Formation and Properties of Americium Colloids in Aqueous Systems

1981 ◽  
Vol 6 ◽  
Author(s):  
U. Olofsson ◽  
B. Allard ◽  
K. Andersson ◽  
B. Torstenfelt
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Storage Time ◽  
Large Fraction ◽  
Average Charge ◽  
Particle Sizes ◽  
Aqueous Systems ◽  
Ph Range ◽  
And Storage ◽  
Solution Changes

ABSTRACTThe formation and sorption properties of colloidal americium in aqueous solutions have been studied with variations of pH (2–12), ionic strength (0.01–1.0 M NaClO4), americium concentration (10−7 −10−11 M) and storage time (6 h–6 months). A large fraction of the americium is sorbed on the container walls or on Al2O3 in the pH-range 7–11. Around pH 5–8 and at pH above 12 centrifugable fractions (particle sizes greater than 100 nm) are obtained. The fraction formed at pH above 12, which seems to be a true hydroxide colloid, migrates through an A12O3-filled column with very little retention. The average charge of americium species in solution changes from positive values at pH below 7–8 to negative values at pH above 10–11, as indicated from electromigration studies.

Generation and Transport Properties of Colloidal Tri-And Tetravalent Actinide Species in Geologic Environments

1983 ◽  
Vol 26 ◽  
Author(s):  
U. Olofsson ◽  
M. Bengtsson ◽  
B. Allard
Keyword(s):  
Aqueous Solutions ◽  
Transport Properties ◽  
Storage Time ◽  
Colloidal Particle ◽  
Large Fraction ◽  
Salt Medium ◽  
Tetravalent Actinide ◽  
Vessel Walls ◽  
Ph Range ◽  
Waste Repositories

ABSTRACTThe formation of colloidal particle fractions of triand tetravalent actinides (Am(III), Th(IV), Pu) has been studied in aqueous solutions under various conditions. (Variations of nuclide concentration 10-7-10-11 M; pH 3-12; salt medium 0.01-1.0 M NaCl04; storage time 6 h-6 months; temperature 5°C, 25°C, 70°C). A large fraction of the nuclides is sorbed on the vessel walls, but there is also a formation of centrifugable particles. For americium this fraction has two maxima, at pH 5-8 and at pH above 12. For thorium and plutonium this fraction is very small except at pH about 12. In the pH-range 7-9, which is expected in underground waste repositories, the particle fractions do not seem to be highly mobile. Plutonium behaves very similar to thorium in all studied systems, so it is probably tetravalent to a large extent.

The Electroreduction of Periodate Anion in Alkaline Media

1971 ◽  
Vol 49 (16) ◽  
pp. 2657-2663 ◽  
Author(s):  
W. R. Fawcett ◽  
Y. C. Kuo Lee
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Double Layer ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Alkaline Media ◽  
Dropping Mercury Electrode ◽  
Ph Range ◽  
Theoretical Developments

The electroreduction of periodate anion was studied at a dropping mercury electrode in aqueous solutions in the pH range 11–13.3 where the process is markedly affected by the double layer. The electrode reaction was found to be complex, its mechanism depending on both pH and ionic strength. The effects of the double layer on the component reactions are discussed with respect to current theoretical developments.

scholarly journals BUFFER SOLUTIONS BASED ON TAURINE

2021 ◽  
Vol 26 (1(77)) ◽  
pp. 48-64
Author(s):  
T. S. Ben’kovs’ka ◽  
R. E. Khoma ◽  
A. N. Chebotaryov ◽  
A. A.-A. Ennan ◽  
L. T. Osadchiy
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Buffer Capacity ◽  
Water System ◽  
Acid Base ◽  
Buffer Zones ◽  
Base Interaction ◽  
Temperature Range ◽  
Temperature Dependences ◽  
Ph Range

The acid-base interaction in the aminoethanesulfonic acid (taurine, Tau) – potassium aminoethanesulfonate – water system was studied by pH-, redox- and conductometric methods in the temperature range 293–313 K. The ion-molecular composition of NH2CH2CH2SO3H –NH2CH2CH2SO3K – H2O system was calculated. It is shown aminoethanesulfonic acid in aqueous solutions to exist at the ratio CKOH/QTau < 0.5 mainly in the zwitterion form similar to systems with glycine, aminomethanesulfonic acid and its N‑alkylated derivatives. The content of the aminoethanesulfonate anion is directly proportional to the CKOH/QGly ratio. The studied system ionic strength and acid-base dissociation constant for the second stage of the aminoethanesulfonic acid concentration and temperature dependences were determined. The ionic strength values at the isoelectric point (mi.p.)are directly proportional to С0Tau and practically do not depend on the temperature within the error for the same series С0Tau and С0KOH .The pH limits of the buffer action are determined and the buffer capacity of these systems is estimated. It has been established that effective buffer zones of Tau aqueous solutions can to maintain acidity in the higher then physiological pH range at temperature range 293–313 K. The buffer capacity of NH2CH2CH2SO3H – NH2CH2CH2SO3K – H2O system exceeds the analogous values of YNHCH2SO3H – YNHCH2SO3K – H2O (Y = H, CH3, CH2CH2OH, C(CH3)3 and C2H5C6H5) systems. The obtained data on the buffer capacity of the aminoethanesulfonic acid – potassium aminoethanesulfonate – water system can be used in chemical analysis, microbiological and biochemical studies, and the acidity data of the solutions studied can simulate the chemisorption of acid gases (carbon and sulfur dioxides).

