scholarly journals Ammonia/ammonium dissociation coefficient in seawater: A significant numerical correction

2007 ◽  
Vol 4 (3) ◽  
pp. 183 ◽  
Author(s):  
Thomas G. Bell ◽  
Martin T. Johnson ◽  
Timothy D. Jickells ◽  
Peter S. Liss
Keyword(s):  
Ionic Strength ◽  
Natural Waters ◽  
Ammonia Toxicity ◽  
Acid Dissociation ◽  
Gaseous Ammonia ◽  
Accurate Estimation ◽  
Environmental Processes ◽  
Climate Regulation ◽  
Natural Temperature ◽  
Ammonia Exchange

Environmental context. Quantifying ammonia concentrations in natural waters is important for our understanding of environmental processes that relate, in particular, to aquaculture toxicity and to the transfer of gaseous ammonia into the atmosphere where it plays a role in new particle formation and climate regulation. The proportion of ammonia present in natural waters is determined in part by variations in temperature and salinity. This work identifies that a previous equation for predicting ammonia concentrations over natural temperature and salinity ranges is incorrect and suggests alternative, more appropriate equations. A more accurate estimation of environmental ammonia concentrations is essential if improved estimates are to be made of the flux of ammonia into the atmosphere and the level of ammonia toxicity within aquacultures. Abstract. The equilibrium between ammonia (NH3) and ammonium (NH4+) in aqueous solution is a function of temperature, pH and the ionic strength of the solution. Here we reveal a 30-year-old error in published work on the thermodynamics of ammonium dissociation in seawater, which has propagated throughout the literature. The work in question[1] [K. H. Khoo, C. H. Culberson, R. G. Bates, J. Solution Chem. 1977, 6, 281] presents an incorrect expression for the variation of the acid dissociation coefficient (Ka) of ammonium with temperature and ionic strength. We detail the error and reveal that it can lead to as much as a 500% overestimation in calculated NH3 concentration under environmental conditions. This finding is highly relevant, particularly for studies of ammonia toxicity and air–sea ammonia exchange. In addition, we recommend two expressions that better reproduce previous experimental work: (i) taken from the work of Johansson and Wedborg,[2] and (ii) our own derivation using the dataset of Khoo et al.[1]

scholarly journals High ionic strength dissociation assay (HISDA) for high drug tolerant immunogenicity testing

Bioanalysis ◽  
2020 ◽  
Author(s):  
Gregor Jordan ◽  
Alexander Pöhler ◽  
Florence Guilhot ◽  
Meike Zaspel ◽  
Roland F Staack
Keyword(s):  
Ionic Strength ◽  
Acid Treatment ◽  
Structural Integrity ◽  
Drug Tolerance ◽  
High Ionic Strength ◽  
Acid Dissociation ◽  
High Drug ◽  
Overnight Incubation ◽  
Antidrug Antibody ◽  
High Doses

Aim: Antidrug antibody (ADA) assessment may be challenged in studies that involve the administration of high doses of biotherapeutics and/or with long half-lives. In such cases, ADA assays with optimized drug tolerance are desired. Material & Methods: We evaluated the use of MgCl2 to develop high ionic strength dissociation assays in two investigational examples (bridging enzyme-linked immunosorbent ADA assays) to attain high drug tolerance while maintaining best possible structural integrity of ADAs. Results: Both ADA-bridging assays treated with MgCl2 showed improved drug tolerance and higher signal-to-blank values compared with overnight incubation or acid treatment. Conclusion: The use of MgCl2 treatment in ADA-bridging assays provides a sensitive, drug tolerant and easy-to-use alternative in cases where acid dissociation is not possible or unwanted.

The comparative chemistry of ammine and methylamine complexes of rhodium(III) and cobalt(III)

1977 ◽  
Vol 55 (17) ◽  
pp. 3166-3171 ◽  
Author(s):  
Thomas Wilson Swaddle
Keyword(s):  
Ionic Strength ◽  
Spectral Data ◽  
Electron Donor ◽  
Dissociation Constants ◽  
Base Hydrolysis ◽  
Acid Dissociation ◽  
Rate Coefficients ◽  
Acid Dissociation Constants ◽  
First Order ◽  
Kinetics Of

For the aquation of (CH3NH2)5RhCl2+, the first order rate coefficients are represented by ΔHaq* = 101.9 kJ mol−1 and ΔSaq* = −50.2 JK−1 mol−1 in 0.1 M HClO4, while for base hydrolysis the rate is first order in [(CH3NH2)5RhCl2+] and [OH−] at ionic strength 0.10 M and the rate coefficients (in M−1 s−1) are represented by ΔHOH*> = 108.6 kJ mol−1 and ΔSOH* = 74.1 J K−1 mol−1. Acid dissociation constants are reported for (RNH2)5MOH23+ (R = H or CH3; M = Rh or Co), and these, combined with spectral data, show CH3NH2 to be a poorer electron donor than NH3 in complexes of this type, contrary to expectations. The comparative kinetics of reactions of (RNH2)5MCl2+ support the assignment of an Ia mechanism to aquation when M = Rh or Cr, Id to aquation when M = Co, and Dcb for base hydrolysis in all these cases.

