Simultaneous Thermogravimetric Analysis Research Articles

Enhancing chemical heat storage performance of nanocarbon porous particle based MgO/Mg(OH)2 composite by calcination method

The application of MgO/Mg(OH)2 in heat storage technology has been limited due to slow hydration rate and easy agglomeration. In this paper, nanoporous carbon particle (NCP) as a carrier was used to prepare NCP/MgO chemical heat storage composite materials by impregnation and calcination methods, respectively. The microstructure characterization, hydration reaction, and simultaneous thermogravimetric analysis experiments were carried out on the prepared composite materials. The results showed that the internal distribution of MgO in the composite material prepared by calcination method was more uniform, and the particle size of MgO was smaller. Under the conditions of 110 ℃ hydration temperature and 57.8 kPa water vapor partial pressure, the hydration conversion ratio of the composite material prepared by calcination method after 120 min of hydration conversion ratio reached 93 %, which was 17.7 % higher than that of the impregnated composite material and 50 % higher than that of pure MgO. Under the comprehensive influence of specific surface area, pore structure, and active component particle size, compared with pure materials and impregnated composite materials, the dehydration rate of the composite material prepared by calcination method at 300 ℃ was twice that of impregnated method and 6 times that of pure MgO, and the heat storage density reached 1039kJ/kg. After 10 cycles, the heat storage density still maintained an initial state of 95.8 %. Compared with pure materials and impregnated composite materials, NCP/MgO composite materials prepared by calcination method had better heat storage performance and higher cyclic stability.

A high-speed method to obtain Ni-Zn ferrite nanoparticles by microwave hydrotalcite decomposition for magnetic applications

Nanoparticles of Zn0.375Ni0.625Fe2O4 ferrite were successfully synthesized using an innovative, rapid, and efficient synthesis method based on microwave-assisted hydrotalcite decomposition, enabling nanoparticle crystallization in less than 15 minutes. A single composition was studied to better assess the impact of the synthesis method on structural, morphological, and magnetic properties. This new synthesis route was compared with the traditional ceramic method. The prepared hydrotalcite was analyzed by high-resolution transmission electron microscopy (HRTEM), identifying hydrotalcite diffraction planes consistent with selected area electron diffraction (SAED) and X-ray diffraction (XRD) patterns. The decomposition phases of the hydrotalcite were identified by simultaneous thermogravimetric and differential thermal analysis (DTA/TG). After hydrotalcite decomposition, the ferrite obtained was analyzed by XRD, confirming a single-phase cubic structure. Scanning electron microscopy (SEM) micrographs revealed nanoparticles less than 100 nm in size with the new method and larger than 2 µm with the traditional route. At a temperature of 5 K, the M-H graph obtained with a superconducting quantum interference device (SQUID) indicated that the spinel-type ferrite exhibited a smooth ferrimagnetic behavior, which was also corroborated by electron paramagnetic resonance (EPR). Magnetic saturation values of 105.73 emu/g were obtained in the synthesis microwave-assisted hydrotalcite decomposition and 51.49 emu/g in the traditional synthesis, representing an increase of over 100 %. The two synthesis methods were also compared using density functional theory (DFT) calculations, confirming the influence of morphology on magnetic properties, obtained thanks to different synthesis methods. These results indicate that the synthesized Ni-Zn spinel ferrite nanoparticles can be used in high-frequency applications, such as ceramic induction plates.

Acidic pathway in formation of SiO2–AlO2–PO2 geopolymeric ceramic: Investigation of structural evolution and electrical behaviour

The investigation into the acidic pathway in geopolymer formation has been overlooked compared to the alkaline pathway. This study seeks to fill the gap by exploring the development mechanism and electrical properties of this type of geopolymer. The microstructural properties of geopolymer ceramics were assessed through the deconvolution of attenuated total reflectance-Fourier-transform infrared spectra (ATR-FTIR), powder X-ray diffraction (PXRD), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), simultaneous thermogravimetric analysis and differential thermal analysis (TGA/DTA). Furthermore, the electrical properties of the prepared ceramics were monitored using solid-state impedance spectroscopy (ss-IS). Maintaining an Al to P molar ratio of 1:1, various post-treatment temperatures (60 °C, 105 °C, 300 °C, 1200 °C) were employed to observe their effects on the (micro)structural properties of the samples under investigation. This ratio ensures the formation of an amorphous structure of SiO2·Al2O3·P2O5·nH2O. Additionally, the emergence of new crystalline aluminium and phosphate phases was observed.

