Thermochemical Properties Research Articles

Algae-Based Biopolymers for Batteries and Biofuel Applications in Comparison with Bacterial Biopolymers-A Review.

Algae-based biopolymers can be used in diverse energy-related applications, such as separators and polymer electrolytes in batteries and fuel cells and also as microalgal biofuel, which is regarded as a highly renewable energy source. For these purposes, different physical, thermochemical, and biochemical properties are necessary, which are discussed within this review, such as porosity, high temperature resistance, or good mechanical properties for batteries and high energy density and abundance of the base materials in case of biofuel, along with the environmental aspects of using algae-based biopolymers in these applications. On the other hand, bacterial biopolymers are also often used in batteries as bacterial cellulose separators or as biopolymer network binders, besides their potential use as polymer electrolytes. In addition, they are also regarded as potential sustainable biofuel producers and converters. This review aims at comparing biopolymers from both aforementioned sources for energy conversion and storage. Challenges regarding the production of algal biopolymers include low scalability and low cost-effectiveness, and for bacterial polymers, slow growth rates and non-optimal fermentation processes often cause challenges. On the other hand, environmental benefits in comparison with conventional polymers and the better biodegradability are large advantages of these biopolymers, which suggest further research to make their production more economical.

How well do one-electron self-interaction-correction methods perform for systems with fractional electrons?

Recently developed locally scaled self-interaction correction (LSIC) is a one-electron SIC method that, when used with a ratio of kinetic energy densities (zσ) as iso-orbital indicator, performs remarkably well for both thermochemical properties as well as for barrier heights overcoming the paradoxical behavior of the well-known Perdew-Zunger self-interaction correction (PZSIC) method. In this work, we examine how well the LSIC method performs for the delocalization error. Our results show that both LSIC and PZSIC methods correctly describe the dissociation of H2+ and He2+ but LSIC is overall more accurate than the PZSIC method. Likewise, in the case of the vertical ionization energy of an ensemble of isolated He atoms, the LSIC and PZSIC methods do not exhibit delocalization errors. For the fractional charges, both LSIC and PZSIC significantly reduce the deviation from linearity in the energy vs number of electrons curve, with PZSIC performing superior for C, Ne, and Ar atoms while for Kr they perform similarly. The LSIC performs well at the endpoints (integer occupations) while substantially reducing the deviation. The dissociation of LiF shows both LSIC and PZSIC dissociate into neutral Li and F but only LSIC exhibits charge transfer from Li+ to F- at the expected distance from the experimental data and accurate abinitio data. Overall, both the PZSIC and LSIC methods reduce the delocalization errors substantially.

Thermodynamics of Reversible Hydrogen Storage: Are Methoxy‐Substituted Aromatics better through Oxygen Functionality?

AbstractAn attractive option for the storage of hydrogen is the reversible hydrogenation of an aromatic substance, a so‐called liquid organic hydrogen carrier. For hydrogen release, it is desirable to find substances with low enthalpies of reaction for dehydrogenation. It has been demonstrated that substitution, e.g., with methyl groups, on the ring can have a positive effect in this regard. In this study, thermochemical properties of methoxy‐substituted pyridines and quinolines and their respective hydrogenated counterparts have been analyzed from a thermodynamic point of view. Combustion calorimetry has been utilized to measure the enthalpy of formation and the transpiration method for determining the vapor pressure. Additionally, high‐level quantum‐chemical approaches have been applied to obtain caloric data in the gas phase, which provide a basis for comparison and evaluation of the experimental data. The results reveal two main effects of methoxy substitution. First, oxygenated substituents like methoxy groups have stronger effect on the Gibbs energy of reaction and thus the temperature needed thermodynamically for hydrogen release than methyl groups. Second, the effect is highly depending on the position of the substitution on the ring. Particularly methoxy groups close to a N heteroatom can have a significant positive effect, which might enable hydrogen release at equilibrium temperatures more than 50 K lower than for their unsubstituted analogue.

