The Influence of Alkali Metal Hydroxides on Silica Condensation Rates: The Role of Ion Pairing

1988 ◽  
Vol 121 ◽  
Author(s):  
A. V. McCormick ◽  
A. T. Bell ◽  
C. J. Radke
Keyword(s):  
Alkali Metal ◽  
Ion Pairs ◽  
Ion Pairing ◽  
Alkaline Solutions ◽  
Nmr Spectrum ◽  
Metal Hydroxides ◽  
Selective Inversion ◽  
Metal Silicate ◽  
Cation Size

ABSTRACTThe condensation kinetics and the role of Ion pairing are investigated for silicate anions in alkaline solutions. Selective, and non-selective inversion recovery experiments are performed using the Si NMR spectrum of alkali metal silicate solutions. In this way the rates of condensation of silicate monomers is studied as a function of the nature of the base. These rates exhibit maxima with increasing cation size. The maxima are interpreted in terms of the concentration and activity of ion pair intermediates of the Si exchange reaction.Interactions between alkali metal cations and larger silicate anions in silicate solutions are investigated using NMR spectroscopy of the cations. The chemical shift and the resonance llnewidths are used to estimate the concentration of cation-silicate ion pairs. The concentration of pairs involving large anions increases with increasing cation size. Thus it is expected that condensation kinetics are influenced by the size of the silicate fragment.

The Effect of Alkali Metal Cations on The Structure of Dissolved Silicate Oligomers

1987 ◽  
Vol 111 ◽  
Author(s):  
Alon V. McCormick ◽  
A. T. Bell ◽  
C. J. Radke
Keyword(s):  
Nmr Spectroscopy ◽  
Alkali Metal ◽  
Base Composition ◽  
Ion Pairs ◽  
Metal Cations ◽  
Ion Pairing ◽  
Alkali Metal Cations ◽  
Silicate Anion ◽  
Cation Size ◽  
Dissolved Silicate

AbstractBy means of 29Si spectroscopy, it is established that the distribution of silicate anions in alkaline silicate solutions is a moderate function of base composition. At a fixed SiO2. concentration and silicate ratio, the proportion of Si present in oligomeric and cage-like structures increases in progressing from Li to Cs hydroxide. Interactions between alkali metal cations and silicate anions are investigated using NMR spectroscopy of the cations; in this way the concentration of ion pairs is measured as a function of cation size. As a result the silicate redistribution is ascribed to cation-silicate anion pairing and to a higher selectivity for ion pairing by large silicate anions as cation size increases.

Spectrophotometric study of ion pairing in diphenylmethyl alkali metals salts

1979 ◽  
Vol 57 (9) ◽  
pp. 999-1005 ◽  
Author(s):  
E. Buncel ◽  
B. C. Menon ◽  
J. P. Colpa
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Ion Pairs ◽  
Ion Pairing ◽  
Spectrophotometric Study ◽  
Metal Salts ◽  
Effect Of Temperature ◽  
Alkali Metal Salts ◽  
Nmr Studies ◽  
Temperature Changes

A spectrophotometric study of diphenylmethyllithium (DPM−Li+) and diphenylmethyl-potassium (DPM−K+) in ethereal solvents has yielded information on ion pairing and solvation phenomena in these carbanion systems. Different spectral absorptions are observed, characteristic of two types of contact ion pairs (unsolvated and partially solvated) as well as the solvent separated ion pair species, on varying the cation and solvent. This contrasts with our previous observations with triphenylmethyl alkali metal salts where only contact and solvent separated ion pairs were observed. The effect of 18-crown-6 polyether and the effect of temperature changes on the ion pairing equilibria are evaluated. Thermodynamic parameters are obtained for equilibria pertaining to the DPM−Li+/THF and DPM−Li+/DME systems. The results are discussed in relation to literature reports on ion pairing in these systems as derived from nmr studies. Comparison with triphenylmethyl alkali metal salts yields information relating to delocalization and steric effects on ion pairing.

