Friedman Models Research Articles

Bioenergy potential from Ecuadorian lignocellulosic biomass: Physicochemical characterization, thermal analysis and pyrolysis kinetics

Lignocellulosic biomass offers a sustainable and renewable method for producing high-quality fuels and value-added chemicals. In this study, residues from peach palm (top, inner sheath, and meristem), sugarcane (top), and pineapple (mother plant) were characterized based on their physicochemical properties and thermal degradation behavior to estimate their bioenergy potential. The biomass residue kinetic constraints were analyzed using three isoconversional models: the Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and differential Friedman (DF) models. Physicochemical characterization showed the peach palm top's notably high cellulose content of 35.71 ± 0.47 % wt. Calorific values of the residues ranged from 13.73 ± 0.08 to 16.91 ± 0.90 MJ kg−1. X-ray diffraction analysis indicated the carbonaceous and crystalline nature of the biomass residues. Mean activation energy values ranged from 105.02 to 370.10 kJ mol−1 for KAS, 111.50–360.99 kJ mol−1 for FWO, and 108.60–360.27 kJ mol−1 for DF. Finally, thermodynamic analysis revealed the endothermic nature of the pyrolysis process across the entire conversion range for the samples. Overall, these samples demonstrate major potential as feedstock for biorefineries and the development of Ecuador's circular economy.

Pyrolysis-gasification conversion of waste pharmaceutical blisters: Thermo-kinetic and thermodynamic study, fuel gas analysis and machine learning modeling

It delved into the pyrolysis-gasification behavior of waste pharmaceutical blisters (WPBs), exploring both kinetics and thermodynamics, and employing machine learning modeling. The decomposition of WPBs occurred in three stages, with temperature intervals of 140–350, 350–500, and 500–900 °C, respectively. Cyclization/aromatization reactions were hindered, as indicated by mass spectrometric analysis, which revealed the main evolved products, including CxHy, CH3OH, CH4, and H2. Apparent activation energy values obtained from FWO, KAS, Friedman, Cai & Chen models were comparable, showing a decreasing trend ranging from 264.9 to 48.4 kJ mol−1 at α ≤ 0.70, followed by a subsequent increase to 283.1 kJ mol−1 at a conversion of 0.80. The D1 model was more reliable in describing the pyrolysis-gasification process of WPBs. Machine learning modeling results indicated that the ANN19 with a topology structure of 5 ∗ 15 ∗ 1 and genetic programming models showed superior performance in predicting TG data.

Biopolymeric degradation of jute sticks under pyrolytic thermal stresses

For the first time pyrolytic degradation of biopolymers and multi-pseudo component of jute sticks (JS) was executed through thermogravimetric analysis. Gaussian deconvolution of first order derivative have been registered in the current manuscript to find individual signals related to each pseudo component (hemicellulose, cellulose and lignin) in biomaterial. The JS characteristics, pyrolysis reaction kinetics, reaction mechanism and nature of the volatile compounds released were examined by various analytical instruments and methods, such as elemental analyzer, FTIR, AAS, TGA, GC-MS and kinetics models. The average activation energy values for JS 243.77, 234.05, 246.61, 246.74 and 260.03 kJ.mol−1 when OFW, KAS, STM, TANG and Friedman models, respectively, were used for analysis. Thermodynamic parameters (ΔH, ΔS, and ΔG) of different component of JS were also evaluated and discussed in the current context. Z(α) analysis has shown that the experimental curves have followed Avrami- Erofeyev (A2, A3, A4), power-law (P2), geometric (R2, R3), diffusional (D1, D2, D3) and reaction (F1) curves according to Criado’s master plots, indicating complex nature of pyrolysis process. Finally, it was confirmed that alcohols are major pyrolysates, followed by hydrocarbon and benzene among all other components released during pyrolysis action of JS. The finding of the study contributes to the potential of jute stick as a raw material for bioenergy and renewable chemical production. It also proves to be useful in the design and optimization of JS-based thermochemical degradation processes.

