Pyrolysis and kinetic analyses of Camel grass (Cymbopogon schoenanthus) for bioenergy

Pyrolysis and combustion of industrial hemp, coal and their blends for thermal analysis by thermogravimetric analysis/Fourier transform infrared spectrometer

In this study, the thermal behaviours of Cannabis sativa (CS), coal and their five different blends at a heating rate (β) of 10, 20, 30, 40 and 50°C min-1; the synergistic effects between CS and coal; and the distribution of gases formed during pyrolysis and combustion were investigated by using the thermogravimetric analysis/Fourier transform infrared spectrometer (TGA/FTIR) integrated system. The TG and DTG curves showed that the thermal decomposition of pyrolysis and combustion of all feedstocks at all β values had three main decomposition stages. The synergistic effect was observed for DTGmax, mass loss (ML), or final residue (FR) at least once at a given β of each blend; and the synergy was more effective for DTGmax and ML in pyrolysis than in combustion, whereas the opposite was true for FR. The lowest emissions of CO2, CH4, NOx and SO2 except CO during pyrolysis occurred at the blend of 0% CS + 100% Coal. However, the highest emissions of CO, CH4, NOx and SO2 except CO2 during combustion were observed at the blend of 80% CS + 20% Coal. The emissions of CO, CO2, NOx and SO2 from all samples during pyrolysis were lower than that of combustion, indicating that pyrolysis can be preferred due to its lower emission to the environment. Different structural properties of CS, coal and their blends caused different thermal behaviours, synergistic effects and gas products during pyrolysis and combustion by TGA/FTIR, suggesting detailed further investigation for upper-scale pyrolysis and combustion applications.

Pyrolysis Characteristics and Determination of Kinetic and Thermodynamic Parameters of Raw and Torrefied Chinese Fir

Torrefaction influences the structural and physicochemical properties of biomass, thus further altering its thermal degradation behavior. In this study, the pyrolysis characteristics, reaction kinetics, and thermodynamic parameters of raw and torrefied Chinese fir (CF) were investigated. The torrefaction was conducted at 220 °C (mild) and 280 °C (severe), the pyrolysis was performed from ambient temperature to 600 °C, and four different heating rates (i.e., 5, 15, 25, and 35 °C/min) were adopted. The activation energy for pyrolysis was estimated by adopting three isoconversional methods. The master-plot method was employed to analyze the reaction mechanism. Furthermore, thermodynamic parameters, i.e., the enthalpy change (ΔH), Gibbs free energy change (ΔG), and entropy change (ΔS), were calculated. The average activation energy increased with the torrefaction temperature, whose values estimated by using different methods ranged from 88.57 to 97.70, from 121.04 to 126.35, and from 167.51 to 179.74 kJ/mol for raw, mildly, and severely torrefied CF samples, respectively. A compensation effect between the activation energy and pre-exponential factor was observed for all samples. The degradation process was characterized as endothermic, involving the formation of activated complexes and requiring extra energy for torrefied samples.

Thermal behaviour of hydrochar derived from hydrothermal carbonization of food waste using leachate as moisture source: Kinetic and thermodynamic analysis

The effect of leachate (L) as a reaction medium in hydrothermal carbonization (HTC) of food waste (FW) on the thermal behaviour of the resulting hydrochar (H) was investigated. The physicochemical and structural characterization of FW hydrochar produced using leachate (FWH-L) at different process temperatures (180/210/240 °C) confirmed the improved properties over raw FW. Kinetic analysis using Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman methods revealed that FWH-L have a lower activation energy (E_a) than raw FW. The average E_a values for raw FW by FWO, KAS and Friedman methods were 196.18, 196.85, 206.34 kJ/mol, respectively, while for FWH-L they were 127.89, 124.22 and 134.5 kJ/mol, respectively. The computed thermodynamic parameters showed that FWH-L has improved combustion behaviour. The results of FWH-L are well comparable to FW hydrochar produced using distilled water (FWH-DW). These findings demonstrated that residual ions in leachate would act as a catalyst, benefiting the HTC degradation reaction path.

The invasive Egeria densa macrophyte and its potential as a new renewable energy source: A study of degradation kinetics and thermodynamic parameters

The increase in global demand, along with environmental concerns, has led to the need for new sources that can supply the energy needed for socioeconomic development while reducing pollutant emissions. Aquatic biomasses, especially those of invasive aquatic macrophytes, can be potential energy sources, and this study evaluated the thermal degradation of the invasive Egeria densa macrophytes (EDM) in an inert environment at four heating rates to evaluate its potential as a low-cost biomass and bioenergy source. Pyrolysis experiments were performed using a thermogravimetric analyzer. The thermal profile of invasive EDM has three main events (multiple stages). Stages (i) and (ii) occur at a temperature range of 125-395 °C and represent the decomposition of carbohydrates such as hemicellulose and cellulose. Stage (iii) occurs between 395 and 500 °C and mainly relates to the decomposition of lignin. Thermal data have been used to analyze kinetic parameters through isoconversional methods, and the activation energy (E_a) value of EDM showed variation at different conversion points. The highest E_a values were observed for conversion rates of 0.3-0.6 due to the increased energy required to break down the lignocellulosic chains during decomposition. The small difference between the enthalpy change and E_a values for the different isoconversional methods can be due to a small potential energy barrier, which reflects the feasibility that the reaction can occur under the expected conditions. Gibbs free energy (137-145 kJ mol^-1) and high heating value (13.40 MJ/kg) revealed a significant bioenergy potential for EDM biomass.

A comparative study on pyrolysis kinetics and thermodynamic parameters of little millet and sunflower stems biomass using thermogravimetric analysis

Several biochemical and thermochemical routes including pyrolysis, liquefaction, combustion and gasification are used to convert biomass to several bioproducts and green fuels. The current investigation included two important biomass namely, little millet stem (LMS) and sunflower stem (SS), whose potentiality as useful feedstocks is largely unexplored. The presence of considerable level of cellulose accumulation (approx. 30 %), volatiles (approx. 67 %) and high heating value (approx. 14 MJ/kg) in both the biomass, inferred their potentiality to be used as feedstocks in the pyrolysis process. The estimate of activation energy for LMS was reported as 191.14 kJ/mol (FWO), 191.46 kJ/mol (KAS) whereas for SS, the activation energy was estimated as 166.52 kJ/mol (FWO) and 162.68 kJ/mol (KAS). The difference between change in enthalpy and activation energy was small (5 to 6 kJ/mol) for both the biomasses, indicating the feasibility of combustion process. From Z(α) analyses, the experimental curve was seen passing through different theoretical curves, indicating complex nature of pyrolysis process for both the biomass.

