•Pyrolysis and Copyrolysis of various medical waste were characterized.•Blending of various MW components reduced the activation energy of process.•SY5MG5, SY7CS3, and MG7CS3 pyrolysis followed R3, ...D2, and D1 reaction models.•Copyrolysis of SY, MG, and CS brought significant changes to the products distribution of MW.
The COVID-19 pandemic has caused a substantial rise in the amount of medical waste, posing additional hurdles in waste management. Disposing of this waste properly is essential to curb transmission of the diseases. The pyrolysis reaction kinetics, synergistic interactions, and pyrolysis gas release behavior of typical constituents of medical waste (MW): syringe (SY), medical gloves (MG), cotton swab sticks (CS), and their blends were examined by utilizing advanced analytical techniques including TG, TG-FTIR, TG-MS, and kinetic models (Friedman, KAS). The experiments were conducted using a wide range of heating rates, namely 10, 20, 30, and 40 °C⋅min−1. The pyrolysis reactions were mainly endothermic, with main stages ranging from 352.0–480.0 °C, from 381.0–511.0 °C, from 200.0–404.5 °C, 336.6–509.9 °C, 375.4–477.6 °C, 384.0–500.9 °C, for SY, MG, CS, SY5MG5, SY7CS3, and MG7CS3, respectively. According to the KAS method, the average activation energies for the mono-pyrolysis of SY, MG, and CS were determined as 240.8, 226.1, and 147.5 kJ⋅mol−1 respectively. Interestingly, during the pyrolysis of blends such as SY5MG5, SY7CS3, and MG7CS3, the activation energies decreased to 177.2, 159.9, and 149.1 kJ⋅mol−1 respectively. Notably, the experimental activation energy values (Eexp) obtained during the co-pyrolysis were significantly lower than the calculated values (Ecal), revealing an apparent synergistic effect during the pyrolysis of various MW blends. The pyrolysis process of MW blends resulted in the release of significant volatile components, including CH4, CO, C3H6, CO2, C2H5OH, C4H8, C5H8, C6H6, C6H14, C7H8, and C8H10. The specific composition of these volatile components varied depending on the types of waste present in the blends.
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•This study investigates microplastic thermodegradation behaviors.•Less than 20% of HDPE in silica can retain microplastic pyrolysis characteristics.•The developed model predicts ...pyrolysis kinetics with fit quality higher than 95%.•HDPE microplastic pyrolysis activation energy is between 273.89 and 292.90 kJ‧mol−1.•Microplastics have a lower activation energy than plastics.
The research of pyrolytic thermodegradation of plastic wastes has received much attention. However, detailed combustion behavior and pyrolysis kinetics of microplastics are still absent in the current research. Understanding the characteristics and kinetics of microplastic pyrolysis is vital for designing and optimizing operational conditions. Adding silica to high-density polyethylene (HDPE) microplastics can effectively avoid the agglomeration of microplastics during pyrolysis, thereby better elucidating their thermodegradation. In the experiment, HDPE microplastics are mixed with SiO2 at different weight ratios (10 %, 20 %, 50 %, 70 %, and 100 %) to observe the dispersion effect on the microplastic thermodegradation. The results suggest that less than 20 % of PE in the mixture can retain microplastic pyrolysis characteristics. In combustion analysis, 10 % PE undergoes a faster thermo-oxidation reaction than pure HDPE. This study applies the independent parallel reaction (IPR) model and particle swarm optimization (PSO) algorithm to investigate microplastic pyrolysis kinetics. The pyrolysis activation energy is between 273.89 and 292.90 kJ‧mol−1, with fit quality high than 95 %, and rises with decreasing dispersion degree and increasing heating rate. This indicates that microplastic thermodegradation has low activation energy and is affected by heat transfer rate. The Py-GC/MS analysis indicates that up to 83.6 % of alkene and 52.3 % of products comprise high carbon numbers (17-Pentatriacontene and 1-Octatriacontene), respectively, suggesting the suppression of the secondary reaction of microplastics in the pyrolysis reaction. The calculated kinetic parameters are beneficial for understanding microplastic thermodegradation characteristics and can provide useful information for reactor design in industrial pyrolyzers or gasifiers.
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•Pyrolysis of peanut shells were studied using non-isothermal TGA.•Thermal degradation occurred in three stages, one belonging to devolatilization.•CR and combined isoconver.-Criado ...methods yielded Ea values in 169–287 kJ/mol range.•Kinetic triplet computed by combined method described experimental values better.•ΔG, ΔH and ΔS were computed in 173–187 , 164–259 kJ/mol and −37–141 J/mol.K ranges.
