Thermokinetic Studies Research Articles

Co-pyrolysis of municipal sewage sludge and microalgae Chlorella Vulgaris: Products’ optimization; thermo-kinetic study, and ANN modeling

Co-pyrolysis of microalgaeChlorella vulgaris(MCV) and municipal sewage sludge (MSS) was performed in a fixed-bed reactor to explore the influence of temperature (400–600 °C), mixing ratio (MCV/MSS = 0–1), and Argon flow rate of 0.20 to 0.80 L/min on pyrolysis products. The process was optimized using RSM to maximize bio-oil (BIO), minimize biochar (BIC), and biogas (BIG) yields. According to the ANOVA results, the mixing ratio has the most remarkable impact on BIO yield, and temperature has the highest influence on both BIC and BIG efficiency. By using numerical optimization, the optimum values of reaction parameters were T = 520 °C, mixing ratio (MCV/MSS) = 0.82, and Argon flow rate of 0.55 L/min. The third, second, and third-order of chemical reaction models can fit the pure MSS, MCV, and mix pyrolysis utilizing the Coats-Redfern technique, respectively. Also, master plots approaches were used to identify dominant reaction mechanisms. The values of the Eα calculated from non-model fitting methods for MSS, MCV, and co-pyrolysis are obtained in the domain of 79.19–125.59, 182.41–194.73, and 149.55–216.61 kJ/mol, in that order. The presence of the synergetic and inhibitive influences generated by the co-pyrolysis of MSS and MCV has been demonstrated by the improved and reduced weight loss rate, respectively. Furthermore, artificial neural network (ANN) models with the architectures (3*8*3) and (2*8*1) were built to simulate and predict pyrolysis yields and the thermal decomposition of individual and co-pyrolysis process, demonstrated a strong agreement between the actual data and predicted data (R2 ⩾ 0.999) are considerably closer to 1.

Experimental investigation on thermal behavior and thermo-kinetic study on pyrolysis of de-oiled microalgae

Experimental investigation on thermal behavior and thermo-kinetic study on pyrolysis of de-oiled microalgae

Biochemical characterization and thermodynamic principles of purified l-Asparaginase from novel Brevibacillus borstelensis ML12

l-Asparaginase from Brevibacillus borstelensis ML12 was purified and sequentially studied for biochemical characterization. A 1.94 fold purification using 80% ammonium sulphate fractionation was obtained. The molecular weight was found out to be 39.5 kDa following SDS-PAGE method. The purified l-Asparaginase showed enzyme stability in the alkaline range7.6–8.8 and maximum activity at pH 8.6. Co2+ proved to be a good activator in all the three respective concentrations (5mM10 mM, 20 mM) that were selected in the study. Effect of various surfactants, bile salt, organic reagents, chelators were also incorporated and Tween 80 and bile salt were found to enhance enzyme activity. Vmax and Km values were calculated by using Lineweaver-Burk plot and the values came out to be 204.081 μmol ml-1 min-1 and 0.253 mM respectively. Thermo kinetics study revealed that deactivation energy as obtained from Arrhenius equation was 10.882 kJmol-1. The z-value was calculated as 185.16K in case of thermal inactivation of asparaginase.

Thermo-kinetic study to explicate the bioenergy potential of Holy Thistle (HT)

Biomass is one of the key components for bioenergy generation in recent epoch as traditional resources and depleting swiftly. Going through this fact, the present study aims to appraise the feasibility of Holy Thistle (HT) to produce energy and valuable organic chemicals through pyrolysis. The HT was pyrolyzed at four heating rates including, 10, 20, 30, and 40 °C min −1 to perform thermo kinetic modeling and estimate thermodynamics parameters to establish the pyrolysis reaction process. The pyrolysis process of HT illustrated about 85–88 % of thermal degradation achieved through three different stages from 30 to 800 °C. The major degradation stage was observed from 170 to 450 °C with 55% to 60 % product formation from mainly cellulose and hemicelluloses components. Moreover, the average activation energy and pre-exponential factors demonstrated to be 183–184 kJ mol −1 and 10 10 min −1 to 10 25 min −1 , respectively. The pyrolytic products exhibited agreement to the cleaner production of bio-gas, char and bio-oil which is evident for the potential and productivity of the feed combination.

