Thermal Kinetic Analysis Research Articles

Study on safe disposal of cephalosporins based on kinetic pyrolysis mechanism

Abstract Based on the global goals for cleaner production and sustainable development, the pyrolysis behavior of cephalosporin residues was studied by TG-MS method. The influence of full temperature window on the safe disposal of residues was analyzed based on the “3-2-2” and “1+1” of thermal analysis kinetics, and the gas by-products of thermal degradation were monitored. Results showed that the pyrolysis of distillation residues were divided into low and high-temperature zones, including six stages. Maximum error rate (8.55%) by multiple scan rate was presented based on “3-2-2” pattern and maximum total fluctuation (33.7) by single scan rate was presented based on “1+1” pattern, which implied that the comprehensive multi-level comparison method was very reliable. The E value “E” of six stages showed an increasing trend ranging 166.8 to 872.8 kJ/mol. LgA (mean) was 27.28. Most mechanism function of stage 1, 2 were Z-L-T equation (3D), stage 3, 4, 6 were Avrami-Erofeev equation (AE3, AE4, AE2/3) and stage 5 was Reaction Order (O2). In addition, various small molecular micromolecule substances were detected such as C2H4O, C2H6, NH3, CH4, CO2 under full temperature windows and a possible pyrolysis path of residues was provided.

Reutilization of Reclaimed Asphalt Binder via Co-Pyrolysis with Rice Husk: Thermal Degradation Behaviors and Kinetic Analysis.

Realizing the utilization of reclaimed asphalt binder (RAB) and rice husk (RH) to reduce environmental pollution and expand the reutilization technique of reclaimed asphalt pavement (RAP), co-pyrolysis of RAB with RH has great potential. In this study, the co-pyrolysis behaviors, gaseous products, and kinetics were evaluated using thermogravimetric analysis and Fourier transform infrared spectroscopy (TG-FTIR). The results showed that incorporating RH into RAB improved its pyrolysis characteristics. The interactions between RAB and RH showed initial inhibition followed by subsequent promotion. The primary gaseous products formed during co-pyrolysis were aliphatic hydrocarbons, water, and carbon dioxide, along with smaller amounts of aldehydes and alcohols originating from RH pyrolysis. All average activation energy values for the blends, determined through iso-conversional methods, decreased with RH addition. The combined kinetic analysis revealed two distinct mechanisms: (1) at the lower conversion range, the pyrolysis of the blend followed a random nucleation and three-dimensional growth mechanism, while (2) at the higher conversion range, the control mechanism transitioned into three-dimensional diffusion.

Thermal Characterization, Kinetic Analysis and Co-Combustion of Sewage Sludge Coupled with High Ash Ekibastuz Coal

Efficient utilization of natural resources and possible valorization of solid waste materials such as sewage sludge into secondary materials via thermal conversion and simultaneously recovering energy is vital for sustainable development. The continuous increase in metropolises leads to an enormous production of wet sewage sludge, which creates major environmental and technical issues. In this paper, the samples of sewage sludge from Astana’s waste water treatment plant are analyzed for their thermochemical properties, followed by thermogravimetric and kinetic analysis using the Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose methods. Overall, the calorific value of sewage sludge sample was 18.87 MJ/kg and was comparable to that of the bituminous coal samples. The activation energy varied from 140 to 410 kJ/mol with changing conversion from 0.1 to 0.7. Further, mono-combustion and co-combustion experiments of the sewage sludge with high ash bituminous coal were conducted using the laboratory scale bubbling fluidized bed rig, respectively. The difference in NOx emissions between mono-combustion of sewage sludge and co-combustion with coal were at around 150 ppm, while this value for SO2 was similar in average, but fluctuates between 150 and 350 ppm. Overall, the findings of this study will be useful in developing a co-combustion technology for a sustainable disposal of municipal sewage sludge.

