Thermodynamic Data Research Articles

Modeling of Solubility Product of TiN in Ti‐Microalloyed Steels

Most carbonitride solubility products of Ti do not consider the influence of commonly contained alloying elements such as Mn and Si in predicting the dissolution law of carbonitrides in steels, which would cause a deviation between the experimental data and predicted values. To solve this problem, the solubility product models of TiN and TiC in austenite considering the influence of Mn, Mo, Cr, Si, and Al are established in the present study based on the two‐sublattice model and relevant thermodynamic data. Different austenitizing temperatures are designed to analyze the precipitation law of the precipitates of a C–Si–Mn–Al–Mo–Ti–N steel. The experimental results show that the complete solution temperature of TiC is consistent with the calculation results of the TiC solubility product model. Due to the similar method establishing the TiC solubility product model, it is reasonably inferred that the predicting accuracy by the TiN solubility product model can be ensured. Additionally, as the austenitizing temperature increases, TiC particles completely dissolve between 1050 and 1100 °C, and then TiN particles begin to ripen when the temperature exceeds 1200 °C.

Space Charges at SrTiO3|Mixed Ionic and Electronic Conducting Oxide Heterojunctions and Their Relation to Defect Chemistry.

Mixed ionic and electronic conductors (MIECs) are a highly relevant material class in the field of solid-oxide cells and are, for example, promising candidates for electrodes with fast interfacial reaction kinetics. While there are many studies dealing with the bulk conductivities of such MIECs, models describing the interfaces between two mixed-conducting oxides have been far less developed. This study focuses on the investigation of space charges at the interfaces of the model perovskite SrTiO3 with different MIECs. Impedance spectroscopic measurements at 500 °C revealed that the MIECs under investigation can be divided into materials leading to negligible (YBa2Cu3O7-δ), moderate [(La,Sr)FeO3-δ, (La,Sr)CoO3-δ], and large [(La,Sr)MnO3-δ, (La,Sr)CrO3-δ] space charge resistances in SrTiO3 single crystals. The fundamental cause for these different space charge resistances is different space charge potentials, and we show that these can be determined by various methods with excellent agreement, ranging from X-ray photoelectron spectroscopy to impedance spectroscopy and photovoltage measurements. A model is introduced to correlate the ionic and electronic driving forces determining the space charges and to predict the space charge potentials from the electronic and ionic bulk properties of the corresponding mixed-conducting oxides. This model is also used to relate space charge potentials with reducibilities of MIECs, i.e., transition points from hole to vacancy compensation of an acceptor dopant in defect chemical Brouwer diagrams. The predicted trends are in good agreement with thermodynamic data on defect formation energies from the literature. Accordingly, the given model provides a widely applicable framework to predict and describe the space charge properties of a variety of MIEC heterojunctions.

Fate of phosphorus and potassium in gasification of wheat bran and sunflower seed shells

Fate of phosphorus and potassium in gasification of wheat bran and sunflower seed shells

Heat capacity and absolute standard entropy of Sr(BH4)2

Abstract Strontium boranate (Sr(BH4)2) has garnered significant interest within the hydrogen storage community due to its relatively high hydrogen content of approximately 6%. The design of reactive hydride mixtures for reversible hydrogen storage requires the availability of reliable thermodynamic data. This article details the synthesis of Sr(BH4)2 using a wet chemical metathesis reaction. Subsequent to this, the heat capacity of Sr(BH4)2 was determined between 1.8 K and 550 K using two different calorimetric methods. Utilizing these values, the absolute standard entropy at 298.15 K was calculated to be S°(298.15 K) = (147.1 ± 3.7) J mol−1 K−1.

Determination of the Enantiomerization Barrier of Midazolam in Aqueous Conditions by Electronic Circular Dichroism and Dynamic Enantioselective HPLC/UHPLC

