scholarly journals Ruthenium redox equilibria: 2. Thermodynamic analysis of disproportionation and comproportionation conditions

2016 ◽  
Vol 6 (1) ◽  
pp. 135 ◽  
Author(s):  
Igor Povar ◽  
Oxana Spinu
Keyword(s):  
Linear Algebra ◽  
Thermodynamic Analysis ◽  
Metal Ion ◽  
Ph Value ◽  
Total Concentration ◽  
Chemical Species ◽  
Heterogeneous Chemical ◽  
Valence States ◽  
Degree Of Oxidation ◽  
Redox Equilibria

<p class="PaperKeywordTitle"><em>The key property of Frost diagram has been confirmed using thermodynamic and linear algebra methods. On the basis of the thermodynamic data, the areas of thermodynamic stability of ruthenium chemical species in different valence states as a function of pH for each degree of oxidation have been determined. Subsequently, based on the </em><em> diagrams, calculated for several values of pH, a narrow </em>Δ<em>pH value is determined, in which the dismutation of appropriate form takes place. Based on thermodynamic analysis, the exact </em><em> value of the beginning of disproportionation (or comproportionation) is found. Finally, the developed revised Frost diagrams of ruthenium heterogeneous chemical and redox equilibria, as a function of pH and the total concentration of metal ion in solution, have been built. </em></p>

Thermodynamic Analysis of Doped Titanium Dioxide Powders by Coprecipitation-Coating Process

2011 ◽  
Vol 412 ◽  
pp. 415-421
Author(s):  
Chen Jing Yang ◽  
Jing Hong Du ◽  
Guo You Gan ◽  
Ji Kang Yan ◽  
Jia Min Zhang ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Thermodynamic Analysis ◽  
Metal Ion ◽  
Ph Value ◽  
Total Carbon ◽  
Precipitation Reaction ◽  
Coating Process ◽  
Total Ammonia ◽  
Doped Titanium Dioxide ◽  
Reaction Equilibrium

On the basis of the mechanism of ions precipitation reaction equilibrium, the thermodynamic analysis of Men+(La3+, Ni2+, Fe3+, Al3+)-CO32--NH3•H2O system was discussed in this paper. The relation curves between total concentrations of each metal ion and pH values at different total ammonia concentrations cN and total carbon concentrations cC were obtained. The suitable pH value of the complete precipitation reaction for all metal ions was also determined. It shows that when cN = 0.010 mol•L-1 and cC = 1.000 mol•L-1, the optimal pH is 9.0 to prepare the doped titanium dioxide powders by coprecipitation-coating process and using NaHCO3 and NH3•H2O as the precipitants.

scholarly journals Revised Pourbaix diagrams for the vanadium – water system

2019 ◽  
Vol 9 (2) ◽  
pp. 75-84 ◽  
Author(s):  
Igor Povar ◽  
Oxana Spinu ◽  
Inga Zinicovscaia ◽  
Boris Pintilie ◽  
Stefano Ubaldini
Keyword(s):  
Thermodynamic Analysis ◽  
Total Concentration ◽  
Water System ◽  
Chemical Species ◽  
Calculated Data ◽  
Inorganic Ions ◽  
Pourbaix Diagrams ◽  
Oxidation Reduction ◽  
Novel Approach ◽  
Major Chemical

The forms of occurrence of vanadium metal are determined by the major chemical reactions in the aquatic environment such as hydrolysis, oxidation, reduction, and precipitation. Depending on pH, potential and total concentration of inorganic ions and organic ligands, vanadium compounds may undergo various transformations to produce a whole range of chemical forms in aqueous systems. In this paper, a novel approach has been applied for calculating potential-pH (Pourbaix) diagrams, based on the developed thermodynamic analysis of chemical equilibria in the V–H2O system. On the basis of currently revised thermodynamic data for V(III), V(IV) and V(V) hydrolysis and original thermodynamic and graphical approach used, the repartition of their soluble and insoluble chemical species has been investigated. By means of ΔG–pH diagrams, the areas of thermodynamic stability of V(IV) and V(V) hydroxides have been established for a number of analytical concentrations of vanadium in heterogeneous mixtures. The obtained results, based on the thermodynamic analysis and graphic design of calculated data, are in good agreement with available experimental data.