Insights into kinetic and thermodynamic analyses of co-pyrolysis of wheat straw and plastic waste via thermogravimetric analysis

This work studied the co-pyrolysis of wheat straw (WS) and polyethylene (PE) via thermogravimetric experiments from room temperature to 1000 °C at various heating rates (10, 20, and 30 °C/min). Thermal behavior revealed that the maximum decomposition of WS, PE, and their blend occurred in three temperature ranges, viz. 250 - 496, 200 - 486, and 200 - 501 °C. Kinetic parameters were determined using model-free isoconversional methods. Activation energy from KAS (163.56, 220.26 and 196.78 kJ/mol for WS, PE, and blend), FWO (165.97, 222.05, 198.86 kJ/mol for WS, PE, and blend), and Starink (163.45, 220.05, 196.46 kJ/mol for WS, PE, and blend) method was estimated. From among various solid-state kinetic models, first-order reaction kinetics and one and two-dimensional diffusion models dominated co-pyrolysis of WS and PE. Thermodynamic parameters confirmed the feasibility of co-pyrolysis of WS and PE while differential thermal analysis signified that endothermic and exothermic reactions occur simultaneously.

Biochar Synthesis from Mineral- and Ash-Rich Waste Biomass, Part 1: Investigation of Thermal Decomposition Mechanism during Slow Pyrolysis

Synthesizing biochar from mineral- and ash-rich waste biomass (MWB), a by-product of human activities in urban areas, can result in renewable and versatile multi-functional materials, which can also cater to the need of solid waste management. Hybridizing biochar with minerals, silicates, and metals is widely investigated to improve parent functionalities. MWB intrinsically possesses such foreign materials. The pyrolysis of such MWB is kinetically complex and requires detailed investigation. Using TGA-FTIR, this study investigates and compares the kinetics and decomposition mechanism during pyrolysis of three types of MWB: (i) mineral-rich banana peduncle (BP), (ii) ash-rich sewage sludge (SS), and (iii) mineral and ash-rich anaerobic digestate (AD). The results show that the pyrolysis of BP, SS, and AD is exothermic, catalyzed by its mineral content, with heat of pyrolysis 5480, 4066, and 1286 kJ/kg, respectively. The pyrolysis favors char formation kinetics mainly releasing CO₂ and H₂O. The secondary tar reactions initiate from ≈318 °C (BP), 481 °C (SS), and 376 °C (AD). Moreover, negative apparent activation energies are intrinsic to their kinetics after 313 °C (BP), 448 °C (SS), and 339 °C (AD). The results can support in tailoring and controlling sustainable biochar synthesis from slow pyrolysis of MWB.

Pyrolysis of anaerobic digested residues in the presence of catalyst-sorbent bifunctional material: Pyrolysis characteristics, kinetics and evolved gas analysis

We investigated the potential application of anaerobically digested residues for generating bioenergy in the presence of alkali bifunctional material, sodium zirconate (Na₂ZrO₃, NZ) using a thermogravimetric analyzer connected to a mass spectrometer. Isoconversional kinetic models, compensation effect and master-plots method were used on data obtained under multiple heating rates (10, 15 and 20 °C min^-1) to calculate the activation energy (E_α) and pre-exponential value (A) and reaction mechanism. The average E_α for blend samples C-DSW (NZ mixed with digested municipal solid waste (DSW)), and C-DSM (NZ mixed with digested swine manure (DSM)) were 172.24 and 171.63 kJ mol^-1, which were much lower when compared to plain samples, DSW (202.51 kJ mol^-1) and DSM (215.22 kJ mol^-1). The total gas yields increased by 19.5 and 17.1% for NZ blended samples C-DSW and C-DSM, respectively. In addition, the hydrogen yields also increased by 79 and 44% for C-DSW and C-DSM, respectively.

Torrefaction, temperature, and heating rate dependencies of pyrolysis of coffee grounds: Its performances, bio-oils, and emissions

The torrefaction pretreatment is of great significance to the efficient conversion of biomass residues into bioenergy. In this study, the effects of the three torrefaction temperatures (200, 250, and 300 °C) on the pyrolysis performance and products of coffee grounds (CG) were quantified. The torrefaction treatment increased the initial devolatilization and maximum peak temperatures of the CG pyrolysis. Activation energy of CG250 was lower than that of CG and more conducive to the pyrolysis. Torrefaction altered the distributions of the pyrolytic products and promoted the generation of C=C. Torrefaction changed the composition ratio of the pyrolytic bio-oils although cyanoacetic acid and 2-butene still dominated the bio-oils. The joint optimization pointed to pyrolysis temperature > 600 °C and torrefaction temperature ≤ 270 °C as the optimal conditions. Our experimental results also verified that torrefaction of CG may be more suitable at 200 and 250 °C than 300 °C.

Synergistic Effects on the Co-pyrolysis of Agricultural Wastes and Sewage Sludge at Various Ratios

This study investigated the co-pyrolysis of blends of sewage sludge (SS) with rice husk (RH) and with hemp straw (HS) at different ratios by using thermogravimetry (TG) and its rate (DTG, derivative TG) analysis at heating rates of 10, 20, and 30 K/min. The resulting kinetic parameters of activation energy (E _a) were calculated by both Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose models, followed by comparison of experimental values with calculated values to reveal the synergistic effects of SS/RH and SS/HS. With increasing additions of RH or HS to SS, a gradual decreasing trend in the experimental pyrolysis temperature range was evident, ranging from 144.5 to 95.2 °C for SS/RH and from 144.5 to 88.8 °C for SS/RH. Moreover, such temperature ranges were 6.7-20.4 °C less than the calculated values at the same blending ratio. The fitting results of the two kinetic models showed that with the same SS mass ratio, the experimental E _a ^* (average activation energy) of both SS/RH and SS/HS were less than the calculated E _a ^*. Especially, the experimental E _a ^* of 7SS-3RH was lower around 43.8% than the calculated E _a ^*, whereas the experimental E _a ^* of 3SS-7HS was lower by about 39.4% than the calculated E _a ^*. Synergistic analysis demonstrated that the co-pyrolysis of RH or HS with SS at various mass ratios presented obvious synergistic effects and then the decrease of E _a. The mechanism experiment showed that the co-pyrolysis of SS/HS may promote the decrease of E _a by changing the co-pyrolysis gas products or by increasing the overflow of volatile matter and then forming intermediate transition products, while SS/RH may accelerate the decrease of the E _a by using an appropriate K addition ratio from RH as a metal catalyst.

