scholarly journals An Electrochemical Study of Hydrothermal Reactions at Elevated Temperatures

2021 ◽  
Author(s):  
◽  
Edward Kazimierz Mroczek
Keyword(s):  
Dissociation Constant ◽  
Sulphuric Acid ◽  
Elevated Temperatures ◽  
Equilibrium Constants ◽  
Sodium Tetraborate ◽  
Liquid Junction ◽  
Solution Ph ◽  
Hydrogen Electrode ◽  
Cell Compartments ◽  
Temperature Variable

<p>A high temperature hydrogen electrode concentration cell based on a design published by Macdonald, Butler and Owen1, was constructed and used to study the following protolytic equilibria. Thermodynamic equilibrium constants were derived by the usual method of extrapolation to zero ionic strength. 1. The ionization of water at temperatures from 75 to 225 degrees C in 0.1, 0.3, 0.5 and 1.0 mol kg-1 KCl solution. pK degrees w = 7229.701 /T + 30.285logT - 85.007 2. The pH calibration of 0.01 and 0.05 mol kg-1 sodium tetraborate at temperatures from 75 to 250 degrees C in O.1, 0.3 and 0.5 mol kg-1 NaCl solution. 0.0l mol kg-1 Sodium Tetraborate Solution pH = -0.4830t1 + 5.5692t2 + 7.7167t3 + 8.6983 0.05 mol kg-1 Sodium Tetraborate Solution pH = -0.0455tl + 8.3987t2 + O.2123t3 8.8156 3. The second dissociation of sulphuric acid at temperatures from 75 to 225 degree C in 0.1, 0.3 and 0.5 mol kg-l KCl solution. pK degrees 2 = 5.3353t1 - 15.9518t2 - 111.4929t3 + 3.8458 pK degrees 2 = 6.1815t*1 + 12.7301t*2. + 3.0660 (up to 150 degrees C) Where the t1 to t3= and t*1 and t*2 are the Clark-Glew temperature variable terms at reference temperatures of 423.15 and 373.15 K respectively2. 4. The acid hydrolysis of K-feldspar to K-mica and quartz at a temperature of 225 degrees C. The determination of the hydrolysis equilibrium constant was limited to one temperature because of the very slow reaction rate at temperatures less than 300 degrees C. log(mK+/mH+) = 4.2 (at 225 degrees C) Where a comparison could be made, the results of this study agreed well with previously published work, with the exception of the second dissociation constant of sulphuric acid at temperatures above 150 degrees C. Accurate values for the molal dissociation constant of the KSO-4 ion pair are required at elevated temperatures before the pK degrees 2 results can be fully evaluated. This research was severely restricted by the unpredictable loss of electrical continuity between the two cell compartments at temperatures above 150 degrees C. The problem appeared to be associated with the non-wettability of the porous Teflon plug which formed the liquid junction.</p>

scholarly journals An Electrochemical Study of Hydrothermal Reactions at Elevated Temperatures

2021 ◽  
Author(s):  
◽  
Edward Kazimierz Mroczek
Keyword(s):  
Dissociation Constant ◽  
Sulphuric Acid ◽  
Elevated Temperatures ◽  
Equilibrium Constants ◽  
Sodium Tetraborate ◽  
Liquid Junction ◽  
Solution Ph ◽  
Hydrogen Electrode ◽  
Cell Compartments ◽  
Temperature Variable

<p>A high temperature hydrogen electrode concentration cell based on a design published by Macdonald, Butler and Owen1, was constructed and used to study the following protolytic equilibria. Thermodynamic equilibrium constants were derived by the usual method of extrapolation to zero ionic strength. 1. The ionization of water at temperatures from 75 to 225 degrees C in 0.1, 0.3, 0.5 and 1.0 mol kg-1 KCl solution. pK degrees w = 7229.701 /T + 30.285logT - 85.007 2. The pH calibration of 0.01 and 0.05 mol kg-1 sodium tetraborate at temperatures from 75 to 250 degrees C in O.1, 0.3 and 0.5 mol kg-1 NaCl solution. 0.0l mol kg-1 Sodium Tetraborate Solution pH = -0.4830t1 + 5.5692t2 + 7.7167t3 + 8.6983 0.05 mol kg-1 Sodium Tetraborate Solution pH = -0.0455tl + 8.3987t2 + O.2123t3 8.8156 3. The second dissociation of sulphuric acid at temperatures from 75 to 225 degree C in 0.1, 0.3 and 0.5 mol kg-l KCl solution. pK degrees 2 = 5.3353t1 - 15.9518t2 - 111.4929t3 + 3.8458 pK degrees 2 = 6.1815t*1 + 12.7301t*2. + 3.0660 (up to 150 degrees C) Where the t1 to t3= and t*1 and t*2 are the Clark-Glew temperature variable terms at reference temperatures of 423.15 and 373.15 K respectively2. 4. The acid hydrolysis of K-feldspar to K-mica and quartz at a temperature of 225 degrees C. The determination of the hydrolysis equilibrium constant was limited to one temperature because of the very slow reaction rate at temperatures less than 300 degrees C. log(mK+/mH+) = 4.2 (at 225 degrees C) Where a comparison could be made, the results of this study agreed well with previously published work, with the exception of the second dissociation constant of sulphuric acid at temperatures above 150 degrees C. Accurate values for the molal dissociation constant of the KSO-4 ion pair are required at elevated temperatures before the pK degrees 2 results can be fully evaluated. This research was severely restricted by the unpredictable loss of electrical continuity between the two cell compartments at temperatures above 150 degrees C. The problem appeared to be associated with the non-wettability of the porous Teflon plug which formed the liquid junction.</p>