scholarly journals Ruthenium redox equilibria: 1. Thermodynamic stability of Ru(III) and Ru(IV) hydroxides

2016 ◽  
Vol 6 (1) ◽  
pp. 123 ◽  
Author(s):  
Igor Povar ◽  
Oxana Spinu
Keyword(s):  
Thermodynamic Stability ◽  
Graphical Representation ◽  
Solid Phase ◽  
Chemical Species ◽  
Calculated Data ◽  
Solution Ph ◽  
Chemical Equilibria ◽  
Heterogeneous Chemical ◽  
Homogeneous Chemical ◽  
Redox Equilibria

<p class="PaperKeywordTitle"><span lang="EN-US">On the basis of the selected thermodynamic data for Ru(III) and Ru(IV) compounds in addition to original thermodynamic and graphical approach used in this paper, the thermodynamic stability areas of sparingly soluble hydroxides as well as the repartition of their soluble and insoluble chemical species towards the solution pH and initial concentrations of ruthenium in heterogeneous mixture solid phase–saturated solution have been investigated. By means of the Δ<em>G</em>–pH diagrams, the areas of thermodynamic stability of Ru(III) and Ru(IV) hydroxides have been established for a number of analytical concentrations in heterogeneous mixtures. The diagrams of heterogeneous and homogeneous chemical equilibria have been used for graphical representation of complex equilibria in aqueous solutions containing Ru(III) and Ru(IV). The obtained results, based on the thermodynamic analysis and graphic design of the calculated data in the form of the diagrams of heterogeneous chemical equilibria, are in good agre­ement with the available experimental data. </span></p>

scholarly journals A Personal Journey across Fluorescent Sensing and Logic Associated with Polymers of Various Kinds

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1351 ◽  
Author(s):  
Chao-Yi Yao ◽  
Seiichi Uchiyama ◽  
A. Prasanna de Silva
Keyword(s):  
Phase Separation ◽  
Metal Ion ◽  
Chemical Species ◽  
Polymer Science ◽  
Molecular Sensing ◽  
Fluorescent Sensing ◽  
Molecular Logic ◽  
Fluorescent Molecular Sensing ◽  
Molecular Scale ◽  
Identification Tags

Our experiences concerning fluorescent molecular sensing and logic devices and their intersections with polymer science are the foci of this brief review. Proton-, metal ion- and polarity-responsive cases of these devices are placed in polymeric micro- or nano-environments, some of which involve phase separation. This leads to mapping of chemical species on the nanoscale. These devices also take advantage of thermal properties of some polymers in water in order to reincarnate themselves as thermometers. When the phase separation leads to particles, the latter can be labelled with identification tags based on molecular logic. Such particles also give rise to reusable sensors, although molecular-scale resolution is sacrificed in the process. Polymeric nano-environments also help to organize rather complex molecular logic systems from their simple components. Overall, our little experiences suggest that researchers in sensing and logic would benefit if they assimilate polymer concepts.

scholarly journals Comparison between Different Keratin-composed Biosorbents for the Removal of Heavy Metal Ions from Aqueous Solutions

2002 ◽  
Vol 20 (4) ◽  
pp. 393-416 ◽  
Author(s):  
Fawzi Banat ◽  
Sameer Al-Asheh ◽  
Dheaya‘ Al-Rousan
Keyword(s):  
Aqueous Solutions ◽  
Human Hair ◽  
Metal Ion ◽  
Ph Value ◽  
Freundlich Isotherm ◽  
Operating Conditions ◽  
Ion Uptake ◽  
Chicken Feathers ◽  
Initial Ph ◽  
Metal Ion Uptake