Catalytic Fast Pyrolysis of Soybean Straw Biomass for Glycolaldehyde-Rich Bio-oil Production and Subsequent Extraction

In this study, soybean straw (SS) as a promising source of glycolaldehyde-rich bio-oil production and extraction was investigated. Proximate and ultimate analysis of SS was performed to examine the feasibility and suitability of SS for thermochemical conversion design. The effect of the co-catalyst (CaCl₂ + ash) on glycolaldehyde concentration (%) was examined. Thermogravimetric-Fourier-transform infrared (TG-FTIR) analysis was applied to optimize the pyrolysis temperature and biomass-to-catalyst ratio for glycolaldehyde-rich bio-oil production. By TG-FTIR analysis, the highest glycolaldehyde concentration of 8.57% was obtained at 500 °C without the catalyst, while 12.76 and 13.56% were obtained with the catalyst at 500 °C for a 1:6 ratio of SS-to-CaCl₂ and a 1:4 ratio of SS-to-ash, respectively. Meanwhile, the highest glycolaldehyde concentrations (%) determined by gas chromatography-mass spectrometry (GC-MS) analysis for bio-oils produced at 500 °C (without the catalyst), a 1:6 ratio of SS-to-CaCl₂, and a 1:4 ratio of SS-to-ash were found to be 11.3, 17.1, and 16.8%, respectively. These outcomes were fully consistent with the TG-FTIR results. Moreover, the effect of temperature on product distribution was investigated, and the highest bio-oil yield was achieved at 500 °C as 56.1%. This research work aims to develop an environment-friendly extraction technique involving aqueous-based imitation for glycolaldehyde extraction with 23.6% yield. Meanwhile, proton nuclear magnetic resonance (¹H NMR) analysis was used to confirm the purity of the extracted glycolaldehyde, which was found as 91%.

Thermogravimetric analysis of the pyrolysis and combustion kinetics of surface dead combustibles in the Daxing'an Mountains

In boreal regions, the frequency of forest fires is increasing. In this study, thermogravimetric analysis was used to analyze the pyrolysis kinetics of dead surface combustibles in different forest types within the Daxing'an Mountains, China. The results show that the combustible material load of forest types, the Larix forest (LG) is relatively high. Base on the E of kinetic parameters, the LG, and Quercus forest (QM) forest types had relatively high combustibility values and comprehensive combustibility values for 1-, 10-, and 100-h time lags. According to the obtained P values, the pyrolysis of dead surface fuels with 1-, 10-, and 100-h time lags is relatively difficult in the Larix / Betula mixed forest (L-B) and QM forest types. Therefore, mixed forests of the LG, L-B, and QM tree species can be established as fire-resistant forests to establish a fire barrier, reduce the combustibility of forest stands, and reduce the possibility of forest fires.

Kinetic and thermodynamic study of finger millet straw pyrolysis through thermogravimetric analysis

Pyrolysis kinetics of finger millet straw (FMS) was studied using a thermogravimetric analyzer under N₂ environment. Physico-chemical characteristics of FMS were comparable with the established pyrolysis feedstocks. FMS thermally decomposed in three stages: drying, active pyrolysis, and char formation resulting in 70.37% overall weight loss. Average activation energy determined by Friedman and Starink methods was 177.80 and 172.18 kJ mol^-1, respectively. Frequency factor was found to be in the range of 10⁸ to 10²⁹. Reaction pathway followed diffusion, nucleation, and order-based mechanisms. The pyrolysis of FMS was characterized by empirical modeling and predicted well with model adequacy of 97.55%. Thermodynamic parameters (ΔG and ΔH) revealed the non-spontaneous and endothermic nature of FMS pyrolysis. The biochar obtained at multiple heating rates were characterized for its physicochemical, functional, and morphological characteristics. The kinetic and thermodynamic analyses illustrate the feasibility of exploiting finger millet straw as a pyrolysis feedstock to derive biofuels.

Pyrolysis of almond (Prunus amygdalus) shells: Kinetic analysis, modelling, energy assessment and technical feasibility studies

The aim of this work was to study the thermogravimetric analysis through the pyrolysis of almond (Prunus amygdalus) shells for evaluating its potential for bioenergy at different heating rates (10, 25, and 50 K min^-1). The activation energy values for the process were of the range of 153.0, 152.02, and 152.73 kJ mol^-1 as calculated by Kissenger-Akahira-Sunrose (KAS), Ozawa-Flynn-Wall (OFW) and Starink models respectively. The change in the Gibbs free energy was ~181 kJ mol^-1. Diffusion-based reaction, followed by the chemical reaction mechanism,was dominant thermal degradation as envisaged by the Coats-Redfern method. The validation of the experiments was accomplished through the artificial neural network, reiterating its further usage in any conversional studies of biomass. A difference of < 10 kJ mol^-1 between the values of activation energy and enthalpy of the degradation reaction indicated favourable product formation. The results offer potential application of almond shells for energy production through pyrolysis.

Pyrolysis of Solid Digestate from Sewage Sludge and Lignocellulosic Biomass: Kinetic and Thermodynamic Analysis, Characterization of Biochar

This study investigates the pyrolysis behavior and reaction kinetics of two different types of solid digestates from: (i) sewage sludge and (ii) a mixture of sewage sludge and lignocellulosic biomass—Typha latifolia plant. Thermogravimetric data in the temperature range 25–800 °C were analyzed using Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose kinetic methods, and the thermodynamic parameters (ΔH, ΔG, and ΔS) were also determined. Biochars were characterized using different chemical methods (FTIR, SEM–EDS, XRD, heavy metal, and nutrient analysis) and tested as soil enhancers using a germination test. Finally, their potential for biosorption of NH4+, PO43−, Cu2+, and Cd2+ ions was studied. Kinetic and thermodynamic parameters revealed a complex degradation mechanism of digestates, as they showed higher activation energies than undigested materials. Values for sewage sludge digestate were between 57 and 351 kJ/mol, and for digestate composed of sewage sludge and T. latifolia between 62 and 401 kJ/mol. Characterizations of biochars revealed high nutrient content and promising potential for further use. The advantage of biochar obtained from a digestate mixture of sewage sludge and lignocellulosic biomass is the lower content of heavy metals. Biosorption tests showed low biosorption capacity of digestate-derived biochars and their modifications for NH4+ and PO43− ions, but high biosorption capacity for Cu2+ and Cd2+ ions. Modification with KOH was more efficient than modification with HCl. The digestate-derived biochars exhibited excellent performance in germination tests, especially at concentrations between 6 and 10 wt.%.