Hydrolysis of Co(II) at elevated temperatures

1978 ◽  
Vol 56 (4) ◽  
pp. 435-440 ◽  
Author(s):  
Gaétan Giasson ◽  
Param H. Tewari
Keyword(s):  
Elevated Temperatures ◽  
Initial Solution ◽  
Cobalt Concentration ◽  
Liquid Junction ◽  
Solution Ph ◽  
Concentration Cell ◽  
Hydrolysis Of

Hydrolysis of Co(II) has been studied up to 200 °C using a concentration cell with liquid junction of the type Pt(H2)|H+(a1)||H+(a2)|(H2)Pt. The effect of varying the initial solution pH and cobalt concentration has been studied at different ionic strengths. The hydrothermal hydrolysis for cobalt solutions between pH 3.9 and 9.6 is consistent with the equilibrium Co2+ + H2O → CoOH+ + H+. Higher hydrolytic species are not important. Hydrolysis increases with temperature and produces a buffering action at 200 °C. Thermodynamic quantifies for the hydrolysed species are reported.

scholarly journals Correlation between composition and activity of gold nanoparticle conjugates with streptococcal protein G

2020 ◽  
Vol 10 (2) ◽  
pp. 4988-4992
Keyword(s):  
Dissociation Constant ◽  
Equilibrium Constants ◽  
Gold Surface ◽  
Binding Activity ◽  
Protein G ◽  
Binding Ability ◽  
Adsorbed Protein ◽  
Streptococcal Protein G ◽  
The Stability ◽  
Nanoparticle Complex

The composition of the conjugates of gold nanoparticles with streptococcal protein G was studied using fluorescence spectroscopy. The method for determining the composition is based on measuring the intrinsic fluorescence of tryptophan as part of the protein. The equilibrium constants of protein binding by the gold surface were determined using the Sketchard method. An increase in the dissociation constant of the protein–nanoparticle complex for increasing the amount of bound protein was demonstrated, and a relationship was established between the stability of the conjugates, their antigen-binding activity, and the dissociation constant. The effectiveness of the conjugates of different compositions in immunochromatographic assay of specific antibodies against the lipopolysaccharide antigen of Brucella abortus was compared. The binding ability of the conjugates increased along with the amount of protein G to ~200 molecules per nanoparticle. A further increase in the amount of adsorbed protein led to a deterioration in the functional activity of the conjugates.

scholarly journals Evaporation of sulphate aerosols at low relative humidity

2016 ◽  
Author(s):  
Georgios Tsagkogeorgas ◽  
Pontus Roldin ◽  
Jonathan Duplissy ◽  
Linda Rondo ◽  
Jasmin Tröstl ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Thermodynamic Properties ◽  
Sulphuric Acid ◽  
Activity Coefficients ◽  
Vapour Pressure ◽  
Equilibrium Constants ◽  
Cloud Chamber ◽  
Aerosol Dynamics ◽  
Sulphate Aerosols

Abstract. Here we explore the vapour pressure of sulphuric acid at very low relative humidity, where evaporation of sulphuric acid from particles can be important in the atmospheres of Earth and Venus. We performed experiments in the CLOUD chamber at CERN forming sulphuric acid particles via nucleation and then measuring evaporation versus temperature and relative humidity. We modelled the experiments with the ADCHAM model to constrain the thermodynamic properties governing the evaporation of sulphuric acid. ADCHAM includes a thermodynamics module coupled to an aerosol dynamics module. We derived the mole fractions and activity coefficients of H2SO4, HSO4−, SO42− and SO3 in the particles and then simulated the condensation and evaporation of H2SO4 and SO3. We constrained the equilibrium constants for the dissociation of H2SO4 to HSO4− (KH2SO4) and the dehydration of H2SO4 to SO3 (xKSO3). Our results suggest that particle shrinkage is mainly governed by H2SO4 evaporation, however, we cannot dismiss a contribution from SO3 evaporation. We conclude that KH2SO4 = 2–4 ∙ 109 mol ∙ kg−1 at 288.8 ± 5 K and xKSO3 ≥ 1.4 ∙ 1010.

