Absorption of Na, K, and Ca by barley roots at constant ionic strength

1963 ◽  
Vol 18 (1) ◽  
pp. 133-139 ◽  
Author(s):  
A. K. Helmy ◽  
M. N. Hassan ◽  
S. Taher
Keyword(s):  
Ionic Strength ◽  
Constant Ionic Strength

Adsorption of chlorate and bromate ions on mercury electrodes from constant ionic strength solutions

1988 ◽  
Vol 85 ◽  
pp. 523-527
Author(s):  
M.M. Zuleika ◽  
Palhares SILVA ◽  
Ernesto Rafael GONZALEZ ◽  
Luis Alberto AVACA ◽  
Artur de Jesus MOTHEO
Keyword(s):  
Ionic Strength ◽  
Constant Ionic Strength ◽  
Mercury Electrodes

Kinetics and Mechanism of Hexachloroiridate(IV) Oxidation of Arsenic(III) in Acidic Perchlorate Solutions

1992 ◽  
Vol 57 (7) ◽  
pp. 1451-1458 ◽  
Author(s):  
Refat M. Hassan
Keyword(s):  
Ionic Strength ◽  
Fractional Order ◽  
Activation Parameters ◽  
Order Reaction ◽  
First Order Reaction ◽  
Intermediate Complex ◽  
Constant Ionic Strength ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Kinetics Of

The kinetics of oxidation of arsenic(III) by hexachloroiridate(IV) at lower acid concentrations and at constant ionic strength of 1.0 mol dm-3 have been investigated spectrophotometrically. A first-order reaction in [IrCl62-] and fractional order with respect to arsenic(III) have been observed. A kinetic evidence for the formation of an intermediate complex between the hydrolyzed arsenic(III) species and the oxidant was presented. The results showed that decreasing the [H+] is accompanied by an appreciable acceleration of the rate of oxidation. The activation parameters have been evaluated and a mechanism consistent with the kinetic results was suggested.

Speciation of protactinium(V) at tracer scale

2009 ◽  
Vol 97 (7) ◽  
Author(s):  
Claire Le Naour ◽  
M. V. Di Giandomenico ◽  
Y. Zhao ◽  
M. Mendes
Keyword(s):  
Ionic Strength ◽  
Solvent Extraction ◽  
Distribution Coefficient ◽  
Systematic Study ◽  
Chelating Agent ◽  
Constant Ionic Strength ◽  
Diethylene Triamine ◽  
Sulphate Chloride

AbstractSolvent extraction in the conditions of tracer scale chemistry was used to study protactinium(V) complexation with sulphate, chloride, oxalate and diethylene-triamine-pentaacetate. Extraction experiments were conducted using the chelating agent thenoyltrifluoroacetone (TTA) in toluene at constant ionic strength and temperature. Information on the species involved in partition equilibria relative to protactinium(V) complexation were deduced from a systematic study of the variations of distribution coefficient of Pa(V) as function of ligands, protons and TTA concentration.

scholarly journals Fluorimetric studies on the dimerization equilibrium of protoporphyrin IX and its haemato derivative

1983 ◽  
Vol 209 (2) ◽  
pp. 547-552 ◽  
Author(s):  
R Margalit ◽  
N Shaklai ◽  
S Cohen
Keyword(s):  
Ionic Strength ◽  
Fluorescence Quenching ◽  
Fluorescence Intensity ◽  
Salt Concentration ◽  
Equilibrium Constants ◽  
Protoporphyrin Ix ◽  
Constant Ionic Strength ◽  
Aggregation Process ◽  
Buffer Concentration ◽  
Common Anion

The aggregations of protoporphyrin IX and haematoporphyrin IX in aqueous solutions were studied by fluorimetric techniques. Porphyrin concentrations were limited to 0.001-0.1 microM and 0.01-1 microM for protoporphyrin and haematoporphyrin respectively, where dimerization is the dominant aggregation process. The dimerization equilibrium constants (at 25 degrees C, neutral pH, 50 mM-Tris/HCl buffer) were determined to be 3×10(7) M and 4×10(5) M for the proto and the haemato derivatives respectively. The fluorescence intensity of a given protoporphyrin solution (within the range indicated above) was markedly decreased by salts in the system, over the salt concentration range 0.1-7 mM at constant ionic strength, in the sequence CaCl2 greater than MgCl2 greater than KCl greater than NaCl. The direction of this effect, fluorescence quenching, suggests that these salts promote an increase in aggregation. The differences in the magnitudes of the effect, among different salt species sharing a common anion, at constant ionic strength, imply that the effect is cation-specific. In contrast, the fluorescence intensity of a given solution of haematoporphyrin (within the range indicated above) was unaffected by these salts, under similar concentrations, nor was it sensitive to the total buffer concentration, or to the type of buffer in the system.

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