Enhanced activation roasting of cobalt-rich copper sulfide ore for efficient extraction of cobalt assisted by sodium sulfate

The strategic position of cobalt is increasing with the advancement of global electrification. In order to solve the problem of low extraction of cobalt in ordinary activated roasting, the process of enhanced activation roasting assisted by sodium sulfate was proposed. The feasibility of the process was verified theoretically by thermodynamic predominance area calculation and thermal behavior comparison. The optimal roasting and leaching conditions were determined and the average extraction of cobalt was increased by nearly 10% than ordinary activated roasting. The reaction mechanism of enhanced activation roasting was discussed, indicating that Na2SO4 was not only conducive to the oxidation reactions, but also promoted the migration of valuable components. The thermal kinetics analysis also proved that Na2SO4 had inhibitory effect on the decomposition of sulfates. The proposed technology could realize utilization of cobalt-rich copper sulfide ore and effective extraction of cobalt and copper.

Reaction mechanism of stearic acid pyrolysis via reactive molecular dynamics simulation and TG-IR technology

Stearic acid provides a basis for developing renewable energy, such as solar energy and biomass energy. A thermogravimetric-infrared spectroscopy (TG-IR) experimental test is conducted to obtain the thermal decomposition progress and the main gaseous products of stearic acid. The result shows that small gaseous products (H2O, CO2, CO, alkanes, olefins, etc.) are released. Furthermore, the method of reactive molecular dynamics simulation (ReaxFF-MD) is utilized to look into the pyrolysis reaction mechanism of stearic acid. The main pyrolysis products of stearic acid received by ReaxFF-MD are C2H4, H2, C2H2, CH4, H2O, CO2, and CO, consisting of the result of the TG-IR test. The effect of the simulated system density and temperature on the distribution of main products is also explored. Also, the thermal kinetic analysis is conducted by the initial consumption of stearic acid under different temperatures. The primary reaction mechanism of stearic acid pyrolysis is that the stearic acid molecules dissociate through C–C bonds break to generate C2H4, CH4, C2H2, C3H6, and other small molecules and radicals, and a typical reaction mechanism scheme of stearic acid pyrolysis is presented. The results provide a reference for explaining the macroscopic explosion characteristics of dust at the microscopic mechanism level.

Thermal stability and kinetic analysis of isophorone diisocyanate (IPDI)

Dynamic experiments were performed by differential scanning calorimeter (DSC) to obtain thermodynamic parameters to evaluate the thermal hazards of isophorone diisocyanante (IPDI). The apparent activation energy was calculated by the isoconversional Friedman method. And the kinetic model was evaluated by fitting experimental curves, which consisted of two stages: the initiation stage of the n-order type, and the autocatalytic stage. Furthermore, thermal behaviors under isothermal and adiabatic conditions were simulated, and the results indicated that a large amount of thermal energy was released. Estimation of time to maximum rate under adiabatic conditions (TMRad) demonstrated that the operational temperature should not exceed 223.64±0.30°C during production and operation. For a limit value of 10%, the time to conversion limit of IPDI is 11.36 d with an error of less than 0.66 at 200°C, while it only took within 0.1 d at 260°C.

Thermal and Pyrolysis Kinetics Analysis of Glass Wool and XPS Insulation Materials Used in High-Rise Buildings

This study investigates the kinetics data of glass wool (GW) and extruded polystyrene (XPS) insulation materials used in cladding systems using a systematic framework. The determination of appropriate kinetic properties, such as pre-exponential factors, activation energy and reaction orders, is crucial for accurately modelling the full-scale fire performance of insulation materials. The primary objective of this research is to extract thermal and kinetics data of XPS and GW insulation materials employed in high-rise buildings. To obtain these properties, thermogravimetric analysis (TGA) is conducted at four different heating rates: 5, 10, 15 and 20 K/min. The TGA results serve as the basis for determining the kinetic properties using a combination of model-free and model-based methods. The outcomes of this study are expected to be highly beneficial in defining the pyrolysis reaction steps and extracting kinetics data for fire modelling of such insulation materials. This information will enhance the understanding of the fire behaviour and performance of these materials during fire incidents, aiding in developing more accurate fire models and improving fire safety strategies for cladding systems in high-rise buildings.