Effect of Humic Substances on Americium (III) Retention onto Silica

1988 ◽  
Vol 127 ◽  
Author(s):  
Valerie Moulin ◽  
Denise Stammose
Keyword(s):  
Ionic Strength ◽  
Humic Substances ◽  
Safety Assessment ◽  
Natural Waters ◽  
Major Influence ◽  
Liquid Interfaces ◽  
Aquifer Systems ◽  
Humic Materials ◽  
Solid Liquid ◽  
Influence Of Ph

ABSTRACTThe migration/retention phenomena of radionuclides in geological systems are of great interest for the safety assessment of a nuclear disposal. Interactions at solid/liquid interfaces play a significant role in the speculation and transport of radionuclides in aquifer systems. Oxide surfaces and humic substances which occur in natural waters in large concentration ranges (from few mg/1 to several hundred mg/1) may have a major influence on radionuclides behaviour. For this purpose, studies have been carried out on a ternary system: oxide-humic substances-americium (III). The influence of pH, ionic strength and humic concentration on the adsorption of americium onto silica has been investigated. The ionic strength of the solution (0.1 and 0.01) has little effect on the americium adsorption. In the presence of humic materials, the fixation of americium is enhanced at low pH (pH<5) whereas, at higher pH (pH>5), the adsorption is lowered and dependent of humic concentration.

scholarly journals Effect of ionic strength on the ion exchange equilibrium between AMX membrane and electrolyte solutions

2015 ◽  
Vol 51 (1) ◽  
pp. 60-68 ◽  
Author(s):  
Islem Louati ◽  
Fatma Guesmi ◽  
Akram Chaabouni ◽  
Chiraz Hannachi ◽  
Béchir Hamrouni
Keyword(s):  
Ionic Strength ◽  
Ion Exchange ◽  
Anion Exchange ◽  
Natural Waters ◽  
Electrolyte Solutions ◽  
Anion Exchange Membrane ◽  
Exchange Equilibrium ◽  
Thermodynamic Constants ◽  
Separation Factors ◽  
Exchange Membrane

The effect of ionic strength variation on the ion exchange equilibrium between AMX anion exchange membrane and electrolyte solutions containing the most dominant anions on natural waters (Cl−, NO3−, and SO42−) was studied. All experiments were carried out at a constant temperature of 25 °C. Ion exchange isotherms were established, at different ionic strengths from 0.1 to 0.5 M, for the systems (Cl−/NO3−), (Cl−/SO42−) and (NO3−/SO42−). Obtained results showed that for I = 0.1 M the affinity order is SO42 −&gt;NO3−&gt;Cl−. For I = 0.2 M this order is NO3−&gt;SO42−&gt;Cl−. For 0.3 and 0.5 M the AMX membrane becomes more selective for chloride than for nitrate or sulfate. Selectivity coefficients KNO3−Cl−, K2Cl−SO42− and K2NO3−SO42−, thermodynamic constants, and separation factors were calculated and decreased with the increase of ionic strength.

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).

Pyridine nitrosazones and their cobalt(III) chelates

1977 ◽  
Vol 55 (21) ◽  
pp. 3707-3711 ◽  
Author(s):  
Ahmad Sami Shawali ◽  
Ikhlass M. Abbass
Keyword(s):  
Ionic Strength ◽  
Spectral Data ◽  
Dissociation Constants ◽  
Ring Structure ◽  
Membered Ring ◽  
Acid Dissociation ◽  
Acid Dissociation Constants ◽  
Transition Energies ◽  
Amyl Nitrite ◽  
Good Agreement

Nitrosation of pyridine aldehyde p-tolylhydrazones 2 with amyl nitrite gives rise to p-tolueneazopyridine aldoximes 4 which form stable tris chelates with cobalt(III). Spectral data (ir, uv, and 1Hmr) indicate that the ligands exist mainly in the assigned azooxime structure 4, and that their chelates have five-membered ring structure 7. Also, the 1Hmr spectra imply mer-configuration 9 for the chelates examined. No evidence for the tautomeric nitrosohydrazone structure 3 for the ligands and the fac-configuration 8 for Co(III) chelates could be obtained. Using the HMO method, the azooxime form 4 for the ligand was shown to be more stable than the nitrosohydrazone structure 3. Also, good agreement was obtained between observed transition energies and those calculated by the HMO method. The acid dissociation constants of the ligands in 50 vol% ethanol–water at 25 °C and ionic strength of 0.1 were determined spectrophotometrically.