Thermal stability and decomposition kinetics of polybenzoxazine and oligomeric polyhedral octaphenyl silsesquioxane nanocomposites

AbstractIn this study, the impact of octaphenyl polyhedral oligomeric silsesquioxane (POSS) on the thermal stability of polybenzoxazine resin at 1, 3, and 5 wt% POSS loading through dynamic thermogravimetric analysis (TGA) at heating rates of 10, 20, 30 and 40°C min−1 was investigated. Besides, the decomposition kinetics of polybenzoxazine resin (PBZ) and various nanocomposites were studied using Kissinger, Friedman, Flynn‐Wall‐Ozawa (FWO) and Coats‐Redfern (CR) models and also, the activation energies of samples were calculated. At first, benzoxazine monomer was synthesized and then nanocomposites were prepared via solution mixing method. The qualitative dispersion of nanoparticles in benzoxazine resin was examined through the utilization of scanning electron microscopy and x‐ray diffraction experiments. The results showed that the addition of nanoparticles improved the thermal stability of PBZ resin specially at 1 wt% POSS loading and at higher POSS content the thermal stability of the resin decreased. As determined by TGA, the char yield of resin was enhanced by 2.6% upon the addition of 1 wt% nanoparticles. In addition, in 1 weight percent of nanoparticles, as the heating rate rose from 10 to 40°C min−1, the Integral Program Decomposition Temperature (IPDT) has increased by about 260°C, and this increase is about 183°C compared to the resin, and also elevating the heating rate, Td (5%) and Td (10%) weight loss of samples shifted to higher temperatures. The degradation mechanism of the resin and nanocomposites was evaluated through Kissinger, Friedman, FWO and CR models. The results displayed that the addition of 1 wt% nanoparticles increased the activation energy (Ea) values of the nanocomposites compared to that of neat resin and above this filler content, the Ea values decreased. The findings derived from the FWO model indicated that the inclusion of a 1 wt% filler raised the Ea values of the first and second stages of PBZ resin decomposition from 136–200 and 151–214 kJ mol−1 to 148–210 and 180–228 kJ mol−1, respectively.

Thermogravimetric analysis and kinetic modeling of the pyrolysis of different biomass types by means of model-fitting, model-free and network modeling approaches

This work aims at comparing the ability of 7 modeling approaches to simulate the pyrolysis kinetics of spruce wood, wheat straw, swine manure, miscanthus and switchgrass. Measurements were taken using a thermogravimetric analyzer (TGA) with 4 heating rates comprised between 5 and 30 K min−1. The obtained results were processed using 3 isoconversional methods (Kissinger–Akahira–Sunose (KAS), Ozawa–Flynn–Wall (OFW) and Friedman), 1-step and 3-step Kissinger models, as well as an advanced fitting method recently proposed by Bondarchuk et al. [1] (Molecules 28:424, 2023, https://doi.org/10.3390/molecules28010424). Seventeen reaction models were considered to derive rate constant parameters, which were used to simulate the variation of the fuel conversion degree α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha$$\\end{document} as a function of the temperature T\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$T$$\\end{document}. To complement this benchmarking analysis of the modeling approaches commonly used to simulate biomass pyrolysis, a network model, the bio-CPD (chemical percolation devolatilization), was additionally considered. The suitability of each model was assessed by computing the root-mean-square deviation between simulated and measured α=f(T)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha =f(T)$$\\end{document} profiles. As highlights, the model-free methods were found to accurately reproduce experimental results. The agreement between simulated and measured data was found to be higher with the Friedman model, followed by the KAS, FWO, 3-step, and 1-step Kissinger models. As for the bio-CPD, it failed to predict measured data as well as the above-listed models. To conclude, although it was less efficient than the Friedman, KAS or OFW models, the fitting approach from Bondarchuk et al. [1] (Molecules 28:424, 2023, https://doi.org/10.3390/molecules28010424) still led to satisfactory results, while having the advantage of not requiring the selection of a reaction model a priori.

