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This work provides insight into possibilities of maximum utilization of C3-C4 energy crops for thermo-chemical conversion (slow pyrolysis) into high value biochemicals, platform chemicals, drop-in fuels and combustible gases, using coupled kinetic and thermodynamic analyses. In order to examine the kinetics of decomposition of lignocellulosic components, model-free and model-based methods faded from thermal analysis data were used. Thermodynamic compensation was used for explicatory of entropy controlled process, where conformational changes and chemical exchange directly affect the type and distribution of obtained pyrolytic products. It was shown that external variable (i.e. the heating rate/temperature) does not change either an entire reaction mechanism (mechanistic nature of MG and AD pyrolyses) or transition state, but it changes activation enthalpy and activation entropy which lead to differences in terms of heat energy consumption, pyrolysis favorability and thus rates of generation of activated complex among feedstocks. To investigate the interplay of catalysts (present in feedstocks as minerals) and reactants, selective energy transfer (SET) model was applied. The model showed an activity of catalyst with different outputs towards two reactants, lignin part of the structure in MG and 1,8-cineole in AD. It was shown that AD is more convenient for thermal conversion than MG, regarding to lower transformation energy requirement, higher reactivity, as well as much faster accumulation of products. © 2023 Elsevier B.V.

The actual paper analyses the performance of different energy crop biomasses, Miscanthus x giganteus Greef et Deu (EC-1) and Arundo donax L. (EC-2) stems, during slow pyrolysis process monitored by simultaneous TG-DTG-MS techniques, through chemical exergy analysis. In addition to considering the physical and chemical characteristics of given feedstocks for their efficient thermo-chemical conversion into pyrolytic gas, in this study, a theoretical simulation for their implementation use in the gasification process was also performed. The performed thermodynamic study with detailed exergy analysis showed that the large contribution of exergy in syngas components such as CO and H2 originates primarily from cellulose pyrolysis of EC-1, while large exergy contribution in syngas component as CH4 originates from lignin pyrolysis of EC-2. It was founded that the exergy efficiency of syngas for EC-1 equals 19.04%, which is lower than the exergy efficiency of syngas for EC-2 (20.46%), as a result of higher ash content in EC-1. Also, it was reported that higher carbon (C) and hydrogen (H) contents present in the EC-2 sample generate higher gaseous energy and exergy values, i.e. the increment of exergy efficiency of syngas, by both approaches (pyrolysis and gasification exergy analysis), but results in a lower biomass chemical exergy (18.28 MJ kg−1). The methodology applied to the gasification process was shown a higher exergy efficiency for EC-2 (∼36 – 42%) than for EC-1 (∼33 – 39%), dependant on the equivalence ratio (ER).

Sustainable development and mitigation of the climate changes are one of the main challenges of the circular economy, while the use of food industry residues could make an important contribution in tackling these challenges. In order to improve energy efficiency aspects of the industry residue treatment, generally, the drying process as the first step of the entire processing chain should be further analyzed. Regarding this, a comprehensive kinetic study was performed to provide the detailed mechanism of moisture removal from base raw material. Industrial residues from apple juice production were used for isothermal thermogravimetric analysis in the air atmosphere at different temperatures. Based on experimental data, different kinetic models were applied to determine kinetic parameters and dominant conversion functions. The dependence of the activation energy evaluated by Friedman’s isoconversional method on the conversion degree shows that the drying process is complex one. The mechanism of drying process and corresponding kinetic parameters were determined by multivariate nonlinear regression program (model-based analysis) and checked by modulated isothermal prediction (for quasi-isothermal conditions) and the isothermal prediction (for different isothermal conditions) tests. It was pointed out that temperature-dependent reaction step controlling overall mechanism represents releasing of CO2 which can suppress autocatalytic action of the ethylene, influencing the flavor and texture changes of the apple tissue. Obtained results can be used for prediction of the life-time of studied material, corresponding to selected temperatures and different conversion levels.