Kinetic triplet, thermal degradation behaviour and thermodynamic properties of peanut shells were determined on the basis of non-isothermal thermogravimetric experiments conducted at three different heating rates under N2 atmosphere. A single differential peak was observed for the devolatilization stage. The kinetic triplet of devolatilization stage was determined using Coats-Redfern and a combined method consisting the utilization of isoconversional and Criado methods. Kinetic validation revealed that the kinetic triplet determined using the combined method described the experimental values more precisely. The reaction mechanism ascertained by the combined method was D5-D3 combination. The Ea value was strong function of conversion, and computed using isoconversional methods (Boswell, Flynn-Wall-Ozawa, Starink, Tang) between 169 and 268 kJ/mol. Entalphy, entrophy and Gibbs energy changes were computed in 164–259 kJ/mol, −37–141 J/(mol.K) and 173–187 kJ/mol ranges, respectively. The comprehensive pyrolysis index values were also calculated, and shown to increase with increasing heating rate.
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•Co-pyrolysis of TPU and PAW greatly reduces the activation energy of decomposition.•PAW makes the degradation of TPU move to the low temperature range.•Co-pyrolysis increases the ...yield of char and pyrolysis oil.•PAW promotes cyclization of polyester polyols in TPU.
Co-pyrolysis of plastics and biomass offers an effective approach for waste disposal. In this study, the synergistic effects during the co-pyrolysis of thermoplastic polyurethane (TPU) and paulownia wood (PAW) were investigated in terms of pyrolysis kinetics and product properties using tube furnace, TG-FTIR and GC/MS. The results revealed that co-pyrolysis promoted the material pyrolysis and facilitated the pyrolysis process taking place at low temperatures. By adopting the Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO) and Starink methods, the average activation energies of pure TPU, PAW, and TPU/PAW blends with a 1:1 mass ratio were determined to be 139 kJ/mol, 288 kJ/mol, and 126 kJ/mol. It is indicated that co-pyrolysis significantly reduced the activation energies and enhanced reactivity. Tube furnace experiments demonstrated that TPU/PAW blend with 1:1 mass ratio exhibited the highest synergism. The TPU melt acted as a physical barrier, leading to increased production of char and oil, and lower production of volatile gas. In the pyrolysis oil, the synergistic effect effectively hindered a formation of alcohol phenols. In the meanwhile, the synergistic effect also boosted generations of aliphatic compounds and ketones, increasing the heat value use of pyrolysis oil. Furthermore, a reaction pathway and mechanism of co-pyrolysis of TPU and PAW was proposed. The active molecules and free radicals generated by the pyrolysis of PAW promote the hydrogen transfer cyclization of polyester polyols decomposed by TPU, and the hydrogen free radicals released by TPU promote the depolymerization and activation of PAW. Moreover, the catalytic effect of alkali metal elements in PAW promotes the synergistic effect. The results of the study provide a basis for the co-pyrolysis of waste plastics and biomass to achieve high value utilization of waste.
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•Global kinetic parameters were determined using isoconventional, generalized master plot, model based, and Frazer-Suzuki deconvolution methods.•Lumped kinetic model applied to ...Organosolv lignin pyrolysis, and calculated kinetic parameters showed lignin to liquid was predominant pathway.•Effect of AAEMs on kinetic, and product characterization on Organosolv lignin pyrolysis analyzed systematically.•2.0 wt% Mg loading was the strongest effect on Organosolv lignin pyrolysis.
The pyrolysis characteristics and kinetics of Organosolv lignin from pine trees were investigated using isoconventional, generalized master plot, model-based, and Frazer-Suzuki deconvolution methods. With these approaches, the activation energies of Organosolv lignin pyrolysis were determined to be in the range of 70.11–385.58 kJ/mol. In addition, the activation energies of 3 pseudo-reactions were calculated to be 15.71, 204.49, and 32.76 kJ/mol, respectively, by the Frazer-Suzuki deconvolution method. The experimental data of Organosolv lignin pyrolysis were best fitted with the 4th power-law model (P4) with an absolute error of 3.24 %. Entropy (ΔSo), Gibbs free energy (ΔGo), and enthalpy (ΔHo) were also calculated to understand the reaction pathways from a thermodynamic point of view. Based on the pyrolysis mechanisms proposed in this study, the reaction rate constants of different steps were determined. The primary reaction route was identified to be the pyrolysis of Organosolv lignin to liquid products such as bio-oils. Among the alkali and alkaline earth metals (AAEMs) tested, 2.0 wt% Mg showed the most effective on Organosolv lignin pyrolysis, decreasing the mean activation energy (Ea) from 181.67 to 156.55 kJ/mol in the range 0 ≤ X ≤ 0.85. The compositions of gaseous and liquid products formed by pyrolysis were analyzed using a micro-tubing reactor. CO, CO2, and CH4 were observed as the main gaseous products, while Organosolv lignin was primarily decomposed into phenol and guaiacol derivatives. The Organosolv lignin was also depolymerized into lower-molecular-weight (LMW) components during the pyrolysis process.
