thermodynamic probability
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CORROSION ◽  
10.5006/3917 ◽  
2021 ◽  
Author(s):  
Kang Wang ◽  
Charles Demarest ◽  
Mathew Asmussen ◽  
John Scully ◽  
Bi-Cheng Zhou

Rubidium (Rb) generated from the β-decay of Kr-85 has been theorized to be corrosive toward steel, specifically in the storage of Kr-85 nuclear waste streams. In the present study, the phase equilibria of RbxCryOz oxides with Rb in dry oxygen and water are investigated to understand a possible pathway to unusual deterioration of the corrosion resistance of canister steels in the presence of Rb. It was found that, in dry oxygen environments, the accumulation of Rb (more than 0.01 mol) can completely consume the Cr in 1 mol of AISI 4130 steel by forming -Rb2CrO4 and Rb3CrO4 and prevent the formation of protective Cr2O3 scale. In aqueous environments, RbxCryOz oxides are metastable species. In order to investigate their role, the probability of forming various oxides is invoked in order to avoid the all-or-nothing approach to oxide formation typical of E-pH diagram, which only predicts the most stable species dissolved, ionized or solid ionized. Thus, the probability of forming RbxCryOz was considered and reported herein. It was found RbxCryOz can possess a larger than 7% probability of forming over Cr2O3 in Rb rich case and 15% in Cr rich case, indicating that it is expected to find small amount of RbxCryOz in the thermodynamically formed reaction products. Even though Cr2O3 is more stable than RbxCryOz oxides, the protective Cr2O3 scale is likely to have some vulnerability to Rb, leading to one possible route for the decline in the corrosion resistance of steel canisters in aqueous environments. Therefore, from a thermodynamic perspective, the current study supports the hypothesis that Rb can thermodynamically react with Cr in steels and can lead to formation of RbxCryOz at certain potentials and pH levels, showing the Rb influence of steel corrosion cannot be discounted. The paper considers experimental mixed potential and pH levels observed and relationship to thermodynamic probability. From this relative corrosion resistance can be assessed in a preliminary way in aqueous environments.


Surface ◽  
2020 ◽  
Vol 12(27) ◽  
pp. 20-35
Author(s):  
О. V. Filonenko ◽  
◽  
E. M. Demianenko ◽  
V. V. Lobanov ◽  
◽  
...  

Quantum chemical modeling of orthophosphoric acid adsorption sites on the hydrated surface of anatase was performed by the method of density functional theory (exchange-correlation functional PBE0, basis set 6-31 G(d,p)). The influence of the aqueous medium was taken into account within the framework of the continual solvent model. The work uses a cluster approach. The anatase surface is simulated by a neutral Ti(OH)4(H2O)2 cluster. The results of analysis of the geometry and energy characteristics of all the calculated complexes show that the highest interaction energy is inherent to the intermolecular complex of orthophosphoric acid and hydrated surface of anatase, where the oxygen atom of the phosphoryl group (О=Р≡) forms a hydrogen bond with a hydrogen atom of the coordinated water molecule of Ti(OH)4(H2O)2 cluster and two hydrogen atoms of the hydroxyl groups of the orthophosphoric acid molecule form two hydrogen bonds with two oxygen atoms of the titanol groups. The formation energy effect of this complex is -134.0 kJ/mol. The formation energy effect of the complex with separated charges by the proton transfer from the molecule H3PO4 to the Ti(OH)4(H2O)2 cluster with the formation of dihydrogen phosphate anion and the protonated form of the titanol group (º) is -131.1 kJ/mol, so indicating less thermodynamic probability of such intermolecular interaction. The smallest thermodynamic probability (-123.9 kJ/mol) of complexation between orthophosphoric acid and hydrated anatase surface where a water molecule moves from the coordination sphere of the titanium atom. The calculation results indicate a possible adsorption of the H3PO4 molecule in an aqueous solution on the hydrated anatase surface. Taking into account the effect of the solvent within the polarization continuum insignificantly changes the adsorption energy, which is -44.5 kJ/mol; for vacuum conditions this value is -49.0 kJ/mol.