This study examined and compared the ability of chicken feathers, human hair and animal horns, as keratin-composed biosorbents, for the removal of Zn2+ and Cu2+ ions from single metal ion aqueous solutions under different operating conditions. The three biosorbents investigated in this study were all capable of adsorbing Zn2+ and Cu2+ ions from aqueous solutions. The biosorbent showing the highest uptake of Zn2+ and Cu2+ ions was animal horns. Chicken feathers showed a higher Cu2+ ion uptake and a lower Zn2+ ion compared to human hair. Increasing the initial concentration of Zn2+ or Cu2+ ions, or increasing the initial pH value, increased the metal ion uptake. Such uptake decreased when the temperature was raised from 25°C to 50°C for all adsorbent/metal ion combinations except for Zn2+ ion/human hair where the uptake increased with temperature. It was demonstrated that the addition of NaCl salt to the metal ion solution depressed the metal ion uptake. The Freundlich isotherm model was found to be applicable to the adsorption data for Cu2+ and Zn2+ ions.

scholarly journals Equilibrium modeling of mono and binary sorption of Cu(II) and Zn(II) onto chitosan gel beads

2016 ◽  
Vol 37 (4) ◽  
pp. 485-501 ◽  
Author(s):  
Józef Nastaj ◽  
Małgorzata Tuligłowicz ◽  
Konrad Witkiewicz
Keyword(s):  
Metal Ion ◽  
Ph Value ◽  
Experimental Studies ◽  
Process Conditions ◽  
Optimal Process ◽  
Sorption Data ◽  
Gel Beads ◽  
Two Component ◽  
Equilibrium Data ◽  
Chitosan Gel

Abstract The objective of the work are in-depth experimental studies of Cu(II) and Zn(II) ion removal on chitosan gel beads from both one- and two-component water solutions at the temperature of 303 K. The optimal process conditions such as: pH value, dose of sorbent and contact time were determined. Based on the optimal process conditions, equilibrium and kinetic studies were carried out. The maximum sorption capacities equaled: 191.25 mg/g and 142.88 mg/g for Cu(II) and Zn(II) ions respectively, when the sorbent dose was 10 g/L and the pH of a solution was 5.0 for both heavy metal ions. One-component sorption equilibrium data were successfully presented for six of the most useful three-parameter equilibrium models: Langmuir-Freundlich, Redlich-Peterson, Sips, Koble-Corrigan, Hill and Toth. Extended forms of Langmuir-Freundlich, Koble-Corrigan and Sips models were also well fitted to the two-component equilibrium data obtained for different ratios of concentrations of Cu(II) and Zn(II) ions (1:1, 1:2, 2:1). Experimental sorption data were described by two kinetic models of the pseudo-first and pseudo-second order. Furthermore, an attempt to explain the mechanisms of the divalent metal ion sorption process on chitosan gel beads was undertaken.

scholarly journals Effective removal of heavy metal ions from aqueous solutions using a new chelating resin poly [2,5-(1,3,4-thiadiazole)-benzalimine]: kinetic and thermodynamic study

2015 ◽  
Vol 6 (2) ◽  
pp. 310-324 ◽  
Author(s):  
Selvaraj Dinesh Kirupha ◽  
Selvaraj Kalaivani ◽  
Thangaraj Vidhyadevi ◽  
Periyaraman Premkumar ◽  
Palanithamy Baskaralingam ◽  
...  
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Ph Value ◽  
Thermo Gravimetric Analysis ◽  
Kinetic Studies ◽  
Ion Concentration ◽  
Chelating Resin ◽  
Gravimetric Analysis ◽  
Equilibrium Data ◽  
Experimental Values

