Pub Date : 2025-02-01DOI: 10.1016/j.tca.2024.179918
Tagore M , Suganthi K S , Haariz J A , Rajan K S
This work investigates the influence of different nanoparticles on the reduction of the supercooling degree of tin (phase change material) and the quantity of latent heat recovered during the early stages of freezing in nanoparticle-enhanced phase change materials (NePCM). Different nanoparticles (Cu, CuO, MgO, SiOx, TiO2, ZnO) at various concentrations (0.125 wt. %, 0.25 wt. %, 0.5 wt. %, 1 wt. %, 2 wt. %) were used to prepare NePCM using planetary ball milling. The supercooling degree of tin (43.9 K) was found to be suppressed to 22 K in NePCM. The NePCM containing 0.25 wt. % of Cu and the one containing 0.5 wt. % of MgO allowed extraction of 64.2 % and 54.8 % of thermal energy stored, respectively, at temperatures greater than the onset temperature of freezing of pure tin. Thus, our study has uniquely demonstrated the impact of chosen nanomaterials in improving the freezing characteristics of tin.
{"title":"New insights on thermal energy storage using nanoparticle enhanced tin","authors":"Tagore M , Suganthi K S , Haariz J A , Rajan K S","doi":"10.1016/j.tca.2024.179918","DOIUrl":"10.1016/j.tca.2024.179918","url":null,"abstract":"<div><div>This work investigates the influence of different nanoparticles on the reduction of the supercooling degree of tin (phase change material) and the quantity of latent heat recovered during the early stages of freezing in nanoparticle-enhanced phase change materials (NePCM). Different nanoparticles (Cu, CuO, MgO, SiO<sub>x</sub>, TiO<sub>2</sub>, ZnO) at various concentrations (0.125 wt. %, 0.25 wt. %, 0.5 wt. %, 1 wt. %, 2 wt. %) were used to prepare NePCM using planetary ball milling. The supercooling degree of tin (43.9 K) was found to be suppressed to 22 K in NePCM. The NePCM containing 0.25 wt. % of Cu and the one containing 0.5 wt. % of MgO allowed extraction of 64.2 % and 54.8 % of thermal energy stored, respectively, at temperatures greater than the onset temperature of freezing of pure tin. Thus, our study has uniquely demonstrated the impact of chosen nanomaterials in improving the freezing characteristics of tin.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"744 ","pages":"Article 179918"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.tca.2024.179920
Mengxu Xu , Shushuang Yao , Yujuan Gao , Yang Bai , Jiayong Teng , Weiyao Liu , Wanshun Cui , Zilin Meng , Pingke Yan
Prepared by hydrothermal method, the nesquehonite (MgCO3·3H2O) was characterized through different testing and analysis techniques. The study investigated the influence of l-aspartic acid regulation on the morphology, structure, and thermal stability of the nesquehonite. SEM and DSC results indicated that the sample had larger size and higher thermal stability. Building on it, the reaction mechanism using magnesium l-aspartate as a reactant was further explored, confirming that the formation of O-Mg coordination bonds induced nucleation self-assembly of crystals, effectively enhancing thermal stability. Compared to conventional methods, the initial decomposition temperature of the crystals prepared in this study increased by 42.5 %. This study provides a theoretical basis for the indirect mineralization of CO₂ to produce magnesium carbonates. Furthermore, the direct incorporation of biomolecular polymeric salts offers a novel perspective for understanding the role of organic additives in the process of crystals mineralization.