Curing and degradation kinetics of crosslinked epoxidized soybean oil with isosorbide-based curing agent

This work explores the synthesis of the isosorbide-based curing agent with methyltetrahydrophthalic anhydride (MTHPA). Synthesized for the first time, the isosorbide methylphthalate acid (IMPA) and its effects on the crosslinking of epoxidized soybean oil (ESO) are investigated. The curing and degradation kinetics of the synthesized compounds were investigated for molar ratios 1:1, 1:0.50 and 1:0.25 for ESO/IMPA and 1:1 ESO/MTHPA. ESO/IMPA 1:0.50 had the lowest cure activation energies during the highest cure conversion range, between 10% and 55%, and the highest degradation activation energies during the 30 and 60% conversion. The Friedman and Vyazovkin isoconversional models provided R2 > 0.99 for cure, except for the ESO/MTHPA composition, presenting a lower R2. In degradation kinetics, the Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) kinetic models presented R2 > 0.99, while the degradation mechanisms were adequately adjusted with Avrami-Erofeev (An) and autocatalytic (n,m)th order (Cnm) during the first and second degradation step. Microstructural analyzes and deeper investigations into the degradation mechanisms in the solid state indicated that in the ESO/IMPA and ESO/MTHPA compounds the processes are controlled by diffusion.

Clinical Utility of Melanoma Sentinel Lymph Node Biopsy Nomograms.

For patients with melanoma, the decision to perform sentinel lymph node biopsy (SLNB) is based on the estimated risk of lymph node metastasis. We assessed 3 melanoma SLNB risk-prediction models' statistical performance and their ability to improve clinical decision making (clinical utility) on a cohort of melanoma SLNB cases. Melanoma patients undergoing SLNB at a single center from 2003 to 2021 were identified. The predicted probabilities of sentinel lymph node positivity using the Melanoma Institute of Australia, Memorial Sloan Kettering Cancer Center (MSK), and Friedman nomograms were calculated. Receiver operating characteristic and calibration curves were generated. Clinical utility was assessed via decision curve analysis, calculating the net SLNBs that could have been avoided had a given model guided selection at different risk thresholds. Of 2,464 melanoma cases that underwent SLNB, 567 (23.0%) had a positive sentinel lymph node. The areas under the receiver operating characteristic curves for the Melanoma Institute of Australia, MSK, and Friedman models were 0.726 (95% CI, 0.702 to 0.750), 0.720 (95% CI, 0.697 to 0.744), and 0.721 (95% CI, 0.699 to 0.744), respectively. For all models, calibration was best at predicted positivity rates below 30%. The MSK model underpredicted risk. At a 10% risk threshold, only the Friedman model would correctly avoid a net of 6.2 SLNBs per 100 patients. The other models did not reduce net avoidable SLNBs at risk thresholds of ≤10%. The tested nomograms had comparable performance in our cohort. The only model that achieved clinical utility at risk thresholds of ≤10% was the Friedman model.

Composites made of Ginkgo biloba fibers and polylactic acid exhibit non-isothermal crystallization kinetics

Polymer crystallization affects material microstructure and the final product quality, and the crystallization kinetics that govern this process are critical. In this study, alkali-treated Ginkgo biloba fibers (GFs) were melt blended with polylactic acid (PLA) to obtain GF/PLA blends. The non-isothermal crystallization kinetics of the GF/PLA composites were subsequently investigated using the Avrami, Jeziorny, Ozawa, and Liu-Mo methods, and the crystallization activation energies of the systems were calculated by Kissinger and Friedman models. The results showed that the GFs significantly promoted PLA crystallization, accelerated the crystallization rate, and shortened the crystallization time. The Avrami method showed some deviation from the linear relationship due to the effect of secondary crystallization, while the numeric value obtained by the Jeziorny method increased with the cooling rate. The Ozawa method could only be used in a very narrow range of temperatures, while the Liu-Mo method showed a more desirable fit. Crystallization activation energy calculations showed that the GFs promoted an increase in the crystallization capacity of the blend and a decrease in the effective potential barrier. This resulted in more selective biocomposites than pure PLA, offering greater applicability in domains including tissue engineering and 3D printing.