Dynamically coupled kinetic chemistry in brown dwarf atmospheres – II. Cloud and chemistry connections in directly imaged sub-Jupiter exoplanets

ABSTRACT With JWST slated to gain high-fidelity time-dependent data on brown dwarf atmospheres, it is highly anticipated to do the same for directly imaged, sub-Jupiter exoplanets. With this new capability, the need for a full three-dimensional (3D) understanding to explain spectral features and their time dependence is becoming a vital aspect for consideration. To examine the atmospheric properties of directly imaged sub-Jupiter exoplanets, we use the 3D Exo-FMS general circulation model to simulate a metal-enhanced generic young sub-Jupiter object. We couple Exo-FMS to a kinetic chemistry scheme, a tracer-based cloud formation scheme and a spectral radiative-transfer model to take into account the chemical and cloud feedback on the atmospheric thermochemical and dynamical properties. Our results show a highly complex feedback between clouds and chemistry on to the 3D temperature structure of the atmosphere, bringing about latitudinal differences and inducing time-dependent stormy features at photospheric pressures. This suggests a strong connection and feedback between the spatial cloud coverage and chemical composition of the atmosphere, with the temperature changes and dynamical motions induced by cloud opacity and triggered convection feedback driving chemical species behaviour. In addition, we also produce synthetic latitude-dependent and time-dependent spectra of our model to investigate atmospheric variability and periodicity in commonly used photometric bands. Overall, our efforts put the included physics in 3D simulations of exoplanets on par with contemporary 1D radiative-convective equilibrium modelling.

Comparison of Thermochemical and Physical Properties of Some Indonesian Agricultural Wastes

Indonesia is one of the largest agricultural countries in the world. Two main agricultural sub-sectors in Indonesia are food crops and estate crops. Agricultural waste is one of the biomass energy sources that has the potential to replace fossil energy sources. The weakness of energy sources from different types of agricultural waste is their heterogeneous thermochemical and physical properties. The objective of the experimental study is to compare the thermochemical and physical properties of fourteen selected agricultural wastes in Indonesia. The thermochemical properties that were compared are high heating value (HHV), percentage of lignocellulosic components, and ultimate analysis, while that of physical properties are the grindability, hydrophilicity, and proximate analysis. A material with high fixed carbon, low moisture, and low ash contents is preferred as a solid fuel source. Based on the experimental results of proximate analysis, coffee husk has the highest fixed carbon content (20.85%). Empty fruit bunch has the lowest moisture content (7.04%). Palm kernel shell has the lowest ash content (1.82%). Based on the results of the ultimate analysis, the palm kernel shell is the sample with the highest carbon content (49.42%), while the empty fruit bunch has the highest hydrogen content (6.69%). The coconut shell was identified as containing the lowest nitrogen (0.14%) and sulfur 0.052%). Peanut shell is the easiest to grind, while empty fruit bunch is the hardest to grind materials. The hydrophilicity of sugarcane trash is lower than other samples (9.34%). Coconut shell has the highest percentage of cellulose (47.21%). Several pairs of agricultural waste have similar properties that can be used as considerations for handling management and co-utilization.

Thermochemical modeling and performance evaluation of freeze desalination systems

Freeze desalination (FD) is a method in which saline water is cooled below its freezing point and freshwater is separated from the brine in the form of ice crystals. FD is relatively insensitive to the salinity of the feed solution, making it suitable for desalination of high concentration brines such as the brine rejected from the seawater desalination plants. The design of the FD system and the thermochemical behavior of the brine upon freezing are critical factors in the energy performance of this method. To date, thermochemical properties of the concentrated seawater during cooling, such as the threshold of formation of ice and salt-hydrates and their corresponding cooling load of formation, are not well known. Likewise, the optimal configuration of the FD system to achieve the maximum energy efficiency has not been investigated. This work provides comprehensive data about the cooling load of freezing of concentrated brine rejected from seawater desalination plants along with the threshold of formation of ice and salt-hydrates backed-up by validation. Furthermore, the optimal configuration of the FD system is identified and the effects of the compressor isentropic efficiency and effectiveness of the system's heat exchangers on the work consumption of the FD system were investigated.