Inspecting the bioenergy potential of noxious Vachellia nilotica weed via pyrolysis: Thermo-kinetic study, neural network modeling and response surface optimization

In the present study, Vachellia nilotica (VN) was valorized via thermal pyrolysis. A thermogravimetric analyzer studied the thermal degradation of VN under non-isothermal conditions. Kinetic parameters were determined using seven isoconversional methods. The Eavg was ranged from 142.15 to 166.21 kJ/mol, with the advanced isoconversional approach showing significantly better performance than general methods. Thermodynamic analysis of VN pyrolysis suggested the possibility of conversion. Neural network modeling was significantly employed to predict the value of dα/dt. The effect of temperature (350–550 °C), heating rate (10–50 °C/min), and particle size (0.1–1 mm) on process performance in terms of products yield were systematically studied and analyzed. The process variables of temperature, heating rate, and particle size were also optimized using response surface methodology (RSM). The ideal operating parameters of temperature at 500 °C, and a heating rate of 25 °C/min with 0.4 mm particle size were determined and experimentally confirmed. The characteristics of the resulting product were determined using ultimate analysis, FTIR, and GC-MS, and it was discovered that the principal constituents in the VN pyrolysis process include phenolics, furfural, and dehydroacetic acid. VN has a high thermochemical conversion potential for bioenergy, as evidenced by their physicochemical properties and thermo-kinetic findings.

Artificial Neural Networks for Pyrolysis, Thermal Analysis, and Thermokinetic Studies: The Status Quo.

Artificial neural networks (ANNs) are a method of machine learning (ML) that is now widely used in physics, chemistry, and material science. ANN can learn from data to identify nonlinear trends and give accurate predictions. ML methods, and ANNs in particular, have already demonstrated their worth in solving various chemical engineering problems, but applications in pyrolysis, thermal analysis, and, especially, thermokinetic studies are still in an initiatory stage. The present article gives a critical overview and summary of the available literature on applying ANNs in the field of pyrolysis, thermal analysis, and thermokinetic studies. More than 100 papers from these research areas are surveyed. Some approaches from the broad field of chemical engineering are discussed as the venues for possible transfer to the field of pyrolysis and thermal analysis studies in general. It is stressed that the current thermokinetic applications of ANNs are yet to evolve significantly to reach the capabilities of the existing isoconversional and model-fitting methods.

A comprehensive insight into devolatilization thermo-kinetics for an agricultural residue: Towards a cleaner and sustainable energy

Stubble burning is a widely implemented agricultural malpractice that poses a serious environmental threat along with air pollution and global warming as the major consequences. This study aims to investigate an alternate conversion of the rice stubble feedstock to the thermochemical route by detailed kinetic and thermodynamic analysis. Initial assessment about the feedstock was made through physical and chemical characterization which indicated its energy potential with the high carbon content 47.61% along with 14.43 MJ kg−1 heating value. Subsequently, devolatilization kinetics was studied through a series of non-isothermal thermogravimetric analysis which showed the dependence on the plant cell wall component with overall conversion in active pyrolysis zone was 50.30%. Reaction pathways suggested a chain initiation and propagation mechanism associated with each constituent macromolecule. Friedman and simplified distributed activation energy methods were employed and the average apparent activation energy was estimated as 261.47 and 251.08 kJ mol−1 with corresponding pre-exponential factor as 7.85 × 1036 and 1.74 × 1021 s−1 respectively. Kinetic compensation effect was also observed within these parameters with its constants as 0.070 mol kJ−1 s−1 and 22.24 s−1. Master plots indicated that nuclei growth starts in the initial part of the reaction which exponentially increases to random nucleation and finally diffusion effects are dominant at the end of devolatilization. The empirical model mathematically showed an excellent correlation with the experimental data with a fitting percentage of 69.34%. Finally, thermodynamic parameters indicated an endothermic, non-spontaneous and high degree of randomness in the reaction. Altogether, the thermo-kinetic study suggested the energy feasibility of the overall process.

