Thermochemical Properties Research Articles

Optimization of waste biomass demineralization through response surface methodology and enhancement of thermochemical and fusion properties

This study examines the impact of leaching with dilute hydrochloric acid solution on the reduction of ash content and the thermal degradation behavior of sugarcane bagasse. Response surface methodology (RSM) was used to statistically design the experiments and investigate the effect of three independent variables: treatment time, solid-to-liquid ratio, and reagent concentration. The leaching conditions were further optimized and experimentally validated for maximum ash reduction for suitability of treated biomass as feedstock for thermochemical conversion technologies. Reagent concentration and treatment time directly affected ash reduction, while the solid-to-liquid ratio inversely influenced it. Concentration had the highest impact, and treatment duration had the least. The maximum 78.2% ash reduction was achieved by treating the biomass with 1 M HCl for 80 min at a solid-to-liquid ratio of 50:1 (wt/vol). This ash reduction also resulted in a 9.82% increase in higher heating value (HHV). Hemicellulose hydrolysis during leaching was observed through chemical composition and Fourier-transform infrared spectroscopy (FTIR). Ash fusion temperatures increased, indicating more thermally stable biomass. Thermogravimetric analysis (TGA) showed elevated maximum degradation temperature and activation energy.

New insight into molecular interactions of surface-active ionic liquid (SAIL) with some biomolecules: Experimental and computational approaches

Understanding the influence of ionic liquids (ILs) on the solubility of biomolecules in aqueous solutions is crucial for designing and optimizing novel biotechnological processes. However, the molecular-level mechanisms underlying this influence remain inconclusive and not fully elucidated. To contribute toward the understanding of molecular interactions between amino acids and ionic liquid in aqueous media, measurements of the densities and speeds of sound for L-serine and glycyl-L-serine in (0.00, 0.005, 0.01, 0.03, and 0.05) mol·kg−1 aqueous solutions of 1-octyl-3-methylimidazolium bromide were conducted at T = (288.15, 298.15, 308.15, and 318.15) K. From experimental data various thermodynamics paramours such as apparent molar volume (Vϕ), the partial molar volume (Vϕ0), standard partial molar volumes of transfer (ΔVϕ0) partial molar isentropic compression (Kϕ,s) and partial molar isentropic compression of transfer (ΔKϕ,S0) have been examined. Along with experiment results, computational tools were also utilized for a deeper understanding of the molecular changes. From density functional theory (DFT), the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were calculated and utilized to obtain molecular descriptors such as ionization energy (I), electron affinity (A), hardness (η), softness (S), chemical potential (μ), and electronegativity (χ). Thermochemical properties, including change in enthalpy (ΔH), and change in Gibbs free energy (ΔG), were predicted. Molecular docking studies were used to analysis the molecular interaction of ionic liquid with I-Motif structure and structural changes.

Photo- and Thermo-Chemical Properties and Biological Activities of Saclipins, UV-Absorbing Compounds Derived from the Cyanobacterium Aphanothece sacrum

Photo- and Thermo-Chemical Properties and Biological Activities of Saclipins, UV-Absorbing Compounds Derived from the Cyanobacterium <i>Aphanothece sacrum</i>

Numerical investigation of the influence of thermal runaway modelling on car park fire hazard and application to a Lithium-ion Manganese Oxide battery

This article presents numerical simulations of a Nissan LEAF 2011 electric car fire inside a concrete parking facility. Variations in the thermo-chemical properties of thermal runaway are analysed, and the way they affect the heat received by the concrete structure and a nearby parked vehicle is evaluated. Three key parameters are identified: the composition of the gas flowing through the pressure vent, the associated flow rate, and the peak heat release rate. These parameters are established independently, and the model is closed by adjusting the stoichiometry of the combustion reaction of the vented gas. Four simulations are conducted to capture the uncertainty. The net heat flux and surface temperature on the concrete and on a neighbouring parked car are monitored during each simulation. The study includes a sensitivity analysis of the impact of input variables on the net heat fluxes and surface temperatures, and investigations are carried out to understand the role of internal heat release. Variations in the gaseous mixture composition, heat release rate, and internal heat release have little impact on the resulting thermal conditions around the burning car because the combustion of the polymers in the passenger cabin drives the total heat release rate.