Thermal decomposition features of micro-nano rice husk/polylactic acid blends for 3D printing

The thermal decomposition process of 3D printed filament made from micro-nano rice husk (MNRH)/polylactic acid (PLA) blends was studied by dynamic thermogravimetric analysis. The characteristic temperatures and apparent activation energies of unmodified, single modified, and double modified RH/PLA composites were calculated by Friedman (FD), Flynn-Wall-Ozawa (FWO), Coats-Redfern (CR), and Kissinger (KS) kinetic models. With the modification of MNRH and PLA in the composites, the initial thermal decomposition temperature of the composite increased from 236.3°C to 244°C. At the same time, the thermal degradation degree decreased and the transition temperature interval increased. The apparent activation energy (AAE) values of different modified composites ranged from 90 to 120 kJ/mol, depending on the modification method and calculation method of the material. These four kinetic models provide methods to analyze the thermal stability of composites. It is helpful to known the thermal decomposition behavior of MNRH/PLA composites, and it will contribute to the development of MNRH/PLA filament for 3D printing in the application of automotive interior parts production.

Kinetics and Thermodynamics of the Pyrolysis of Waste Polystyrene over Natural Clay

Due to the massive increase in polymer manufacture, there has been a remarkable increase in plastic waste. With fewer landfills being used to dump plastic waste each year, it is becoming increasingly important to use effective recycling methods for plastic waste decomposition. In the present work, waste polystyrene was degraded in the presence of natural clay (K<sub>0.02</sub>, Ca<sub>0.15</sub> [Mg<sub>0.25</sub>, Al<sub>0.69</sub>, Fe<sub>0.06</sub>], [Si<sub>2.0</sub>, Al<sub>0.6</sub>] O<sub>6.8</sub> (O<sub>10</sub>) nH<sub>2</sub>O). The waste polymer was pyrolyzed at different heating rates i.e., 5, 10, 15 and 20°C min<sup>-1</sup> in an inert environment using nitrogen within the temperature range of 40 to 600°C. Thermogravimetric data were interpreted using various models, including fitting kinetic methods i.e., Coats-Redfern and model-free methods i.e., Ozawa-Flynn-Wall, Kissinger-Akahira-Sunose and Friedman method. The activation energy determined by Coats-Redfern, Ozawa-Flynn-Wall, Kissinger-Akahira-Sunose and Friedman models were in the range of 83.22-150.37, 74.52-133.71, 73.16-131.23, and 78.40-140.67 kJmol<sup>-1</sup>, respectively. Among them, the lowest activation energy for polystyrene degradation was observed using Kissinger-Akahira-Sunose method. The calculated kinetic parameters would be useful in determining the reaction mechanism of the solid-state reactions in a real system.

Pyrolysis and kinetic behavior of neem seed biomass using thermogravimetric analysis for the production of renewable fuel

Abstract Renewable fuel is gaining more attention in the current energy crisis, and biomass is one of the potential sources of producing renewable fuel. The objective of the present research is to analyze the pyrolysis and kinetic behavior of neem seed biomass. Pyrolysis and kinetic behavior of neem seed were analyzed using thermogravimetric analysis (TGA) at different heating rates, viz. 5, 10, 15, and 20 K min−1. The kinetic study was conducted on the neem seed using various kinetic models such as Friedman, Kissinger, Flynn–Wall–Ozawa (FWO), and Kissinger–Akahira–Sunose (KAS). Thermodynamic analysis was carried out using the data extracted from the TGA curves. The results showed that the neem seed degraded in three stages, stage I: <100 °C, stage II: 100–550 °C, and stage III: >550 °C. A maximum mass loss of 73.14 % occurred at stage II owing to the loss of cellulose and hemicellulose. The activation energy determined by Friedman, KAS, and FWO models was 5.11–18.64, 10.62–57.41, and 13.77–61.51 kJ mol−1, respectively. Thermodynamic analysis revealed that the pyrolysis of neem seed was an endothermic and spontaneous process. Moreover, the previously reported average activation energy required for the pyrolysis of various seeds and shells was compared with the present study and concluded that the variation in activation energy of neem seed adheres to the outcomes reported earlier.

