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Kinetic triplets and thermodynamic parameters of the pyrolysis of Putranjiva roxburghii (PR) and Cassia fistula (CF) non-edible oilseeds were studied using thermogravimetric analyzer. The kinetic parameters were assessed using both model-free [Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (OFW), Starink (STR), Li and Tang (LTA), Friedman (FRM), Vyazovkin (VYZ), Kissinger (KN), Avrami (AVM), and Master plot (MP)] and model-fitting [Coats-Redfern (CR)] methods at four different heating rates (10, 25, 40, and 55 °C/min) somewhere in the range of 10% and 80% conversions. The reaction mechanisms were found to be in good agreement with the experimental thermal analysis data. Thermodynamic parameters (ΔG, ΔH, and ΔS) are also determined by model-free isoconversional method. The kinetic and thermodynamic parameters recommended the appropriateness of PR and CF non-edible oilseeds for pyrolysis process.

It is very requisite to demonstrate the characterization of lignocellulosic biomass for converting into renewable fuels and valuable chemicals. In this work, the physicochemical and thermochemical characterization of some non-edible oil seeds such as Putranjiva (Putranjiva roxburghii), Amaltas (Cassia fistula), and Siris (Albizia lebbeck) were carried out by extractive analysis via Soxhlet solvent extraction, compositional analysis, proximate analysis, elemental (CHNSO) analysis, heating value, bulk density, crystallinity index via XRD, functional groups via FTIR, mineral content via EDX, slagging and fouling indices via XRF, and degradation profile via TGA. It was noticed that all seeds consist of a maximum percentage of extractives such as Putranjiva 50.55%, Amaltas 18.22%, and Siris 22.8%. The results showed that these seeds have a higher cellulose content compared with hemicellulose and lignin. Further, it was confirmed from the Van Krevelen diagram, CHO index, as well as devolatilization index. Also, from the kinetic analysis, the activation energy (Ea) obtained of these seeds was in the order of PR > AL > CF. The chemical features and thermal degradation behaviour reaffirmed that these non-edible oilseeds have good energy potential for reproducibility of biofuel and green chemicals production.

The pyrolysis kinetics of Argemone mexicana seed, an extensively found naturalized weed in agricultural fields, was studied via thermogravimetric analysis under N2 atmosphere at heating rates of 10 °C/min, 20 °C/min and 30 °C/min. Five kinetic approaches, viz. Kissinger–Akahira–Sunose (KAS), Ozawa-Flynn-Wall (OFW), Friedman (FRM), Starink (STR) and Vyazovkin (VYZ) methods, and a model-fitting approach (Kennedy and Clarke method) were employed on thermogravimetric information of Argemone mexicana seed to evaluate the kinetic parameters such as activation energy, pre-exponential factor and thermodynamic parameters. Activation energies procured from KAS, OFW, FRM, STR and VYZ methods were 174, 185.08, 212.86, 175.11 and 174.36 kJ/mol, respectively. Furthermore, an appropriate reaction mechanism was identified by the master plot method. The average pre-exponential factor obtained through the Kissinger approach was 8.23E + 22, 1.68E + 22 and 8.05E + 21 s−1 at three different heating rates. The average values of thermodynamic parameters (ΔH, ΔG and ΔS) were 169.28 kJ/mol, 212.64 kJ/mol and − 70.95 J/mol at a lower heating rate of 10 °C/min. Experimental results reveal that kinetic parameters from the five model-free isoconversional methods are in better compliance with similar biomass materials, and Argemone mexicana seed can prove to be a promising alternating source for biofuel production.

Thermogravimetric analysis of two invasive weeds Prosopis juliflora (PJ) and Lantana camara (LC) are carried out by pyrolysis under dynamic conditions (20 to 900 °C) at different heating rates 5, 10, 20 and 40 °C/min. Gross calorific values of PJ and LC are estimated to 18.2 and 18.92 MJ/kg respectively. Activation energy obtained by FRM, M-FRM, KAS, OFW, STR, NL-INT, NL-DIF methods are 157.56, 151.24, 140.86, 143.39, 140.74, 141.19, 157.59 kJ/mol for PJ and 169.98, 167.67, 149.39, 151.51, 149.23, 149.70, 169.98 kJ/mol for LC respectively. Kinetic compensation effects were well fitted with the experimental data, which provided the value of the pre-exponential factor. To identify the appropriate reaction mechanism, the Popescu and Master-plot methods are employed. Thermodynamic parameters (ΔG, ΔH, and ΔS) are also determined by NL-INT, NL-DIF, and M-FRM methods. Results of kinetic and thermodynamic parameters confirm the suitability of PJ and LC invasive weeds as potential biomasses for pyrolysis process.

Pyrolysis kinetics and thermodynamic parameters of two non-edible seeds, Pongamia pinnata (PP) and Sapindus emarginatus (SE), and their blend in the ratio of 1:1 (PS) were studied using the thermogravimetric analyzer. Kinetic triplets were determined using both model-free [Starink (STR), Friedman (FRM), Iterative Kissinger-Akahira-Sunose (IT-KAS), Iterative Ozawa-Flynn-Wall (IT-OFW), Vyazovkin (VYZ), and Master plot (MP)] and model fitting Coats-Redfern (CR) methods at three different heating rates 10, 30 and 50 °C/min. Activation energies were 192.66, 179.44, and 163.25 kJ/mol for PP, SE, and PS, respectively. It was found that the blend of the two-biomass (PS) showed promising results with lower activation energy compared to the individual biomass. Thermodynamic parameters (ΔG, ΔS, and ΔH) were obtained using the model-free isoconversional method. The three hidden layers of complex neuron topology are well fitted to the experimental DTG curves by artificial neural network (ANN). The study confirmed that the heating rate had a significant impact on the kinetics and thermodynamic parameters. The reaction mechanism was also in consonance with the experimental data. The study suggests that the PP and SE seeds can be an appropriate feed for pyrolysis, and their blend (PS) can be a viable alternative in optimizing the entire process.

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.