Biocidal polymer coatings based on porphyrin-modified epoxy-amine networks

For the first time, a pronounced biocidal activity of modified polymers with a porphyrin content of 21.4 μM (0.002 wt%) against Staphylococcus aureus was demonstrated. In order to develop new biocidal polymer coatings, a study was carried out on diglycidyl ether of bisphenol A (DGEBA) and porphyrin-modified oligomeric diamine systems. The study investigated the solubility of porphyrins in oligomers through experimental and theoretical means, using Van Krevelen's approach of additive group contributions. Fully cured epoxy-amine polymer materials modified with varied free-base tetraarylporphyrins were obtained. The materials were studied by means of thermogravimetry, differential scanning calorimetry, UV–Vis and fluorescence spectroscopy. The proposed approach to the formation of modified epoxy-amine materials allows preservation of the photophysical properties of porphyrins, including their photostability. The addition of modifiers in 4.28–21.4 μM range of concentrations makes it possible to keep the thermophysical and thermochemical properties of the polymer matrix.

Post-CCSD(T) Thermochemistry of Chlorine Fluorides as a Challenging Test Case for Evaluating Density Functional Theory and Composite Ab Initio Methods.

Quantum chemistry plays a key role in exploring the chemical properties of highly reactive chlorine polyfluorides compounds (ClFn). Here, we investigate the thermochemical properties of ClFn species (n = 2-6) by means of high-level thermochemical procedures approximating the CCSDT(Q) and CCSDTQ5 energies at the complete basis set limit. We consider total atomization energies (TAEs), Cl-F bond dissociation energies (BDEs), F2 elimination energies (F2 elim.), ionization potentials (IPs), and electron affinities (EAs). The TAEs have significant contributions from post-CCSD(T) correlation effects. The higher-order triple excitations, CCSDT-CCSD(T), are negative and amount to -0.338 (ClF2), -0.727 (ClF3), -0.903 (ClF4), -1.335 (ClF5), and -1.946 (ClF6) kcal/mol. However, the contributions from quadruple (and, where available, also quintuple) excitations are much larger and positive and amount to +1.335 (ClF2), +1.387 (ClF3), +2.367 (ClF4), +2.399 (ClF5), and +3.432 (ClF6) kcal/mol. Thus, the contributions from post-CCSD(T) excitations exceed the threshold of chemical accuracy in nearly all cases. Due to their increasing hyper-valency and multireference character, the ClFn series provides an interesting and challenging test case for both density functional theory and low-level composite ab initio procedures. Here, we highlight the limitations in achieving overall chemical accuracy across all DFT and most composite ab initio procedures.

Thermodynamic modeling of liquid binary alloys of the Al–Er system

The paper presents the results of a study of the thermochemical properties of the Al–Er system. The thermodynamic characteristics were evaluated (△fH0298, S0298, (H0298−H00), Cp(T) and Cp(liq)) for the intermetallic compounds Al3Er, Al2Er, AlEr, Al2Er3, AlEr2. The values of△fH0298 calculated based on the semiempirical Miedema model adapted for the group of Al–REM alloys were taken for calculations and amounted to –47.7, –58.4, –63, –55.2, –46.8 kJ/mol∙at, respectively. The mixing characteristics of liquid alloys of this system were evaluated by Terra software package for modeling the equilibrium states of heterogeneous inorganic systems with an extensive database of properties of individual substances. The model of ideal solutions of interaction products was used as a computational model. Modeling of equilibrium composition and properties of melts was carried out in the temperature range of 1900–2100 K, in an argon atmosphere at a total pressure of 0.1 MPa in the system. Comparison of the obtained results with the simulation results in the approximation of an ideal solution, allowed us to determine the excess integral thermodynamic properties of liquid alloys (Gibbs energy, enthalpy, and entropy). It is shown that in the studied temperature range, with an increase of temperature, there is a natural, though not significant, decrease in the values of these parameters by absolute value. It is established that the formation of liquid alloys of the Al–Er system is accompanied by significant heat release: the value of the integral enthalpy of mixing at a temperature T = 2100 K is –58.9 kJ/ mol∙at. When comparing the thermochemical properties of the Al–Er system with the binary systems Al–Y and Al–Sc studied by the same methods, it is shown that all energy curves pass through the extremum at XSc,Y,Er ≈ 0.5. The strongest interaction of the components is observed in the Al–Y system, (ΔHmix = –58.9 kJ/mol∙at), which is close enough to the maximum modulo value of the enthalpy of mixing in the Al–Er system. The weakest interaction is observed in the Al–Sc system (ΔHmix = –44.8 kJ/mol·at). The results obtained in this work provide a theoretical basis for further experimental study of erbium–containing aluminum alloys.