2020 ◽  
Vol 63 (9) ◽  
pp. 83-89
Author(s):  
Larisa N. Maskaeva ◽  
◽  
Anastasia V. Beltseva ◽  
Andrew V. Pozdin ◽  
Vyatcheslav F. Markov ◽  
...  

Analysis of the literature showed that narrow-gap lead sulfide PbS (0.4 eV at 300 K), due to its unique properties, has found wide application in such devices as photodetectors with a wide (from infrared to ultraviolet) radiation range, solar energy converters, chemical sensors, temperature sensors, flame detectors, etc. Doping of lead sulfide with various metal ions can affect the bandgap, and hence expand the scope of its application. Of particular interest is the preparation of thin film solid solutions in the PbS – FeS system, which can lead to the appearance of ferromagnetism in lead sulfide. To obtain doped films of lead sulfide and solid solutions based on it, the method of chemical deposition from aqueous media is considered promising, which, in addition to its cost-effectiveness and simplicity of the process, allows one to determine in advance the areas of formation of the semiconducting metal chalcogenides of interest. The analysis of ionic equilibria in the systems "PbAc2 – FeCl2 – Na3Cit – NH4OH – N2H4CS", "PbAc2 – FeCl2 – NaAc – NH4OH – N2H4CS "and " PbAc2 – FeCl2 – Na2С2О4 – NH4OH – N2H4CS "made it possible to reveal predominantly forms of metals in a given pH range. To assess the conditions for the deposition of the main and impurity phases by thermodynamic calculations taking into account the sizes of critical nuclei, the boundary conditions and regions of the formation of FeS, PbS, Fe(OH)2, Pb(OH)2 in the reaction systems under study were found. It is shown that the most promising for the preparation of the three-component PbFeS compound, which does not contain impurity phases of lead and iron hydroxides, is the reaction system "PbAc2 – FeCl2 – Na3Cit – NH4OH – N2H4CS". The possibility of obtaining PbS: Fe films with a uniform iron distribution of ~ 0.5 at.% and deviation from stoichiometry towards Pb deficiency (47.7 at.%) and S excess (50.7 at.%) was experimentally demonstrated.


2020 ◽  
Author(s):  
JAYDIP DATTA

In our earlier Review some descriptive statistical features like linear regression aspects of Karl Pearson Coefficient / Correlation coefficient [ 1 ] has been studied specially. But the knowledge of Basic Statistics is the foundation course of STATISTICAL THERMODYNAMICS . The significant Correlation ( R^2 lies between 0.2 – 0.85 ) is nothing but the measure of PROBABILITY . Thus the Thermodynamic Probability (T.P ) is a function of Weights of the Configuration ( W ) [2]Stirling’s approximation [ 2 ] is also a good convergence with T.P as well randomisation aspects of Entropy or Weights of Configuration ( W ) .


2020 ◽  
Vol 299 ◽  
pp. 968-973
Author(s):  
Denis A. Rogozhnikov ◽  
Andrey A. Shoppert ◽  
L.M. Karimova

This article describes the problems of deterioration of the quality of processed raw materials due to depletion of mineral resources. It is proposed to use nitric acid for the processing of complex refractory low-grade concentrates containing non-ferrous and noble metals. It was found that the studied concentrate contains: sphalerite (26.9 %), pyrite (22.0 %), chalcopyrite (19.9 %), silica (13.9 %), alumina (5.5 %), galena (1.7 %), oxidized forms of iron (Fe2O3) (12 %). Gold and silver are associated with sulfide minerals. Typical reactions of interaction of these minerals with nitric acid are considered. A sufficiently high thermodynamic probability of these reactions in a wide temperature range is established. With the use of mathematical methods, the optimal conditions of the process of nitric acid leaching are selected: the ratio of L:S = 5:1; the concentration of nitric acid 10 mol/L; the duration of the process is 60 minutes. In this case, the extraction of copper, zinc, iron and sulfur into the solution was 99.00 %, 99.84 % 98.60 %, 88.51 %, respectively.