A novel poly [2,5-(1,3,4-thiadiazole)-benzalimine] abbreviated as TDPI adsorbent was synthesized using simple polycondensation technique. The synthetic route involves the preparation of 2,5-diamino-1,3,4-thiadiazole from 2,5-dithiourea and subsequent condensation with terephthalaldehyde. The resin was chemically characterized using Fourier transform infrared (FT-IR), 1H-NMR, and 13C-NMR spectroscopic analysis. Surface morphology and thermal stability were analyzed using scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA). The effect of the pH value of solution, contact time, adsorbent dose, and initial metal ion concentration were investigated by batch equilibrium adsorption experiments. Kinetic studies show that the adsorption of metal ions onto the resin proceeds according to the pseudo-second-order model and the equilibrium data were best interpreted by the Redlich–Peterson isotherm. The experimental values of the adsorption capacities of Pb2+, Cu2+, Ni2+, and Cd2+ on to TDPI could reach up to 437.2, 491.6, 493.7, and 481.9 mg.g−1 respectively. The exothermic nature of the process, the affinity of the adsorbent towards the metal ions and the feasibility of the process are explained in the thermodynamic parameters. The resin stability and re-usability studies suggest that the resin is chemically stable (0.3 N HCl and H2SO4) and could be regenerated without any serious decline in performance.

GAS EXCHANGES AND BLOOD GAS CONCENTRATIONS IN THE FORG RANA RIDIBUNDA

1974 ◽  
Vol 60 (3) ◽  
pp. 901-908
Author(s):  
M. G. EMíLIO
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Ph Value ◽  
Total Concentration ◽  
Blood Gas ◽  
Gas Exchanges ◽  
Arterial Blood ◽  
Low Levels ◽  
Time Courses ◽  
Metabolic Carbon

1. The respiratory exchanges through the lungs and skin of frogs and the time courses of blood gas concentrations were studied during emergence and diving periods. 2. Most of the total oxygen uptake is carried out through the lungs. The partial pressure of oxygen in arterial blood falls to very low levels a few minutes after diving, showing that the cutaneous respiratory surface cannot compensate for the lack of lung respiration. 3. Most of the metabolic carbon dioxide is disposed of through the skin. Although the skin output is maintained through diving periods, there is an important rise in the partial pressure of carbon dioxide in blood following submergence. However, the total concentration of CO2 in the blood decreases, as does the blood pH value. 4. This phenomenon is probably the result of a metabolic acidosis due to the switching on of anaerobic processes during diving periods.

scholarly journals Preparation of hydroxyapatite-based porous materials for absorption of lead ions

2019 ◽  
Vol 80 (7) ◽  
pp. 1266-1275
Author(s):  
Zejun Wang ◽  
Kangqi Sun ◽  
Yufeng He ◽  
Pengfei Song ◽  
Dawei Zhang ◽  
...  
Keyword(s):  
Porous Materials ◽  
Metal Ion ◽  
Ph Value ◽  
Soybean Protein ◽  
Protein Isolate ◽  
Soybean Protein Isolate ◽  
Bet Analysis ◽  
Initial Ph ◽  
Infrared Spectrometer ◽  
Composition Structure

Abstract In this paper, soybean protein isolate (SPI) was used as template, hydroxyapatite was crystallized on protein chains of SPI by in-situ synthesis, then the obtained inorganic HA/biopolymer SPI composite (HA@SPI) was calcined at suitable temperature, which afforded a novel hydroxyapatite-based porous materials (HApM). The results indicated that the product showed a porous morphology structure and excellent absorption performance for Pb2+. HApM maximum removal of lead was attained (96.25%) at an initial pH value of 7.4, temperature of 25 °C and contact time of 30 min with an initial metal concentration of 60 mg/L. In order to identify composition, structure and functional groups involved in the uptake of Pb2+, Fourier transform infrared spectrometer (FTIR), thermogravimetric analysis (TG), X-ray diffraction (XRD) scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Brunauer–Emmett–Teller (BET) analysis were carried out. Therefore, the hydroxyapatite-based porous materials (HApM) is a promising candidate for the treatment of liquid wastes containing toxic Pb2+ metal ion, heavy metal ion antidotes and other related fields.

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