Midazolam is a benzodiazepine that is utilized for the induction of anesthesia and the facilitation of procedural sedation. Despite the absence of stereogenic centers, the non-planar seven-membered ring devoid of reflection symmetry elements confers planar stereogenicity to the molecule. Due to the rapid conformational inversion of the Rp and Sp enantiomers, which occurs via a simple ring flip, high-performance liquid chromatography (HPLC) enantiomeric separation is restricted to sub-room temperature conditions. In this study, the energy barriers for the racemization of midazolam at five distinct temperatures and in acetonitrile/water mixtures were determined by monitoring the decay of the circular dichroism signal at a specific wavelength over time. The kinetic and thermodynamic data obtained were compared with those determined by dynamic enantioselective high-performance liquid chromatography using the Chiralpak IG-3 chiral stationary phase, which contains the amylose tris(3-chloro-5-methylphenylcarbamate) as the selector. The temperature-dependent dynamic HPLC of midazolam was carried out at the same temperatures and with the same aqueous mixtures used in parallel kinetic off-column experiments. To simulate dynamic chromatographic profiles, a lab-made computer program based on a stochastic model was utilized. The results indicated that the moderate influence of the stationary phase resulted in a slight increase in the activation barriers, which was more pronounced as the time spent in the column increased. This phenomenon was found to be mitigated when switching from a 250 mm × 4.6 mm, 3 µm, Chiralpak IG-3 column to a 50 mm × 4.6 mm, 1.6 µm, Chiralpak IG-U UHPLC column. The outcomes obtained under UHPLC conditions were found to be more closely aligned with those obtained through the ECD technique, with a discrepancy of only 0.1 kcal/mol or less, indicating a high degree of concordance between the two methods.

Modeling dynamic pressure loss by absorption in oleo-pneumatic shock absorbers without separator

Abstract A model for the dynamic pressure loss in standard oleo-pneumatic shock absorbers without gas-oil separator for avionics applications is introduced. The dynamics of such a device under load variations are primarily determined by the throttle between the oil chamber and the gas chamber. During operation, gas is absorbed by the oil upon compression and desorbed upon expansion, which are processes that extend over time and entail hysteresis. It is found that the assumption of isothermal conditions is sufficient. An excellent alignment is achieved by the model and the measured hysteresis across diverse drop test scenarios, adjusting a single parameter to a value that is physically reasonable. The standard deviation of the error in pressure is $${\sigma _{p}=0.49\,\textrm{bar}}$$ σ p = 0.49 bar . Moreover, the model rests on thermodynamic considerations and experimental gas solubility data, while it is consistent with other laboratory data from the literature.

Novel green magnetite-chitosan adsorbent using Ricinus communis plants to adsorption of lead (II) from wastewater solution: anodic linear sweep voltammetry, isotherms, and kinetics study.

This study centered on removing toxic Pb (II) ions from wastewater using Fe3O4 with natural biopolymer chitosan and green plant extracts from Ricinus communis (Castor plant) to synthesize a novel magnetic chitosan nano-composites (GCS-Fe3O4) adsorbent. The nano-material was synthesized using the co-precipitation method and characterized using FTIR, XRD, FESEM, TEM, SEM, AFM, TGA-DTA, DLS, UV-Vis, and VSM. The green-synthesized nanocomposites (GCS-Fe3O4) have been used to remove Pb (II) from a wastewater solution. A study was conducted on the experimental parameters, such as the pH range, contact time, adsorbent dosage, and temperature effects, the highest capacity of adsorptionPb (II) ions observed at a pH 6.8, a temperature of 30℃,acontact time of 60min., with an adsorbent dose of 0.30g/L. The maximum removalof Pb (II) ions was 99.2%, obtained at a concentration of 0.30g/L. The Freundlich isotherm stipulated the most precise simulation of the adsorption equilibrium. The maximum adsorption capacity was determined to be48.64mg/g at 30℃ using the Freundlich isotherm. The pseudo-second-order kinetic model most accurately represented the adsorption kinetics of Pb (II). In contrast, thermodynamic data shows an endothermic adsorption process with temperature, the adsorption efficiency also increases to 5.35, 7.17, and 8.90kJ/mol respectively. The Pb (II) ions were determined by 797 VA anodic linear sweep voltammetry Computrace (Metrohm). Hence, the synthesized green magnetite chitosan composite (GCS-Fe3O4) is suitable for removing Pb (II) ions from wastewater solutions.