Unexpected enhanced reactivity of aluminized nanothermites by accelerated aging

• First thermokinetic study on Aluminized nanothermites to predict their aging and shelf-life. • Certain annealing conditions boost the combustion performance while sacrificing heat reservoir. • Al based thermites are thermally stable for one century until 200 °C. • Al/oxide interface chemistry has more impact on the reactivity than reaction progress evolution. We examine the thermal aging of four Al based thermites chosen among the most commonly used in microenergetic systems: Al/CuO, Al/Fe 2 O 3 , Al/Fe 3 O 4 and Al/Co 3 O 4 . For each nanothermite system, we applied the modified Friedmann isoconversional method from DSC signals to calculate the kinetic parameters of reactions and the function of the reaction progress in air and argon. As result, it is found that all thermites should be thermally stable for one century when stored at temperatures below 200 °C, except for Al/Fe 3 O 4 which readily converts into Al/Fe 2 O 3 before the thermite reaction onset. Then, we designed annealing experiments to a fixed reaction progress : (i) as simulated after 100 years storage at the ambient temperature, (ii) up to 5%. The pressure development and burning rate of aged thermites are compared with as-prepared ones. After annealing at 200 °C in air and 400 °C in argon, an unforeseen faster reaction and pressurization rates are observed for Al/CuO and Al/Fe 2 O 3 thermites. STEM and EDX show that the annealing provokes a modification of the aluminum particles structure accompanied with a softening of the alumina which explains the enhanced pressure performances and burn rates. Whereas the same nanothermites, Al/CuO and Al/Fe 2 O 3 , annealed at 400 °C in air, feature a reduced reactivity due to the over-oxidations of the aluminum core and the formation of crystalline alumina shell. These results reveal the high complexity of aging processes in powdered nanothermites as it provokes, not only a consumption of the heat reservoir, but also a modification of the Al/oxidizer interface morphology and chemistry which has a greater impact on the material reactivity than cumulative heat release and reaction progress evolution.

Thermo-kinetic study to elucidate the bioenergy potential of Maple Leaf Waste (MLW) by pyrolysis, TGA and kinetic modelling

The present study aims to evaluate the feasibility of Maple Leaf Waste (MLW) for the first time to produce biofuel-bioenergy and chemicals. It is meaningful to understand the thermochemical conversion and degradation pattern of the MLW to evaluate its biofuel-bioenergy potential. Different degradation stages and zones based on temperature and mass loss were identified to understand the pyrolytic behaviour in depth. Four different heating rates were used to conduct kinetic and thermodynamic analysis. The pyrolysis temperature was concluded ranged from 200 °C to 430 °C at all heating rates to obtain maximum bioenergy products. The kinetic parameters of pyrolysis were obtained by analysing through iso-conversional models of Kissinger-Akahira-Sunose (KAS), Friedman and Flynn–Wall–Ozawa (FWO). The average values of activation energies (75–91 kJ mol−1), high heating values (16.32 MJ kg−1), Gibb’s free energies (261–269 kJ mol−1) and change in enthalpy (68–85 kJ mol−1) have shown the significant potential for bioenergy production and suitability of co-pyrolysis with other waste and biomass feedstock.

Alteration of Activation Energy of a Reaction in the Catalase of Human Erythrocyte by Cimetidine, an In vitro Thermokinetic Study

Background: Hydrogen peroxide is normally formed during the metabolic pathway of the body. It is a toxic compound for vital cells, which can oxidize many macromolecules and cause damage in cells. Catalase can degrade H2O2 in cells and prevent cell injury. Cimetidine is a histamine H2 receptor blocker which decreases the release of stomach acid and is used for gastrointestinal diseases. Cimetidine inhibited catalase by mixed inhibition. Objective: In this study, the effect of temperature on the binding of cimetidine to human erythrocyte catalase was investigated and kinetic factors of the binding were determined. Results: Dixon plot confirmed the mixed type of inhibition and determined the Ki of the drug. The maximum activity of the enzyme was observed at 30°C. Arrhenius plot demonstrated that the activation energy of the enzyme reaction in the absence and presence of cimetidine was about 4.7 and 8.13 kJ/mol, respectively. The temperature coefficient (Q30-40) was determined as about 1.11 and 1.09 in the absence and presence of cimetidine. Conclusion: Cimetidine was able to increase the activation energy of the reaction of catalase, which confirmed the inhibition of the enzyme based on the kinetic results.