Thermal properties and kinetic analysis of pyrolysis products of nicotine salts from e-cigarettes using pyrolysis-gas chromatography/mass spectrometry

Volatile organic chemicals (VOCs) released from e-cigarettes are a special source of air pollutants. In this work, we investigated the VOCs released from six nicotine salts (namely, nicotine benzoate, nicotine tartrate, nicotine citrate, nicotine malate, nicotine lactate, and nicotine levulinate) that are commonly used in e-cigarettes. The pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetric methods were used to analyze the thermogravimetric characteristics and product release behavior of different nicotine salts. Moreover, the kinetic models and thermodynamic parameters of nicotine salts during the thermal decomposition process were obtained. Thermogravimetric characteristic parameters of six nicotine salts showed significant differences. By the use of Py-GC/MS, our data showed that the pyrolysis products of nicotine salts were mainly from nicotine, acid anhydrides, carboxylic acids, and N-heterocycles, while more than 90% of the nicotine of citrate, tartrate, and malate was transferred to smoke. The result revealed that activation energies of the nicotine salts range from 21.26 to 74.10 kJ mol-1, indicating that the pyrolysis of the nicotine salts is a non-spontaneous heat absorption process, and the organic acid was the key factor affecting the release of nicotine into the ambient air.

Thermal Stability, Kinetic Analysis, and Safe Temperature Assessment of Ionic Liquids 1-Benzyl-3-Methylimidazolium Bis (Trifluoromethylsulfonyl) Imide for Emerging Building and Energy Related Field

Ionic liquids are molten salts that possess excellent chemical and thermal stability. Due to their inherent qualities in green chemistry, ionic liquids have been identified as potential substitutes for traditional organic solvents. These useful physical and chemical properties lead to some promising applications in fields such as building polymer engineering alternative materials and renewable energy technologies. Although they are classified as green solvents, these new solvents exist in a high-temperature environment, which is related to thermochemical reactivity and safety; there are few related studies. To analyze the possible high-temperature application environment of ionic liquids in the future, we analyzed the new ionic liquid 1-Benzyl-3-methylimidILlium bis (trifluoromethylsulfonyl) imide ([BZMIM][TF2N]), which lacks thermal analysis basis. This study used thermogravimetric analysis as the basis of the reaction model. We calculated the thermal hazard, kinetics, and parameter analysis of the reaction characterized by experimental thermal analysis data. The reaction model can be used to construct the actual temperature change calculation. The results show that [BZMIM][TF2N] will enter a runaway reaction when the temperature exceeds 270 °C. When operating [BZMIM][TF2N] at high temperatures, attention should be paid to the possibility of thermal hazards caused by its self-decomposition reaction.

High-temperature detoxification strategy based on thermal analysis kinetics for resource utilization of biopharmaceutical waste

High-temperature pyrolytic detoxification reactions based on thermal analysis facilitate the resource reuse of solid waste from the biopharmaceutical industry. This study described thermodynamic parameters, gas by-products, and safety assessment. The most common emissions (H2O, O, NH3) peak at 345–440 °C, accompanied by a shift in the micro-interfacial reaction mechanism, resulting in the largest rate of weight loss and the most significant release of gaseous by-products from the reaction. The peak CO2, SO2, and N2 emissions were dominated by deamination and sodium enrichment reactions, following the Mampel Power law mechanism. The growth trends of protein-nucleated Chlorella indicated the safety of the product at each stage. Compared to sample 375, sample 440 promoted the growth of Chlorella to a certain extent (maximum boost of 0.24 g⋅L-1⋅d-1), indicating non-toxicity and neutral pH, which may be due to a shift in pH to neutral as a result of pyrolytic detoxification, thus increasing safety and facilitating resource recovery. Possible reaction pathways for the pyrolysis of solid products were derived, and the availability of end products that contribute to the safe reuse of final value-added products from biopharmaceutical waste.