Pyrolysis of folic acid: Identification of gaseous/volatile products and structural evolution of N-doped graphitic carbon

Folic acid (FA) is a low-cost and suitable source for producing different N-doped carbon materials by pyrolysis. However, the pyrolytic steps of FA are not entirely understood, particularly above 350 °C, which hampers the intelligent design of tailor-made carbon materials by a one-pot route. In this work, the pyrolytic decomposition steps of FA were investigated by simultaneous thermogravimetric analysis (TGA) and differential scanning calorimetry (TGA-DSC). The released gaseous/volatile products were probed by coupling TGA to infrared spectroscopy and mass spectrometry (TGA-FTIR-MS). Considering the thermal analysis data, FA was pyrolysed in a furnace at 350, 430, 570, 800, and 1000 °C, and the products were analysed by X-ray diffractometry (XRD), vibrational spectroscopy, and X-ray photoelectron spectroscopy. In situ high-temperature X-ray diffractometry (HT-XRD) experiments were also conducted under the nitrogen atmosphere. According to the data set, insights about FA decomposition steps could be proposed, including gaseous/volatile products released during the process and the structural evolution of N-doped graphitic carbon. The formation of carbonaceous material initiated between 200 and 350 °C through polymerisation/condensation reactions, and this step was marked by the release of 2-pyrrolidone and aniline. The graphitisation was enhanced above 350 °C, increasing graphitic nitrogen while the amide groups vanished. The process was accompanied by deoxygenation (i.e., CO and CO2 release) and denitrogenation (e.g., NH3, HNCO, and HCN) reactions. In the 570–800 °C range, the N-enrichment of carbon material (N-pyridine, N-pyrrole/Csp2-N in 5,7-membered rings, and nitrile) could occur by the reaction of released NH3 over the char surface. Graphitic-like structures containing mainly N-graphite and N-pyridine were obtained above 800 °C. The original data about the thermal decomposition steps of FA allow for optimising the synthesis of N-doped carbon materials suitable for applications in adsorption, sensing, catalysis, and energy storage.

Physical and chemical techniques for a comprehensive characterization of river sediment: A case of study, the Moquegua River, Peru

River sediment is comprised of complex mineral systems composed by different kinds of organic and inorganic matter, and thus, is difficult to characterize. Besides, some standard techniques, such as X-ray diffraction (XRD), energy dispersive X-ray (EDX), optical and scanning electron microscopy, Fourier transmission infrared spectroscopy, inductively couple plasma-mass spectrometry (ICP-MS), and simultaneous Thermogravimetric Analysis – Differential Thermal Analysis (TGA-DTA), Mössbauer spectroscopy and magnetometry can provide substancial information about the compositional, physical, and chemical characteristics. In the current study, the versality of these methods is tested and the information provided by these methods for eight sediment samples, collected from the Moquegua River, Peru is compared. Qualitative analysis indicates that the samples consist of sand grains with different shapes, sizes, and colors coexisting with the presence of some diatoms. The chemical and mineralogical analysis reveal that the samples are composed mainly of silicon (Si), aluminium (Al), sodium (Na), potassium (K), aluminon–silicates, and carbonates, typical for river sediment. More detailed information obtained by these techniques include the discovery of adsorbed oxygen–hydrogen (O–H), carbon–H (C–H) and C, from organic matter, the thermal reactions and decomposition of the components, and the identification of the minor iron–oxides components. Further, other properties such as magnetic interaction are also analyzed in detail.

PH-Triggered Controlled Release of Chlorhexidine Using Chitosan-Coated Titanium Silica Composite for Dental Infection Prevention.