Kinetic Decomposition Models for Ammonium Percholorate Hybrid Catalyzed with Nanothermite Particles

Ferric oxide is a universal catalyst. Reactive metal fuel can act as a high energy dense material such as aluminum which is marked by the very high gravimetric and volumetric heat output. This manuscript reports on the fabrication of colloidal ferric oxide nanoparticles of 5 nm. Colloidal ferric oxide/aluminum nanothermite mixture was integrated into ammonium percholorate (AP) via the coprecipitation technique. The shape and particles size of the prepared nano ferric oxide were investigated by using TEM instrument. Uniform dispersion of Al/Fe2O3 in the ammonium perchlorate matrix was verified using EDAX instrument. Nanothermite particles offered enhanced AP decomposition enthalpy by 120 % using DSC. Nanothermite colloid offered a decrease in AP activation energy by 51 and 40 % using Friedman and Ozawa models respectively. AP decomposition mechanism was reported to go through three consequent mechanisms including the first order mechanism, two-dimensional diffusion reactions, and one- dimensional diffusion mechanism according to extent of reacted fraction (α) of 0-0.25, 0.3-0.6, and 0.6-0.9 respectively. The results show that the catalyzing ability of the nanothermites was confirmed and has shown a superior effect on the AP energetic system.

Pyrolysis of oil-based drill cuttings from shale gas field: Kinetic, thermodynamic, and product properties

Oil-based drill cuttings (OBDC), as a by-product produced from the exploration and extraction of shale gas fields, have received increasing attention as both hazardousness and potential energy resources. In this study, the pyrolysis performance of OBDC was investigated using a thermogravimetric analyzer (TGA) and fixed-bed reactor. Results showed that the primary decomposition of OBDC occurred at 85–360 °C. The average activation energy calculated by model-free methods Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (OFW), Starink, and Friedman (FM) models were 53.11, 57.87, 53.38, and 64.23 kJ/mol, respectively. The reaction model depended on the degree of conversion. Moreover, high heating rates were conductive to predict the reaction mechanism. The analysis results of pyrolysis products showed that with the temperature increased from 450 °C to 600 °C, the oil yield presented a first increased and then decreased tendency, and reached the highest (14.94%) at 500 °C, then decreased to 12.10% at 600 °C. The oil was mainly composed of diesel fraction (C12-C22), which can be used as a fuel or raw material. Moreover, the lower heating value (LHV) of gaseous products was the highest (31.80 MJ/Nm3) at 600 °C. In addition, the oil content of char was far below 0.3%, and the heavy metal content in char was below the national standards (CJ/T 362–2011, China), suggesting that OBDC pyrolysis could achieve energy recovery and harmless treatment simultaneously. The results can provide a theoretical basis and data support for optimizing and developing OBDC pyrolysis reactors and processes.

A comparative study on morphology, composition, kinetics, thermal behaviour and thermodynamic parameters of Prosopis Juliflora and its biochar derived from vacuum pyrolysis

P. juliflora biochar derived from vacuum pyrolysis was subjected to physicochemical characterization using elemental, TG-DTG, SEM, BET analysis was studied. The maximum biochar yield was recorded to be around 32% at 500 °C for 40 min of residence time. Larger surface area and mesoporous structure (72 m2/g, and 0.083 cm3/g) were recorded for biochar. Thermal profile for P. juliflora was examined at 10, 20, 30 °C/min heating rates in a TG analyser. The maximum mass loss (55–58%) occurred between 180 and 400 °C for all heating rates 10, 20, and 30 °C/min. Kinetic and thermodynamic parameters for both P. juliflora and biochar were evaluated by model-free methods such as Flynn–Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Starink, and Friedman method. Biochar showed lower activation energy value (33.67, 33.35, 30.24, and 22.39 kJ/mol) as compare to P. juliflora (150.52, 150.47, 149.51, and 147 kJ/mol) for FWO, KAS, Starink, and Friedman models.

Determination of the Kinetics and Thermodynamic Parameters of Lignocellulosic Biomass Subjected to the Torrefaction Process.