{"title":"Polymorphism and thermal stability of nesquehonite (MgCO3·3H2O) regulated by magnesium L-aspartate: For CO2 mineral sequestration","authors":"Mengxu Xu , Shushuang Yao , Yujuan Gao , Yang Bai , Jiayong Teng , Weiyao Liu , Wanshun Cui , Zilin Meng , Pingke Yan","doi":"10.1016/j.tca.2024.179920","DOIUrl":"10.1016/j.tca.2024.179920","url":null,"abstract":"<div><div>Prepared by hydrothermal method, the nesquehonite (MgCO<sub>3</sub>·3H<sub>2</sub>O) was characterized through different testing and analysis techniques. The study investigated the influence of <span>l</span>-aspartic acid regulation on the morphology, structure, and thermal stability of the nesquehonite. SEM and DSC results indicated that the sample had larger size and higher thermal stability. Building on it, the reaction mechanism using magnesium <span>l</span>-aspartate as a reactant was further explored, confirming that the formation of O-Mg coordination bonds induced nucleation self-assembly of crystals, effectively enhancing thermal stability. Compared to conventional methods, the initial decomposition temperature of the crystals prepared in this study increased by 42.5 %. This study provides a theoretical basis for the indirect mineralization of CO₂ to produce magnesium carbonates. Furthermore, the direct incorporation of biomolecular polymeric salts offers a novel perspective for understanding the role of organic additives in the process of crystals mineralization.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"744 ","pages":"Article 179920"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143166477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-29DOI: 10.1016/j.tca.2025.179948
Benjamin Sanders , Matthew North , Edward Cant , Michael Jenkins
Polyamide 12 (PA-12) is a strong and durable thermoplastic commonly used within advanced polymer processing techniques, such as powder bed fusion (PBF). The use of PA-12 for the fabrication of functional, end-use components is highly dependent on the morphology, size, shape, and stability of the crystalline phase. Secondary crystallisation, an aging process rarely studied in previous PA-12 Lature, can cause further developments in crystallinity that also alter the property profile of the material during PBF. To the best of the authors knowledge, this is the first in-depth investigation into the secondary crystallisation behaviour of PA-12 using fast scanning calorimetry (FSC). Results indicated that, across a wide isothermal crystallisation temperature (Tc) range, the crystalline structure, rate of secondary crystallisation, and the mechanism of lamellar thickening, are all closely correlated to crystallisation time (tc) and temperature (Tc). At crystallisation temperatures between 100 °C and 130 °C, PA-12 crystallises into the hexagonal gamma (γ) phase, whilst Tc ≥ 140 °C, larger and more thermodynamically stable alpha-prime (α’) crystals are able to grow. Independent of crystal polymorph, there is significant evidence of secondary crystallisation. For extended tc, the melting endotherm progressively shifts to higher temperatures, indicative of a slow, yet continuous lamellar thickening process. In γ crystals, the melting enthalpy and melting temperature increase linearly as a function of the logarithm of tc (R2 > 0.96), suggesting that solid-state diffusion processes such as chain-sliding and chain refolding are the dominant cause of lamellar thickening. However, within the α’ phase, hydrogen bonding can be more easily attained, resulting in a more rigid crystal structure that reduces chain mobility and prevents lamellar thickening via chain sliding or refolding. Thickening instead occurs through the incorporation of inter-lamellae amorphous chains, across the melt-crystal interface, via Hay's reptation-diffusion mechanism. This is evidenced by the thickening of α’ crystals becoming dependent on the square root of time (R2 > 0.96). Such insight into the secondary crystallisation behaviour of PA-12 could be useful within the PBF industry in order to help predict the volume shrinkage effects associated with polymer crystallisation, allowing improvements to the dimensional precision and performance of final components. Similarly, an enriched understanding of the mechanisms and rate of secondary crystallisation could reveal more information about the thermal properties of un-sintered PA-12 powder, and its suitability for re-use in future build cycles.