Study on the mechanism of an enteromorpha-based compound inhibitor for inhibiting the spontaneous combustion of coal using in situ infrared spectroscopy and thermal analysis kinetics

To alleviate the environmental pressure caused by enteromorpha (EP) and improve the efficiency of inhibiting spontaneous combustion of coal, attapulgite (ATP) was combined with EP to prepare an enteromorpha-based composite inhibitor (EPH-ATP). The effect of adding different substances on the surface morphology of the synthesized inhibitor was investigated using scanning electron microscopy (SEM). The effects of three inhibitors (enteromorpha hydrogel (EPH), ATP, and EPH-ATP) were analyzed using thermal analysis kinetics and in situ fourier transform infrared spectroscopy (FTIR). The results showed that the addition of ATP had little effect on the apparent morphology and was uniformly distributed in EPH. At heating rates of 5.0, 10.0, 15.0, and 20.0 K/min, it was found that the degree of the completion of spontaneous combustion of coal was directly related to the heating rate, and coal was more likely to react at low heating rates. In addition, during the combustion and decomposition stage, the average activation energy of coal samples treated with EPH-ATP increased by 306%, which greatly improved the reaction difficulty of the spontaneous combustion of coal. According to the changes in the functional groups with temperature, the in situ infrared process was divided into three stages of slow reaction, violent reaction and stable reaction for the first time. Moreover, the mechanism of EPH-ATP reducing the intensity of reaction by scavenging free radicals was clarified. The results show that the enteromorpha-based composite inhibitor has a good inhibitory effect, realizes the sustainable use of EP, and provides a new scientific basis for the prevention and control of the spontaneous combustion of coal.

Kinetics of thermal degradation of raw lacquer enhanced by formaldehyde urea prepolymer

In this study, formaldehyde-urea prepolymer (FUP) were synthesized, which were used to modify the raw lacquer (RL) and this composition named LF, while the basic properties of the RL were tested. Thermal gravimetric (TG) analysis and scanning electron microscopy (SEM) were used to analyze the degradative characteristics and the surface morphology of RL before and after modification. The result indicated that FUP can significantly improve the performance of RL. The drying time of the LF is significantly shortened, the gloss, the pencil hardness, and the impact performance are significantly enhanced at the same time. TG analysis and thermal decomposition kinetics analysis illustrated that the thermal stability and the activation energy of LF2 were stronger than that of RL. In addition, SEM analysis illustrated that the surface smoothness of RL were also improved.

Insight into pyrolysis behavior of silicone-phenolic hybrid aerogel through thermal kinetic analysis and ReaxFF MD simulations

Phenolic aerogel matrix nanocomposites are modified to improve their thermal stability and oxidation resistance, while the pyrolysis behavior will become more complex. Herein, the pyrolysis behavior of silicone-phenolic hybrid aerogel, as the pyrolyzable component of the nanocomposites, was investigated by thermal analysis experiments (TG-MS, TG-FTIR, and Py-GC/MS), kinetic studies (isoconversional methods and distributed activation energy model (DAEM)), and reactive force field molecular dynamics (ReaxFF MD) simulations. Experimentally, it was found that the main product of silicone-phenolic hybrid aerogel during the first decomposition stage is CH4, which was also validated by ReaxFF MD simulation. The main product CH4 was predominantly formed by hydrogen extraction reaction from silicone aerogel. The main decomposition products and pyrolysis kinetics of silicone-phenolic hybrid aerogel were analyzed by a combination of the multi-DAEM and ReaxFF MD simulations. The five-pseudo-components DAEM was utilized to reveal the decomposition of silicone-phenolic hybrid aerogel in five stages, which were in good agreement with the experimental conversion rates. The rearrangement of the Si-O-Si backbone of silicone aerogel at elevated temperatures forms silica-like species with antioxidant performance. This study can provide reliable guidance for the characterization and design of phenolic aerogel matrix nanocomposites and the selection of antioxidant modifiers.