Thermo-Kinetic Study of Adsorption of Methylene Blue in Aqueous Solutions Using Algerian Illite Natural and Activated Mineral Clay

In this study, a local mineral clay was used as an adsorbent for the elimination of a cationic dye: methylene blue (MB), in an aqueous solution by adsorption technique. Early on, we performed mineralogical and textural analyses of a clay sample using various techniques, namely X-ray diffraction, Brunauer-Emmett-Teller analysis and Fourier-transform infrared spectroscopy. The experimental results showed that this adsorbent is a mesoporous and non-swelling clay with illite and kaolinite as the major components with a specific area of about 110m2/g. The study of MB adsorption on the clay was carried out by optimizing the conditions of adsorption, notably the initial concentration of pollutant C0, the mass of clay m, the contact time t, the potential of hydrogen of the solution pH and the temperature T. Experimental results have shown that the equilibrium data are well adjusted by a Langmuir isotherm equation. Thermodynamic parameters such as the changes in Gibbs free energy, enthalpy, and entropy were determined from batch experiments. Results revealed that the adsorption of MB onto illitic clay was endothermic and spontaneous process. Kinetic modeling was also carried out. Experimental data adjusted the kinetic model of pseudo-second order with two stages of intraparticle diffusion.

Study on Thermokinetic Parameters of Coal-oxygen Reaction Path with Constant Temperature Difference Guiding Method

ABSTRACT The low-temperature oxidation of coal includes processes such as coal-oxygen reactions and pyrolysis. As heat generated from coal-oxygen reaction is the fundamental driver of coal spontaneous combustion, the thermokinetic studies of coal spontaneous combustion should be focused on that. However, the pyrolysis path will impact the coal-oxygen reaction, resulting in limited capability of characterizing the t accurate hermokinetic parameters of coal-oxygen reaction process. Therefore, this paper proposed a new method to test the heat generation characteristics of coal-oxygen reaction path and the theoretical model of the method was established. The experimental results show that the method can achieve successful experiments within a short period of time, and exclude the impacts from heat absorption of water evaporation and pyrolysis, and well characterize the nature of coal spontaneous combustion. Meanwhile, the thermokinetic parameters such as heat generation rate and heat production can be obtained quickly and accurately. The coal-oxygen reaction path is divided into three stages by using the heat generation characteristics. By analyzing in-situ FTIR results, it is concluded that the gradual participation of different active groups is the main reason for the three stages. There are two main factors affecting the starting and heat generation of each stage, one is the activity of active groups which can participate in the initial reaction, and the other one is the number and activity of active groups that can participate in the reaction.

Thermokinetic study of magnesium hydroxide obtained from seawater

In this paper, magnesium hydroxide has been obtained from seawater by a well-known industrial process which involves the chemical reaction between magnesium ions of seawater with dolomite lime to produce the magnesium hydroxide precipitate. Furthermore, the precipitate was modified by ultrasound of high intensity. The purpose was to obtain magnesium hydroxide with high purity and reduced particle size without agglomeration. The precipitated magnesium hydroxide is characterized by the particle size distribution determined by the laser scattering method in the range of 20 nm–2 mm, and by the SEM analysis. Likewise, in order to investigate the effect of particle size on the thermal stability, thermokinetic study of magnesium hydroxide samples was performed by non-isothermal thermogravimetry in an inert atmosphere at different heating rates. The gained thermogravimetric data were utilized for the kinetic analysis, which was performed by using the isoconversional Friedman method in combination with the multivariate nonlinear regression method. For each degradation stage of investigated samples, kinetic parameters (activation energy, pre-exponential factor and kinetic model) were calculated and compared.

A thermo-kinetic study on co-pyrolysis of oil shale and polyethylene terephthalate using TGA/FT-IR

This study explored the effects of polyethylene terephthalate (PET) blending during the pyrolysis of oil shale (OS). Dynamic pyrolysis and co-pyrolysis tests at heating rates in the range from 5 to 40 °C/min were carried out using a thermogravimetric analyzer (TGA) coupled to a Fourier transform infrared spectrometer (FT-IR) to determine the kinetic parameters of the process and for online detection of evolved gasses. Pyrolytic decomposition of OS included a multi-stage decomposition process, while PET decomposed only in a single step. The kinetics of pyrolysis and co-pyrolysis was determined via model-free iso-conversional methods, namely Friedman, FWO, Starink, Vyazovkin, in a conversion degree range of 0.1–0.9. The kinetic models were validated with the obtained data to describe pyrolytic and co-pyrolytic degradation mechanisms, and the regression coefficients were between 0.9823 and 0.9999. The results showed that the activation energy of co-pyrolysis was evidently lower than that of PET or OS pyrolysis. This led to the conclusion that co-pyrolysis could be a potential method for obtaining shale oil due to the synergy between OS and PET.

