◽  
Imidazolium Ionic Liquid ◽  
Imidazolium Cation ◽  
Long Term Preservation

AbstractThe activity of the α-amylase enzyme incubated in aqueous solutions with a high concentration (80.2% w/v) of imidazolium ionic liquid, [C4C1im]Br, has been studied. Contrary to the complete deactivation hitherto reported in the literature, a way is found to preserve the enzyme, by adding the appropriate salt, so that the activity is saved for a long grace period. Different salts are studied and the concentration is optimized in view of the enzyme hydration. Due to the limited amount of free water available to the enzyme at higher salt concentrations, the activity decreases. The best results are obtained by adding potassium acetate, 0.200 mol dm−3. Some 90% of the activity is saved in a 2-week incubation, and a half activity remains in a month. Precipitates are observed in the samples of the solution without salt. No precipitation is noticed when acetate is present. Regardless of the fluorescence quenching, the activity is saved. The effect of the acetate on the α-amylase preservation is probably related to the ability of the acetate anion to interact with the imidazolium cation thus shielding the enzyme from being salted out and precipitated. Compared with potassium bromide, which does not interact with [C4C1im]Br, precipitation and fast inactivation are observed.

scholarly journals XEOL spectroscopy of lanthanides in aqueous solution

2017 ◽  
Vol 95 (11) ◽  
pp. 1198-1204
Author(s):  
Astrid Jürgensen
Keyword(s):  
Aqueous Solutions ◽  
Luminescence Intensity ◽  
Lanthanide Ions ◽  
High Concentration ◽  
Double Crystal ◽  
Electronic Interactions ◽  
Double Crystal Monochromator ◽  
Luminescence Peak ◽  
Solution Increase ◽  
Solvent Molecules

As part of an ongoing study of the electronic interactions between solute and solvent molecules, a method for X-ray excited optical luminescence (XEOL) analysis of aqueous solutions was developed at the double-crystal monochromator beamline (DCM) of the Canadian Synchrotron Radiation Facility (CSRF). It was tested using a series of solutions containing lanthanide ions. The samples were contained in a sample holder for liquids with a 3 μm Mylar window separating them from the vacuum (≤3 × 10−6 torr, 1 torr = 133.3224 Pa) in the solid state absorption chamber of the DCM beamline. Terbium, samarium, and dysprosium have 4 intense and narrow luminescence peaks between 450 and 700 nm, well separated from the luminescence peak of the Mylar window between 300 and 425 nm. The intensity of the rare earth (RE3+) luminescence peaks was lower for the solutions than for solid RECl3·6H2O. In part, this was caused by the lower RE3+ concentration in the solutions than in the solid. In addition, the solvent (water) acts as a quencher. The disorder and the molecular motion in the solution increase the availability of nonradiative de-excitation pathways. A high concentration of SO42− in the solution enhanced the luminescence intensity, probably by inhibiting some nonradiative de-excitation pathways. This study has shown that it is in principle possible to investigate the luminescence of aqueous solutions with XEOL spectroscopy. Furthermore, it is possible to use this technique as a quantitative analytical tool for concentrated luminescent solutions and to study the shielding effects of anions in the solution that increase the luminescence intensity.

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