{"title":"Investigating secondary crystallisation of polyamide-12 using fast scanning calorimetry","authors":"Benjamin Sanders , Matthew North , Edward Cant , Michael Jenkins","doi":"10.1016/j.tca.2025.179948","DOIUrl":"10.1016/j.tca.2025.179948","url":null,"abstract":"<div><div>Polyamide 12 (PA-12) is a strong and durable thermoplastic commonly used within advanced polymer processing techniques, such as powder bed fusion (PBF). The use of PA-12 for the fabrication of functional, end-use components is highly dependent on the morphology, size, shape, and stability of the crystalline phase. Secondary crystallisation, an aging process rarely studied in previous PA-12 Lature, can cause further developments in crystallinity that also alter the property profile of the material during PBF. To the best of the authors knowledge, this is the first in-depth investigation into the secondary crystallisation behaviour of PA-12 using fast scanning calorimetry (FSC). Results indicated that, across a wide isothermal crystallisation temperature (T<sub>c</sub>) range, the crystalline structure, rate of secondary crystallisation, and the mechanism of lamellar thickening, are all closely correlated to crystallisation time (t<sub>c</sub>) and temperature (T<sub>c</sub>). At crystallisation temperatures between 100 °C and 130 °C, PA-12 crystallises into the hexagonal gamma (γ) phase, whilst T<sub>c</sub> ≥ 140 °C, larger and more thermodynamically stable alpha-prime (α’) crystals are able to grow. Independent of crystal polymorph, there is significant evidence of secondary crystallisation. For extended t<sub>c</sub>, the melting endotherm progressively shifts to higher temperatures, indicative of a slow, yet continuous lamellar thickening process. In γ crystals, the melting enthalpy and melting temperature increase linearly as a function of the logarithm of t<sub>c</sub> (R<sup>2</sup> > 0.96), suggesting that solid-state diffusion processes such as chain-sliding and chain refolding are the dominant cause of lamellar thickening. However, within the α’ phase, hydrogen bonding can be more easily attained, resulting in a more rigid crystal structure that reduces chain mobility and prevents lamellar thickening via chain sliding or refolding. Thickening instead occurs through the incorporation of inter-lamellae amorphous chains, across the melt-crystal interface, via Hay's reptation-diffusion mechanism. This is evidenced by the thickening of α’ crystals becoming dependent on the square root of time (R<sup>2</sup> > 0.96). Such insight into the secondary crystallisation behaviour of PA-12 could be useful within the PBF industry in order to help predict the volume shrinkage effects associated with polymer crystallisation, allowing improvements to the dimensional precision and performance of final components. Similarly, an enriched understanding of the mechanisms and rate of secondary crystallisation could reveal more information about the thermal properties of un-sintered PA-12 powder, and its suitability for re-use in future build cycles.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"745 ","pages":"Article 179948"},"PeriodicalIF":3.1,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143171560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-21DOI: 10.1016/j.tca.2025.179947
Arcady Kossoy, Yury Akhmetshin, Elena Koludarova
Reaction calorimetry (RC) is a powerful experimental technique with a wide range of applications. A significant advantage of RC is the ability to simultaneously measure the heat generated by the reaction and the current composition of the reacting mixture, which provides more complete information about the reaction and its kinetics. This makes it a useful tool for studying reaction kinetics, although this method is rather complicated and requires a thorough elaboration of the methodology of experimentation and data processing.
The literature on RC theory is extensive, yet there is a lack of recognition regarding some methodical aspects of utilizing RC data to construct kinetic models. This paper aims to draw attention to these aspects. In particular:
the need for careful analysis of experimental data is emphasized and demonstrated,
the importance of applying the concept of key species to obtain unique kinetics is shown, as is the need to consider the effects of feed rate and reactants’ ratios to properly plan kinetic experiments,
the usefulness of kinetic modeling for better understanding of reaction progress is demonstrated.
The material is based on the results of a study of the well-known methanol - acetic anhydride esterification reaction taken from the literature.