Effects of multi-strain pretreatment on thermochemical properties and component structure of paulownia

This study aims to delve into the impact of long-term multi-strain pretreatment on the thermochemical characteristics of paulownia. The nine-month experimental analysis reveals that the fourth month marks a crucial turning point in the pretreatment process. From Stage I (0–4 months) to Stage II (4–9 months), the pyrolysis temperature range continuously narrows, reducing a maximum of 31.47%. The char yield initially increased by 10.25% and then decreased by 6.95%. Calorific value showed a slow initial decline of 3.98–4.08%, followed by a subsequent increase of 7.66%. The ignition point continued to rise by 5.61%− 5.78%. The compositional experimental results indicate that in the first stage, strain primarily depolymerize the high-polymer lignin, resulting in a decrease in calorific value. The increase in the relative content of syringyl lignin (S) contributes to the rise in char yield. In Stage II, the S units are converted into guaiacyl lignin (G), which has a lower char yield, while the exposed hemicellulose and cellulose undergo severe erosion. The relative content of lignin and enzymatic products with stubborn structures increases, leading to an increase in calorific value. However, the higher breaking temperature of bonds in these structures results in a continuous increase in the ignition point. This study clearly establishes that after nine months of pretreatment, the paulownia exhibits characteristics of rapid pyrolysis, high calorific value and ignition point, which provides a reliable basis for uncovering the potential reuses of paulownia.

Valorization of Coffee Residue from Convenience Store and Retail Mass-Selling Store for Producing Highly Porous Carbon Materials and Taiwan Perspectives

In Taiwan, a considerable amount of coffee residue is produced from commercial activities without valuable utilization. To evaluate high-value valorization in the production of highly porous carbon materials, this study investigated the thermochemical properties of coffee residues and further pyrolysis for producing highly porous biochar products at an elevated temperature (i.e., 850 °C) and a moderate residence time of 30 min. Our findings indicate that this biomass has a relatively high calorific value (about 27 MJ/kg, dry basis) due to its low ash and high lignocellulose content. It can be also concluded that the non-activated biochar products are highly porous carbon materials with excellent pore properties (i.e., a BET surface area of about 800 m2/g and a total pore volume of 0.4 cm3/g), which are slightly lower than those of commercial activated carbon products. Based on the above-mentioned results and the high-value circular bio-economy promoted by regulatory policy in Taiwan, the prospects for the possible valorization of coffee residue from commercial shops are addressed here, focusing both on the reuse of plant-based residue (or agricultural waste) as a high-value bioresource in the production of biomass-based fuels and on carbon materials. The former includes solid recovered fuel (SRF) and biomass-to-biogas power. By contrast, the latter aims at the production of plant-based carbon as natural, edible colorants in accordance with the regulation of food safety and sanitation in Taiwan.

Solar-blind ultraviolet photodetector based on Nb2C/β-Ga2O3 heterojunction

β-Ga2O3 has been widely investigated for its stability and thermochemical properties. However, the preparation of β-Ga2O3 thin films requires complex growth techniques and high growth temperatures, and this has hindered the application of β-Ga2O3 thin films. In this study, β-Ga2O3 thin films with good crystalline quality were prepared using a green method, and an ultraviolet (UV) detector based on β-Ga2O3 with a photocurrent of 2.54 × 10–6 A and a dark current of 1.19 × 10–8 A has been developed. Two-dimensional materials have become premium materials for applications in optoelectronic devices due to their high conductivity. Here, we use the suitable energy band structure between Nb2C and Ga2O3 to create a high carrier migration barrier, which reduces the dark current of the device by an order of magnitude. In addition, the device exhibits solar-blind detection, high responsiveness (28 A W−1) and good stability. Thus, the Nb2C/β-Ga2O3 heterojunction is expected to be one of the promising devices in the field of UV photoelectric detection.

A Detailed Study of Solvent-Ligand Interactions and in Silico Biological Activity Predictions on Hydroxychloroquine

In this study, the effects of solvent environment changes, which are of critical importance in drug production processes, on the geometric structure and physicochemical parameters of the Hydroxychloroquine (HQC) molecule were investigated. For this purpose, optimized molecule structures were obtained using Density Functional Theory in vacuum and solvent environments. Based on the optimized structures, the molecule's thermochemical properties, atomic charges, and chemical reactivity data were calculated in vacuum and solvent environments. Moreover, the molecule's molecular electrostatic potential map and HOMO-LUMO contour maps were drawn. Vibrational frequencies, intensities, and assignments in solvent environments were determined. The characteristics of the hydrogen bonding interactions established between solvent molecules and HQC were determined in detail. ADME, toxicity, and drug-likeness predictions of the molecule were made. The study results showed that while the structural, chemical, and physical properties of the HQC molecule were severely affected when transferred to the solvent environment, they were less affected by the changes between solvent environments. In addition, very strong h-bond interactions are established between the solvent molecules and HQC.