Thermodynamic factors for selecting suitable hydrate formers for saline water treatment in the Mekong Delta

AbstractThis study presents a significant advancement in the field of water treatment, specifically in the techniques used for identifying an appropriate hydrate former for saline desalination in agricultural regions. Salinization is a growing concern in the Mekong Delta, particularly impacting Ben Tre province, where agriculture heavily influences the local economy and livelihoods. The focus was on 1,1,1,2‐tetrafluoroethane (R134a), propane, pentafluoroethane (R125a), and sulfur hexafluoride (SF6) as potential candidates. Simulation studies assessed hydrate formation with these formers in various water sources, including pure water, saline water from Ben Tre province in the Mekong Delta, Vietnam, and seawater from Con Dao Island, Vietnam. The phase equilibria for the four selected formers were predicted using CSMGem commercial software and the Hu–Lee–Sum (HLS) correlation. Raman spectroscopy revealed that guest molecules were confined to the large cages of structure II hydrates. The simulation outcomes, corroborated by experimental data demonstrated good consistency. The thermodynamic data guided the desalination process design, highlighting R134a as the optimal hydrate former for desalination. In conclusion, the study utilized thermodynamic principles and simulation to determine a suitable hydrate former for desalination, with R134a emerging as the preferred choice. The study's implications for improving the sustainability of water resources in salinized regions are of international relevance.

Innovative Synthesis and Characterization of Nano Hydroxyapatite: A Potential Adsorbent for Methyl Violet 6B Removal from Aqueous Solutions

AbstractIn this study, the use of nano Hydroxyapatite (HAp) adsorbent as an adsorbent for the removal of methyl violet 6B (MV 6B) dye from aqueous solution was investigated. Nano adsorbent characterization was carried out by X‐Ray Diffractometer (XRD), scanning electron microscopy (SEM), spot energy dispersive spectroscopy (EDS) analyses. The dye removal study was carried out using the classical batch adsorption process. In addition, isotherm, kinetic and thermodynamic adsorption studies were carried out for methyl violet 6B. In adsorption studies, the effects of initial dye concentration (10–40 mg/L), solution pH (2‐8), adsorbent dosage (0.5–2.5 mg) and contact time (15–90 min.) on dye removal were investigated. At dye concentration was 10 mg/L, adsorbent dosage was 1 mg, solution pH was 6, contact time was 30 min and ambient temperature 25 °C, the highest MV 6B removal was 95.86 % and 1200 mg/g adsorption capacity was obtained. As a result of adsorption isotherm and kinetic studies, it was observed that the adsorption values obtained from the models were compatible with Langmuir isotherm model and pseudo‐second order kinetic model. According to the thermodynamic data obtained, it was determined that the adsorption process was spontaneous and exothermic.

Study on Exergy Analysis of the Soda Ash Production Process by the Ammonium Sulfate-Soda Method.

The exergy calculation, especially chemical exergy calculation, is very intricated in the soda ash production process by the ammonium sulfate-soda method because the gas-liquid reaction and salt precipitation reaction occur simultaneously with the electrolyte ionic reaction in the Na2SO4-NH3-CO2-H2O electrolyte system. The main aim of this study is to propose a significant and novel approach to calculate the chemical exergy of an aqueous electrolyte system accompanied by gas-liquid reaction and salt precipitation reaction, based on the Pitzer equation. We simulated the soda ash production process using Aspen Plus and performed exergy analysis based on the thermodynamic data obtained from the simulation. As a result, the exergy destruction of the entire process is 99.945 kW and exergy efficiency is 59.57%. In addition, the units with low exergy efficiency in the process are condenser and absorption towers such as NH3 absorption tower, carbonation tower, and water washing tower, which are the primary targets of energy saving.

Reflectometric-based sensor arrays for the screening of kinase-inhibitor interactions and kinetic determination.

Kinases are involved in numerous cellular processes but possibly also in tumor progression. Several kinase inhibitors are approved as drugs and there is an intense search for new inhibitors in pharmaceutical research. In this study, we present a new analytical method based on reflectometric interference spectroscopy, RIfS, for kinase and inhibitor screening. First, the sensor surface was optimized to reduce non-specific binding. Different inhibitors, e.g. staurosporine or fasudil, were immobilized on the transducer surface. Different kinases (focal adhesion kinase and cAMP-dependent protein kinase) were flushed over the sensor with the immobilized inhibitors. The specific interaction was proven by binding inhibition assays. The kinase-inhibitor interaction was monitored label-free and recorded in real time allowing the binding curves to be used to determine the association and dissociation rate constants as well as the affinity. These constants differed depending on the specific kinase-inhibitor pair, which was well expected from parallel docking simulations and measurements with microscale thermophoresis. The strategy was successfully transferred to 1-lambda reflectometry, a modification of RIfS, to enable the simultaneous monitoring of several kinase-inhibitor interactions in 5×7 small spots increasing throughput and automation on a sensor array with imaging detection. Importantly, the techniques developed here can provide both kinetic and thermodynamic data for a multitude of kinases in a single screening approach, which allows for both protein kinase and inhibitor screening.