Experimental and numerical analysis to enhance the thermodynamic properties and biofuel stability: Sapindus mukorossi

ABSTRACT Microscale additives face challenges like sedimentation, conglomeration, and uneven size distribution, which can adversely impact biodiesel stability and thermochemical properties. This study investigates the stability and thermochemical properties of magnesium-doped calcium oxide (MdC) in Sapindus mukkarosi (SMBD25) biodiesel emulsified with antioxidants SPAN80 (SP80) and TWEEN80 (TW80) at different concentrations. 9 sets of experiments were carried out with the L9 OA as per the design matrix. Minitab 16 software was used to simplify the analysis of the results using the Taguchi method. Also, this research encompassed a comprehensive investigation by employing GCFID, SEM and XRD techniques. From the results, the heating value and cetane number for SMBD25 + 30 mg/L MdC + 30 mg/L TW80 + 30 mg/L SP80, surfactant and dispersant (1:1 ratio) biodiesel blend is improved. The enhanced absorbance and reduced transmittance for SMBD25 + 30 mg/L MdC + 30 mg/L TN80 + 30 mg/L SP80 were estimated to be 4.63 and 0.53%, respectively, while the heating value and cetane number were calculated to be 42.13 MJ/kg and 56, respectively. The Taguchi method revealed that SMBD27.8, 34ppm nanocatalyst, and 24ppm dispersant were optimum process parameters. The biodiesel blend is highly effective (71.18%) in controlling the optimal biodiesel thermochemical properties, followed by the dispersant (19.55%).

Physiochemical View of Fuel Jet Impingement and Ignition Upon Contact with a Cylindrical Hot Surface

This study delves into ignition and flame dynamics involving a cylindrical hot surface impact. Previous studies have focused on the flat-wall hot surface interacting with fuel spray, leaving gaps in understanding the effects of cylindrical hot surfaces on fuel-air mixing and ignition. Using high-fidelity large-eddy simulations (LES), this study investigates how fluid elements, upon contacting an electronically activated glow plug structure, exhibit mixing and thermochemical properties. The analysis examines how this type of structure enhances fuel-air mixing and subsequently influences the thermochemistry behavior in conjunction with the fuel-specific combustion behavior. The study includes scenarios with free spray and non-thermal deposit cases to assess their mixing impact, alongside testing five different electric voltage inputs to study the thermally assisted ignition process. Results demonstrate that the cylindrical structure hinders flow, reducing its inertia and increasing flow residence time. Moreover, a significant Coandă effect due to the circular wall structure is identified, potentially serving as a mechanism for enhancing flame-holding. Furthermore, varying the input voltage notably affects ignition timing, revealing a non-monotonic ignition delay pattern with lower voltages. Detailed analysis highlights the critical role of negative temperature coefficient (NTC)-driven low-temperature chemistry (LTC) in the ignition process.

TFE Terpolymers: Once Promising - Are There Still Perspectives in the 21st Century? Part II: Processing, Properties, Applications.