MLatom 3: A Platform for Machine Learning-Enhanced Computational Chemistry Simulations and Workflows.

Machine learning (ML) is increasingly becoming a common tool in computational chemistry. At the same time, the rapid development of ML methods requires a flexible software framework for designing custom workflows. MLatom 3 is a program package designed to leverage the power of ML to enhance typical computational chemistry simulations and to create complex workflows. This open-source package provides plenty of choice to the users who can run simulations with the command-line options, input files, or with scripts using MLatom as a Python package, both on their computers and on the online XACS cloud computing service at XACScloud.com. Computational chemists can calculate energies and thermochemical properties, optimize geometries, run molecular and quantum dynamics, and simulate (ro)vibrational, one-photon UV/vis absorption, and two-photon absorption spectra with ML, quantum mechanical, and combined models. The users can choose from an extensive library of methods containing pretrained ML models and quantum mechanical approximations such as AIQM1 approaching coupled-cluster accuracy. The developers can build their own models using various ML algorithms. The great flexibility of MLatom is largely due to the extensive use of the interfaces to many state-of-the-art software packages and libraries.

A comparative DFT analysis of chiral laterally semi-fluorinated liquid crystals

Liquid crystalline materials have the property to flow like a liquid while maintaining their molecular order. They are valuable material for technological integration. In this work, we have investigated a chiral semi-fluorinated liquid crystal material with the chemical structure C21H17F2NCS in two distinct laterally fluorine-substituted configurations. Employing density functional theory computations, we undertake a comprehensive comparative analysis of both configurations, assessing their charge dynamics, electrical characteristics, thermochemical properties, and nonlinear attributes. Intriguingly, the configuration featuring fluorine substitution on adjacent benzene rings exhibits remarkably superior properties in contrast to its counterpart, where fluorine is substituted on the same benzene ring. This research underscores the significance of structural nuances in elucidating the enhanced performance of liquid crystalline materials.

A quantum chemical investigation of the interaction of perfluoropropionic acid with monoethanolamine and sulfuric acid in the atmosphere

Perfluoroalkyl substances (PFASs) including Perfluoroalkyl acids (PFAAs), known for their chemical and thermal stability, are widely used in many industrial applications. However, their toxicity and bioaccumulative potential raise environmental and health concerns. PFAAs like Perfluoroalkyl carboxylic acids (PFCAs), detected in atmospheric aerosols, pose risks due to their long-range dispersion. Employing DFT we investigate the interactions of Perfluoropropionic acid (PFPA), a persistent organic pollutant, with atmospheric molecules like Sulfuric acid (SA) and monoethanolamine (MEA). Performing a systematic quantum-chemical analysis on structural and thermochemical properties of various ternary PFPA-SA-MEA clusters, we observe that PFPA forms stable hydrogen-bonded molecular clusters with SA and MEA which may facilitate its propagation in the atmosphere. The presence of both SA and MEA is essential to enhance the interaction capacity of PFPA in ambient condition as indicated by the calculated binding energies. A significant increase in scattering intensities of solar radiation is observed when PFPA forms clusters.

Impacts, Barriers, and Future Prospective of Metal Hydride‐Based Thermochemical Energy Storage System for High‐Temperature Applications: A Comprehensive Review