{"title":"How to correctly evaluate kinetics based on experimental data of reaction calorimetry","authors":"Arcady Kossoy, Yury Akhmetshin, Elena Koludarova","doi":"10.1016/j.tca.2025.179947","DOIUrl":"10.1016/j.tca.2025.179947","url":null,"abstract":"<div><div>Reaction calorimetry (RC) is a powerful experimental technique with a wide range of applications. A significant advantage of RC is the ability to simultaneously measure the heat generated by the reaction and the current composition of the reacting mixture, which provides more complete information about the reaction and its kinetics. This makes it a useful tool for studying reaction kinetics, although this method is rather complicated and requires a thorough elaboration of the methodology of experimentation and data processing.</div><div>The literature on RC theory is extensive, yet there is a lack of recognition regarding some methodical aspects of utilizing RC data to construct kinetic models. This paper aims to draw attention to these aspects. In particular:</div><div>the need for careful analysis of experimental data is emphasized and demonstrated,</div><div>the importance of applying the concept of key species to obtain unique kinetics is shown, as is the need to consider the effects of feed rate and reactants’ ratios to properly plan kinetic experiments,</div><div>the usefulness of kinetic modeling for better understanding of reaction progress is demonstrated.</div><div>The material is based on the results of a study of the well-known methanol - acetic anhydride esterification reaction taken from the literature.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"745 ","pages":"Article 179947"},"PeriodicalIF":3.1,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-18DOI: 10.1016/j.tca.2025.179936
Yuguo Gao , Yanan Zhao , Xinyu Wang , Mohammaderfan Mohit , Minghan Xu , Agus P. Sasmito
The phenomenon of supercooling in phase change materials has been a major obstacle to the effective use of these materials in thermal energy storage systems. Numerous studies have shown that nanoparticles display significant advantages over other methods of supercooling inhibition in terms of increased nucleation rate, enhanced thermal conductivity, reduced supercooling, and improved cycling stability. Yet, the mechanism of supercooling inhibition by nanoparticles has not been comprehensively discussed or reviewed in published articles. The objective of this review is to provide a comprehensive analysis of the mechanisms by which nanoparticles promote nucleation and reduce supercooling in phase change materials, as well as to discuss the most influential factors such as the type, concentration, and size of the nanoparticles, as well as ultrasonic and synergistic effects. Additionally, the paper focuses on an overview of recent advances in the application of machine learning to control the supercooling of nanofluid phase change materials. The potential for practical applications of machine learning techniques to enhance the thermophysical properties of phase change materials and suppress phase change material supercooling is one of our major findings.
{"title":"Review of supercooling suppression of phase change materials based on nanoparticles","authors":"Yuguo Gao , Yanan Zhao , Xinyu Wang , Mohammaderfan Mohit , Minghan Xu , Agus P. Sasmito","doi":"10.1016/j.tca.2025.179936","DOIUrl":"10.1016/j.tca.2025.179936","url":null,"abstract":"<div><div>The phenomenon of supercooling in phase change materials has been a major obstacle to the effective use of these materials in thermal energy storage systems. Numerous studies have shown that nanoparticles display significant advantages over other methods of supercooling inhibition in terms of increased nucleation rate, enhanced thermal conductivity, reduced supercooling, and improved cycling stability. Yet, the mechanism of supercooling inhibition by nanoparticles has not been comprehensively discussed or reviewed in published articles. The objective of this review is to provide a comprehensive analysis of the mechanisms by which nanoparticles promote nucleation and reduce supercooling in phase change materials, as well as to discuss the most influential factors such as the type, concentration, and size of the nanoparticles, as well as ultrasonic and synergistic effects. Additionally, the paper focuses on an overview of recent advances in the application of machine learning to control the supercooling of nanofluid phase change materials. The potential for practical applications of machine learning techniques to enhance the thermophysical properties of phase change materials and suppress phase change material supercooling is one of our major findings.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"745 ","pages":"Article 179936"},"PeriodicalIF":3.1,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143170461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.1016/j.tca.2025.179933
Peter Šimon , Peter J. Skrdla , Tibor Dubaj , Zuzana Cibulková
Kinetics of condensed-phase processes are routinely studied by methods based on the general rate equation. It is demonstrated here that, for the kinetic analysis, two degrees of conversion should be employed: (i) the degree of conversion used in classical kinetics, αkin, conventionally defined as the reacted amount of a reactant normalized to its initial amount; (ii) the thermoanalytical degree of conversion, α, defined as the thermoanalytical effect observed at temperature T (or at time t for isothermal measurements) divided by the total thermoanalytical effect. For elementary reactions, αkin = α so that the general rate equation is a true rate equation describing the mechanism of the reaction. For complex processes, αkin and α differ considerably in general; they are equivalent for some special cases only. In this case, the general rate equation represents the single-step approximation. The values of α thus describe the kinetics of heat exchange (for DSC) or mass loss (for TG) and so do the kinetic parameters obtained from the treatment of experimental data. Even though no mechanistic conclusions should be drawn from such kinetic parameters, they still enable us to model the kinetics of complex processes from the point of view of the quantity measured.
