Thermokinetic Studies Research Articles

Pyrolysis conversion of multi-layer packaging waste under a CO2 atmosphere: Thermo-kinetic study, evolved products analysis and artificial neural networks modeling

Packaging waste such as beverage carton forms a significant part of municipal solid waste and its pyrolysis behavior, kinetics, and thermodynamics were studied. A four-stage decomposition process was revealed: dehydration below 200 ℃, paperboard degradation at 200–400 ℃, polyethylene devolatilization at 400–550 ℃, and inorganic decomposition at 550–900 ℃. The evolved products included furans and acetic acid during stage II, followed by the presence of 2-butene and 1-pentene in the subsequent stage. Apparent activation energy (Ea) were determined using model-free models, revealing a notable level of comparability among these results. The average Ea was 123.6 kJ/mol within α range of 0.10–0.60, increasing to 233.3 kJ/mol beyond that range. The most probable reaction mechanism was determined, with the one-dimensional model proving more reliable. An artificial neural network model was developed to predict the thermal degradation. The selected topology of 5*15*1 displayed a robust ability to predict the thermal data.

Thermokinetic study of tannery sludge using combustion and pyrolysis process through non-isothermal thermogravimetric analysis

Sludge from the tannery is produced in enormous amount. This work has investigated the thermal analysis behaviour of the tannery sludge by use of the thermogravimetric analysis (TGA). The TGA experiments is carried out in both air and nitrogen environment at the varied heating rates of 5, 10, 20 and 40 °C/min from the temperature range of 30–900 °C. In the assessment of kinetic parameters, the model fitting (Combined kinetics) method was employed. It was investigated that thermal degradation of the tannery sludge sample occurred in three stages. Majorly the conversions were observed in stage II for both in air and nitrogen environment. The activation energy (Ea) value for the combustion is 165.9 kJ/mol while for the pyrolysis the Ea value is obtained as 65.2 kJ/mol from the conversion range between 0.2 and 0.8 which is a promising approximation supported by a strong R2 value of 0.9719 and 0.93 for combustion and pyrolysis respectively. It is estimated from the master plots that six ideal models A1/2, A1/3, A1/4, F3, F4 and D5 were probably in approximation with the linear fitted data for both air and nitrogen. Various thermodynamic parameters which include the ΔH, ΔG and ΔS are also complimented that indicates the formation of activated complex and non-spontaneity of the reaction. The detailed thermokinetic study of the tannery sludge in combustion and pyrolysis offers a novel approach to understanding how this waste material decomposes under different temperature conditions. This holistic perspective contributes valuable insights into waste management practices, environmental impacts, resource recovery, and process optimization within the leather industry. Furthermore, the optimization of leather production processes on a large scale can minimize waste generation and enhance energy efficiency, strengthening the competitiveness and sustainability of the leather industry.

Quantum chemical pathways for the formation of 2,3,7,8-tetrachloro dibenzo-p-dioxin (TCDD) from 2,4,5-trichlorophenol: a mechanistic and thermo-kinetic study.

Dioxins, specifically 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD), are highly toxic dioxins known for their severe health impacts and persistent environmental pollutants. This study focuses on understanding the formation pathways of TCDD from its precursor molecule 2,4,5-trichlorophenol (2,4,5-TCP). In our exploration of reaction pathways from 2,4,5-trichlorophenol (TCP), we delve into three reaction mechanisms: free-radical, direct condensation, and anionic. Our findings highlight the significance of the radical mechanism, particularly propagated by H radicals, with a notable increase in dioxin formation around 900K. These results are consistent with experimental observations indicating an increase in the conversion of trichlorophenol from 600 to 900K in the non-catalytic gas phase reaction. Thermodynamic parameters (∆H, ∆S, and ∆G), reaction barriers, and rate constants (k) were calculated across a temperature range of 300-1200K to support the findings and provide insights into the optimal temperature range for controlling dioxins during the incineration process. In this study, quantum chemical calculations were conducted using density functional theory (DFT) with the B3LYP functional and the 6-311 + + G(d,p) basis set in Gaussian 16 software. Stationary points, including transition states (TS), were confirmed with frequency calculations. Intrinsic reaction coordinate (IRC) calculations ensured minimum energy paths between TS and products, visualized in GaussView 6.0 Program. Single-point energy calculations utilized a more precise basis set, 6-311 + + G(3df,2p), for enhanced energy accuracy, incorporating zero-point vibrational energy (ZPE) and other energy corrections. These calculations were repeated over a temperature range of 298.15-1200K at 1atm pressure. Finally, rate constant (k) expressions associated with TCDD formation were determined using transition state theory (TST).

