Simultaneous Thermogravimetric Analysis Research Articles

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.

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.

Hydrogen reduction of spent lithium-ion battery cathode material for metal recovery: Mechanism and kinetics.

Hydrogen reduction is becoming a promising method for recycling lithium-ion battery cathode materials. However, the reaction mechanism and kinetics during hydrogen reduction are unclear, requiring further investigation. Therefore, non-isothermal and isothermal reduction experiments were conducted to evaluate the temperature dependence of the hydrogen reduction kinetics using simultaneous thermogravimetric and differential thermal analysis equipped with mass spectrometry. XRD and SEM were used to characterize the reduction products to understand the underlying reduction mechanisms. The hydrogen reduction profile could be divided into three main stages: decomposition of cathode materials, reduction of the resultant nickel and cobalt oxides, and reduction of LiMnO2 and residual nickel and cobalt oxides. The hydrogen reduction rate increased with increasing temperature, and 800°C was the optimum temperature for separating the magnetic Ni-Co alloy from the non-magnetic manganese oxide particles. The apparent activation energy for the isothermal tests in the range of 500–700°C was 84.86 kJ/mol, and the rate-controlling step was the inward diffusion of H2(g) within each particle. There was an downward progression of the reduction through the material bed for the isothermal tests in the range of 700–900°C, with an apparent activation energy of 51.82 kJ/mol.

Flexural strength and thermal properties of carbon black nanoparticle reinforced epoxy composites obtained from waste tires

Abstract In this study, both mechanical and thermal properties of epoxy@carbon black nanocomposite (EP@CB-NC) produced by adding 0.3, 0.6, and 1% by weight carbon black nanoparticle obtained from waste automobile tires to epoxy were investigated. The chemical and structural composition of EP@CB-NC was characterized by Fourier transform infrared spectroscopy (FTIR) in scanning electron microscopy (SEM). In addition, simultaneous thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) experiments, and thermal conductivity measurements were performed to determine the thermal stability of the prepared EP@CB-NC. Increasing the strength of modified epoxy composites by means of nanoparticles obtained with waste may pave the way for obtaining new materials with clean environment and superior properties. The mechanical and thermal properties were improved by adding carbon black to the bare samples.

Water-based drill cuttings, a shale gas extraction waste as supplementary cementitious material and optimization

• A method of preparing a novel supplementary cementitious material based on water-based drill cuttings was provided. • A central composite design was conducted to optimize the four factors (calcination temperature, calcination time, replacement ratio, and fineness) for WDC preparation, and optimal values were obtained. • The hardened specimens, prepared with a mixture of standard sand, ordinary Portland cement, and water-based drill cuttings, meet the compressive strength specified in ASTM-618. • The mechanisms of WDC acting in the OPC system were investigated. The water-based drill cuttings, a kind of solid waste from shale gas extraction, are examined for their utility as supplementary cementitious material. After drying, calcining, and grinding, water-based drill cuttings are expected to partially replace ordinary Portland cement for their high calcium silicate and grinding-friendly nature. A central composite design investigated four variables (calcination time, calcination temperature, replacement ratio, and fineness) for their effects on the response (compressive strength). The optimization results suggest that the best product meeting the mechanical criteria and saving energy could be obtained by replacing 10 wt% ordinary Portland cement when controlling the calcination temperature of 830–870 °C, calcination time of 28–32 min, and fineness of sieving is 1600 mesh. The compressive strength was shown to be 39.00 MPa at 7 days, 47.00 MPa at 28 days, and 52.00 MPa at 90 days. Furthermore, the mechanisms of water-based drill cuttings were characterized to confirm the feasibility of supplementary cementitious material by various analytical techniques such as X-ray fluorescence, laser particle size analyzer, simultaneous thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy.

Determination of Cocombustion Kinetic Parameters for Bituminous Coal and Pinus Sawdust Blends

Cocombustion of bituminous coal (HC) and Pinus sawdust (PS) was investigated in this paper with the aim of determining the kinetic parameters relevant to cocombustion reactions of their fuel blends. PS was used because it is a waste biomass product capable of generating energy. Motivated by the need to partly substitute HC used in existing boilers with PS, the optimum kinetic parameters at different blending ratios were thus investigated with the ultimate goal of diversifying the energy portfolio for these boilers. Blended samples were prepared with a PS substitution by mass ranging from 0 to 30%, thus producing five samples, namely:100HC, 90HC10PS, 80HC20PS, 70HC30PS, and 100PS. A simultaneous thermogravimetric analyzer was used to investigate the degradation of the fuel samples under a synthetic air atmosphere using 5, 12.5, and 20 °C/min heating rates. The kinetic parameters were evaluated using the distributed activation energy model (DAEM) due to its ability to evaluate complex parallel chemical mechanisms. The influential homogenous volatile combustion and heterogenous combustion stages produced an increasing trend for activation energy (Ea) with increased PS (100HC to 70HC30PS) from an average of 61.80–104.34 kJ/mol while the pre-exponential factor increased from 1.31 × 105 to 6.52 × 108. Generally, blending of HC with PS did not produce a linear variation of the kinetic parameters; thus, by using various plots, an optimum blending ratio of 80HC20PS was deduced.

Influence of Emerging Semiconductive Nanoparticles on AC Dielectric Strength of Synthetic Ester Midel-7131 Insulating Oil.

Exploring impressively effective dielectric nanofluids for transformers to improve dielectric strength and thermal stability is indispensable. It is crucial to determine the modification mechanism of dispersed nanomaterials in insulating oil for operative applications in power transformers. This paper aspires to authenticate the experimental evidence of the enhancing AC dielectric strength of synthetic ester Midel-7131 using two newly introduced semiconductive nanoparticles, CdS and Co3O4, and uncover the potential reasons for enhanced AC dielectric strength. The AC breakdown voltage (BDV) of synthetic ester and nanofluids was investigated and statistically evaluated. The mean AC breakdown voltage of SE/CdS and SE/Co3O4 was increased by 31.9% and 31.3%, respectively. The augmentation in AC breakdown strength is possibly due to the facilitated charge-scavenging ability owing to the large specific surface area and wide bandgap. Simultaneous thermogravimetric analysis, differential scanning calorimetry, and derivative thermogravimetry analyses (TGA–DSC–DTG) confirmed that the initial decomposition temperature was high and heat dissipation was low, indicating that the nanofluids were thermally stable in both air and nitrogen. Hence, emerging semiconductive CdS and Co3O4-based nanofluids of synthetic ester possess remarkable dielectric strength and thermal stability enhancement for their application in power transformers.