Study of Oxidation Degradation Eosin by Ferrate

2014 ◽  
Vol 989-994 ◽  
pp. 15-18
Author(s):  
Dang Sheng Li ◽  
Xi Liang Chen
Keyword(s):  
Wastewater Treatment ◽  
Comparative Study ◽  
Reaction Temperature ◽  
Elevated Temperatures ◽  
Removal Rate ◽  
Solution Ph ◽  
Oxidation Degradation

This paper presents a comparative study of the performance of ferrate (VI) towards wastewater treatment. The effects of solution pH, reaction temperature and amount of ferrate on the eosin removal rate were investigated. Results demonstrated that increasing the amount of ferrate (VI) and low acidity leads to good removal performance of ferrate towards eosin. So ferrate (VI) is an effective reagent for dyes treatment. The reaction temperature, however, has little influence on the removal rate which may be due to the degradation effects of ferrate at elevated temperatures.

scholarly journals Beiträge zur Chemie des Phosphors, 139 [1] Triethyl-cyclotriphosphan, Trimethyl-cyclotriphosphan; Gleichgewichte zwischen Cyclophosphanen (PR)n bei erhöhten Temperaturen/Contributions to the Chemistry of Phosphorus, 139 [1] Triethylcyclotriphosphane, Trimethylcyclotriphosphane; Equilibria between Cyclophosphanes (PR)n at Elevated Temperatures

1984 ◽  
Vol 39 (4) ◽  
pp. 438-444 ◽  
Author(s):  
Marianne Baudler ◽  
Josef Hahn ◽  
Erwin Clef
Keyword(s):  
Thermodynamic Equilibrium ◽  
Thermodynamic Data ◽  
Elevated Temperatures ◽  
Equilibrium Constants ◽  
Fractional Distillation ◽  
Ring Strain ◽  
Product Mixture

Triethylcyclotriphosphane, (PEt)3 (1), has been generated by thermolysis of tetraethylcyclotetraphosphane, (PEt)4. 1 can be obtained as a 43% solution in 1,2,3-triethyl-1,2,3-triphosphole, (PEt)3C2H2 (3), by fractional distillation of the product mixture formed in the reaction of K2(PEt)4 with ClHC=CHCl. 3 has been isolated and fully characterized. Furthermore 1 as well as (PMe)3 (2) and (PPh)3 exist besides (PR)4 (R = Et, Me, Ph) in thermodynamic equilibrium with (PR)5 at elevated temperatures; for R = Ph(PPh)6 is also formed. The thermodynamic data of the reactions 3/5 (PMe)5 ⇌ (PMe)3 and 4/5 (PMe)5 ⇌ (PMe)4 have been calculated from the equilibrium constants between 60 and 160 °C. The ring strain of 2 is much smaller than that of cyclopropane but increases with increasing size and bulk of the substituents R at the phosphorus threemembered ring.

Kinetics and Equilibrium of Binding of Fe3+ by a Fulvic Acid: A Study by Stopped Flow Methods

1975 ◽  
Vol 53 (20) ◽  
pp. 2979-2984 ◽  
Author(s):  
Cooper H. Langford ◽  
Tahir R. Khan
Keyword(s):  
Ionic Strength ◽  
Complex Formation ◽  
Fulvic Acid ◽  
Metal Ion ◽  
Equilibrium Constants ◽  
Acid Dissociation ◽  
Stopped Flow ◽  
Solution Ph ◽  
Sulfosalicylic Acid ◽  
Flow Measurements

The first report of a rate of binding of a metal ion (Fe3+) by a soluble fulvic acid is derived from stopped flow measurements. The rate of complex formation is normal in Wilkins' sense and similar to that for sulfosalicylic acid. Dissociation is slow (t1/2 > 10 s). The binding of Fe3+ by the fulvic acid in acid solution, pH = 1–2.5, was investigated by kinetic analysis in which the reaction of free Fe3+ with sulfosalicylic acid was followed by stopped flow spectrophotometry on a time scale short compared to release of Fe3+ by fulvic acid. Conditional equilibrium constants found were 1.5 ± 0.3 × 104 at pH = 1.5 and 2.5, and 2.8 ± 0.3 × 103 at pH = 1.0 at 25 °C (ionic strength 0.1).

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