Thermo-kinetics study of microalgal biomass in oxidative torrefaction followed by machine learning regression and classification approaches

Solid biofuels derived from microalgae represent a low-cost, high-volume bioproduct opportunity with excellent CO2 biofixation capability, contributing significantly to the attainment of net zero. Oxidative torrefaction also offers a more economical pretreatment to upgrade its solid fuel properties. This study investigates the thermo-kinetics aspect of oxidative torrefaction of microalgae with varying O2 concentrations using thermogravimetric and differential thermal analysis (TGA-DTA). Isoconversional kinetic modeling is applied to mass-loss data and shows average activation energies of 172.57, 174.68, 199.42, and 209.03 kJ‧mol−1 at 0, 3, 12, and 21 % O2 concentrations, respectively. The effect of O2, especially at 12 vol%, significantly reduces the calculated activation energy at lower conversion. DTA also reveals lower heat flow values under oxidative than inert torrefaction. Thermo-kinetics data are then utilized to conduct machine learning approaches. Regression via artificial neural networks shows that the prediction of conversion and heat flow values are predominantly dictated by the temperature, followed by heating rate and O2 concentration. Finally, classification using the k-nearest neighbors algorithm highlights the effects of factors at specific ranges of conversion and heat flow responses. The O2 concentration is significant only at early conversion (X<0.1) and contributes to generally lower heat flow values.

Thermokinetic study of coconut husk pyrolysis in the devolatilization zone using volatile state approach

Thermokinetic study of coconut husk pyrolysis in the devolatilization zone using volatile state approach

Effects of compositional uncertainties in cracked NH3/biosyngas fuel blends on the combustion characteristics and performance of a combined-cycle gas turbine: A numerical thermokinetic study

Blending of partially cracked ammonia with biosyngas is an attractive strategy for improving NH3 combustion. In practice, products of biomass gasification and those of thermo-catalytic cracking of NH3 are subject to some compositional uncertainties. Despite their practical importance, so far, the effects of such uncertainties on combustion systems remained largely unexplored. Hence, this paper quantifies the effects of small compositional uncertainties of reactants upon combustion of partially cracked NH3/syngas/air mixtures. An uncertainty quantification method, based on polynomial chaos expansion and a data-driven model, is utilised to investigate the effects of uncertainty in fuel composition on the laminar flame speed (SL) and adiabatic flame temperature (Tad) at different inlet pressures (Pi). The analysis is then extended to the power output of a combined-cycle gas turbine fuelled by the reactants. It is found that 1.5% fuel compositional uncertainty can cause 12–21% of SL uncertainty depending on the inlet pressure. Furthermore, the effect of compositional uncertainty on Tad increases at higher ratios of H2 to NH3. Sensitivity analysis reveals that the uncertainty of CO contribution to SL uncertainty is higher than that of NH3, while the trend is reversed for the Tad uncertainty. In addition, the power output from the combined-cycle gas turbine system varies between 4 and 6% with 1.5% of fuel compositional uncertainty. This become more noticeable at elevated Pi [5–10 atm], particularly when the fuel mixture contains high H2 which is the main contributor to Tad variability.