Experimental and Computational Analyses of Thermal Runaway Behavior of Lithium Ion Pouch Battery at Low Ambient Pressure

Abstract Safety issue concerning “thermal runaway (TR) behavior” of lithium-ion battery (LIB) is one of the core concerns for users. We have studied TR behaviors at various ambient pressures. The thermal runaway onset time (t1) occured in advance at ambient pressure decreasing to 50 kPa from 90 kPa (90, 80, 70, 60, and 50 kPa). At 50 kPa, thermal runaway onset time of LIBs was 177 s earlier than that at 90 kPa. With the decreasing ambient pressure, several values declined, such as battery peak surface temperature, heat release rate (HRR), peak flue gas temperature, and total heat release (THR). Moreover, the peak concentrations of CxHy and CO increased as the ambient pressure decreased, whereas peak concentrations of CO2 and NO showed the opposite trend. Based on the previous studies of the thermal analysis kinetics model of LIBs, a pressure correction factor kp was introduced to establish a prediction model for thermal runaway temperature at low pressure conditions. Based on the model output, the error of thermal runaway onset time t1 could be controlled within ±2 s, and the error of thermal runaway peak temperature Tmax could be controlled within ±2 °C. Our results have been well consistent with the results of simulation, and have been beneficial to further reveal LIBs thermal runaway behavior under low ambient pressure.

Thermal degradation characteristics, kinetic and thermodynamic analyses of date palm surface fibers at different heating rates

The potential of the least-exploited date pam waste was presented as feedstock for bio-oil production. The surface fibers of the date palm are widely available as waste material in the Gulf region, the Middle East, and Africa. Chemical composition analysis and physiochemical characterization showed that surface fibers are valuable feedstock for energy production. Surface fibers were analyzed thermogravimetrically at different heating rates (10, 20, and 30 °C /min) in an inert atmosphere. Decomposition was carried out in three stages: dehydration, devolatilization, and solid combustion. Kinetic analysis was performed on the devolatilization region using the Coats–Redfern model–fitting method using twenty–one reaction mechanisms from four different solid-state reaction mechanisms. Two diffusion models: one–way transport (g(x) = α2) and Valensi equation (g(x) = α+(1-α) × ln(1-α)) showed the highest regression coefficient (R2) with the experimental data. The activation energy (Ea) and the pre-exponential factor (A) was estimated to be 91.40 kJ/mol and 1.59 × 103 –29.39 × 103 min−1, respectively. The kinetic parameters were found to be dependent on the heating rate. The surface fibers' thermodynamic parameters ΔH, ΔG, and ΔS were 80–97, 151–164, and −0.17- −0.18 kJ/mol, respectively. This indicates that the pyrolysis of surface fibers is endothermal and not spontaneous. Since there is not much experimental work on the pyrolysis of surface fibers available in the literature, the reported results are crucial for designing the pyrolysis process.

Co-combustion of municipal solid waste and hydrochars under non-isothermal conditions: Thermal behaviors, gaseous emissions and kinetic analyses by TGA–FTIR

Co-combustion of municipal solid waste (MSW) with hydrochars was proposed as an effective way for both simultaneous treatments of MSW with biomass and energy recovery. In this work, thermogravimetric analyzer coupled with Fourier transform infrared spectrometer was employed to study the (co-)combustion, gaseous emissions and combustion kinetics characteristics of MSW, hydrochars and their blends. The addition of hydrochars to MSW leads to lower burnout temperatures and the shorter combustion time. Hydrochar prepared at 200 °C (SD200) has a better co-combustion performance than hydrochars prepared at 230 (SD230) and 260 °C (SD260) in term of ignition, burnout and comprehensive combustion characteristic index, hydrochar prepared at 260 °C has a better co-combustion evenness. The addition of hydrochar to MSW changed the gaseous products emission patterns of MSW and reduced the release of CO, HCN, NO and HCl. Kissinger-Akahira-Sunose (KAS) and Flynn–Wall–Ozawa (FWO) methods were used to estimate the activation energy of MSW, SD200 and their blends, the minimum average activation energy was observed when the SD200 blending ratio was 70%, which was 75.65 kJ mol−1 by KAS and 82.12 kJ mol−1 by FWO, respectively.