Peri-implantitis is a growing pathological concern for dental implants which aggravates the occurrence of revision surgeries. This increases the burden on both hospitals and the patients themselves. Research is now focused on the development of materials and accompanying implants designed to resist biofilm formation. To enhance this endeavor, a smart method of biofilm inhibition coupled with limiting toxicity to the host cells is crucial. Therefore, this research aims to establish a proof-of-concept for the pH-triggered release of chlorhexidine (CHX), an antiseptic commonly used in mouth rinses, from a titanium (Ti) substrate to inhibit biofilm formation on its surface. To this end, a macroporous Ti matrix is filled with mesoporous silica (together referred to as Ti/SiO2), which acts as a diffusion barrier for CHX from the CHX feed side to the release side. To limit release to acidic conditions, the release side of Ti/SiO2 is coated with crosslinked chitosan (CS), a pH-responsive and antimicrobial natural polymer. Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) and Fourier transform infrared (FTIR) spectroscopy confirmed successful CS film formation and crosslinking on the Ti/SiO2 disks. The presence of the CS coating reduced CHX release by 33% as compared to non-coated Ti/SiO2 disks, thus reducing the antiseptic exposure to the environment in normal conditions. Simultaneous differential scanning calorimetry and thermogravimetric analyzer (SDT) results highlighted the thermal stability of the crosslinked CS films. Quartz crystal microbalance with dissipation monitoring (QCM-D) indicated a clear pH response for crosslinked CS coatings in an acidic medium. This pH response also influenced CHX release through a Ti/SiO2/CS disk where the CHX release was higher than the average trend in the neutral medium. Finally, the antimicrobial study revealed a significant reduction in biofilm formation for the CS-coated samples compared to the control sample using viability quantitative polymerase chain reaction (v-qPCR) measurements, which were also corroborated using SEM imaging. Overall, this study investigates the smart triggered release of pharmaceutical agents aimed at inhibiting biofilm formation, with potential applicability to implant-like structures.

The Influence of Alkaline Pretreatment of Waste Nutshell for Use in Particulate Biocomposites

The aim of this work was to determine how different types of alkaline pretreatment influence the properties of waste almond and hazelnut nutshell, as well as their compatibility with model inorganic geopolymer matrixes for the formation of biocomposites with potential use in civil engineering. For alkaline pretreatment, 3, 6 and 9% NaOH water solutions and milk of lime were used under different temperature and time conditions. The rise in the crystallinity index was confirmed by X-ray powder diffraction analysis, while the corroboration of the removal of amorphous and undesirable components was demonstrated through Fourier-transform infrared spectroscopy. Furthermore, the effectiveness of the pretreatments was confirmed via simultaneous differential thermal and thermogravimetric analysis, and the positive change in the morphology of the surface of the waste nutshell (WN) and the deposition of the desired phases was established using scanning electron microscopy. Surface free energy and adhesion parameters were calculated using the Owens, Wendt, Rabel and Kaelble method for WN as fillers and geopolymers as model novel inorganic binders. This research indicates that the 6% NaOH treatment is the optimal pretreatment process for preparing WN as the filler in combination with potassium and metakaolin geopolymer that has been cured at room temperature.

Optimising thermochemical energy storage: a comprehensive analysis of CaCO3 composites with CaSiO3, CaTiO3, and CaZrO3.

With the increasing amount of renewable energy produced, many governments and industries are pushing for the installation of battery energy storage system (BESS) solutions. Thermal batteries are systems that store heat made from various energy sources, and can be used to produce electricity upon demand. These systems are easily scalable and can be installed in cities, homes and remote locations. Thermochemical energy storage (TCES) uses the enthalpy of a chemical reaction to store and release heat through endothermic and exothermic processes, respectively. CaCO3 has been identified as an ideal TCES material as it is cheap and abundant, but maximising long-term cyclability is key to ensure battery longevity. This article investigates the addition of CaSiO3, CaTiO3 and CaZrO3 to CaCO3 in a 1 : 1 ratio to ascertain the reaction properties and cyclic capacity over time. Cycling longevity and thermodynamic properties were determined using simultaneous differential scanning calorimetry and thermogravimetric analysis (DSC-TGA) along with the Sieverts technique, and their reaction pathway studied by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The low cost of the CaCO3-CaSiO3 material of $1.8 USD per kW hth suggests that if a suitable particle refinement agent were to be employed to ensure cycling longevity this material would be an excellent TCES material. Despite the CO2 cycling capacity of the CaCO3-CaZrO3 system only reducing by 16 wt% over 100 cycles, the cost of ZrO2 brings the materials cost to $30.9 USD per kW hth, making this material currently unsuitable for application. The CaCO3-CaTiO3 system showed only a 17% drop in total CO2 uptake over 100 cycles, although the cost was $11.1 USD per kW hth.