Synergistic transformation: Kinetic and thermodynamic evaluation of co-pyrolysis for low-rank bituminous coal and polyurethane foam waste

Co-pyrolysis is regarded as a sustainable and ecologically friendly method of improving waste management, pollution control, and renewable energy security. This investigation reports a thermo-kinetic study of low-rank coal-polyurethane foam waste (C-PU) blends through co-pyrolysis and was characterized using a number of techniques such as CHNS-O, GCV, and FTIR. The thermal degradation behavior of C-PU blends during co-pyrolysis via TGA is studied, whereas the degradation process happens in three stages i.e. moisture, devolatilization, and slow degradation of the char in the temperature ranges viz. (25 –140 °C), (140 – 580 °C), and (580 – 900 °C) respectively. Synergistic effects observed may improve product qualities compared to those from separate pyrolysis. The presence of synergistic effects during co-pyrolysis was demonstrated by the positive variation in WL% and DTGmax values. The Coats-Redfern integral method was utilized to investigate the thermo-kinetic parameters of C-PU blends through twelve (12) reaction mechanism models. The activation energy (Ea) for 100C and 100PU was 60.08 kJ/mol and 100.8 kJ/mol via F2 and F3 models, although the optimum blend (50 C-50PU) showed 67.01 kJ/mol and 26.74 kJ/mol via F2 and D3 model in the first and second stage. Thermodynamic characteristics i.e. (∆G) and (∆H) displayed positive values, while (∆S) for each C–PU blend was negative, but the best blend further lowered it. It was found that the fuels could be ranked in the following order 100PU> 50 C-50PU> 100 C based on mean reactivity and pyrolysis factor. The co-pyrolysis of polyurethane foam waste with low-rank coal to develop alternative energy sources has been proposed as a potential method and is critical for designing an effective large-scale reactor system thus understanding the solid-state co-pyrolytic kinetics.

Comparative thermokinetic study of vegetable oils and deoxygenated derivatives

This study shows the usefulness of thermokinetic analysis in the characterization of vegetable oils and their deoxygenated derivatives (bioparaffin mixtures). The approach allows obtaining information about the complexity and nature of the process rate-controlling steps (inter- or intra-molecular), to establish quality criteria and to estimate the cohesive forces in liquids and fuels in general. The study also reveals the influence of the gaseous products, Ps, on the limit temperature, Tl, at which the liquid–vapor interface coexists or vanishes. The presence of multiple steps and stages, and the energy barrier variability between ∼ 120 and > 250 kJ mol−1 in the starting vegetable oils, demonstrates the importance of the origin and composition of triglyceride and the effect of unsaturation degree (C = C)n in the fatty acid degradation pathway. Besides, the isoconversional analysis of the deoxygenated products (bioparaffins) describes a kinetics controlled by a single-step, with almost constant activation energy barriers ∼ 70 kJ mol−1, related to the inter-molecular cohesive forces, usually E(α) < 100 kJ mol−1, equivalent to the vaporization enthalpy, ΔvH. The results are validated by a complementary thermokinetic analysis of pure solvents (n-decane and n-hexadecane). Finally, the study describes several experimental observations of great relevance and interest to understand and control the nature of thermally activated processes in vegetable oils and biofuels.

Thermo-kinetic studies of in vitro digestion and colonic fermentation of inulin/Lactobacillus rhamnosus GG co-encapsulated composite beads

In this study, Lactobacillus rhamnosus GG (L.GG) and inulin were successfully co-encapsulated into alginate/pectin composite beads using high efficiency vibration technology with freeze-drying. The addition of inulin did not substantially affect the morphology or particle size of microcapsules but improved the survival number of L.GG during encapsulation process, storage and in vitro digestion. Isothermal microcalorimetry was used for the first time to investigate the thermo-kinetics properties of these encapsulated L.GG during in vitro gastrointestinal digestion and colon fermentation, revealing that the co-encapsulation with inulin increased the growth rate of L.GG in the logarithmic growth phase, without change the total heat production. The number of probiotic microcapsules surviving after 60 days of storage was still more than 8 Log CFU/g. Inulin co-encapsulation also significantly improved the storage and heat stability of L.GG, with the highest viability of 8 Log CFU/g after 60-day storage, 5.58 Log CFU/g after heating at 63 °C for 30 min, and 7.85 Log CFU/g at 72 °C for 3 min, respectively. These microcapsules also altered the composition and diversity of mice gut microbiota, increasing the relative abundance of Lactobacillus and decreasing that of Bacteroides. This study introduces a novel colon-targeted probiotic-delivery system and a method to understand the control-release thermodynamics of the encapsulated probiotics in simulated gastrointestinal digestion and colonic fermentation.