Thermodynamics of (NH4)2SO4(aq) and Solubilities of (NH4)2MII(SO4)2·6H2O (M = Mg, Fe, Zn, Cu) Tutton Salts with Implications to Thermochemical Storage

Abstract Available thermodynamic data for (NH4)2SO4(aq) have been critically evaluated and used to parameterize an extended ion interaction (Pitzer) model. The model satisfactorily represents the available activity and thermal data from below the eutectic temperature to 110 °C. At near ambient temperatures (5–40 °C) the model accurately predicts the water activities in supersaturated solutions to about 30 mol·kg–1. The model has been used to determine the solubility products of (NH4)2SO4(s) from the eutectic temperature to 110 °C. Solubilities in the ternary Tutton salt forming systems (NH4)2SO4–MgSO4–H2O, (NH4)2SO4–FeSO4–H2O, (NH4)2SO4–ZnSO4–H2O, and (NH4)2SO4–CuSO4–H2O have been used to determine the ternary interaction parameters in the Pitzer model and to calculate the solubilities and deliquescence humidities of the Tutton salts (NH4)2MIISO4·6H2O (with M = Mg, Fe, Zn, Cu). Using additional literature data of decomposition vapor pressures, the phase diagrams of the Tutton salts have been established and the suitability of the salts as thermochemical heat storage materials has been critically evaluated.

The use of Al2O3 as heat-sink during vanadium extraction by thermite process

Vanadium is prepared by aluminothermic reduction of oxides. As the reaction with V2O5 is highly vigorous, the reduction is carried out with V2O5/V2O3 mixture for controlled reaction. Reduction of V2O5 alone to vanadium with the addition of Al2O3 as heat-sink is proposed in this work. While keeping the heat of process constant at 3680 kJ/kg in laboratory thermite reactors, the slag fluidiser CaO was partially and then fully replaced with Al2O3. Use of Al2O3 resulted in controlled reaction (with recovery as metal reaching from 50% to 83%), lesser loss in slag (from 10% to 1% vanadium) and lower nitrogen (from 1000 ppm to 130 pm) in metal. MgO of the reactor sometimes participates in the reaction. The loss of vanadium in slag is related to MgAl2O4 content of the slag. Molten Al2O3 appears to scavenge the dissolved nitrogen from molten vanadium. Results have been explained from available thermodynamic data.

Synthesis of potential adsorbent for removal of malachite green dye using alginate hydrogel nanocomposites.

Synthesis of potential adsorbent for removal of malachite green dye using alginate hydrogel nanocomposites.

Trace element transport by volcanic gases at Vulcano (Sicily, Italy) – Speciation, deposition and fluxes

Trace element transport by volcanic gases at Vulcano (Sicily, Italy) – Speciation, deposition and fluxes

Accelerating phase-field simulation of multi-component alloy solidification by shallow artificial neural network

Accelerating phase-field simulation of multi-component alloy solidification by shallow artificial neural network

High-Accuracy Prediction of Mechanical Properties of Ni-Cr-Fe Alloys Using Machine Learning

Artificial intelligence-driven prediction models have emerged as powerful tools for estimating material properties with high accuracy, yet the preparation of training datasets often demands labor-intensive and time-consuming experimental procedures. Leveraging the Computational Materials Science (CMS) approach, this study utilizes phase transformation calculations and thermodynamic data to simulate the mechanical properties of Ni-Cr-Fe alloys. Using JMatPro software, mechanical properties (0.2% Proof Stress, Fracture Stress, and Young's Modulus) of 50 Ni-Cr-Fe alloy compositions were simulated across a temperature range of 540–920°C, generating a dataset of 1000 rows. This dataset was used to train an Artificial Neural Network (ANN) model, with 80% allocated for training and 20% for validation and testing. The trained AI model demonstrated robust predictive capabilities, achieving a 96,61% accuracy rate in forecasting material compositions with the desired thermo-physical properties at specific temperatures. To validate the model's reliability, predicted alloy compositions were re-simulated under identical conditions in JMatPro, confirming the high fidelity of the model's predictions. The results underscore the efficacy of Computational Materials Science (CMS)-generated datasets as a scalable and reliable source for training AI models in materials science. This study highlights the potential of integrating Computational Materials Science (CMS) and Machine Learning approaches to accelerate material design and development processes, delivering significant improvements in prediction speed and accuracy.