Studies on individual pyrolysis and co-pyrolysis of corn cob and polyethylene: Thermal degradation behavior, possible synergism, kinetics, and thermodynamic analysis

The knowledge on thermo-kinetics, synergistic effect, and reaction mechanism of pyrolysis/co-pyrolysis of biomass with plastics is crucial for designing efficient reactor system and subsequently the pyrolysis/co-pyrolysis process. The present work explores thermal response, kinetics, reaction mechanism and thermodynamic analysis of pyrolysis and co-pyrolysis of individual corn cob (CC) and polyethylene (PE), and their blend in the ratio of 3:1 (w/w). Thermogravimetric analysis (TGA) data was obtained under inert atmosphere at various heating rates of 10, 20, and 30 °C/min and synergistic effect in the co-pyrolysis of CC and PE is discussed. The obtained TGA data was processed using various model-free isoconversional methods like KAS, FWO, Friedman, Starink, and Vyazovkin for determination of kinetics of pyrolysis/co-pyrolysis process of CC and PE. Average activation energy for CC pyrolysis was estimated to be 240 ± 51.25 kJ/mol, 240 ± 51.51 kJ/mol, 237 ± 49.67 kJ/mol, and 245 ± 52.10 kJ/mol according to KAS, Starink, FWO, and Vyazovkin models, respectively. Statistical analysis showed that the variation in reported values of activation energy was not significantly different (p = 0.994). Similar statistically insignificant difference was also observed for pyrolysis of PE and co-pyrolysis of CC and PE. Results showed that co-pyrolysis (CC + PE) requires 10% less activation energy than pyrolysis of CC alone. For the co-pyrolysis process, the extent of synergistic effect was discussed by difference in mass loss (ΔW). Investigation also revealed that residue left for co-pyrolysis of CC and PE is 50% less than pyrolysis of CC alone showing synergistic effect during co-pyrolysis. Thermodynamic parameters were calculated to illustrate complex mechanism of the process. Third order reaction, 3D diffusion Jander, and Ginstling-Brounshtein (D4) models were found to be best fitted for CC pyrolysis, PE pyrolysis, and co-pyrolysis, respectively. Results obtained are expected to be useful in the design of corn cob and waste polyethylene co-pyrolysis systems.

Synergetic Effects during Co-Pyrolysis of Sheep Manure and Recycled Polyethylene Terephthalate

Continuous growth in energy demand and plastic waste production are two global emerging issues that require development of clean technologies for energy recovery and solid waste disposal. Co-pyrolysis is an effective thermochemical route for upgrading waste materials to produce energy and value added products. In this study, co-pyrolysis of sheep manure (SM) and recycled polyethylene terephthalate (PET) was studied for the first time in a thermogravimetric analyzer (TGA) in the temperature range of 25-1000 °C with heating rates of 10-30-50 °C min^-1 under a nitrogen atmosphere. The synergetic effects of co-pyrolysis of two different waste feedstock were investigated. The kinetic parameters are determined using the Flynn-Wall-Ozawa (FWO) model. The results revealed that the mean values of apparent activation energy for the decomposition of sheep manure into a recycled polyethylene terephthalate blend are determined to be 86.27, 241.53, and 234.51 kJ/mol, respectively. The results of the kinetic study on co-pyrolysis of sheep manure with plastics suggested that co-pyrolysis is a viable technique to produce green energy.

Detection and kinetic simulation of animal hair/wool wastes pyrolysis toward high-efficiency and sustainable management

Large quantities of solid wastes are produced each year in the leather industry. The considerable wastes generated exhibit tremendous application potential in terms of renewable energy sources and functional materials. Among them, animal hair/wool wastes possess high carbon content, which can be used sustainably and efficiently by using pyrolysis. Herein, the pyrolysis process of hair/wool wastes was investigated using TG-IR and Py-GC/MS, while the pyrolysis kinetic and thermodynamic were analyzed using "model-free" methods. The results showed that the hair/wool waste pyrolysis process can be divided into three stages: dehydration, devolatilization, and carbonization. The volatile products were mainly phenols (7.42%) and heterocyclic compounds (21.26%), which can be directly used as bio-energy (bio-gases and bio-oil) or converted to other useful chemical products. The kinetic parameters (E_a and A) calculated using the Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and Kissinger methods indicated the complexity of the decomposition reactions, which was also confirmed by thermodynamic (ΔH, ΔG, and ΔS) calculation. Some suggestions have also been provided for the preparation of functional biochar with heteroatoms (i.e., N, O, and S) doping. These results not only provide a guide for designing the pyrolysis of hair/wool wastes but can also help develop a potential method to convert the hair/wool wastes into bioenergy to achieve sustainable development of the leather industry.

Characterization and Thermal Behavior Study of Biomass from Invasive Acacia mangium Species in Brunei Preceding Thermochemical Conversion

Acacia mangium is a widely grown tree species across the forests in Brunei Darussalam, posing a threat to the existence of some native species in Brunei Darussalam. These species produce large quantities of lignocellulosic biomass from the tree parts comprising the phyllodes, trunk, bark, twigs, pods, and branches. This study examined the thermochemical characteristics and pyrolytic conversion behavior of these tree parts to assess the possibility of valorization to yield bioenergy. Proximate, ultimate, heating value, and Fourier Transform Infrared Spectroscopy (FTIR) analyses were performed to assess the thermochemical characterization, while thermogravimetric analysis was conducted to examine the pyrolytic degradation behavior. Proximate analysis revealed a moisture content, volatile, fixed carbon, and ash contents of 7.88–11.65 wt.%, 69.82–74.85 wt.%, 14.47–18.31 wt.%, and 1.41–2.69 wt.%, respectively. The heating values of the samples were reported in a range of 19.51–21.58 MJ/kg on a dry moisture basis, with a carbon content in the range of 45.50–50.65 wt.%. The FTIR analysis confirmed the heterogeneous nature of the biomass samples with the presence of multiple functional groups. The pyrolytic thermal degradation of the samples occurred in three major stages from the removal of moisture and light extractives, hemicellulose and cellulose decomposition, and lignin decomposition. The bio-oil yield potential from the biomass samples was reported in the range of 40 to 58 wt.%, highlighting the potential of Acacia mangium biomass for the pyrolysis process.

Elucidating the pyrolysis reaction mechanism of Calotropis procera and analysis of pyrolysis products to evaluate its potential for bioenergy and chemicals

The present study was focused on evaluating the bioenergy potential of waste biomass of desert plant Calotropis procera. The biomass was pyrolyzed at four heating rates including 10 °Cmin^-1, 20 °Cmin^-1, 40 °Cmin^-1, and 80 °Cmin^-1. The pyrolysis reaction kinetics and thermodynamics parameters were assessed using isoconversional models namely Kissenger-Akahira-Sunose, Flynn-Wall-Ozawa, and Starink. Major pyrolysis reaction occurred between 200 and 450 °C at the conversion points (α) ranging from 0.2 to 0.6 while their corresponding reaction parameters including activation energy, enthalpy change, Gibb's free energy and pre-exponential factors were ranged from 165 to 207 kJ mol^-1, 169-200 kJ mol^-1, 90-42 kJ mol^-1, and 10¹⁸-10²⁶ s^-1, respectively. The narrow range of pre-exponential factors indicated a uniform pyrolysis, while lower differences between enthalpy change and activation energies indicated that reactions were thermodynamically favorable. The evolved gases were dominated by propanoic acid, 3-hydroxy-, hydrazide, hydrazinecarboxamide and carbohydrazide followed by amines/amides, alcohols, acids, aldehydes/ketones, and esters.