This article summarizes various thermochemical energy storage (TCES) systems based on their thermochemical properties, operating temperature, and storage density. Metal hydride (MH)‐based TCES is a potential energy storage system due to its higher energy storage density (>100 kWh m−3), higher operating temperature (>500 °C), relatively better reaction kinetics, and minimal or no energy losses (theoretically). MHs operate at various temperature ranges, and based on temperature, they are classified as low‐temperature MH and high‐temperature MH. This article highlights potential metal alloys operating above 300 °C, with an energy storage density of more than 100 kWh m−3, suitable for concentrated solar thermal power generation and industrial process heating applications. Magnesium (Mg) alloy‐based hydrides have shown good cyclic stability (up to 1500 cycles) at a temperature above 400 °C. The lower cost of material, higher energy storage capacity, better reversibility, and higher thermal stability of Mg‐based alloys have been explored in several small‐scale experimental investigations. The thermal energy storage (TES) efficiency of MH‐based TCES systems is reported ≈ 90%, which is significantly higher than sensible and latent TES systems. Challenges associated with MH‐based TES systems, such as heat transfer enhancement, cost reduction, and chemical and thermal stability, have been discussed in detail.

Application of thermodynamics at different scales to describe the behaviour of fast reacting binary mixtures in vapour-liquid equilibrium

The use of reactive working fluids in thermodynamic cycles is currently being considered as an alternative to inert working fluids, because of the preliminarily attested higher energy-efficiency potential. The current needs to simulate their use in thermodynamic cycles, which may operate in liquid, vapour or vapour-liquid state, are an accurate real-fluid equation of state and ideal gas thermochemical properties of each molecule constituting the mixture, to calculate the equilibrium constant. To this end, the appeal to a multi-scale theoretical methodology is paramount and its definition represents the objective of the present work. This methodology is applied and validated on the system N2O4 ⇌ 2NO2. Firstly, the equations solved for simultaneous two-phase and reaction equilibrium are presented. Secondly, ideal gas thermochemical properties of N2O4 and NO2 are computed at atomic scale by quantum mechanics simulations. Then, to apply the selected cubic equation of state, pure-component properties of the species forming the reactive mixture (critical point coordinates and acentric factor) are required as input. However, these properties are not measurable, since NO2 and N2O4 do not exist in nature as pure components. To get around this difficulty, the methodology relies on molecular Monte Carlo simulations of the pure N2O4 and NO2, as well as on the reactive N2O4 ⇌ 2NO2, enabling the determination of those missing pure-component properties and thus the calculation, on a macroscopic scale, of the reactive mixture properties. Finally, the comparison of calculated mixture properties with available experimental data leads to validate the accuracy of the proposed methodology.

Advancing Pyrrole Synthesis through DDQ Catalysis: A Comprehensive Research Incorporating DFT, ADMT, and Molecular Docking Analysis

AbstractThe construction of pyrroles is an important heterocyclic group comprising many compounds with interesting properties that have led to numerous applications in various fields. We delineate a new synthetic method for the rapid construction of tree‐substituted pyrroles from readily available ketoximes as starting materials and also a new mechanism and method has been proposed. It is presented that substituted pyrroles were efficiently synthesized in high yields (up to 81 % yield) through the cyclization reaction of starting ketoximes mediated by 2,3‐dichlor‐5,6‐dicyanobenzoquinone (DDQ). Utilizing this protocol various pyrrole derivatives were synthesized from diethyl acetylene dicarboxylate (DEAD). We then developed the dehydrogenation reaction mechanism of this formation, also studied in detail, also all synthesized compounds were analyzed in detail by spectroscopic techniques (FT‐IR, 1H NMR, 13CNMR) which were compared with the computational data estimated at B3LYP/6‐311G** level. The thermochemical and electronic properties of the pyrroles were evaluated after optimizing and then confirming the equilibrium structures. ADMT scores were also considered to estimate/elucidate the possible bioavailability tendencies as well as the toxicity. In addition, the interactions of the optimized molecules were evaluated by molecular docking methods against BSA “Bovine Serum Albumin” and LIF “Leukemia Inhibitory Factor”. The results obtained from this study will ideally provide a fundamental source in contemporary drug design in terms of both the key electronic properties underlying the possible reactivity features and toxicity.