Thermokinetic study of residual solid digestate from anaerobic digestion

Anaerobic digestion (AD) has become an effective waste management method in the agri-food sector to dispose of livestock and food wastes. As AD becomes more widely used new challenges emerge, such as the disposal of digestate by-products. Currently, the principal method for handling solid digestate (SD) is direct application to land as an organic fertiliser. However, as the sector grows, this option is less viable due to nutrition loading on the land and increased eutrophication. This paper explores the potential of using SD as a biofuel source. Additionally, the pyrolysis kinetic triplet of residual SD and thermal predictions was reported for the first time using Advanced Kinetics and Technology Solutions (AKTS) thermokinetics software to model and calculate the activation energy (Ea) and other kinetic parameters. ASTM-E698, Ozawa-Flynn-Wall and differential iso-conversional (model-free) methods were used and the Ea values calculated from each model were 169.8, 75 – 175.0, and 85 – 190.0 kJ mol−1, respectively. The kinetic triplet can be used in the scale-up or designing of reactor systems considering SD as a feedstock. The kinetic prediction of isothermal pyrolysis of SD indicated that a temperature higher than 210 °C is required for onset of decomposition in the sample. Furthermore, SD has the potential to produce an additional ~27.9 MJ per day at a 500 kW standalone on-farm AD plant. This work has highlighted the potential of waste solid digestate as a potential solid biofuel that could add an additional revenue stream to AD plants and make them more sustainable.

Extensive thermogravimetric and thermo-kinetic study of waste motor oil based on iso-conversional methods

The pyrolytic kinetics of waste motor oil (WMO) based on various differential and integral based model-free methods is studied utilizing the data obtained from TGA. For the different heating rates, i.e., 5 °C/min, 10 °C/min, and 40 °C/min the overall volatile conversion was found to be > 90%. The calculation of activation energy is performed using four different models (a) Friedman (b) Kissinger-Akahira-Sunnose (c) Flynn-Wall-Ozawa and (d) Starink methods. The mean activation energy was found to be 139.863 kJ/mol, which has been later used for the determination of z(α) master plots. Moreover, the prediction of the reaction model has been made by analyzing the different theoretical and experimental z(α) master plots. Further, the unknown parameters of the Sestak & Berggrens’s model are obtained using the model fitting methods in MATLAB. The obtained reaction model is fα=dαdt=3.21x1010βe-139863RT(1-α)3.049α-6.994-ln1-α5.626 which followed the autocatalytic (sigmoidal) mechanism. Furthermore, the thermodynamic stability of the system had been determined by calculating the change in entropy, enthalpy and Gibbs free energy. The kinetic parameters along with the thermodynamic results recommend a highly reactive system feasible for waste to energy generation using pyrolysis.

Thermo-kinetic studies on azodicarbonamide/potassium periodate airbag gas generants

In this study, thermal characterisation of stoichiometric azodicarbonamide/potassium periodate (C2H4O2N4/KIO4) fuel/oxidizer mixtures were systematically carried out for potential application as non azide non-toxic airbag gas generants. The onset temperature of the mixture was found to be 190°C. The thermo-kinetic studies of the mixture and pure azodicarbonamide compositions at different heating rates were also carried out using Ozawa and Kissinger method and the Arrhenius parameters were computed. The activation energy of the C2H4O2N4/KIO4 mixture by Ozawa method was found to be 81.5kJ mol−1 and 78.9kJmol−1 by Kissinger method. It was found that the activation energy of the pure azodicarbonamide was higher compared to the mixture. Ballistic tank tests to obtain the pressure Vs time plots were also done and the mixture gave time response of 45.2ms and 55.54ms to peak pressure. The experimental results have shown that C2H4O2N4/KIO4 mixture can be used as a replacement to existing azide based airbag gas generant compositions. Thus, the paper attempts to thermally characterize a non-toxic C2H4O2N4/KIO4 airbag gas generant mixture which can replace toxic azide based airbag gas generants and thereby facilitate safer driving.