Studies on Horseradish Peroxidase. VII. A Kinetic Study of the Oxidation of Iodide by Horseradish Peroxidase Compound II

1971 ◽  
Vol 49 (18) ◽  
pp. 3059-3063 ◽  
Author(s):  
R. Roman ◽  
H. B. Dunford ◽  
M. Evett
Keyword(s):  
Ionic Strength ◽  
Horseradish Peroxidase ◽  
Kinetic Study ◽  
Rate Constant ◽  
Ph Dependence ◽  
Order Rate Constant ◽  
Acid Dissociation ◽  
Ph Range ◽  
Compound Ii ◽  
Kinetics Of

The kinetics of the oxidation of iodide ion by horseradish peroxidase compound II have been studied as a function of pH at 25° and ionic strength of 0.11. The logarithm of the second-order rate constant decreases linearly from 2.3 × 105 to 0.1 M−1 s−1 with increasing pH over the pH range 2.7 to 9.0. The pH dependence of the reaction is explained in terms of an acid dissociation outside the pH range of the study.

scholarly journals Amine-based Carbon Dioxide Absorption: The Ionic Strength Effect on the Monoethanolamine Protonation Constant at Temperatures from 313 to 333K

2020 ◽  
Vol 19 (2) ◽  
pp. 83
Author(s):  
Sholeh Ma'mun ◽  
Panji Kumala Setiawan ◽  
Egip Indrayanto
Keyword(s):  
Carbon Dioxide ◽  
Ionic Strength ◽  
Protonation Constant ◽  
Acid Dissociation ◽  
Reactive System ◽  
Co2 Removal ◽  
Co2 Absorption ◽  
Pka Values ◽  
Ionic Strength Effect ◽  
Strength Effect

Amine-based absorption has been extensively used for carbon dioxide (CO2) removal processes, such as CO2 absorption from flue gas as well as from natural gas. As a reactive system in which the chemical reaction, as well as mass transfer, occur simultaneously, an experimental determination of equilibrium reaction constants, e.g. acid dissociation/protonation constant (Ka), is, therefore, necessary to be conducted. This study aims to evaluate the ionic strength effect from 0.06 to 6.0 m (mol/kg water) on the Ka value of monoethanolamine (MEA) at temperatures between 313 and 333K. The experimental results indicate that the pKa values tend to be increasing as the ionic strength increases. This is contradicting to the temperature effect where the pKa values tend to be decreasing as the temperature increases. Furthermore, the extended Debye-Hückel formulation was implemented to predict the species activity coefficients.

scholarly journals Concentration effect of Sodium Chloride Salt on Benzoic Acid Solubility and Dissociation into Water at 298 K Temperature

2021 ◽  
pp. 47-52
Author(s):  
Shiv Prakash Mishra
Keyword(s):  
Sodium Chloride ◽  
Ionic Strength ◽  
Benzoic Acid ◽  
Dissociation Constant ◽  
Acid Dissociation ◽  
Concentration Effect ◽  
Chloride Salt ◽  
Acid Dissociation Constant ◽  
Basic Solution ◽  
Acid Solubility

In article, we have been reported the study of a concentration effect of sodium chloride (NaCl) salt on benzoic acid solubility and its dissociation in water at 298 K temperature. At this temperature the benzoic acid solubility into water and their dissociation value for six samples in range of 0.00, 0.05, 0.10, 0.30, 0.40 and 0.50 M. Each of these different ionic strength or concentration of sodium chloride is analyzed by titrimetrically against of 0.05 M sodium hydroxide (NaOH) basic solution. The pH of each solution is measured well by using of calibrated pH-meter. Observation reveals that the value of pH of benzoic acid into water at applying temperature is may inversely related with concentration of NaCl. Graphically, the value of ionic strength (I) of that benzoic acid is plotted versus with dissociation constant (Kc) of acid into water at specific 298 K temperature. The value of benzoic acid dissociation constant for given each six concentration of NaCl is found to be -4.169, -4.045, -3.993, -3.885, -3.848 and -3.788, respectively.