The torrefaction process upgrades biomass characteristics and produces solid biofuels that are coal-like in their properties. Kinetics analysis is important for the determination of the appropriate torrefaction condition to obtain the best utilization possible. In this study, the kinetics (Friedman (FR) and Kissinger–Akahira–Sunose (KAS) isoconversional methods) of two final products of lignocellulosic feedstocks, miscanthus (Miscanthus x giganteus) and hops waste (Humulus Lupulus), were studied under different heating rates (10, 15, and 20 °C/min) using thermogravimetry (TGA) under air atmosphere as the main method to investigate. The results of proximate and ultimate analysis showed an increase in HHV values, carbon content, and fixed carbon content, followed by a decrease in the VM and O/C ratios for both torrefied biomasses, respectively. FTIR spectra confirmed the chemical changes during the torrefaction process, and they corresponded to the TGA results. The average Eα for torrefied miscanthus increased with the conversion degree for both models (25–254 kJ/mol for FR and 47–239 kJ/mol for the KAS model). The same trend was noticed for the torrefied hops waste samples; the values were within the range of 14–224 kJ/mol and 60–221 kJ/mol for the FR and KAS models, respectively. Overall, the Ea values for the torrefied biomass were much higher than for raw biomass, which was due to the different compositions of the torrefied material. Therefore, it can be concluded that both torrefied products can be used as a potential biofuel source.

Thermal degradation kinetics of polyvinyl chloride in presence of zinc oxide

This work investigates the degradation kinetics and the pyrolysis behavior of Poly (vinyl chloride) (PVC) and its mixture with ZnO using thermogravimetric analysis under an inert atmosphere. The investigation was carried out due to the increased interest in the co-thermal treatment of the hazardous waste electric arc furnace dust (EAFD) which contains significant quantities of ZnO with PVC. The degradation of pure PVC was characterized by three main decomposition stages: PVC de-hydrochlorination (two overlapped stages) and subsequent polyene thermal cracking, while ZnO-PVC mixture (ZPVC) demonstrated four decomposition/volatilization stages. The Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Friedman models were utilized for the extraction of the kinetic parameters. The average activation energy for pure PVC de-hydrochlorination was calculated to be 119.8 ± 12.4 kJ/mol, which changed to 110.6 ± 11.2 kJ/mol when a stoichiometric quantity of ZnO was added to it. The suggested mechanism for the ZPVC de-hydrochlorination starts by chlorine abstraction on ZnO at temperatures well-below 272 °C with an activation energy comparable to that of pure PVC de-hydrochlorination (115.8 kJ/mol). The chlorination of ZnO then yields zinc oxy/hydroxide chloride phases (Zn2OCl2·2H2O/β-Zn(OH)Cl) by the reaction between ZnCl2, ZnO and emitted H2O. These phases then decompose at approximately 222 °C into ZnCl2, ZnO, and H2O with a relatively low energy barrier of 102.2 kJ/mol. Formed ZnCl2 then lowers the activation energy for the polyene thermal cracking of PVC from 218.4 ± 17.7 (PVC) to 87.3 ± 9.7 kJ/mol (ZPVC) due to the physical contribution of volatilization to the overall mass loss.

Crossing over the curing and degradation of DGEBA/MTHPA/Eggshell to disclose the reactionary system

Degradation mechanisms and curing on diglycidyl ether of bisphenol A/methyl tetrahydrophthalic anhydride with 2,4,6-tris (dimethylaminomethyl) phenol as synthetic catalyst or eggshell membrane as natural catalyst, i.e., DGEBA/MTHPA/DEH 35 and DGEBA/MTHPA/M, respectively, were investigated by thermogravimetry (TGA) and Fourier transform infrared spectroscopy (FTIR). Thermal stability as commonly reported by TGA in this work was followed up by FTIR, enabling to specify the produced chemical groups from each degradation step. Qualitative and quantitative evaluation of kinetics mechanisms using Friedman, Kissinger, Criado and Coats-Redfern models, were performed and the activation energy (Ea) was computed, as presented the degradation energy for eggshell membrane compound is lower than the curing one, contributing to the latter's favorability. Reactionary schemes based on the theoretical models are proposed in an attempt to macroscopically demonstrate the microscopic morphological changes and reactions.