Ion Pairing and the Reaction of Alkali Metal Ferrocyanides and Persulfates

1971 ◽  
Vol 49 (18) ◽  
pp. 2943-2947 ◽  
Author(s):  
R. W. Chlebek ◽  
M.W. Lister
Keyword(s):  
Alkali Metal ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Ion Pairs ◽  
Activation Parameters ◽  
Ion Pairing ◽  
Similar Rate ◽  
Thermodynamic Quantities ◽  
Kinetics Of

Osmometric measurements have been made on the alkali metal persulfates, and these are interpreted in terms of formation of ion pairs, MS2O8−, by means of the method of Masterton and Berka (5). Equilibrium constants, and the derived thermodynamic quantities are deduced for the reactions [Formula: see text]. These results are applied to the interpretation of the kinetics of the reactions[Formula: see text]With M = K+, Rb+, and Cs+, the reacting species are MFe(CN)63− + MS2O8−, with very similar rate constants; with M = Li+, Na+ the species are MFe(CN)63− + S2O82−; and for lithium the reaction of Fe(CN)64− + S2O82− is also important. Rate constants and activation parameters are deduced.

Role of Cation Size on the Structural Behavior of the Alkali-Metal Dodecahydro-closo-Dodecaborates

2009 ◽  
Vol 113 (26) ◽  
pp. 11187-11189 ◽  
Author(s):  
Jae-Hyuk Her ◽  
Wei Zhou ◽  
Vitalie Stavila ◽  
Craig M. Brown ◽  
Terrence J. Udovic
Keyword(s):  
Alkali Metal ◽  
Structural Behavior ◽  
Cation Size

scholarly journals EFFECT OF ION PAIRS ON DECREASE THE RISK OF USING SALINE WATER FOR IRRIGATION

2020 ◽  
Vol 51 (2) ◽  
pp. 637-643
Author(s):  
Rajab & Esmail
Keyword(s):  
Saline Water ◽  
Ion Pairs ◽  
Ion Pairing ◽  
High Permeability ◽  
Medium Permeability ◽  
Saline Waters ◽  
The Mean

This investigation was conducted during January, 2018 to April, 2019 to investigate the role of correcting ion pairs and activity in decreasing the risk of saline water for irrigation. The groundwater of (31) wells in Makhmur district were depended in this study .The results indicated that amount of ions contributing in ion pairing was ranged between (0.77 -15.42 mmole l-1) with the mean of 6.56 mmole l-1.and the dominate ion pairs were (CaSO4)0, (MgSO4)0,(MgHCO3)+ and (CaHCO3)+,with the values of 5.00, 4.50, 2.37 and 1.33 mmolc l-1 respectively. The studied saline  water in Makhmur  district did not suitable for irrigation the soils having low, medium and high permeability, while after correcting ion pairs and activity 14 of the studied saline waters were suitable for irrigation (3 of them for soil having medium permeability and 11 of them for soils having high permeability). It means correcting ion pairs and activity caused removal the risk of 14 saline waters for irrigation or caused decrease the risk of 45% of the studied saline water. Correcting ion pairs and activity caused shifting water class from no suitable for irrigation to suitable for irrigation depending on salinity potential values and Doneen classification.

Recognition of Alkali Metal Halide Contact Ion Pairs by Uranyl−Salophen Receptors Bearing Aromatic Sidearms. The Role of Cation−π Interactions

2005 ◽  
Vol 127 (11) ◽  
pp. 3831-3837 ◽  
Author(s):  
Massimo Cametti ◽  
Maija Nissinen ◽  
Antonella Dalla Cort ◽  
Luigi Mandolini ◽  
Kari Rissanen
Keyword(s):  
Alkali Metal ◽  
Ion Pairs ◽  
Alkali Metal Halide ◽  
Metal Halide ◽  
Π Interactions ◽  
Contact Ion Pairs
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