Thermal decomposition of fluorinated polymers used in plasticized explosives and munitions

AbstractA number of military explosives and munitions employ fluorinated polymers as binders or components, e. g., PBXN‐5. To determine potential environmental releases during disposal operations, the thermal decomposition of the fluorinated polymers Viton A, Kel‐F, and Teflon were examined alone and in combination with the explosive HMX. Although PBXN‐5 only contains 5 % by weight Viton A, laboratory prepared analogs were made with 5 % polymer as well as with 50 % polymer to ensure polymer decomposition products could be detected. Under air and under nitrogen decomposition was examined by SDT [simultaneous differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)], TGA‐infrared (IR) spectrometry, and pyrolysis gas chromatography with mass spectrometric analysis (GC‐MS). All three techniques, SDT, TGA‐IR, and pyrolysis GC‐MS, suggest that decomposition of HMX could be completed at low temperature before polymer decomposition ensues. To confirm this observation, pyrolysis GC‐MS was performed at temperatures below 350 °C since above this temperature all three polymers exhibited some fluorinated decomposition products.

A novel super high latent heat ternary eutectic salt for high temperature thermal energy storage

This work is concerned with a novel ternary eutectic salt based phase change material (PCM) for high temperature thermal energy storage applications. We designed the PCM formulation in a FactSage environment and demonstrated that the formulation had a very high latent heat. The microstructure, thermal physical properties, thermal stability and cycling service life of the eutectic salt were measured experimentally with various analytical methods including scanning electron microscopy (SEM), X-ray diffractometer analysis (XRD), simultaneous thermogravimetric analyzer (STA) technique, differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The results indicated that the eutectic salt had a melting point of 552.23 °C with a superhigh fusion enthalpy of 661.33 J/g. The change of melting point and latent heat of salt after 1500 cycles is 0.48% and 7.84%, respectively, showing excellent cycle stability.

Towards a heat‐ and mass‐balanced kinetic model of TATB decomposition

AbstractTATB (1,3,5‐triamino‐2,4,6‐trinitrobenzene) was thermally degraded by two small‐scale analytical methods – simultaneous differential scanning calorimetry and thermogravimetric analysis (SDT) and a hot‐stage microscope with Fourier Transform Infrared (FTIR) analysis capabilities. SDT used ramped heating, isothermal soaking, and thermal pretreatment at various conditions. The heat flow and mass loss were monitored during various treatment conditions to derive chemical decomposition kinetics and Arrhenius parameters. FTIR experiments used isothermal heating, and changes were monitored spectroscopically. Solid samples generated at specific conditions were collected from both methods and were analyzed by DMSO extraction followed by chemical speciation by optical and mass spectrometric methods. Characterization provided the following reaction insights:1. TATB decreases in a sigmoidal pattern in isothermally heated samples. Other soluble products gradually increase in concentration and then abruptly decline in concentration during the second exotherm, such as diamino‐dinitro‐benzofurazan and amino‐nitro‐benzodifurazan.2. FTIR showed gradual changes in the amino and nitro functionality, shifting positions and decreasing intensity for the first 40 min. Then the solid gradually appeared more like an amorphous C with N incorporated, similar to previous studies on thermally degraded TATB‐type materials.3. Extracted residues (DMSO‐soluble components removed) examined by FTIR showed an abrupt change in chemical composition between 40‐ and 45‐min isothermal treatment, indicating early forming solids are different than later forming residues.4. A reliable mass‐ and energy‐balanced global reaction network must include at least two autocatalytic reactions, either in parallel or series, and at least one must have an explicit initiation reaction having a low activation energy.

Abstract 125: Elevated Bacterial Fatty Acid Metabolism And Fecal Calorific Values Are Associated With Reduced Diet-induced Adiposity And Weight Gain In Mice