Chemija ◽  
2019 ◽  
Vol 30 (4) ◽  
Author(s):  
Kazimieras Mikulskis ◽  
Stasė Kanapeckaitė ◽  
Arvydas Survila

The distribution of species in Cu(II)-glycine solutions, containing sulfate or perchlorate as a supporting electrolyte, is considered. Substantial differences are observed at pH < 4.5, where the molar fraction of monoligand complex (associate) CuSO4 reaches up to 20 percent of the total Cu(II) concentration. Cu(I)-containing species are generated at the Cu|solution interface. These are Cu+ aqua-complexes (acid media) or mono- and bidentate Cu(I)-glycine complexes (alkaline media). The addition of sulfate reduces the content of Cu+ ions, but practically does not affect the distribution of Cu(I) complexes. The study of acidbase equilibria involving Cu+ ions shows that the thermodynamic probability of Cu2O formation remains low in both perchlorate and sulfate media. HSO4– ions formed in acid media should be treated as rather labile proton donors. This is quantitatively confirmed by experimental data, according to which the rate of hydrogen evolution increases correspondingly when perchlorate is replaced by sulfate in glycine solutions.


2018 ◽  
Author(s):  
Б.А. Усербаева ◽  
С.Т. Тлеуова ◽  
А.С. Тлеуов ◽  
S.D. Arystanova

To study the multifunctional sorption properties of local bentonite clays, physicochemical studies of the chemical, mineralogical, and phase characteristics of Darbazin clays and the intumescent oil sludge additive were conducted. Physico - chemical studies have established the contents of the mineral and organic part of sludge. As a result, it was found that paraffin-naphthenic and aromatic compounds predominate in the organic part, while compounds of silicon, calcium, aluminum and iron predominate in the mineral part. Studies on the method of modifying local bentonites with acid and heat treatment, which activate the sorption properties, due to the cation exchange of the initial elements of montmorillonite minerals. The method of temperature-reduction and desorption of hydrogen absorption region are set at °350C, 650°Cand stripping at 433C.° The thermodynamic studies of calculation of Gibbs energy of possible reactions with adsorbents synthetic minerals additive sludge found that the highest thermodynamic probability minerals characterized by synthesis in the presence of C6H6, and the smallest - in the presence of CH4. Для изучения многофункциональных сорбционных свойств местных бентонитовых глин проведены физико – химические исследования химических, минералогических и фазовых особенностей Дарбазинских глин и вспучивающей добавки нефтяных шламов. Физико – химическими исследованиями установлены содержания минерологической и органической части нефтешламов. В результате установлено, что в органической части преобладают парафинно – нафтеновые и ароматические соединения, а в минеральной части преобладают соединения кремния, кальция, алюминия и железа. Проведенные исследования метода модифицирования местных бентонитов кислотной и термической обработкой, которые активируют сорбционные свойства, за счет катионного обмена исходных элементов монтмориллонитовых минералов. Методом термопрограммированного восстановления и десорбции водорода установлены области поглощения при 350оC, 650оС и десорбции при 433оС. Термодинамическими исследованиями расчета энергии Гиббса возможных реакций синтеза минералов сорбентов с добавкой нефтешлама установлено, что наибольшей термодинамической вероятностью характеризуется синтез минералов в присутствии С6Н6, а наименьшей – в присутствии СН4.


Author(s):  
Dennis Sherwood ◽  
Paul Dalby

This chapter broadens the reader’s appreciation, and understanding, of entropy. Starting with the reader’s intrinsic recognition of the difference between an ‘ordered’ and a ‘disordered’ state, this chapter introduces the concepts of microstates, macrostates and thermodynamic probability, leading firstly to the Boltzmann equation, and then to the relationships between entropy and the flow of time, entropy and information, and Maxwell’s demon. Finally, this chapter introduces the less familiar topics of ‘thermoeconomics’ - the application of the principles of thermodynamics to economic systems – and ‘organodynamics’ – the idea that high-performing teams are systems which maintain a high degree of order, and low entropy, over time, without breaking the Second Law.


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