Pyrolysis of corn cob: physico-chemical characterization, thermal decomposition behavior and kinetic analysis

Bioenergy out of lignocellulosic biomass, especially from agricultural crop residues, is making massive inroads in our quest for sustainable environment. In the present study, detailed physico-chemical characterization, thermal degradation characteristics, and kinetics of pyrolysis of corn cob are reported. Thermogravimetric experiments were performed at different heating rates, such as, 10, 20, and 30 °C/min in an inert atmosphere. Thermogravimetric (TG) and derivative thermogravimetric (DTG) curves inferred the thermal behavior characteristics of corn cob. Significant content of cellulose and hemicellulose put together (76.23%) suggested tremendous potential of corn cob to give enhanced yield of bio-oil through pyrolysis. Maximum mass loss of 61.92% for corn cob was observed in the temperature range of 180–360 °C. The kinetic parameters for pyrolysis of corn cob were determined by employing model-free isoconversional methods like, Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa, and Starink. Activation energy from FWO (62.44 kJ/mol) and Starink (61.74 kJ/mol) method for pyrolysis of corn cob was found to be in close proximity. The results revealed prospective bioenergy potential of corn cob as a feedstock for pyrolysis process.

Effect of Montmorillonite clay on pyrolysis of paper mill waste

The thermal degradation of paper mill waste (PMW) has been investigated in presence and absence of Montmorillonite clay in the temperature range of ambient to 1000 °C and at the heating rates of 20 °C/min, 25 °C/min and 30 °C/min. Proximate and ultimate analyses and evaluation of calorific value (HHV) of PMW have been carried out using standard protocols. The thermo-gravimetric analysis (TGA) and differential thermogravimetric (DTG) data obtained under both situations have been used to evaluate the kinetic and thermodynamic parameters and elucidate the reaction mechanism. The clay has also been characterized using TGA/DTG analysis, Fourier Transform Infra-Red (FTIR) spectroscopic analysis and X-ray diffraction (XRD), Energy dispersive spectroscopy (EDS), and scanning electron microscopic (SEM) techniques. The activation energy, pre-exponential factor and thermodynamic parameters have been evaluated using the model-free iso-conversional method of Flynn-Wall-Ozawa (FWO) and Vyazovkin and the distributed activation energy model (DAEM). The Montmorillonite clay has influenced the degradation process appreciably through its catalytic action.

Pyrolysis and combustion kinetics of Sida cordifolia L. using thermogravimetric analysis

Sida cordifolia L. (Sida) is an annual invasive plant that remains underutilized in Niger. The goal of this study was to characterize the thermal decomposition of Sida for its valorisation as a source of energy through thermogravimetric analysis (TGA). TGA was carried out under nitrogen and air atmospheres. Thus, five different heating rates were used as 10, 20, 30, 40, 50 °C min^-1. Kinetic and thermodynamic parameters were determined by isoconversional models of Kissenger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The results showed that the average activation energy (Ea) of Sida calculated by KAS and FWO in pyrolysis was found to be 74.74 and 80.74 kJ mol^-1 respectively, while it was 51.08 and 58.91 kJ mol^-1 in combustion respectively. Kinetic and thermodynamic parameters such as Ea, ΔH, ΔS, and ΔG obtained by KAS and FWO show that Sida is a remarkable feedstock for bioenergy.

Comparison of Combustion and Pyrolysis Behavior of the Peanut Shells in Air and N2: Kinetics, Thermodynamics and Gas Emissions

The influences of four heating rates on the combustion and pyrolysis behavior in the N2 and air atmosphere were investigated by the Fourier transform infrared spectrometry (FTIR) and thermogravimetric (TG) analysis. the distributed activation energy model (DEAM) and Flynn-Wall-Ozawa (FWO) were used to estimate Ea and A, ΔH, ΔG and ΔS. Experimental results showed that the similar thermal behavior emerged, but the temperatures in the air and N2 atmospheres representing the end of the reaction were about 500 °C and 550 °C, respectively. The results of FTIR showed the peak positions were basically the same, but the concentrations of aromatics, aldehydes and ketones produced by pyrolysis in the N2 atmosphere were higher. When the heating rate was 20 K/min, the comprehensive combustion parameters were 56.442 and 6.871 × 10−7%2/(min2• K3) in the air and N2 atmospheres, respectively, indicating that the peanut shells had great potential to become bioenergy.

Uncertainty estimation approach in catalytic fast pyrolysis of rice husk: Thermal degradation, kinetic and thermodynamic parameters study

The aim of this study was to understand the influence of catalyst in thermal degradation behavior of rice husk (RH) in catalytic fast pyrolysis (CFP) process. An iso-conversional Kissinger kinetic model was introduced into this study to understand the activation energy (E_A), pre-exponential value (A), Enthalpy (ΔH), Entropy (ΔS) and Gibb's energy (ΔG) of non-catalytic fast pyrolysis (NCFP) and CFP of RH. The study revealed that the addition of natural zeolite catalyst enhanced the rate of devolatilization and decomposition of RH associated with lowest E_A value (153.10 kJ/mol) compared to other NCFP and CFP using nickel catalyst. Lastly, an uncertainty estimation was applied on the best fit non-linear regression model (MNLR) to identify the explanatory variables. The finding showed that it had the highest probability to obtain 73.8-74.0% mass loss in CFP of rice husk using natural zeolite catalyst.

A kinetic study of roadside grass pyrolysis and digestate from anaerobic mono-digestion

The aim of this research is to evaluate the thermogravimetric behaviour of roadside grass and its digestate obtained from mesophilic anaerobic mono-digestion by quantifying its impacts on biomass composition and properties. Thermogravimetric measurements were conducted in a laboratory furnace under nitrogen flowrate of 100 mL/min in the temperature range from 35 to 800 °C at five different heating rates of 2.5, 5, 10, 15 and 20 °C/min. Friedman and Kissinger-Akahira-Sunose differential and integral isoconversional models were applied to determine the distributions of activation energies and modified pre-exponential factors per reacted mass (degree of conversion). The investigation demonstrated that anaerobic digestion of roadside grass can be used to generate biochar-richer material (with significantly greater yield of final residues after pyrolysis) with less energy required for subsequent pyrolysis in comparison with raw roadside grass.

Bioenergy potential of red macroalgae Gelidium floridanum by pyrolysis: Evaluation of kinetic triplet and thermodynamics parameters

The aim of this study was to investigate the bioenergy potential of red macroalgae GF by evaluating its biofuel physicochemical characteristics, and conducting a kinetic study and thermodynamic analysis of pyrolysis for the first time. The thermal decomposition study was performed at low heating rates (5, 10, 20 and 30 °C min^-1) under N₂ atmosphere. The thermal behavior of GF pyrolysis indicated the presence of three different decomposition stages, which are associated with different components in its structure and consequently influence the kinetic and thermodynamic parameters. The kinetic triplet obtained for GF provided a suitable description of experimental thermal behavior. The thermodynamic parameters demonstrated that GF is as a new promising feedstock for bioenergy and presented a similar potential to well-known bioenergy feedstock.