{"title":"Thermoanalytical and kinetic degrees of conversion in the application of general rate equation","authors":"Peter Šimon , Peter J. Skrdla , Tibor Dubaj , Zuzana Cibulková","doi":"10.1016/j.tca.2025.179933","DOIUrl":"10.1016/j.tca.2025.179933","url":null,"abstract":"<div><div>Kinetics of condensed-phase processes are routinely studied by methods based on the general rate equation. It is demonstrated here that, for the kinetic analysis, two degrees of conversion should be employed: (i) the degree of conversion used in classical kinetics, <em>α</em><sub>kin</sub>, conventionally defined as the reacted amount of a reactant normalized to its initial amount; (ii) the thermoanalytical degree of conversion, <em>α</em>, defined as the thermoanalytical effect observed at temperature <em>T</em> (or at time <em>t</em> for isothermal measurements) divided by the total thermoanalytical effect. For elementary reactions, <em>α</em><sub>kin</sub> = <em>α</em> so that the general rate equation is a true rate equation describing the mechanism of the reaction. For complex processes, <em>α</em><sub>kin</sub> and <em>α</em> differ considerably in general; they are equivalent for some special cases only. In this case, the general rate equation represents the single-step approximation. The values of <em>α</em> thus describe the kinetics of heat exchange (for DSC) or mass loss (for TG) and so do the kinetic parameters obtained from the treatment of experimental data. Even though no mechanistic conclusions should be drawn from such kinetic parameters, they still enable us to model the kinetics of complex processes from the point of view of the quantity measured.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"745 ","pages":"Article 179933"},"PeriodicalIF":3.1,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143170460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-15DOI: 10.1016/j.tca.2025.179937
Xinru Li, Jiaqi Wang, Linxue Yan, Can Liu, Yafei Guo, Tianlong Deng
In this study, the isothermal dissolution and wet solid phase methods (Schreinemarkers rule) were applied to systematically investigate (NaNO3 + Sr(NO3)2 + H2O) ternary system at 298.15 and 338.15 K, to develop a green separation of Sr(NO3)2. The phase diagrams and thermodynamic models were designed on the basis of experimental data to elucidate the system's behavior under varying conditions. The phase diagram and physicochemical property diagrams indicate that no complex salts or solid solutions are formed, confirming the system's classification as a simple type. The invariant point (E), consisting solely of NaNO3 and Sr(NO3)2 crystals, was identified using the REFLEX module in Material Studio. An optimized separation process for mixed NaNO3 and Sr(NO3)2 solutions was established, reaching a 96.76 % separation efficiency for Sr(NO₃)₂. This study offers an eco-friendly and efficient approach for recovery of Sr(NO3)2 from sodium nitrate eluate, providing a reliable solution for industrial applications.