Tetrafluoroethylene (TFE) terpolymers have emerged as advantageous substitutes for polytetrafluoroethylene (PTFE). Therefore, they are being considered as alternatives to PTFE in many application areas. The advantages of TFE terpolymers include their facile processability at elevated temperatures, their solubility in some polar organic solvents, their inertness against aqueous acids, aqueous bases and a large number of mostly nonpolar organic solvents, their low dielectric constant, their low refractive index as well as useful electro- and thermochemical properties. This review on TFE terpolymers focuses on their processing including shaping and surface modification as well as on selected properties including wettability, dielectric properties, mechanical response behavior, chemical stability, and degradability. Applications including their use as elastomeric sealing material, liner and cladding layer as well as their use as material for membranes, microfluidic devices, photonics, photovoltaics, energy storage, energy harvesting, sensors, and nanothermitic composites will be discussed. The review concludes with a discussion of the future potential of TFE terpolymers and scientific challenges to be addressed by future research on TFE terpolymers.

Semi-empirical supported, Ab initio derived thermodynamic properties for ClO2 and its sub and extended species, applied in water treatment cycles

This paper describes a group of sixty (60) sub and extended chlorine oxide species with the general formulae of ClxOy (with x ≤ 2, y ≤ 8). Their role in water treatment cycles, behaving as key reactive species, is represented by a complex sequence of chemical inter-dependencies, exposed as a cohesive set of chemical reactions to demonstrate their cyclic role in aqueous media. An empirical/semi-empirical computational approach, supported by Ab Initio simulations, in accordance with open-shell character, has been followed to determine their optimum molecular geometries, to obtain their thermochemical properties. Besides a single molecular analysis, Grand Canonical Ensemble simulations, supported by a revised library of force field parameters, constituted a core component of the computational approach and proved to be invaluable in confirming thermochemical properties. This approach also offered finite estimates of optimum model sizes, a benefit with wider modelling application. Extended molecular species of ClO2 display a complex sequence of bonding character, with a variable charge dissipation (reported as partial charges), which complicates selection of basis sets in optimizing molecular geometries, during Ab Initio analyses.Optimum molecular geometries were obtained using Gaussian and MOPAC, which in turn resulted in reliable Heats of Formation. These correlated well with energies extracted from the open literature. Thermodynamic Analysis of the reaction of selected chlorine oxides with water using FactSage, predicted the production of known and two previously undetected chlorine species, [ClO4]- and [ClOH2]+.

Reduced-order condensed-phase kinetic models for polyethylene, polypropylene and polystyrene thermochemical recycling

Thermochemical recycling of plastic waste (PW) into chemicals and energy vectors requires coupling particle and reactor-scale simulations to accurate condensed phase pyrolysis mechanisms for each constituent. This work proposes a methodology to derive reduced-order condensed-phase kinetic models from validated semi-detailed kinetic mechanisms. Two types of kinetic models are obtained for polyethylene (PE), polypropylene (PP) and polystyrene (PS): reduced semi-detailed models and multi-step fully lumped ones. These families offer different compromises between accuracy and computational cost. The former employ 50–100 gas + liquid species and describe both the radical degradation and the detailed carbon distribution of the products. Conversely, the latter involves 5–10 species per polymer tracking only the main petroleum cuts. The kinetic mechanisms are complemented by the definition of thermochemical properties of gas, liquid, and solid-phase species, accounting for phase-transitions through pseudo-chemical reactions. Model validations are performed by comparison with experimental data and the original semi-detailed mechanisms in terms of mass loss, heat fluxes and product distribution profiles. The resulting CHEMKIN-like condensed-phase models are attached as Supplementary Material and as a GitHub repository. Extending the proposed approach to other polymers and coupling it with existing subsets in the CRECK kinetic framework (e.g., biomass, PVC, PET) offers a powerful tool to model thermochemical recycling of PW and biomass/PW mixtures.