Thermokinetic Study of Aluminum-Induced Crystallization of a-Si: The Effect of Al Layer Thickness.

The effect of the aluminum layer on the kinetics and mechanism of aluminum-induced crystallization (AIC) of amorphous silicon (a-Si) in (Al/a-Si)n multilayered films was studied using a complex of in situ methods (simultaneous thermal analysis, transmission electron microscopy, electron diffraction, and four-point probe resistance measurement) and ex situ methods (X-ray diffraction and optical microscopy). An increase in the thickness of the aluminum layer from 10 to 80 nm was found to result in a decrease in the value of the apparent activation energy Ea of silicon crystallization from 137 to 117 kJ/mol (as estimated by the Kissinger method) as well as an increase in the crystallization heat from 12.3 to 16.0 kJ/(mol Si). The detailed kinetic analysis showed that the change in the thickness of an individual Al layer could lead to a qualitative change in the mechanism of aluminum-induced silicon crystallization: with the thickness of Al ≤ 20 nm. The process followed two parallel routes described by the n-th order reaction equation with autocatalysis (Cn-X) and the Avrami-Erofeev equation (An): with an increase in the thickness of Al ≥ 40 nm, the process occurred in two consecutive steps. The first one can be described by the n-th order reaction equation with autocatalysis (Cn-X), and the second one can be described by the n-th order reaction equation (Fn). The change in the mechanism of amorphous silicon crystallization was assumed to be due to the influence of the degree of Al defects at the initial state on the kinetics of the crystallization process.

Thermo-kinetic Study of Genetically Different Carbon-Source Materials.

A nonisothermal thermogravimetric analysis (TGA) technique was applied to determine the devolatilization kinetic parameters of completely different genesis samples of four groups: coal, biomass, lignite, and petcoke. The physical and chemical characteristics were determined using the proximate and ultimate analysis and the ash composition profile using the X-ray fluorescence method. Heating rates of 10, 15, and 20 °C/min were used in the temperature range of 25-1000 °C during the slow pyrolysis under an inert gas atmosphere. A widely used and proposed first-order Coats-Redfern kinetic model was applied, which showed the highest values of activation energies (Ea) for the petcoke sample from 57.17 to 67.58 kJ/mol at three different heating rates, while the lignite sample represented the lowest Ea values between 12.84 and 16.03 kJ/mol. The thermo-kinetic behavior was explained based on the catalytic effect of the ash composition profile, morphology, and structure of the substances determined using different analytical techniques. For the TGA process, the application of scanning electron microscopy, Fourier-transform infrared spectroscopy, etc., for the physiochemical analysis of the four genetically different carbon-source materials represented the novelty of the present work.

Catalytic Pyrolysis of Hydrochar by Calcined Eggshells for Bioenergy Production: Improved Thermo-Kinetic Studies and Reduced Pollutant Emissions

Bioenergy production from hydrochar via catalytic thermal conversion is of increasing importance to easing the energy shortage. The catalytic pyrolysis characteristics of hydrochar derived from sawdust (HSD) with calcined eggshell (CES) were investigated by the thermogravimetric–Fourier transform infrared spectroscopy–mass spectrometry (TG-FTIR-MS) method. Kinetic and thermodynamic parameters were determined by two iso-conversional model-free methods, namely, Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO). The results demonstrated that HSD exhibited a high fuel quality, with elevated carbon content (54.03%) and an increased high calorific value (21.65 MJ Kg−1). CES significantly enhanced the pyrolysis behavior of HSD by promoting the secondary cracking of organic vapors under the synergistic effect of CaO and mineral elements. Compared to non-catalytic pyrolysis, the residual mass and average activation energy of HSD-CES decreased by 29.61% and 14.10%, respectively, and the gaseous products of H2 and CO from HSD-CES increased by 26.14% and 22.94%, respectively. Furthermore, the participation of CES effectively suppressed the emission of pollutants in the HSD pyrolysis process, with a 27.13% reduction in CH4, a 22.76% reduction in HCN, and a 20.28% reduction in NH3. This study provides valuable guidance on the potential use of hydrochar for renewable energy production.

