The Ionization of Picric Acid in Ethanol–Sulfolane and t-Butyl Alcohol – Sulfolane Mixtures at 30 °C

1975 ◽  
Vol 53 (11) ◽  
pp. 1651-1656 ◽  
Author(s):  
Maurizio Castagnolo ◽  
Angelo De Giglio ◽  
Angelo Dell'atti ◽  
Giuseppe Petrella
Keyword(s):  
Association Constant ◽  
Composition Range ◽  
Dissociation Constants ◽  
Picric Acid ◽  
Preferential Solvation ◽  
Butyl Alcohol ◽  
Weak Acid ◽  
Solvent Composition ◽  
Solvent Mixtures ◽  
Simple Dissociation

Dissociation constants at 30 °C of picric acid have been determined by a spectrophotometric method in ethanol–sulfolane and t-butyl alcohol – sulfolane mixtures over the entire solvent composition range. Picric acid behaves as a weak acid in all mixtures. In pure sulfolane, picric acid undergoes simple dissociation for c < 0.08 M (pKHPI = 7.6). At concentrations higher than 0.08 M more complex equilibria have been observed and interpreted assuming Pi(HPi)2− as the principal picrate species in solution. Complex behavior of dependence of association constant on solvent composition was observed; in both solvent mixtures as sociation of picric acid decreases with decrease of dielectric constant. This behavior was discussed in terms of preferential solvation of picric acid by alcohols, the more basic components of the mixtures. A reaction mechanism of four alcohol molecules with one acid molecule accounts for the behavior observed.

Electrolytic dissociation of sodium tetraphenylborate in 2-methoxyethanol/water binary solvent mixtures

1994 ◽  
Vol 72 (2) ◽  
pp. 339-344
Author(s):  
Fulvio Corradini ◽  
Andrea Marchetti ◽  
Mara Tagliazucchi ◽  
Lorenzo Tassi ◽  
Giuseppe Tosi
Keyword(s):  
Composition Range ◽  
Dissociation Constants ◽  
Picric Acid ◽  
Ion Pair ◽  
Binary Solvent ◽  
Solvent Mixtures ◽  
Experimental Conditions ◽  
Binary Solvent Mixtures ◽  
Electrolytic Dissociation ◽  
Conductance Data

Thermodynamic properties from conductance data are reported for the NaBPh4 electrolytic solutions in 2-methoxyethanol (component 1)/water (component 2) binary solvent mixtures, working at 19 temperatures ranging from −10 to +80 °C and for 6 mixtures covering the 0.1865 ≤ x1 ≤ 1 composition range. Experimental conductivity data were analysed using the Fuoss–Hsia equation, and the chosen salt was found to associate to a certain extent in these solvent mixtures. The resulting dissociation constants (K) of the ion-pair have been used to test some empirical equations K = K(T), K = K(x1), and K = K(T, x1). Furthermore, the present findings have been compared with our previously reported results from working with picric acid in the same mixtures and experimental conditions.

Conductance and viscosity measurements of some electrolytes in binary solvent mixtures of dimethylsulphoxide and dioxane at 25 °C

1991 ◽  
Vol 56 (9) ◽  
pp. 1813-1832 ◽  
Author(s):  
Vijay K. Syal ◽  
Puspha Bisht ◽  
Prakash C. Ranowt
Keyword(s):  
Preferential Solvation ◽  
Viscosity Coefficient ◽  
Solvent Composition ◽  
Binary Solvent ◽  
Viscosity Data ◽  
Solvent Mixtures ◽  
Ionic Conductance ◽  
Binary Solvent Mixtures ◽  
Viscosity Measurements ◽  
Solvation Of Ions

The conductance and viscosity measurements of Bu4NBPh4, Bu4NI, NaBPh4, Pr4NI, Et4NI, Me4NI, Bu4NNO3, KI, KClO4, NaClO4, KNO3, AgNO3, LiNO3 and NaBr have been carried out in the concentration range of (0-100) . 10-4 mol dm-3 for conductance and (0-250) . 10-4 mol dm-3 for viscosity in dimethylsulphoxide (DMSO) and DMSO + dioxane mixtures at 25°C. The conductance and viscosity data have been analysed by the Shedlovsky and Jones-Dole equations, respectively. The limiting ionic conductance (λi0), solvated radii (ri) and the ionic viscosity coefficient (B±) values have been evaluated. The variation of ri and B± value as a function of solvent composition has been interpreted in terms of preferential solvation of ions in these solvent mixtures.

Conductance studies of some 1:1 electrolytes in acetone + dimethylsulphoxide mixtures at 25 °C

1991 ◽  
Vol 56 (9) ◽  
pp. 1803-1812 ◽  
Author(s):  
Vijay K. Syal ◽  
Suvarcha Chauhan ◽  
Alok Katoch ◽  
Mohinder S. Chauhan
Keyword(s):  
Model Evaluation ◽  
Composition Range ◽  
Preferential Solvation ◽  
Solvent Composition ◽  
Rich Region ◽  
Conductance Data ◽  
Ionic Conductances

Precise molar conductances of Bu4NBPh4, Bu4NI, Bu4NNO3, AgNO3, LiNO3, NaBPh4 and KI have been measured in acetone (Ac), dimethylsulphoxide (DMSO) and Ac + DMSO mixtures over the whole solvent composition range at 25°C. The conductance data has been analysed by computer using Shedlovsky conductance equation. Limiting ionic conductances have been calculated by using Gill’s model. Evaluation of solvated radii of Li+, Na+, K+ and Ag+ ions in Ac + DMSO mixtures shows strong preferential solvation for Li+ ion by DMSO. Na+ and Ag+ ions are found to be preferentially solvated by DMSO in Ac-rich region and by Ac in DMSO rich regions. K+, NO3- and I- ions show no preferential solvation in Ac + DMSO mixtures.

Chemical phosphorus removal model based on equilibrium chemistry

2005 ◽  
Vol 52 (10-11) ◽  
pp. 549-555 ◽  
Author(s):  
I. Takács ◽  
S. Murthy ◽  
P.M. Fairlamb
Keyword(s):  
Phosphorus Removal ◽  
Dissociation Constants ◽  
Chemical Precipitation ◽  
Weak Acid ◽  
Chemical Mechanisms ◽  
Model Based ◽  
Precipitation Model ◽  
Physico Chemical ◽  
Ph Range ◽  
Biological Methods

Regulations in many regions of the world require total phosphorus (TP) levels lower than 0.10mgP/L (100μgP/L) in effluents, resulting in the need to achieve very low ortho-phosphate (OP) concentrations. Chemical precipitation is a widely used technology for controlling effluent OP discharge, either on its own or supplementing biological methods. The various chemical and physico-chemical mechanisms that result in extremely low residual OP levels are complex and depend on pH. In practice, engineering calculations frequently use an empirical precipitation model. This model requires pH as input and predicts the lowest achievable OP residual of 35μgP/L at a narrow optimum pH of 6.9 – 7.0, when an excess of ferric is added. The model has been combined with a biokinetic and weak acid/base chemistry based pH model, to allow accurate prediction of pH, OP residuals and chemical sludge production. Analysis of effluent data from the Blue Plains plant shows that residuals as low as 10μgP/L OP can be achieved regularly, over a wider pH range. The precipitation model was recalibrated to match the newly available data. Subsequently it was compared with a new, mechanistic precipitation model based on solubility and dissociation constants for actual chemical compounds. The need for more accurate measurement of extremely low OP concentrations and considering the role of organics, adsorption and coagulation in chemical phosphorus removal is demonstrated.

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