Introduction: Activation of the sympathetic nervous system (SNS) leads to exaggerated immune responses in cardiometabolic conditions. We previously showed that ablation of beta-adrenergic receptors (ADRB) on the bone marrow (BM) hematopoietic cells reduces blood pressure, dampens the immune responses, and modifies gut microbiota, suggesting multisystem host-microbiota interactions. To investigate the role of the microbiota in these complex interactions, we tested the effects of high fat diet (HFD) on the gut microbiota and adiposity in BM mouse chimera characterized by reduced SNS-immune signaling. Methods: Male C5BL/6 wild type (WT) mice were irradiated and reconstituted with BM cells from either the C57BL/6 WT controls or the ADRB 1/2 knock-out mice (KD) to generate BM chimera. Following recovery, mice were fed with a control diet (CNT) or HFD for two weeks ad libitum . Food intake and body weights were measured weekly, and body fat (NMR) and visceral fat pad weights were measured at endpoint. At endpoint, 16S sequencing and metagenomic analyses (QIIME2, PiCRUST2) were performed in cecal samples, and residual fecal calorific values were determined using a simultaneous thermogravimetric analyzer differential calorimeter (TA Instruments). Results: No change in food intake was observed in either group. However, significant increases in body weight, total body fat, and visceral fat weight were observed in the WT compared to KD chimera on HFD ( p<0.05) . HFD elevated gut bacterial Shannon α-diversity (p< 0.05) in the WT but not the KD chimera, and we observed a decrease in g_Faecalibacterium and p_Actinobacteria in WT, and an increase in p_Bacteroidetes and o_Bacteroidales in the KD mice on HDF. Enrichment in fatty acid metabolic pathways and increased fecal calorific values were observed in the KD compared to WT chimera on HFD ( p<0.05) . Conclusion: Reduced SNS-immune signaling is protective against diet-induced weight gain and body fat accumulation. This may in part be mediated by the gut microbiota, reflecting in increased bacterial fatty acid metabolism and elevated residual fecal calorific values, suggesting reduced fat absorption. We propose that selective enrichment of gut bacteria is a potential therapeutic target in diet-induces obesity.

Evaluation of the thermal stability and pyrolysis mechanism of 1-ethyl-3-methylimidazolium dicyanamide and 1-Butyl-3-methylimidazolium dicyanamide by STA, DSC, TG-FTIR

As a common ILs anion, dicyandiamide ILs is widely used in deep desulfurization and denitrogenation of fuel oil. In this study, two types of dicyandiamide salts containing cations with different carbon chain lengths were selected, 1-Ethyl-3-methylimidazolium dicyanamide ([EMIM]DCN) and 1-Butyl-3-methylimidazolium dicyanamide ([BMIM]DCN) were selected to investigate. However, under air conditions, the thermal effects of the two ILs are opposite. Therefore, the relationship between carbon chain length and the thermal stability and pyrolysis mechanism of ILs deserves further research. The thermal stability, exothermic properties and pyrolysis mechanism of the two substances under air conditions using simultaneous thermogravimetric analyzer measurements (STA), differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FTIR).Through thermogravimetric experiments, it was found that the apparent activation energies of [EMIM]DCN and [BMIM]DCN were 120 kJ mol−1 and 101 kJ mol−1, respectively. This explain that the carbon chain length is inversely proportional to the thermal stability of ILs. DSC shows that [BMIM]DCN has three exothermic stages and emits a total of 2075.67 J g−1 heat, while [EMIM]DCN has one endothermic stage and one exothermic stage, releasing 343.44 J g−1 heat, compared to [BMIM]DCN, [EMIM]DCN is clearly more secure. Through FTIR experiments, it was found that due to the longer and less stable carbon chain of [BMIM]DCN, it is more prone to oxidative exothermic generation of CO2, thus [BMIM]DCN exhibits exothermic behavior in the first stage of DSC experiments. The carbon chain of [EMIM]DCN is relatively short and stable, so it fails to oxidize to generate sufficient CO2 in the first stage and needs to absorb heat to generate isocyanates. In the third stage, due to the increase in temperature, the carbon atoms of [EMIM]DCN and [BMIM]DCN are oxidized and converted into CO2, releasing enormous heat, which explains the huge exothermic phenomenon in the final DSC experiment.

Enhanced injectability of aqueous β-tricalcium phosphate suspensions through PAA incorporation, gelling and preshearing

The major shortcoming of aqueous calcium phosphate suspensions used in biomedical applications is their unstable flow during delivery by mechanical means. In this study, microstructural changes and the resulting flow instabilities of aqueous β-TCP suspensions are demonstrated under both pressure-induced and drag-induced flow regimes and then remedied with the incorporation and subsequent gelling and preshearing of Carbopol 940, a biocompatible hydrogel. Mixing and dispersion of calcium phosphate particles into the hydrogel matrix was not efficient under simple agitation conditions. Swelling of the polymer chains was induced at approximately pH = 9.0 by water and particle intrusion within the opened-up coil structure due to deprotonation of the carboxylic acid groups by NaOH. As a result the composite material underwent a rapid viscoplastic transition into a doughy state which was not amenable to further processing without preshearing. Manual kneading converted the material into viscous state and enhanced the flow behavior significantly. Preshearing and probing the microstructure by mechanical spectrometer revealed multiple microstructural mechanisms responsible for the observed stable flow behavior, including improved dispersion of the particles, attrition of the polymeric network into microgel domains, enhanced adhesion and lubrication between the solid and liquid phase, crosslinking of the polymeric network. The net effect of these probable mechanisms was stiffening of the composite matrix, mobilization of solid particles and a marked enhancement in the stability of pressure-induced flow. The resistance of the material to liquid phase migration and its ability to undergo wall-slip and relax under stress were confirmed by simultaneous capillary rheometry and thermogravimetric analyses. The processing method enables improvements in the delivery of this composite material for injection and direct ink writing of scaffolds.