Deep eutectic solvents-based CNT nanofluid – A potential alternative to conventional heat transfer fluids

We investigated Deep eutectic solvents (DES) in this study as a potential substitute for conventional heat transfer fluids. Methyl-triphenylphosphonium-bromide (MTPB) and choline chloride (ChCl) as the hydrogen bond acceptors (HBAs), and ethylene glycol (EG) and triethylene glycol (TEG) as the hydrogen bond donors (HBDs), were used to form DESs. The molar ratio of HBA to HBD was varied between 1:3 and 1:5 to produce a total of 11 DESs. In each of these DESs, carbon nanotube (CNT) was added and dispersed at a constant concentration of 0.04 wt% to form DES-CNT-nanofluids. There was no surfactant added for stabilisation. The nanofluids were homogenised using an ultrasonic bath at 37 kHz for 4 h at room temperature. The freezing points of DES-CNT-nanofluids were analysed using differential scanning calorimetry while their thermal degradations, vapour pressures and weight losses were analysed using a thermogravimetric analyser. DES-CNT-nanofluids were found to have lower freezing points (down to -117.90 °C) as compared to EG and TEG, valued at -13.40 and -4.0 °C, respectively. The addition of HBA, such as MTPB and ChCl to form DESs, was found to increase the thermal stability of EG and TEG from 105 to 128 °C to 130 and 220 °C, respectively. Furthermore, the vapour pressures of DESs derived from EG and TEG, independently, were lower than that of pure EG and TEG by about 73% and 45%, correspondingly. The dispersion of CNT in DESs enhanced their thermal stabilities, activation energies and their kinetic parameters. The degradation reaction order was also determined through Friedman and Avrami models, respectively. Thus, DES has been proven to be a potential substitute for conventional heat transfer fluids due to its improved properties.

Pyrolysis of petroleum sludge under non-isothermal conditions: Thermal decomposition behavior, kinetics, thermodynamics, and evolved gas analysis

Pyrolysis of petroleum sludge is considered as a promising way for energy production from solid waste of petroleum refineries and the ability to predict the thermal decomposition behavior of such processes is necessary for modeling, optimization, and control of the pyrolysis reactors. Therefore, this work focused on developing and applying a systematic methodology for the calculation of kinetics and thermodynamics of the oil sludge pyrolysis and investigation of evolved gases. Thermograms at different heating rates demonstrated that the pyrolysis reactions could be considered under three zones; i) moisture and low molecular weight hydrocarbon volatilization, ii) active pyrolysis, and iii) high-temperature carbonization. During active pyrolysis, two decomposition stages were obtained by deconvolution using the Asym2sig function, which indicated the occurrence of multiple reactions. The average activation energies, calculated by the iso-conversional models, ranged in 106.3–112.7 kJ.mol−1 and 200.9–207.6 kJ.mol−1 for the first and second pyrolysis stages, respectively. Flynn-Wall-Ozawa and Friedman models showed the best consistency between the experimental and predicted values. The average pre-exponential factors were estimated as 9.79 × 106 s−1 and 1.91 × 1012 s−1 for these subsequent sub-stages. Furthermore, enthalpy, Gibbs free energy, and entropy changes were estimated together with monitoring emission profiles of the released gases from the sludge during pyrolysis by coupling TGA with an FT-IR spectrometer. The reported kinetic, thermodynamic parameters and findings on evolved gases can expand the use of this residue in refinery applications, consisting of a great attempt toward its valorization.

Comprehensive Kinetic Study of Pyrolysis of Sunan Candlenut: The Effect of Using Iron Oxide, Zeolite and ZSM-5 as Bed Materials

The purpose of bed material in the pyrolysis process is to reduce the need for heat energy. In this study, three kinds of sands were observed as bed material, namely iron oxide, zeolite, and ZSM-5 in the slow fixed bed pyrolysis of sunan candlenut oilcake (SCO). To evaluate the activation energy, pyrolytic kinetics were carried out using the iso-conversional method with the KAS, OFW, and Friedman models. They involved calculating the data from the thermogravimetric analysis (TGA) test at heating rates of 5, 10, 20 and 40 K/min. Furthermore, the results showed that SCO had a high volatile content of 82.80%, alongside a calorific value of 26.93 MJ/kg. The calculation results showed that the activation energy of SCO was 169.140 kJ/mol which decreased 1.45% in the KAS model, and 1.92% in the OFW model with the addition of ZSM-5 bed material. Therefore, the use of ZSM-5 bed material in the pyrolysis process reduces the activation energy.