Thermal Degradation Characteristic and Kinetic Analysis of the Solid Byproducts Recovered from Vacuum Pressurized/Friction Thermal Sterilization of Hospital Solid Wastes

Thermal Degradation Characteristic and Kinetic Analysis of the Solid Byproducts Recovered from Vacuum Pressurized/Friction Thermal Sterilization of Hospital Solid Wastes

The Role of Graphene Oxide in the Exothermic Mechanism of Al/CuO Nanocomposites.

Metastable intermixed composites (MICs) have received increasing attention in the field of energy materials in recent years due to their high energy and good combustion performance. The exploration of ways of improving their potential release of heat is still underway. In this study, Al-CuO/graphene oxide (GO) nanocomposites were prepared using a combination of the self-assembly and in-suit synthesis methods. The formulation and experimental conditions were also optimized to maximize the exothermic heat. The DSC analysis shows that the addition of the GO made a significant contribution to the exothermic effect of the nanothermite. Compared with the Al-CuO nanothermite, the exothermic heat of the Al-CuO/GO nanocomposites increase by 306.9-1166.3 J/g and the peak temperatures dropped by 7.9-26.4 °C with different GO content. The reaction mechanism of the nanocomposite was investigated using a DSC and thermal reaction kinetics analysis. It was found that, compared with typical thermite reactions, the addition of the GO changed the reaction pathway of the nanothermite. The reaction products included CuAlO2. Moreover, the combustion properties of nanocomposite were investigated. This work reveals the unique mechanism of GO in thermite reactions, which may promote the application of carbon materials in nanothermite.

Thermal behavior and kinetics analysis of co-combustion of petroleum coke and paper sludge-derived hydrochar

The co-combustion reactivity and kinetics of petroleum coke (PC) and paper sludge-derived hydrochar (PS) were investigated via thermogravimetric analysis. The physical and chemical structure features were also systematically tested. The results show that the combustion process of PS could be divided into three stages, while for PC only one stage could be clarified. Due to high volatile content, developed pore structure and low carbon-order degree, the combustion reactivity of PS was higher than that of PC. Although the ignition property of the blends could be significantly improved by addition of PS, it changed little for the burnout temperature and as a result the combustion intensity was deteriorated. For the samples with addition of PS from 20 % to 80 %, the comprehensive combustion index decreased from 3.69 × 10-15 to 2.12 × 10-15. The Kissinger AkahiraSunose model-free method was used in the co-combustion reaction of PC and PS, and good fitting results were obtained. For different samples with varying addition of PS, the activation energies were in the range of 107.51–198.44 kJ/mol, with the lowest value obtained at 20 % of PS, which was also the optimum proportion for co-combustion of PC and PS.

Effects of oxidative torrefaction conditions on the biomass liquid chemical looping reaction from the perspective of thermal behavior and kinetic analysis

Biomass liquid chemical looping conversion process (BLCLP) can produce a high-temperature oxygen-depleted stream. Utilizing the oxygen-depleted air as a torrefaction medium can enhance biomass reactivity and achieve higher energy efficiency. This study aimed to investigate the effect of torrefaction conditions on biomass reactivity in the BLCLP. The torrefaction under proper working conditions effectively enhanced the release of biomass volatiles. The increase in the activation energy of biomass pyrolysis after oxidative torrefaction indicated the need for proper control of the torrefaction condition. More importantly, oxidative torrefaction promoted the reactivity between biochar and liquid oxygen carrier, which was crucial for the BLCLP. The activation energy of the reaction between biochar and Sb2O3 liquid oxygen carrier calculated by the DAEM method was 289.75–296.79 kJ·mol−1, guiding the subsequent reactor design. Ultimately, the optimal torrefaction conditions for the BLCLP were determined as 270 °C and 3 vol% oxygen content.