Investigation of V(V) interaction with Humic Acid in aqueous solution using anion-exchange Ion Chromatography

2021 ◽  
Author(s):  
Lucija Knežević ◽  
Elvira Bura-Nakić
Keyword(s):  
Humic Acid ◽  
Ionic Strength ◽  
Anion Exchange ◽  
Ion Chromatography ◽  
Natural Waters ◽  
Detection System ◽  
Chemical Species ◽  
Research Report ◽  
Complexing Agent ◽  
Model Solutions

&lt;p&gt;The distribution of V chemical species in natural waters has been scarcely studied mainly due to its high reactivity and wide variety of co-existing forms depending on number of factors including metal concentration, pH, Eh, ionic strength, the presence of complexing ligands etc. &lt;sup&gt;1&lt;/sup&gt; Importance of V speciation studies lies in the dependence of toxicity and bioavailability upon different chemical species that V takes form of in natural waters, with V(V) being most toxic and soluble &lt;sup&gt;4&lt;/sup&gt;. Although thermodynamic calculations predict V(V) as dominant species in well oxidized marine environments, V(IV) is also reported to be present due to its ability to form stable complexes with Dissolved Organic Matter (DOM) related ligands found in natural waters &lt;sup&gt;2&amp;#8211;6&lt;/sup&gt;. Furthermore, previous research report that Humic Acid (HA) acts as an adsorbent and complexing agent for many trace metals (Cu&lt;sup&gt;2+&lt;/sup&gt;, Zn&lt;sup&gt;2+&lt;/sup&gt;, Cd&lt;sup&gt;2+&lt;/sup&gt;, Fe&lt;sup&gt;2+&lt;/sup&gt;). However, HA impact on V speciation and potential removal from the water column of natural aquatic systems is still unclear &lt;sup&gt;7&lt;/sup&gt;.&lt;/p&gt;&lt;p&gt;Interaction of V(V) with HA was investigated in model solutions under different conditions using anion-exchange based Ion Chromatography with UV/Vis detection system. The goal of the research was to mimic natural conditions, as experimentally possible, in order to assess likely contribution of HA to changes in V speciation and potential removal from the solution by adsorption on HA colloids. Temporal study on V(V) reduction kinetics was conducted using strong chelator (EDTA) which was added in the filtrated solution prior to measurement in order to stabilize distribution of V species in the model solutions. Removal of V(V) from the solution on HA particles was quantified using calibration curves. Desorption experiments were performed with the addition of EDTA in un-filtrated solutions 24 hours before measurement.&lt;/p&gt;&lt;p&gt;Research showed that V interaction with HA is highly dependant on ionic strength of solution as well as ratios between V(V) and HA present in the solution. Desorption experiments showed almost complete recovery of V in the solutions with higher ionic strength, mainly in the form of V(IV). Observed reduction and removal of V(V) from the solution on the pH of natural waters suggest high impact of DOM on V speciation and consequently its toxicity and bioavailability. &amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References:&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;1&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; P. N. Linnik and R. P. Linnik, Russ. J. Gen. Chem., 2018, &lt;strong&gt;88&lt;/strong&gt;, 2997&amp;#8211;3007.&lt;/p&gt;&lt;p&gt;2&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; J. P. Gustafsson, Appl. Geochemistry, 2019, &lt;strong&gt;102&lt;/strong&gt;, 1&amp;#8211;25.&lt;/p&gt;&lt;p&gt;3&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; P. Bern&amp;#225;rdez, N. Ospina-Alvarez, M. Caetano and R. Prego, Environ. Chem., 2013, &lt;strong&gt;10&lt;/strong&gt;, 42&amp;#8211;53.&lt;/p&gt;&lt;p&gt;4&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; D. Wang and S. A. Sa&amp;#241;udo Wilhelmy, Mar. Chem., 2009, &lt;strong&gt;117&lt;/strong&gt;, 52&amp;#8211;58.&lt;/p&gt;&lt;p&gt;5&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; K. Hirayama, S. Kageyama and N. Unohara, Analyst, 1992, &lt;strong&gt;117&lt;/strong&gt;, 13&amp;#8211;17.&lt;/p&gt;&lt;p&gt;6&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; D. Wang and S. A. Sa&amp;#241;udo-Wilhelmy, Mar. Chem., 2008, &lt;strong&gt;112&lt;/strong&gt;, 72&amp;#8211;80.&lt;/p&gt;&lt;p&gt;7&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; Y. Yu, M. Liu and J. Yang, Chem. Ecol., 2018, &lt;strong&gt;34&lt;/strong&gt;, 548&amp;#8211;564.&lt;/p&gt;

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