Complex Structure of Molten FLiBe (2 LiF – BeF 2 ) Examined by Experimental Neutron Scattering, X-Ray Scattering, and Deep-Neural-Network Based Molecular Dynamics

The use of molten salts as coolants, fuels, and tritium breeding blankets in the next generation of fission and fusion nuclear reactors benefits from furthering the characterization of the molecular structure of molten halide salts, paving the way to predictive capability of the chemical and thermophysical properties of molten salts. Due to its neutronic, chemical, and thermochemical properties, 2LiF-BeF2 is a candidate molten salt for several fusion- and fission-reactor designs. We performed neutron and x-ray total-scattering measurements to determine the atomic structure of liquid 2LiF-BeF2. We also performed and neural-network molecular-dynamics simulations to predict the structure obtained by neutron- and x-ray-diffraction experiments. The use of machine learning provides improvements to the efficiency in predicting the structure at a longer length scales than is achievable with simulations at significantly lower computational expense while retaining near accuracy. We found that the NNMD simulations accurately predicted the BeF42− oligomer formations seen in the experimental first-structure-factor peak. Our combination of high-resolution measurements with large-scale molecular dynamics provided an avenue to explore and experimentally verify the intermediate-range ordering beyond the first-nearest neighbor that has posed too many experimental and computational challenges in previous works. With a deeper understanding of the salt structure and ion ordering, the evolution of salt chemistry over the lifetime of a reactor can be better predicted, which is crucial to the licensing and operation of advanced fission and fusion reactors that employ molten salts. To this end, this work will serve as a reference for future studies of salt structure and macroscopic properties with and without the addition of solutes. Published by the American Physical Society 2024

Calcium-looping thermochemical energy storage and mechanical performance of bio-templated CaO-based pellets under steam-containing environments

The calcium-looping thermochemical heat storage is recognized as a promising technology due to its affordable raw material expense, eco-friendliness, and superior heat storage and release capacity. To investigate the impact of inert support, pore-forming template, and reaction atmosphere on the cyclic thermochemical heat storage capacity and mechanical properties of calcium-based sorbent, spherical CaO-based pellets were prepared using cement as an inert support and microcrystalline cellulose, starch, and sesbania gum as pore-forming templates. The test results demonstrated that the optimal composition ratio for calcium-based particles was 5 wt% cement and 10 wt% pore-forming template. Calcium-based particles containing 5 wt% cement and 10 wt% cellulose demonstrated the highest thermal storage capacity. The steam-containing atmosphere reduced the heat storage ability of the calcium-based particles, but it greatly improved their mechanical characteristics. After undergoing 50 cycles with 10 vol% steam injection during calcination, the calcium-based pellets exhibited a mere 6.09 % reduction in E¯g,N compared to the heat storage cycle without steam addition. In contrast, the average crushing strength experienced a remarkable increase of 42.65 %, while the attrition rate decreased by 30.18 %.

Al–Ni–Ti thermodynamic database from first-principles calculations

First-principles calculations have increasingly become an essential tool for providing additional thermodynamic data for assessing thermodynamic databases using the CALPHAD methodology. As computational power increases and becomes easily accessible, first-principles calculation results have become more presented along with the experimental procedures to determine the thermochemical properties of the phases within a target system. This can help accelerate the alloy development process, even in complex multi-component systems. By using only first-principles calculation data for the both thermodynamic description and interaction parameters of end-members, an Al–Ni–Ti ternary thermodynamic database is constructed. By relying on the existing materials database for ground state stability of the known compounds, the constructed Al–Ni–Ti thermodynamic database can mostly capture all the features related to the solid-state phases appear in the ternary phase diagram comparable to that of the published database from an experimental data assessment.

Machine-learning to predict anharmonic frequencies: a study of models and transferability.

With more and more accurate electronic structure methods at hand, the inclusion of anharmonic effects in the post-processing of such data towards thermochemical properties is the next step. In this context, the description of anharmonicity has been an important topic of physical chemistry and chemical physics for a long time. In this study, anharmonic frequencies of various hydrogen-halides and halogenated hydrocarbon molecular clusters are calculated using harmonic as well as explicitly anharmonic methods, i.e., normal mode analysis and vibrational self-consistent field. Simple harmonic model based descriptors were used to predict anharmonic frequencies via multilinear regression and gradient boosting regression. Gradient boosting regression is capable of predicting reliable anharmonic data and even the simple multilinear regression model yields reasonable predictions that can account for mode-to-mode couplings. Moreover, the transferability to unseen chemical systems is assessed and it is confirmed that the machine-learned models can be applied to larger, unseen molecules.