{"title":"Phase equilibria and phase diagrams of the ternary system NaNO3 + Sr(NO3)2 + H2O: Experimental insights and industrial applications at 298.15 and 338.15 K","authors":"Xinru Li, Jiaqi Wang, Linxue Yan, Can Liu, Yafei Guo, Tianlong Deng","doi":"10.1016/j.tca.2025.179937","DOIUrl":"10.1016/j.tca.2025.179937","url":null,"abstract":"<div><div>In this study, the isothermal dissolution and wet solid phase methods (Schreinemarkers rule) were applied to systematically investigate (NaNO<sub>3</sub> + Sr(NO<sub>3</sub>)<sub>2</sub> + H<sub>2</sub>O) ternary system at 298.15 and 338.15 K, to develop a green separation of Sr(NO<sub>3</sub>)<sub>2</sub>. The phase diagrams and thermodynamic models were designed on the basis of experimental data to elucidate the system's behavior under varying conditions. The phase diagram and physicochemical property diagrams indicate that no complex salts or solid solutions are formed, confirming the system's classification as a simple type. The invariant point (E), consisting solely of NaNO<sub>3</sub> and Sr(NO<sub>3</sub>)<sub>2</sub> crystals, was identified using the REFLEX module in Material Studio. An optimized separation process for mixed NaNO<sub>3</sub> and Sr(NO<sub>3</sub>)<sub>2</sub> solutions was established, reaching a 96.76 % separation efficiency for Sr(NO₃)₂. This study offers an eco-friendly and efficient approach for recovery of Sr(NO<sub>3</sub>)<sub>2</sub> from sodium nitrate eluate, providing a reliable solution for industrial applications.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"745 ","pages":"Article 179937"},"PeriodicalIF":3.1,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-15DOI: 10.1016/j.tca.2025.179924
Gurudas Pakhui, Soja. K. Vijay, Ashish Jain, Suddhasattwa Ghosh
Electromotive force measurements of U-60Zr (79.6 at.% Zr) and U-77Zr (89.7 at.% Zr) alloys in LiCl-KCl-UCl3 melt were carried out in temperature range 670-800 K for determining , the temperature dependence of which was expressed as
Correlation suggested stability of -UZr2 to be higher than what is currently accepted in literature, which is based on its enthalpy of formation at 298.15 K. Cyclic voltammetry with U-Zr alloys as working electrode was also performed in potential range −1.50 to −0.50 V in LiCl-KCl-UCl3 melt for exploring onset potential of dissolution of uranium and zirconium to address consequences of higher stability of UZr2 on spent metal fuel dissolution.
{"title":"Electromotive force measurements of U-Zr alloys in LiCl-KCl-UCl3 melt","authors":"Gurudas Pakhui, Soja. K. Vijay, Ashish Jain, Suddhasattwa Ghosh","doi":"10.1016/j.tca.2025.179924","DOIUrl":"10.1016/j.tca.2025.179924","url":null,"abstract":"<div><div>Electromotive force measurements of U-60Zr (79.6 <em>at.</em>% Zr) and U-77Zr (89.7 <em>at.</em>% Zr) alloys in LiCl-KCl-UCl<sub>3</sub> melt were carried out in temperature range 670-800 K for determining <span><math><mrow><msub><mrow><mi>Δ</mi></mrow><mrow><mtext>f</mtext></mrow></msub><msubsup><mrow><mi>G</mi></mrow><mrow><msub><mrow><mi>UZr</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow><mrow><mo>∘</mo></mrow></msubsup></mrow></math></span>, the temperature dependence of which was expressed as</div><div><span><math><mrow><msub><mrow><mi>Δ</mi></mrow><mrow><mtext>f</mtext></mrow></msub><msubsup><mrow><mi>G</mi></mrow><mrow><msub><mrow><mi>UZr</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow><mrow><mo>∘</mo></mrow></msubsup></mrow></math></span> <span><math><mrow><mrow><mo>(</mo><mtext>kJ/mol-atom</mtext><mo>)</mo></mrow><mo>=</mo><mrow><mo>(</mo><mo>−</mo><mn>59</mn><mo>.</mo><mn>29</mn><mo>±</mo><mn>1</mn><mo>.</mo><mn>37</mn><mo>)</mo></mrow><mo>+</mo><mrow><mo>(</mo><mn>32</mn><mo>.</mo><mn>0</mn><mo>±</mo><mn>1</mn><mo>.</mo><mn>9</mn><mo>)</mo></mrow><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup><mi>T</mi><mrow><mo>(</mo><mtext>K</mtext><mo>)</mo></mrow></mrow></math></span></div><div>Correlation suggested stability of <span><math><mi>δ</mi></math></span>-UZr<sub>2</sub> to be higher than what is currently accepted in literature, which is based on its enthalpy of formation at 298.15 K. Cyclic voltammetry with U-Zr alloys as working electrode was also performed in potential range −1.50 to −0.50 V in LiCl-KCl-UCl<sub>3</sub> melt for exploring onset potential of dissolution of uranium and zirconium to address consequences of higher stability of UZr<sub>2</sub> on spent metal fuel dissolution.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"745 ","pages":"Article 179924"},"PeriodicalIF":3.1,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143171559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-15DOI: 10.1016/j.tca.2025.179938