Thermal analysis of kerosene with 1,2-methyl ethyl 1-methyl pyrrolidinium bis(trifluoromethanesulfonyl) amide as an additive

This paper reports the thermal characterization of kerosene fuel-doped ionic liquid (1, 2-methylethyl 1-methyl pyrrolidinium bis(trifluoromethanesulfonyl) amide) (MEMP TFSA), an antistatic additive used in jet fuel engines. The ionic liquids (ILs) samples are prepared with the mass of 5, 10 and 15% in the kerosene fuel. These fuel samples are subjected to thermal decomposition studies at different scanning rates of 5, 10 and 15 °C min−1 using the differential scanning calorimetry (DSC) method. The onset temperatures of exothermic reactions of kerosene-doped ILs are increased from 360–465 °C, when the mass percentage of ILs increased in the kerosene fuel. The boiling point of the kerosene-doped ILs was displaced to the higher temperature when compared to the pure kerosene. This showed that the doping of antistatic additives of ILs with kerosene increased its thermal stability property than the pure kerosene fuel. The thermo-kinetic studies are also carried out using Ozawa’s Kinetic method to determine the activation energy (Ea) and pre-exponential factor (A). The FTIR analysis showed that the kerosene-doped ionic liquid forms a homogenous mixture rather than prevailing separately.

Water sorption isotherms and drying characteristics of rupturewort (Herniaria hirsuta) during a convective solar drying for a better conservation

Free water contained in porous structure of food plays a fundamental role in proliferation of microorganisms and bacteria that can damage the product materials. This work presents a thermo-kinetic study carried out in a natural and forced convection solar dryer; the objective was to establish the optimal conditions for drying and storing Herniaria hirsuta by testing the impact of different aerothermal conditions (air temperature, air velocity) on water loss of fresh Herniaria hirsuta. The kinetics of drying is studied for three temperatures (50, 60 and 70 °C) in two-air velocities (0.09 and 0.18 m/s). The optimal water activity which is related to conservation is 0.28. The LESPAM model was found to be the most appropriate for describing the sorption curves. The air drying temperature is a principal factor influencing the drying kinetics; the drying rate decreases in low air drying temperature, the air velocity had a small impact on the drying kinetics of Herniaria hirsuta. The Midilli-Kuck model was found to be the best fitted drying curves in thin layers for Herniaria hirsuta. The effective diffusivity of moisture water values changed from 2.5312 10−9 to 18.0511 10−9 m2·s−1, and increased simultaneously with the increase of temperature. The average activation energy of the diffusion process is obtained to be 2938.46 kJ/kg; it expresses the temperature effect on the diffusion coefficient. Dried Herniaria hirsuta under the maximum drying parameters showed highest retention of antioxidant activity, while the total phenolics and flavonoids were decreased by 10 and 46%, respectively.

Fundamental thermokinetic study of a sustainable lithium-ion battery pyrometallurgical recycling process

With increased global consumption of Lithium-ion batteries (LIBs), a sustainable recycling process is necessary to reduce wastes and retrieve highly-valued elements. But to achieve an optimized sustainable recycling process, a fundamental understanding of the thermokinetic reactions during pyrometallurgical LIB recycling is essential. In this work, the thermodynamics and kinetics of high-temperature reactions for LIBs during pyrometallurgical recycling are studied using a thermo-gravimetric analyzer (TGA) equipped with a gas mass spectrometer. Cylindrical composite pellets comprised of cathode and anode active materials were heated from room temperature (RT) to 1500 °C at a constant heating rate of 20 °C/min. By comparing the measurements of the mass loss and simultaneous gas evolution, the anticipated theoretical thermodynamic reactions are confirmed and determined, which is fundamental to the development of a sustainable pyrometallurgical process to recover valuable metals in LIBs. Isothermal reductions from 850 to 1000 °C indicated reactions to be temperature sensitive and mass transfer to be comparatively fast. Using various kinetics models, the uniform internal reduction mechanism was found to be dominant.