Catalytic pyrolysis of Chlorella vulgaris: Kinetic and thermodynamic analysis

In the present study, catalytic pyrolysis of Chlorella vulgaris biomass was conducted to analyse the kinetic and thermodynamic performances through thermogravimetric approach. HZSM-5 zeolite, limestone (LS), bifunctional HZSM-5/LS were used as catalysts and the experiments were heated from 50 to 900 °C at heating rates of 10-100 °C/min. Iso-conversional model-free methods such as Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Starink's, and Vyazovkin (V) were employed to evaluate the kinetic parameters meanwhile the thermodynamic parameters were determined by using FWO and KAS methods. The calculated E_A values of non-catalytic and catalytic pyrolysis of HZSM-5 zeolite, LS, and bifunctional HZSM-5/LS were determined to be in the range of 156.16-158.10 kJ/mol, 145.26-147.84 kJ/mol, 138.81-142.06 kJ/mol, and 133.26 kJ/mol respectively. The results have shown that catalytic pyrolysis with the presence of bifunctional HZSM-5/LS resulted to a lower average E_A and ΔH compared to HZSM-5, and LS which indicated less energy requirement in the process.

Pyrolysis kinetics and synergistic effect in co-pyrolysis of Samanea saman seeds and polyethylene terephthalate using thermogravimetric analyser

This work deals with co-pyrolysis of polyethylene terephthalate (PET) with Samanea saman seeds (SS) to understand the kinetics and synergistic effects between two different feedstocks. SS and PET were blended in different ratios (1:1, 3:1 and 5:1) and iso-conversional models such as Kissinger-Akahira-Sunose (KAS), Friedman method (FM), Starink (ST), Ozawa-Flynn-Wall method (OFW), and Coats-Redfern method (CR) were used to calculate the kinetic parameters. Results substantiate assumed hypothesis that blending of SS and PET at 3:1 provided higher synergistic effect and RMS value, which in turn indicated maximum formation of hot volatiles during pyrolysis. Kinetic analysis confirmed that individual SS and PET required higher activation energy while blended SS and PET at 3:1 ratio required lower activation energy to start the reaction. The thermodynamic and kinetic analysis confirmed that biomass had complex reaction kinetics which depends on reaction rate as well as its order.

Combustion behaviors of pileus and stipe parts of Lentinus edodes using thermogravimetric-mass spectrometry and Fourier transform infrared spectroscopy analyses: Thermal conversion, kinetic, thermodynamic, gas emission and optimization analyses

The combustion behaviors of both Lentinula edodes pileus (LEP) and stipe (LES) were characterized in response to four heating rates in the air atmosphere using thermogravimetric (TG)-mass spectrometry and TG-Fourier transform infrared spectroscopy analyses. There were two and three main peaks of the derivative TG curves for LEP and LES, respectively, with their main combustion stage occurring between 130 and 620 °C. Four iso-conversional models were compared to estimate activation energy values of their combustions. The main emission peaks of most gases ranged from 200 to 350 °C and from 500 to 600 °C for LEP and LES. Their comprehensive combustion parameters at 20 K/min (1.53 and 2.40 × 10^-6 %²/(min²·K³) for LEP and LES, respectively) as well as joint optimizations confirmed their great potential for bioenergy generation. The waste stream of LEP and LES could be well disposed through their combustions with a low level of air pollution.

Potential of Jerusalem Artichoke Stem for Cellulose Production

There is a potential opportunity to convert almost any type of biomass into biofuel and bio- nanomaterials, if the appropriate biotechnological and chemical processing methods are used. The preference for this or that bioresource is due to the stability of the raw material base and the prospect of its use. Jerusalem artichoke stem (Helianthus tuberosus L.) (JA) is widely known as a potential non-food raw material for biofuels due to high biomass extraction (36–49 t/ha (tons per hectare)) and limited cultivation requirements. But little attention is given to study the possibility of using the stems to produce various kinds of cellulose. This article presents samples of cellulose that were obtained from the Jerusalem artichoke stem using mechanical and chemical methods. Cellulose yield from the stem was: cortex 51.1%, pith 65.2% with the α-cellulose content 96–98%. Methods of electron microscopy, atomic absorption, IR spectroscopy, X-ray diffraction, BET for nitrogen adsorption, thermogravimetry were used to study the cortex and the pith of the Jerusalem artichoke stem. Analysis of the cellulose samples confirmed the possibility of obtaining high-quality cellulose.

Pyrolysis and Thermogravimetric Study to Elucidate the Bioenergy Potential of Novel Feedstock Produced on Poor Soils While Keeping the Environmental Sustainability Intact

This work focused on exploring the bioenergy potential of biomass produced on salt-affected soils by growing two types of grasses, namely Parthenium hysterophorus (carrot grass) and Pennesetum benthiumo (mott grass), without using fertilizers or pesticides. The whole plant biomass of both grasses was pyrolyzed at three heating rates (10, 30, and 50 °C min−1) in a joined Thermogravimetry–Differential Scanning Calorimetry (TGA–DSC) analyzer under an inert (nitrogen) environment. The pyrolysis of both grasses was shown to occur in a three-stage process, while most of the thermal transformation occurred at the temperature range of 240–400 °C. The pyrolytic behavior was assessed by estimating the kinetic parameters, using the isoconversional models of Kissenger–Akahira–Sunose and Ozawa–Flynn–Wall. The average values of the activation energy of carrot and mott grasses were shown to be 267 kJ mol−1 (R2 ≥ 0.98) and 188 kJ mol−1 (R2 ≥ 0.98), indicating the suitability of both grasses for co-pyrolysis. Whereas, the difference in the values of enthalpy change and the activation energy was shown to be <~5 kJ mol−1 at each fractional point, which indicated that the product formation was being favored. Moreover, the high heating values of carrot grass (18.25 MJ kg−1) and mott grass (18.63 MJ kg−1) have shown a remarkable bioenergy potential and suitability of co-pyrolysis for both grasses. This study will lead to establishing an energy-efficient and cost-effective process for the thermal transformation of biomass to bioenergy.

Thermogravimetric and kinetic analysis to discern synergy during the co-pyrolysis of microalgae and swine manure digestate

BACKGROUND

Co-pyrolysis of wastes with other feedstock can synergistically improve the rate of biomass decomposition and also help to resolve the issues related to limited availability feedstock. In this regards, synergistic interaction between feedstock during co-pyrolysis is an important aspect of research. As the constituents of aquatic and lignocellulosic biomass are different, and the decomposition pattern of aquatic biomass is dissimilar when compared to lignocellulosic biomass, it is important to understand whether these two biomasses interact during co-pyrolysis.