Nan Fang , Chuan-Yu Zhang , Ming-Jie Wan , Xiao-Peng Huang
As an interstellar molecule, the thermodynamic properties and transition characteristics of FeC hold significant importance. In this study, high-precision ab initio methods were employed to obtain the potential energy functions of the five Λ-S states of FeC. Based on these results, the Partition functions, proportions of each molecular and thermodynamic properties were calculated for temperatures from 50 K to 10,000 K. In addition, the spin orbit coupling effects on the ground state (X3Δ) split it into three Ω states (Ω = 3, 2, 1), with Ω = 3 being the lowest. The rotational spectrum for Ω = 3 at 298.15 K shows significantly higher transition intensity for the v′ = 0 and v′′ = 0 band. Moreover, this paper presents the ultraviolet spectrum of two transitions: X3Δ ↔ 13Π and 13Π ↔ 13Σ−, at a temperature of 298.15 K, with the 13Π ↔ 13Σ− transition having stronger absolute intensity.
{"title":"Theoretical study on the thermodynamic and transition properties of the interstellar molecule: FeC","authors":"Nan Fang , Chuan-Yu Zhang , Ming-Jie Wan , Xiao-Peng Huang","doi":"10.1016/j.tca.2025.179938","DOIUrl":"10.1016/j.tca.2025.179938","url":null,"abstract":"<div><div>As an interstellar molecule, the thermodynamic properties and transition characteristics of FeC hold significant importance. In this study, high-precision ab initio methods were employed to obtain the potential energy functions of the five Λ-S states of FeC. Based on these results, the Partition functions, proportions of each molecular and thermodynamic properties were calculated for temperatures from 50 K to 10,000 K. In addition, the spin orbit coupling effects on the ground state (<em>X</em> <sup>3</sup>Δ) split it into three Ω states (Ω = 3, 2, 1), with Ω = 3 being the lowest. The rotational spectrum for Ω = 3 at 298.15 K shows significantly higher transition intensity for the <em>v</em>′ = 0 and <em>v</em>′′ = 0 band. Moreover, this paper presents the ultraviolet spectrum of two transitions: <em>X</em> <sup>3</sup>Δ ↔ 1<sup>3</sup>Π and 1<sup>3</sup>Π ↔ 1<sup>3</sup>Σ<sup>−</sup>, at a temperature of 298.15 K, with the 1<sup>3</sup>Π ↔ 1<sup>3</sup>Σ<sup>−</sup> transition having stronger absolute intensity.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"745 ","pages":"Article 179938"},"PeriodicalIF":3.1,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143170446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-13DOI: 10.1016/j.tca.2025.179935
Chang-Qing Xiao , Juan Wu , Lu Lai
Amphiphilic carbon dots C1214-ACDs were synthesized from alkyl glucoside APG1214, and had shown good surface activity and high oil removal efficiency. In this study, we have employed ITC to study the demicellization processes of C1214-ACDs and its precursor APG1214 within the temperature range from 288 K to 313 K. The enthalpy change of demicellization ΔHdemic for C1214-ACDs is negative at the lower temperatures as -7.37 J g−1 at 288 K and -4.31 J g−1 at 293 K, gradually decreases to approximate zero around the room temperature, and becomes positive with the increase of temperature as 5.02 J g−1 at 303 K, 10.18 J g−1 at 308 K and 16.68 J g−1 at 313 K. The temperature dependence of ΔHdemic demonstrates that the micellization processes of C1214-ACDs are dominated by the hydrophobic force. The ΔHdemic for APG1214 is more negative than C1214-ACDs below room temperature as -17.20 J g−1 at 288 K and -8.90 J g−1 at 293 K, but becomes more positive than C1214-ACDs above room temperature as 20.97 J g−1 at 313 K. The heat capacity changes ΔCp,demic for APG1214 and C1214-ACDs have been calculated as the values of 1.517±0.027 J g−1 K−1 and 0.958±0.056 J g−1 K−1 respectively. The smaller value of ΔCp,demic for C1214-ACDs indicates that the relatively hydrophobic surface is reduced after polymerization of APG1214. The effects of NaCl and CaCl2 on the demicellization processes of C1214-ACDs have also been investigated. The values of CMC increase slightly, but the values of ΔHdemic decrease significantly in the saline solutions. The results indicate that the effects of NaCl and CaCl2 are mainly attributed to the reduction of water activity and disturbance on the hydration of hydrophobic groups by ions.