The spinel to garnet phase transition in the systems MgO-Al2O3-SiO2 and CaO-MgO-Al2O3-SiO2: new experiments to resolve long-standing discrepancies

The pressure and temperature conditions of the transition from spinel to garnet as the stable aluminous phase in peridotite lithologies of the upper mantle is integral to elucidating the tectonic significance of the ‘garnet signature’ in basalts. It provides an essential constraint on models of mantle partial melting and oceanic crust formation. Existing experimental results on the univariant phase transition in the simple systems MgO-Al2O3-SiO2 (MAS) and CaO-MgO-Al2O3-SiO2 (CMAS) are mutually inconsistent. To resolve this, we have re-determined the P-T coordinates of the univariant transition in both synthetic systems by running experiments containing both systems simultaneously in the piston-cylinder apparatus, along with the MgO-ZnO pressure sensor. These experiments show a ~ 0.4 GPa difference in the pressure of the spinel/garnet phase transition between the two chemical systems at 1400 ºC, double that inferred from a compilation of existing experimental data. Absolute pressure in these experiments can be verified using the MgO-ZnO sensor. The results imply that the thermodynamic data used in recent mineral equations of state based on the Holland-Powell thermodynamic dataset are substantially correct.

Thermodynamic and Kinetic Studies of Mononuclear Non-Heme High-Valent (FeO)2+ Complexes.

Mononuclear nonheme high-valent (FeO)2+ complexes participate in many enzymatic oxidation-reduction cycles in a living body and play a key role in organic synthesis. The concept of molecular ID (molecular identities) was proposed and applied in our previous work; it covers all thermodynamic data for compounds containing an active carbon-hydrogen bond: oxidation potential, hydride anion affinity, proton affinity, and hydrogen atom affinity. To facilitate quantitative analysis of the physical organic chemistry and molecular biology properties of (FeO)2+ complexes, the molecular identities and reaction thermodynamic platform of representative complexes were established based on the thermodynamic data, such as (N4Py)(FeO)2+ and (Bn-TPEN)(FeO)2+, and their kinetic characteristics. Finally, the findings of this study are as follows: first, the reaction between (N4Py)(FeO)2+ and hydride donors 1/2 (Scheme 1) followed a one-step hydride anion transfer mechanism. The reactions between (N4Py)(FeO)2+ and hydride donors 3 (Scheme 1) and between (Bn-TPEN)(FeO)2+ and hydride donors 1 followed the hydrogen atom-electron transfer mechanism. Second, by comparison of high-valent (RuO)2+ complexes and organic hydride acceptors, the essential laws in selecting the reaction mechanism were obtained to determine the reaction mechanism of this study. Third, the reaction between (N4Py)(FeO)2+ and 1 followed the electron-proton-electron transfer mechanism under acidic conditions.

Azo dye adsorption on ZrO2 and natural organic material doped ZrO2

Natural wastes and inorganic adsorbents are used for the removal of diazo dye Congo red (CR), which causes water pollution and is a carcinogen, from wastewater. Organic waste olive pulp (ZK), inorganic ZrO2 (Zr) and three different weight percent ZK/Zr (organic/inorganic) binary adsorbent systems prepared by ball-milling method were investigated for the effective removal of CR from wastewater. Characterization of both single and binary adsorbent systems were carried out by ATR/FTIR and SEM. According to the Langmuir isotherm, qmax values for ZK, Zr, 25ZK-75Zr, 50ZK-50Zr and 75ZK-25Zr at 45 °C were 588 mgg-1, 13 mgg-1, 46 mgg-1, 65 mgg-1 and 84 mgg-1, respectively. According to Frumkin-Fowler–Guggenheim and Temkin isotherms, the adsorption heat was found to be exothermic for ZK and 75ZK-25Zr at all three temperatures, while it was found to be endothermic for Zr, 25ZK-75Zr and 50ZK-50Zr. It was observed that the ΔG° values calculated from the thermodynamic data were consistent with the values in the Flory-Huggings isotherm. According to the kinetic data, it was observed that all adsorbents except ZK obeyed the pseudo-first-order rate equation. It was shown by error calculations that the experimental data obeyed the Langmuir or Freundlich isotherms better. It was observed that a new and effective organic/inorganic adsorbent system could be obtained by adding ZK to ZrO2 for the removal of Congo red (CR) from water.