Water-Soluble Nanocomposites Containing Co3O4 Nanoparticles Incorporated in Poly-1-vinyl-1,2,4-triazole.

New water-soluble nanocomposites with cobalt oxide nanoparticles (Co3O4NPs) in a poly(1-vinyl-1,2,4-triazole) (PVT) matrix have been synthesized. The PVT used as a stabilizing polymer matrix was obtained by radical polymerization of 1-vinyl-1,2,4-triazole (VT). The polymer nanocomposites with Co3O4 nanoparticles were characterized by ultraviolet-visible, Fourier-transform infrared spectroscopy, atomic absorption spectroscopy, transmission electron microscopy, dynamic light scattering, gel permeation chromatography, and simultaneous thermogravimetric analysis. The resulting polymer nanocomposites consist of spherical isolated cobalt nanoparticles with a diameter of 1 to 13 nm. The average hydrodynamic diameters of macromolecular coils are 15-112 nm. The cobalt content in nanocomposites ranges from 1.5 to 11.0 wt.%. The thermal stability of nanocomposites is up to 320 °C.

Investigation of how pressure influences the thermal decomposition behavior of azodicarbonamide

Azodicarbonamide (ADC) is a type of azo compound with outstanding application performance, it is always used as a blowing agent in the production of foamed plastics. Based on previous studies, it has been considered harmless in its practical application process. Nevertheless, our research has overturned this standpoint and denoted the special exothermic behavior of ADC under specific use processes, especially when it was placed in a high-pressure system. In this study, a simultaneous thermogravimetric analyzer (STA) was employed to preliminarily evaluate the thermal stability of ADC under atmospheric pressure. Followed with calorimetric experiments by high-pressure differential scanning calorimetry (HP DSC), the exothermic behaviors of ADC under different initial furnace pressures were investigated. The obtained results revealed that the thermal decomposition rate of ADC linearly increases along with increasing testing pressure, which shows a highly autocatalytic characteristic. The peak power of DSC curve breathtakingly reached 73 W/g when the initial testing pressure was set at 4 MPa, and the overall decomposition heat reached 1261 J/g with the scanning rate at 4 °C/min. Furthermore, the decomposition mechanism, thermal hazards, and explosion potential were comprehensively evaluated in this study for the first time.

Thermal stability and decomposition mechanism analysis of 1, 1’-Azobis(cyclohexanecarbonitrile) by STA, DSC, ARC and TG-FTIR

1, 1′-Azobis(cyclohexanecarbonitrile) (ABCN) is a kind of azo compound, which is widely used as an initiator in the polymer industry. Plenty of heat will be released during the thermal decomposition, and fire or explosive accidents could happen when the cooling system of the polymerization reactor fails. In this manuscript, the thermal decomposition behavior of ABCN under a dynamic temperature environment was investigated by simultaneous thermogravimetric analyzer (STA). Differential scanning calorimeter (DSC) was used to detect the thermal effects of different stages of mass loss. The apparent activation energy was calculated by Kissinger-Akahira-Sunose methods (K-A-S methods). The thermal runaway behavior was investigated by accelerating rate calorimeter (ARC), which was used to predict time to maximum rate under adiabatic condition (TMRad). The results show that the temperatures at TMRad = 8 h and 24 h are 93.0 °C and 89.7 °C, respectively. The self-accelerating decomposition temperature (SADT) is 86.6 °C, which is calculated based on the thermal theory of Semenov. Since ABCN is used at 60–90 °C, a major accident could happen when the heat accumulated in the reactor is not removed timely. The risk of thermal runaway reactions for ABCN was defined against the risk matrix as level Ⅲ, which is an unacceptable risk. The carbon radicals and nitrogen were released during the decomposition of ABCN based on the experiment result of thermal gravimetric analyzer-Fourier transform infrared spectrometer (TG-FTIR) system. Several safety assessment parameters could supply references for the industry to alleviate thermal hazards and prevent critical incidents.