Kinetic analysis of landfill stale garbage (LSG) pyrolysis and combustion behaviour using thermogravimetry coupled MS and FTIR technique

The environmental impact of landfill stale garbage (LSG), particularly concerning methane emissions and the depletion of valuable resources, presents a significant challenge to environmental sustainability. This research examines the thermochemical properties of LSG, establishing a foundation for the development of efficient treatment methods focused on energy and resource recovery. The TG-FTIR-MS technique and the modified Coast Redfern model were used to evaluate thermal behaviour, gas emissions, and decomposition during the pyrolysis and combustion processes of LSG, both individually and in blends. The study demonstrates that blended component pyrolysis attains a conversion efficiency of up to 85 %, in contrast to 65 % for individual components. This indicates a synergistic effect that implies catalytic actions, which notably improve the decomposition process and decrease pollutants such as sulphur, fluorine, nitrogen compounds, and hazardous halogens that may generate dioxins and furans during combustion. Analysis indicated that the activation energy necessary for the pyrolysis of individual LSG components exhibited significant variation, with values ranging from 7.6 to 217.3 kJ/mol. The blended components demonstrated an activation energy range of 20–178.5 kJ/mol for pyrolysis and 14.1–167.7 kJ/mol for combustion. This study suggests that pyrolysis of blended LSG components is preferable to combustion, as it offers greater efficiency and reduced pollutant emissions, despite combustion's notable energy yield and volume reduction. Our research indicates significant advancements in conversion efficiency and pollutant reduction, prompting a strong recommendation for pyrolysis as the optimal method for LSG treatment. This method demonstrates a balance between resource recovery and environmental responsibility.

Modeling biomimetic absorbent compounds for capturing carbon dioxide

Carbon capture and storage is a critical component of negative emission technologies for achieving economy-wide carbon neutrality to mitigate climate change and limit global temperature increase. Removal of CO2 can be undertaken after the standard pollution controls. Yet, the separation of CO2 from flue gas via CO2 capture processes is challenging because a high volume of gas must be treated, the CO2 is dilute, the flue gas is at atmospheric pressure, trace impurities can degrade capture media, and the captured CO2 must be compressed. We present a computational study of a novel family of biomimetic materials for such carbon capture processes based on the Crassulacean Acid Metabolism. Phosphoenolpyruvate serves as a template for designing similar molecules for use as CO2 solvents with designed thermochemical properties.

Perovskite Oxide Materials for Solar Thermochemical Hydrogen Production from Water Splitting through Chemical Looping.

Solar-driven thermochemical hydrogen (STCH) production represents a sustainable approach for converting solar energy into hydrogen (H2) as a clean fuel. This technology serves as a crucial feedstock for synthetic fuel production, aligning with the principles of sustainable energy. The efficiency of the conversion process relies on the meticulous tuning of the properties of active materials, mostly commonly perovskite and fluorite oxides. This Review conducts a comprehensive review encompassing experimental, computational, and thermodynamic and kinetic property studies, primarily assessing the utilization of perovskite oxides in two-step thermochemical reactions and identifying essential attributes for future research endeavors. Furthermore, this Review delves into the application of machine learning (ML) and density functional theory (DFT) for predicting and classifying the thermochemical properties of perovskite materials. Through the integration of experimental investigations, computational modeling, and ML methodologies, this Review aspires to expedite the screening and optimization of perovskite oxides, thus enhancing the efficiency of STCH processes. The overarching objective is to propel the advancement and practical integration of STCH systems, contributing significantly to the realization of a sustainable and carbon-neutral energy landscape.

Thermochemistry of the Mantle Transition Zone Beneath the Western Pacific

AbstractThe Earth's mantle transition zone has significant control on material flux between upper and lower mantle, thus constraining its properties is imperative to understand dynamic processes and circulation patterns. Global seismic data sets to study the transition zone typically display highly uneven spatial distribution. Therefore, complementary geometries are essential to improve knowledge of physical structures, thermochemistry, and impact on convection. Here, we present a new automated approach utilizing machine learning to analyze large seismic data sets, and derive high‐resolution maps of transition zone discontinuity properties. Seismic measurements from ScSScS precursors are integrated with mineralogical modeling to constrain thermochemistry of the western Pacific subduction zone. Our models map recent subduction patterns through the transition zone, indicating stagnation of slabs and accumulation of basalt at its base, and interaction between stagnant slabs and plumes. These results suggest that the thermochemical properties of upper mantle discontinuities can provide high‐resolution images of mantle circulation patterns.