RESULTS

Synergism in the co-pyrolysis of microalgae (MA), swine manure digestate (SWD), and their blends (MA/SWD) (w/w %), 2.5/7.5 (MD-1), 5/5 (MD-2), and 7.5/2.5 (MD-3), was evaluated based on decomposition behavior, gas yields, extent of thermal degradation, and kinetics. Extractives and volatiles in biomass enhanced the reaction kinetics and products yields, as indicated by the reduction in apparent activation energy of the blends, accompanied by an increase in H2, total gas yield, and extent in degradation. Thermogravimetric data, via isoconversional methods, were interpreted to achieve the apparent activation energies for the thermal degradation of the MA, SWD, and their blends. The best fit reaction models were identified using compensation effect and generalized master plots methods. Semi-quantitative method was used to quantify the evolved gas species. H2, CO, and CO2 were noted to be the dominant gases, implying that tar cracking and reforming reactions were predominant.

CONCLUSIONS

Overall, synergy was noticed with respect to the pyrolysis of SWD biomass to gas products in the presence of MA biomass, whereas synergy was witnessed up to 50 w/w % MA in view of kinetic parameters as evaluation criteria.

Thermal degradation kinetics of sugarcane leaves (Saccharum officinarum L) using thermo-gravimetric and differential scanning calorimetric studies

Pyrolysis of sugarcane (Saccharum officinarum L) leaves (SCL) has been investigated using DTA/TGA and DSC techniques. Proximate and ultimate analyses and calorific value measurement have been carried out using standard protocols. The sugar cane leaves contain 44% cellulose, 22% hemicellulose and 17% lignin. The pyrolysis have been carried out at six heating rates varying from 5 to 40 °C/min. Analysis of the pyrolysis results has been carried using iso-conversional model free methods as well as multiple linear regression method. For the fractional conversion range of 0.05-0.95, the average apparent activation energy values evaluated from iso-conversional methods have ranged from 214.9 to 239.6 kJ/mol where as in the case of multiple linear regression analysis it has ranged from 25.06 to 57.23 kJ/mol. The multi-step reaction mechanism has been investigated using the Criado method. The results of this study are useful for the design of large scale biomass thermal conversion process.

Kinetic Analysis of Digestate Slow Pyrolysis with the Application of the Master-Plots Method and Independent Parallel Reactions Scheme

The solid fraction obtained by mechanical separation of digestate from anaerobic digestion plants is an attractive feedstock for the pyrolysis process. Especially in the case of digestate obtained from biogas plants fed with energy crops, this can be considered a lignin rich residue. The aim of this study is to investigate the pyrolytic kinetic characteristics of solid digestate. The Starink model-free method has been used for the kinetic analysis of the pyrolysis process. The average Activation Energy value is about 204.1 kJ/mol, with a standard deviation of 25 kJ/mol, which corresponds to the 12% of the average value. The activation energy decreased along with the conversion degree. The variation range of the activation energy is about 99 kJ/mol, this means that the average value cannot be used to statistically represent the whole reaction. The Master-plots method was used for the determination of the kinetic model, obtaining that n-order was the most probable one. On the other hand, the process cannot be modeled with a single-step reaction. For this reason it has been used an independent parallel reactions scheme to model the complete process.

Acacia Holosericea: An Invasive Species for Bio-char, Bio-oil, and Biogas Production

To evaluate the possibilities for biofuel and bioenergy production Acacia Holosericea, which is an invasive plant available in Brunei Darussalam, was investigated. Proximate analysis of Acacia Holosericea shows that the moisture content, volatile matters, fixed carbon, and ash contents were 9.56%, 65.12%, 21.21%, and 3.91%, respectively. Ultimate analysis shows carbon, hydrogen, and nitrogen as 44.03%, 5.67%, and 0.25%, respectively. The thermogravimetric analysis (TGA) results have shown that maximum weight loss occurred for this biomass at 357 °C for pyrolysis and 287 °C for combustion conditions. Low moisture content (<10%), high hydrogen content, and higher heating value (about 18.13 MJ/kg) makes this species a potential biomass. The production of bio-char, bio-oil, and biogas from Acacia Holosericea was found 34.45%, 32.56%, 33.09% for 500 °C with a heating rate 5 °C/min and 25.81%, 37.61%, 36.58% with a heating rate 10 °C/min, respectively, in this research. From Fourier transform infrared (FTIR) spectroscopy it was shown that a strong C–H, C–O, and C=C bond exists in the bio-char of the sample.

Waste to energy potential in middle income countries of MENA region based on multi-scenario analysis for Kafr El-Sheikh Governorate, Egypt

The environmental risks of traditional waste disposal methods, together with the resource and energy value of waste, had established the foundation for waste-to-energy (WTE) technologies. WTE is rarely implemented in developing countries, mostly due to the lack of knowledge and experience under their specific local conditions. The present research investigates the feasibility of WTE strategies in middle income developing countries of the Middle East and North Africa (MENA) region. Multiple waste management scenarios, involving incineration and anaerobic digestion, were evaluated based on energy, economic, and environmental parameters. A multi-criteria assessment was conducted for the Governorate of Kafr El-Sheikh (Egypt); a 3.2-million rural-urban agro-industrial population with socio-economic and demographic features similar to those of the selected MENA countries. The actual waste generation rates and characteristics of Kafr El-Sheikh were measured through a comprehensive field study. It was found that anaerobic digestion with recycling is the optimum strategy for Kafr El-Sheikh, with annual energy potential of 1170-kWh per ton of waste and net economic savings of 6.5 million USD. This optimum waste management scenario was extended to the selected MENA countries to investigate potential benefits of shifting to WTE-based waste management strategies. The total annual energy production was estimated to be 103,000-GWh, which translates to 17% of the total energy consumption. Moreover, greenhouse gas emissions were reduced by around 98,500-Gg CO₂ annually, which represents around 6.5% of the total annual CO₂ footprint generated by the selected countries. Furthermore, the overall economic benefits ranged between -12 and 200 million USD for the selected countries.

Kinetic and Thermodynamic Analysis of Thermal Decomposition of Deodar (Cedrus Deodara) Saw Dust and Rice Husk as Potential Feedstock for Pyrolysis

A comparative study on thermal analysis of two waste biomass materials of Kashmir namely deodar (Cedrus deodara) saw dust (DSD) and rice husk (RH), was carried out at different heating rates of 10, 25, 50 and 100 °C min−1 in air and nitrogen atmospheres. The onset, peak and burnout temperatures and rates of decomposition of components were determined and compared to understand the combustion and pyrolysis kinetics of selected biomass materials using iso-conversional Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) models. The kinetic parameters calculated were in turn used to calculate the changes in thermodynamic parameters, the enthalpy (ΔH), the Gibbs free energy (ΔG) and the entropy (ΔS). The physicochemical characterisation was carried out by elemental analyser and FTIR spectroscopy. The average activation energy values for RH were found to be 107.6 and 101.2 kJ mol−1 in air atmosphere and 85.5 and 92.1 kJ mol−1 in nitrogen atmosphere based on KAS and OFW models, respectively. The activation energy for DSD on the other hand was found to be 89.9 and 95.3 kJ mol−1 in air, 179.2 and 180.6 kJ mol−1 under nitrogen atmosphere based on KAS and OFW models, respectively. The heating values of the two biomasses (~ 10 to16 MJ kg−1) and Gibbs free energy values (between 165 to 176 kJ mol−1) indicate that the selected biomass can not only prove to be potential feedstock for pyrolysis but also can become a useful source of energy and chemicals.