{"title":"Demicellization thermodynamics of amphiphilic carbon dots via isothermal titration calorimetry","authors":"Chang-Qing Xiao , Juan Wu , Lu Lai","doi":"10.1016/j.tca.2025.179935","DOIUrl":"10.1016/j.tca.2025.179935","url":null,"abstract":"<div><div>Amphiphilic carbon dots C<sub>1214</sub>-ACDs were synthesized from alkyl glucoside APG1214, and had shown good surface activity and high oil removal efficiency. In this study, we have employed ITC to study the demicellization processes of C<sub>1214</sub>-ACDs and its precursor APG1214 within the temperature range from 288 K to 313 K. The enthalpy change of demicellization Δ<em>H</em><sub>demic</sub> for C<sub>1214</sub>-ACDs is negative at the lower temperatures as -7.37 J g<sup>−1</sup> at 288 K and -4.31 J g<sup>−1</sup> at 293 K, gradually decreases to approximate zero around the room temperature, and becomes positive with the increase of temperature as 5.02 J g<sup>−1</sup> at 303 K, 10.18 J g<sup>−1</sup> at 308 K and 16.68 J g<sup>−1</sup> at 313 K. The temperature dependence of Δ<em>H</em><sub>demic</sub> demonstrates that the micellization processes of C<sub>1214</sub>-ACDs are dominated by the hydrophobic force. The Δ<em>H</em><sub>demic</sub> for APG1214 is more negative than C<sub>1214</sub>-ACDs below room temperature as -17.20 J g<sup>−1</sup> at 288 K and -8.90 J g<sup>−1</sup> at 293 K, but becomes more positive than C<sub>1214</sub>-ACDs above room temperature as 20.97 J g<sup>−1</sup> at 313 K. The heat capacity changes Δ<em>C</em><sub>p,demic</sub> for APG1214 and C<sub>1214</sub>-ACDs have been calculated as the values of 1.517±0.027 J g<sup>−1</sup> K<sup>−1</sup> and 0.958±0.056 J g<sup>−1</sup> K<sup>−1</sup> respectively. The smaller value of Δ<em>C</em><sub>p,demic</sub> for C<sub>1214</sub>-ACDs indicates that the relatively hydrophobic surface is reduced after polymerization of APG1214. The effects of NaCl and CaCl<sub>2</sub> on the demicellization processes of C<sub>1214</sub>-ACDs have also been investigated. The values of CMC increase slightly, but the values of Δ<em>H</em><sub>demic</sub> decrease significantly in the saline solutions. The results indicate that the effects of NaCl and CaCl<sub>2</sub> are mainly attributed to the reduction of water activity and disturbance on the hydration of hydrophobic groups by ions.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"745 ","pages":"Article 179935"},"PeriodicalIF":3.1,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143170459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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