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•Pyrolysis kinetics via iso-conversional and master plot are examined for analysis of kinetic parameters of pseudo components.•A combination of Asym2sig deconvolution and combined ...kinetics is applied.•Activation energy of pseudo cellulose was lower than the hemicellulose and lignin.•The kinetic parameters from combined kinetic agreed well with the experimental data.
This study examined the non-isothermal kinetics of the slow pyrolysis of Imperata Cylindrica (IC). Pyrolysis conditions were developed under the pure N2 flow and non-isothermal conditions at the heating rates of 2.5, 5, 10, and 17.5 K/min and over the temperature range of 303–1173 K. The IC pyrolysis profiles could be identified into three parallel reactions, each of which corresponded to pseudo-hemicelluloses (P-Hem), pseudo-cellulose (P-Cell), and pseudo-lignin (P-Lig) decomposition. A systematic kinetic study of the pyrolysis of IC via thermogravimetric analysis (TGA) deconvolution using Asymmetric Double Sigmoidal (Asym2sig), Friedman differential iso-conversional and combined kinetics of biomass pseudo-components was carried out. The kinetics parameters of pseudo components fitted well with the pyrolysis experimental data for all the heating rates. Differential master-plots showed that the reaction mechanisms for pseudo hemicellulose (P-Hem) and pseudo cellulose (P-Cell) were diffusional and order based, and high order based (3rd order) for the pseudo lignin (P-Lig). Mechanism of P-Hem, P-Cell and P-Lig could be further reconstructed to Sestak and Berggren model of fα=α-0.98751-α1.325-ln(1-α)0.0209,fα=α0.33131-α1.4731-ln(1-α)0.0215 and fα=α-2.95511-α2.7642-ln(1-α)0.0074, respectively. The combined kinetic reported the activation energies of pseudo-components were as 194.709 kJ/mol, 179.968 kJ/mol and 219.226 kJ/mol for P-Hem, P-Cell and P-Lig, respectively.
Oily sludge (OS) has attracted special interest because of its hazardous nature and high potential as an energy resource. This study investigated the oil recovery from OS by thermal cracking and ...catalytic pyrolysis. The oil yield increased when the temperature exceeded 450 °C and reached a maximum (76.84 wt%) at 750 °C. Catalysts significantly improved the quality of oil produced during catalytic pyrolysis. Aromatic hydrocarbons were dominant (10.01–52.69%) in pyrolysis oil (PO) from OS catalytic pyrolysis, and the catalysts significantly reduced the presence of oxygen heterocycles. In addition, KOH and CaO reduced the ID (D-band peak intensity)/IG (G-band peak intensity) of OS char (OC) and increased the degree of graphitization. Owing to its higher iodine adsorption value and methylene blue (MB) adsorption value, OC exhibits potential as an adsorbent. The environmental assessment and potential applications of OC, along with possible reaction mechanisms and kinetic characteristics, are also discussed.
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The techniques of co-utilization of biomass and coal are of wide concern due to the benefit of CO2 reduction. Although the co-pyrolysis process was extensively studied over the past few years, the ...effects of different rank coals on synergetic effect and volatile interaction mechanisms remained unclear. In this work, co-pyrolysis of rice husk (RH) and three different rank coals was comprehensively investigated to reveal the volatile release, gas product formation, changes of pore structure, pyrolysis kinetics and the synergetic effect. Co-pyrolysis of RH and coals always showed positive synergetic effect and could release more volatile species compared with individual pyrolysis. The extent of the synergetic effect in terms of volatile release and gas production was profoundly affected by different rank coals and increased remarkably as the blending changed from lignite to bituminous coal. A novel step-wise volatile release and interaction mechanism was proposed to explain the existence of synergetic effect and changes of pore structure in chars on the basis of the research results. In addition, kinetic studies showed that co-pyrolysis reactions of RH and coals were essentially controlled by chemical reaction mechanism from first to third order.
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•Co-pyrolysis of rice husk and coals was studied via TG-FTIR and tubular reactor.•The synergetic effect was observed and profoundly affected by different rank coals.•Co-pyrolysis of rice husk and coals followed reaction mechanism from first to third order.•A novel mechanism of step-wise volatile release and interaction was proposed.
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.
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•1st study concerning the pyrolysis kinetics of putranjiva and amaltas non-edible oilseeds.•Both model-free and model-fitting methods were used.•Non-edible oilseeds pyrolysis model is discriminated by the master-plot method.•Non-edible oilseeds pyrolysis were well represented by An and Rn mechanism.