Thermokinetic Study of Catalytic Pyrolysis of Medium-Density Fiberboards over Beta-Zeolite-Supported Platinum

Catalytic pyrolysis is an attractive alternative for converting biomass into energy and chemicals, replacing fossil sources. Efficient catalysts can be used to remove compounds containing oxygen during pyrolysis, improving the bio-oil properties and thus being an important route towards sustainability. Catalytic pyrolysis of medium-density fiberboard (MDF) residues over platinum (1%) supported on beta zeolite was carried out using a biomass/catalyst ratio of 1.0/0.2. The catalysts were characterized via Fourier transform infrared spectroscopy, flame atomic absorption spectrometry, X-ray diffraction, nuclear magnetic resonance, temperature-programmed reduction, and temperature-programmed desorption of ammonia. The thermokinetic and thermodynamic parameters were determined using the isoconversional and non-isothermal methods of Friedman, Flynn-Wall-Ozawa (FWO), and Kissinger-Ahakira-Sunose (KAS). The Friedman method was the most adequate to describe the reaction and thermodynamic parameters. The results show that the catalysts promote the reduction in activation energy compared to non-catalytic pyrolysis. Non-impregnated and impregnated catalysts showed different activation energies and thus different reactions. The addition of platinum slightly increased the activation energy due to the promotion of reactions that require more energy, for example, cracking and coke deposition.

The Sorption of Erythrosine E127 Dye onto Commercial Kaolin Thermokinetic Studies

In this study, a highly efficient and economical method was used to remove E127 dye using commercial kaolin (CK) as the adsorbent. The optimal pH for adsorption was found to be 4.7, and the maximum surface concentration of the dye was 53.8 mg.g-1 when 125 mg of adsorbent was used. The Freundlich isotherm was used to describe the adsorption process, which suggested that the active sites in the adsorption process were randomly selected. The adsorption capacity (qmax), enthalpy (?H), and entropy (?S) were calculated to be 74.6 mg.g-1, -12.3 KJ.mol-1, and 75.0 J.mol-1, respectively. Both thermodynamic and kinetic analyses indicated that the adsorption process was spontaneous, involved physical adsorption, and followed the pseudo-second-order (PSO) model. The method was effective in extracting the E127 dye up to four times.

Pyrolytic elimination of ethylene from ethoxyquinolines and ethoxyisoquinolines: a computational study

This work reports a thermo-kinetic study on unimolecular thermal decomposition of some ethoxyquinolines and ethoxyisoquinolines derivatives (1-ethoxyisoquinoline (1-EisoQ), 2-ethoxyquinoline (2-EQ), 3-ethoxyquinoline (3-EQ), 3-ethoxyisoquinoline (3-EisoQ), 4-ethoxyquinoline (4-EQ), 4-ethoxyisoquinoline (4-EisoQ), 5-ethoxyquinoline (5-EQ), 5-ethoxyisoquinoline (5-EisoQ), 8-ethoxyquinoline (8-EQ) and 8-ethoxyisoquinoline (8-EisoQ)) using density functional theory DFT (BMK, MPW1B95, M06-2X) and ab initio complete basis set-quadratic Becke3 (CBS-QB3) calculations. In the course of the decomposition of the investigated systems, ethylene is eliminated with the production of either keto or enol tautomer. The six-membered transition state structure encountered in the path of keto formation is much lower in energy than the four-membered transition state required to give enol form. Rate constants and activation energies for the decomposition of 1-EisoQ, 2-EQ, 3-EQ, 3-EisoQ, 4-EQ, 4-EisoQ, 5-EQ, 5-EisoQ, 8-EQ, and 8-EisoQ have been estimated at different temperatures and pressures using conventional transition state theory combined with Eckart tunneling and the unimolecular statistical Rice–Ramsperger–Kassel–Marcus theories. The tunneling correction is significant at temperatures up to 1000 K. Rate constants results reveal that ethylene elimination and keto production are favored kinetically and thermodynamically over the whole temperature range of 400–1200 K and the rates of the processes under study increase with the rising of pressure up to 1 atm.