Prediction of Thermochemical Properties of Long-Chain Alkanes Using Linear Regression: Application to Hydroisomerization.

Linear regression (LR) is used to predict thermochemical properties of alkanes at temperatures (0-1000) K to study chemical reaction equilibria inside zeolites. The thermochemical properties of C1 until C10 isomers reported by Scott are used as training data sets in the LR model which is used to predict these properties for alkanes longer than C10 isomers. Second-order groups are used as independent variables which account for the interactions between the neighboring groups of atoms. This model accurately predicts Gibbs free energies, enthalpies, Gibbs free energies of formation, and enthalpies of formation for alkanes which exceeds the chemical accuracy of 1 kcal/mol and outperforms the group contribution methods developed by Benson et al., Joback and Reid, and Constantinou and Gani. Predictions from our model are used to compute the reaction equilibrium distribution of hydroisomerization of C10 and C14 isomers in MTW-type zeolite. Calculation of reaction equilibrium distribution inside zeolites also requires Henry coefficients of the isomers which can be computed using classical force field-based molecular simulations using the RASPA2 software for which we created an automated workflow. The reaction equilibrium distribution for C10 isomers obtained using the LR model and the training data set for this model are in very good agreement. The tools developed in this study will enable the computational study of hydroisomerization of long-chain alkanes (>C10).

Assessment of thermochemical, physicochemical, and biochemical properties of purple cabbage powder converted by different drying systems

Assessment of thermochemical, physicochemical, and biochemical properties of purple cabbage powder converted by different drying systems

Two Optimization Approaches for a Small‐Scale Power‐to‐Ammonia Cycle

AbstractAmmonia is a promising carbon‐free energy vector. Small‐scale renewable power‐to‐ammonia (P2A) is particularly suited for isolated agricultural areas where ammonia can be used as fuel and fertilizer. This work compares two approaches to simulate and optimize the steady‐state behavior of a novel small‐scale P2A process: Aspen Plus® and MOSAIC®. Aspen Plus® is a commercial flow sheeting software whereas MOSAIC® is a freeware where equations and thermochemical properties need to be specified by hand. It can be shown that the results of MOSAIC® and Aspen Plus® are qualitatively comparable, but not identical. This suggests that the model in MOSAIC® can be improved further, starting with the implementation of a more accurate numeric reactor kinetics and equation of state.

Environmental footprint and material composition comparison of single-use and reusable duodenoscopes.

Infection outbreaks associated with contaminated reusable duodenoscopes (RUDs) have induced the development of novel single-use duodenoscopes (SUDs). This study aimed to analyze the material composition and life cycle assessment (LCA) of RUDs and SUDs to assess the sustainability of global and partial SUD implementation. A single-center study evaluated material composition analysis and LCA of one RUD and two SUDs from different manufacturers (A/B). Material composition analysis was performed to evaluate the thermochemical properties of the duodenoscope components. The carbon footprint was calculated using environmental software. We compared the sustainability strategies of universal use of RUDs, frequent use of RUDs with occasional SUDs, and universal use of SUDs over the lifetime of one RUD. RUDs were substantially heavier (3489 g) than both SUD-A (943 g) and SUD-B (716 g). RUDs were mainly metal alloys (95%), whereas SUDs were mainly plastic polymers and resins (70%-81%). The LCA demonstrated the sustainability of RUDs, with a life cycle carbon footprint 62-82 times lower than universal use of SUDs (152 vs. 10 512-12 640 kg CO2eq) and 10 times lower than occasional use of SUDs (152 vs. 1417-1677 kg CO2eq). Differences were observed between SUD-A and SUD-B (7.9 vs. 6.6 kg CO2eq per endoscope). End-of-life incineration emissions for SUDs were the greatest environmental contributors. Widespread adoption of SUDs has greater environmental challenges; it requires a balance between infection control and environmental responsibility. Carbon footprint labelling can help healthcare institutions make sustainable choices and promote environmentally responsible healthcare practices.