Thermal and electrical transport property study of direct vapour transport grown Cu2SnS3 single crystals

Copper tin sulphide (Cu2SnS3) (CTS) single crystals are grown by vapour transport technique of direct (DVT) type. The stoichiometric compositional analysis; Cu: 40.78 % (37.21 %), Sn: 31.09 % (34.35 %) and S: 28.13 % (28.15 %); showed the crystals to be slightly copper rich and tin deficient, bracket values are standard data. The X-ray diffraction showed the CTS to possess cubic unit structure having lattice parameter of 5.43 Å. The high resolution transmission electron microscopy substantiated the crystalline character. The thermal analysis are carried out by recording simultaneous thermogravimetric, differential thermogravimetric and differential thermal analysis curves. These analysis are done in inert atmosphere for three heating rates of 10, 15 and 20 K⋅min−1 in the range from ambient to 1023 K. The thermocurves are analyzed by two standard methods of Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The thermodynamic parameters like activation energy, changes of entropy, enthalphy and Gibbs free energy are determined using KAS and FWO methods. These determined thermodynamic parameters of as-grown CTS single crystals matches each other stating the validity of the analysis. Temperature variation of electrical transport properties like dc electrical resistivity (ρ) and Seebeck coefficient (S) are measured in the temperature range of 323 K to 473 K. The values of ‘ρ’ decreases with temperature, stating semiconducting nature of crystals. The observed ‘S’ values are found to be positive in entire temperature range, stating crystals to be of p-type semiconducting nature.

Reusing Waste Coffee Grounds in the Preparation of Porous Alumina Ceramics

Porous ceramics can be used in various industrial applications, such as thermal insulation, orthopedic implants, high-temperature filtration, lightweight structural components, and catalyst supports, etc., and can be obtained using various methods. In this study, the sacrificial fugitive method was used to prepare a porous alumina ceramic. The appropriate amount of sacrificial fugitive was combined with raw ceramic powder as a pore-forming agent, and was then evaporated or burned out either before or during the sintering process to create the desired pores. Various materials can be used as pore-forming agents; in this work, eco-friendly waste coffee grounds (WCG) were utilized. First, alumina ceramic green bodies were prepared via slip casting of 60 wt. % alumina suspensions with five different amounts of WCG (0 wt. %, 1 wt. %, 5 wt. %, 10 wt. % and 15 wt. %) and the dispersant Dolapix (0.2 wt. %), and using PVA (0.5 wt. %) as a binder for all solutions. The effect of the various amounts of WCG on the alumina ceramic green bodies, and subsequently on the obtained sintered ceramics, was tracked and validated through different analyses. Suspension viscosity was determined through a rotational viscometer. Simultaneous differential thermal and thermogravimetric (DTA/TGA) analyses were used to observe the thermal decomposition of WCG and to determine the sintering regime. After sintering, the density, porosity, and shrinkage of the samples were examined and calculated. In addition, the phase composition and crystallite size of all sintered samples were determined by powder X-ray diffraction (PXRD) analysis, as well as their morphology and composition using Scanning Electron Microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). The results show that density decreased from 3.743 to 2.172 g/cm3 and porosity increased from 6.12% to 45.52%, both with the increasing amount of WCG (from 0 wt. % to 15 wt. %).

Experiments on Vapor Pressure of KCl at Different Molar Fractions in Mixtures of KCl + K2SO4.

The objective of this paper is to measure the vapor pressure of potassium chloride (KCl) in its mixture with potassium sulfate (K2SO4). Evaporation behavior of pure salts of KCl, K2SO4, and their mixtures at different molar fractions were examined using a simultaneous thermogravimetric analyzer (STA) at different temperatures with a pair of crucibles (outer: platinum; inner: alumina). The dependence of the vapor pressure of KCl on its molar fraction in mixtures of KCl + K2SO4 was obtained on the basis of relative pressure. Results show that vapor pressure of KCl is increased to 1.2 times when a small amount of K2SO4 (molar fraction from 0.05 to 0.20) is added. Evaporation of KCl will be inhibited by K2SO4 when the molar fraction of K2SO4 is higher than 0.27, which is its fraction in the eutectic system of KCl + K2SO4. Vapor pressure of KCl decreases significantly with increasing molar fractions of K2SO4 at its inhibition scope.