Thermokinetic study of intermetallic phase formation in an Al/Cu multilayer thin film system

The solid-state reaction process in a multilayer thin film system (Al/Cu)50 has experimentally been studied using the methods of simultaneous thermal analysis (STA) and in situ electron diffraction. A detailed kinetic analysis of the phase formation processes during the solid-state reaction has shown that the observed solid-state transformations can be described by a statistically significant kinetic model where each stage corresponds to the reaction of the n-th order with autocatalysis. The low-temperature stage has been demonstrated to be attributable to the formation of the θ-Al2Cu phase, with the medium-temperature and high-temperature ones corresponding to the α2-AlCu3 and γ1-Al4Cu9 phases, respectively. The kinetic parameters for the formation of the phases θ-Al2Cu, α2-AlCu3 and γ1-Al4Cu9 have been determined. It has been shown that the kinetic model describing the solid-state reaction in the Al–Cu multilayer thin film system is in best agreement with the experimental data in the case of a competition between the formation stages of the α2-AlCu3 and γ1-Al4Cu9 phases.

Characterization, bioactivity evaluation, thermo-kinetic studies of mango (Mangifera indica L.) peel extract, and its applicability in oxidative stabilization of biodiesel

Characterization, bioactivity evaluation, thermo-kinetic studies of mango (Mangifera indica L.) peel extract, and its applicability in oxidative stabilization of biodiesel

Investigation on Thermokinetic Study and Optimization of Sugarcane Bagasse Thermal Pyrolysis

Investigation on Thermokinetic Study and Optimization of Sugarcane Bagasse Thermal Pyrolysis

Assessing the pyrolysis potential of redgram stalk: Thermo-kinetic study, empirical modelling and product characterization

Pyrolysis characteristics, thermal properties and kinetics of redgram stalk were studied for effective energy generation through pyrolysis process. Thermogravimetric experiments were carried out at five heating rates (10, 20, 30, 40 and 50 °C min−1) and particle sizes (<0.2, 0.2–0.5, 0.5–1, 1–1.5 and 1.5–2 mm). Effect of particle size on functional, morphological and structural characteristics of biochar were studied. The activation energy of redgram stalk was calculated by KAS and FWO methods and was in the range of 132.16–175.76 kJ mol−1 and 113.12–152.53 kJ mol−1. Sestak and Berggren's model revealed that the redgram stalk pyrolysis was dominated by diffusion mechanism. Thermodynamic analysis (ΔG, ΔH, ΔS) indicated the endothermic and non-spontaneous nature of the redgram stalk pyrolysis. Characterization of biochar revealed the well-defined pore structure, progressive stacking of graphene sheets and the formation of aromatic crystallites in smallest particle biochar. The kinetic results and biochar characteristics elucidate the feasibility of redgram stalk for energy and environmental applications.

Thermokinetic Study by Solar Convective Drying of Argan Press-Cake

The argan tree "Argania spinosa" is a typically multi-use tree. It represents the agroforestry systems pivot which has so far succeeded in meeting the needs of the inhabitants of arid and semi-arid areas strongly marked by climatic hazards. Argan press-cake, residue from the argan oil extraction, is used in several fields, namely: cosmetics, agriculture, and pharmacology. In order to keep this argan paste with a pennyworth, solar drying is an economically appropriate solution, energy and environmentally friendly. In this work, an experimental study is performed to improve the sun-drying process of Argan press-cake using an indirect forced convection solar dryer. As a result, the evolution of the temperature and the drying kinetics inside the product have been assessed. The influence of air recycling drying on the drying time has been highlighted and the characteristic drying law was established too. Thus, the optimal storing conditions of argan press-cake were identified.