scholarly journals An LFER study of the protolytic equilibria of 4-aryl-2,4-dioxobutanoic acids in aqueous solutions

2007 ◽  
Vol 72 (12) ◽  
pp. 1201-1216 ◽  
Author(s):  
Tatjana Verbic ◽  
Branko Drakulic ◽  
Mire Zloh ◽  
Jovana Pecelj ◽  
Gordana Popovic ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Parent Compound ◽  
Nmr Spectrum ◽  
Pka Values ◽  
Protolytic Equilibria ◽  
Tautomeric Forms ◽  
Ph Range ◽  
Semi Empirical

The protolytic equilibria of 13 4-aryl-2,4-dioxobutanoic acids (ADKs) were spectrophotometrically studied in aqueous solutions in the pH range 1-9 at 25?1 ?C and an ionic strength of 0.1 mol l-1 (NaCl), with the exception of the 4-OH-derivative which was also potentiometrically studied in the pH range 7-10 at 25?1 ?C and an ionic strength of 0.1 mol l-1 (NaCl). In solution, the compounds simultaneously exist in one diketo and two enolic forms; therefore, the determined acidity constants (pKa1 1.87-2.29, pKa2 6.63-8.13 and pKa3(4-OH-) 9.52) represent system macro constants. The 1H-NMR spectrum of the parent compound (4-phenyl- -2,4-dioxobutanoic acid) (25 ?C, pD 5.0) proved the existence of all tautomeric forms. Using the extended Hammett relation, the determined pKa values were correlated with literature ? values. The predicted pKa values were in fair accordance with the experimentally observed ones. Molecular, monoanionic and dianionic forms of the parent compound were optimized by the semi-empirical molecular orbital PM6 method using the implicit water solvation model (COSMO). The obtained geometries were used to explain the quality of the LFER models.

scholarly journals Disproportionation and Polymerization of Plutonium(IV) in Dilute Aqueous Solutions

1983 ◽  
Vol 26 ◽  
Author(s):  
T. W. Newton ◽  
V. L. Rundberg
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Rate Constants ◽  
Second Order ◽  
Disproportionation Reaction ◽  
Reaction Products ◽  
Constant Ph ◽  
Low Concentrations ◽  
Dilute Aqueous Solutions ◽  
Ph Range

ABSTRACTThe rates of polymerization and disproportionation of Pu(IV) have been studied using low concentrations: (1.7 − 10) × 10−6M Pu, (0.8 − 12) × 10−4M HCI and 0.01M ionic strength. Osmium(II) complexes such as the tris−4,41−2,21−bipyridine complex were found to react rapidly with Pu(IV) but very slowly, if at all, with Pu(IV) polymer, Pu(lll), or Pu(V). Thus, it is possible to determine unreacted Pu(IV) in the presence of reaction products by using Os(II) complexes. Disproportionation reaction products, Pu(IlI) and Pu(V), were determined using their reactions with Ce(IV) sulfate. We find −d[Pu(IV)]/dt = k'[Pu(IV)]2 at constant pH. Log k1 varies from about 4.25 at pH 3 to about 7.0 at pH 4.1 (units for k1 are M−1min−1). The [H+] dependence varies from about −2 to −3 over the pH range studied. The measured rate is the sum of those for polymerization and disproportionation; the latter reaction amounts to about 75% of the total at pH 3 and 20% at pH 4. The second-order rate constants for disproportionation are very much larger than expected on the basis of extrapolation from 0.2 to 1.OM HClO, solutions. The products of the reaction do not affect the rate, but U(VI), aged Pu(IV) polymer, and CO2 increase the rate.

Sorption of Cadmium and Lead by Chelating Ion Exchangers Ostsorb OXIN, Ostsorb DETA, and Ostsorb DTTA

1994 ◽  
Vol 59 (6) ◽  
pp. 1311-1318 ◽  
Author(s):  
Ladislav Svoboda ◽  
Petr Vořechovský
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Sodium Perchlorate ◽  
Exchange Capacity ◽  
Chloride Ions ◽  
Point Of View ◽  
Alkaline Media ◽  
Ion Exchangers ◽  
Acidic Media ◽  
Cadmium And Lead

The properties of cellulose chelating ion exchangers Ostsorb have been studied in the sorption of cadmium and lead from aqueous solutions. The Cd(II) and Pb(II) ions are trapped by the Ostsorb OXIN and Ostsorb DETA ion exchangers most effectively in neutral and alkaline media but at these conditions formation of stable hydrolytic products of both metals competes with the exchange equilibria. From this point of view, Ostsorb DTTA appears to be a more suitable sorbent since it traps the Pb(II) and Cd(II) ions in acidic media already. Chloride ions interfere with the sorption of the two metals by Ostsorb DTTA whereas the ionic strength adjusted by the addition of sodium perchlorate does not affect the exchange capacity of this ion exchanger.

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