Kinetics and thermodynamic analysis in one-pot pyrolysis of rice hull using renewable calcium oxide based catalysts

Thermodynamic and kinetic parameters of catalytic pyrolysis of rice hull (RH) pyrolysis using two different types of renewable catalysts namely natural limestone (LS) and eggshells (ES) using thermogravimetric analysis (TG) approach at different heating rates of 10-100 K min^-1 in temperature range of 323-1173 K are investigated. Catalytic pyrolysis mechanism of both catalysts had shown significant effect on the degradation of RH. Model free kinetic of iso-conversional method (Flynn-Wall-Ozawa) and multi-step reaction model (Distributed Activation Energy Model) were employed into present study. The average activation energy was found in the range of 175.4-177.7 kJ mol^-1 (RH), 123.3-132.5 kJ mol^-1 (RH-LS), and 96.1-100.4 kJ mol^-1 (RH-ES) respectively. The syngas composition had increased from 60.05 wt% to 63.1 wt% (RH-LS) and 63.4 wt% (RH-ES). However, the CO₂ content had decreased from 24.1 wt% (RH) to 20.8 wt% (RH-LS) and 19.9 wt% (RH-ES).

Pyrolysis of Musa balbisiana flower petal using thermogravimetric studies

In the present study, thermogravimetric analysis of Musa balbisiana flower petal was carried out to study the degradation behaviour and the kinetics in the pyrolytic reaction. The pyrolysis was carried out in the temperature range of 35-900 °C at different heating rates of 5, 10 and 20 °C/min. The kinetics was investigated using different models like Kissinger-Akahira-Sunose (KAS), Flynn-Ozawa-Wall (FOW), Friedman and Broido's plot. The average E_a values determined by KAS, FOW and Friedman methods were 137.94, 136.76 and 133.36 kJ/mol respectively. Coats-Redfern method was utilized to determine the pre-exponential factors and the reaction order of the pyrolysis. For the conversion rates 0.1 and 0.2, both Valensi and Ginstling diffusion models were found out to be appropriate for the solid state reaction mechanism. The HHV of Musa balbisiana flower petal was 16.35 MJ/kg, suggested as a potential bio-feedstock energy source from agro-waste.

Thermogravimetric kinetic modelling of in-situ catalytic pyrolytic conversion of rice husk to bioenergy using rice hull ash catalyst

The thermal degradation behaviour and kinetic parameter of non-catalytic and catalytic pyrolysis of rice husk (RH) using rice hull ash (RHA) as catalyst were investigated using thermogravimetric analysis at four different heating rates of 10, 20, 50 and 100 K/min. Four different iso conversional kinetic models such as Kissinger, Friedman, Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) were applied in this study to calculate the activation energy (E_A) and pre-exponential value (A) of the system. The E_A of non-catalytic and catalytic pyrolysis was found to be in the range of 152-190 kJ/mol and 146-153 kJ/mol, respectively. The results showed that the catalytic pyrolysis of RH had resulted in a lower E_A as compared to non-catalytic pyrolysis of RH and other biomass in literature. Furthermore, the high Gibb's free energy obtained in RH implied that it has the potential to serve as a source of bioenergy production.

Pyrolysis and kinetic analyses of a perennial grass (Saccharum ravannae L.) from north-east India: Optimization through response surface methodology and product characterization

The objective of the present investigation was to optimize the pyrolysis condition of an abundantly available and low cost perennial grass of north-east India Saccharum ravannae L. (S. ravannae) using response surface methodology based on central composite design. Kinetic study of the biomass was conducted at four different heating rates of 10, 20, 40 and 60 °C min^-1 and results were interpreted by Friedman, Kissinger Akira Sunnose and Flynn-Wall-Ozawa methods. Average activation energy 151.45 kJ mol^-1 was used for evaluation of reaction mechanism following Criado master plot. Maximum bio-oil yield of 38.1 wt% was obtained at pyrolysis temperature of 550 °C, heating rate of 20 °C min^-1 and nitrogen flow rate of 226 mL min^-1. Study on bio-oil quality revealed higher content of hydrocarbon, antioxidant property, total phenolic content and metal chelating capacity. These opened up probable applications of S. ravannae bio-oil in different fields including fuel, food industry and biomedical domain.

Bioenergy potential of Wolffia arrhiza appraised through pyrolysis, kinetics, thermodynamics parameters and TG-FTIR-MS study of the evolved gases

This study evaluated the bioenergy potential of Wolffia arrhiza via pyrolysis. The biomass was collected from the pond receiving city wastewater. Oven dried powdered biomass was exposed to thermal degradation at three heating rates (10, 30 and 50° C min^-1) using Thermogravimetry-Differential Scanning Calorimetry analyzer in an inert environment. Data obtained were subjected to the isoconversional models of Kissenger-Akahira-Sunose (KSA) and Flynn-Wall-Ozawa (FWO) to elucidate the reaction chemistry. Kinetic parameters including, E_a (136-172 kJmol^-1) and Gibb's free energy (171 kJmol^-1) showed the remarkable bioenergy potential of the biomass. The average enthalpies indicated that the product formation is favored during pyrolysis. Advanced coupled TG-FTIR-MS analyses showed the evolved gases to contain the compounds containing CO functional groups (aldehydes, ketones), aromatic and aliphatic hydrocarbons as major pyrolytic products. This low-cost abundant biomass may be used to produce energy and chemicals in a cost-efficient and environmentally friendly way.

Pyrolysis kinetics and thermodynamic parameters of castor (Ricinus communis) residue using thermogravimetric analysis

Castor plant is a fast-growing, perennial shrub from Euphorbiaceae family. More than 50% of the residue is generated from its stems and leaves. The main aim of this work is to study the pyrolytic characteristics, kinetics and thermodynamic properties of castor residue. The TGA experiments were carried out from room temperature to 900 °C under an inert atmosphere at different heating rates of 5, 10, 15, 20, 30 and 40 °C/min. The kinetic analysis was carried using different models namely Kissinger, Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS). The average E_ɑ calculated by FWO and KAS methods were 167.10 and 165.86 kJ/mole respectively. Gibbs free energy varied from 150.62-154.33 to 150.59-154.65 kJ/mol for FWO and KAS respectively. The HHV of castor residue was 14.43 MJ/kg, considered as potential feedstock for bio-energy production. Kinetic and thermodynamic results will be useful input for the design of pyrolytic process using castor residue as feedstock.