With the increased popularity of using wood stoves for household heating in recent years, numerous experimental research projects have been launched with the goal of generating cleaner and more efficient stove designs. This work is focused on mathematical modeling of combustion process in low-power residential heating appliance (small-scale stove) fuelled by different wood pellets (WP1-Beech (hardwood) and WP2-Pine (softwood)). Kinetic model scheme that encompasses determination of Arrhenius parameters was proposed for applied Finite rate/Eddy Dissipation approach. Types of wood pellets have been combusted on the experimental stand which is equipped with a set of temperature sensors and exhaust analyzer. A comparison of results obtained from combustion in the heating unit has been performed to find relations between established kinetics of devolatilization for various wood pellets and to determine exhaust composition, arising from oxidation reactions. Numerical modeling using computational fluid dynamics (CFD) has been performed for the char and CO oxidations to supplement the experimental results. Due to limitations on installed stove such as poor design, air supply, fume extraction, or heat exchanger can lead to excessive CO emissions or lower energy efficiency. Outcomes show that it is crucial to minimize unused stove volume and to enhance gaseous mixing for reduction of CO emissions, while maintaining sufficiently high temperatures for supporting fast oxidation reactions. Results of comparisons of conducted analyses can be useful in areas related to process optimization and improvement of combustion and devolatilization reaction conditions in the small scale heating units.

The presented paper deals with the influence of the heating rate on combustion characteristics (reactivity and reactivity evaluation, ignition index (Di), burnout index (Df), the combustion performance index (S), and the combustion stability index (RW)) of the protective coronavirus face masks. Two types of commonly used face masks in different state (new and exploited) were investigated by TG-DTG analysis in an air atmosphere, directly coupled with mass spectrometry (MS). Based on the experimental results, the impact of ultimate and proximate analysis data on the evolved gas analysis (EGA) was discussed. Also, the derived values from thermo-analytical (TA) data were compared with the literature reports, related to individual constitutive face mask materials. According to the performed research, it was established that different maximal reaction rate values at various heating rates indicate the complex nature of coronavirus face mask thermo-oxidative degradation, which is stimulated with carbon oxidation reactions and volatile matter (VM) release. By detailed analysis of obtained TG-DTG profiles, it was established that process takes place through the multiple-step reaction pathways, due to many vigorous radical reactions, causes by polymers degradation. The performed research was done to evaluate the possible utilization of coronavirus waste to energy production and sustainable pandemic environmental risk reduction.

The pyrolysis of [4-(hydroxymethyl)phenoxymethyl]polystyrene (Wang) resin was studied by dynamic simultaneous thermogravimetric analysis (TGA) and derivative thermogravimetry techniques. The studied resin is used as the most commonly polymer supports in the peptide synthesis. A developed experimental master plots (exp-MP) model is presented that can be used to describe in more detail the pyrolysis of the resin established upon 4-hydroxybenzyl alcohol (PHB) on polystyrene, occurring throughout TGA experiments. This model assumes that the Wang resin is pyrolyzed through three parallel independent reaction steps, whereby their separation was performed through deconvolution procedure of the complex conversion rate curves. The mechanistic nature of each stage of Wang resin pyrolysis was explained by applying a combination of kinetic models such as diffusion mechanism, random nucleation and subsequent growth and chemical reactions mechanisms. The kinetic triplet parameters obtained in the present paper were then compared with those available in the literature. Within this kinetic study, the fraction distribution analysis (via distributed reactivity model) was performed, enabling reliable prediction of liquid products produced during the pyrolysis of the solid support of the Wang resin. Graphical abstract: [Figure not available: see fulltext.] © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

The preliminary thermogravimetric studies of co-pyrolyzed low rank coals (lignites Kostolac and Kolubara) with waste materials (spent coffee ground and waste rubber granulate) in a form of blends have been performed. Thermal analysis measurements of blend samples were carried out in a nitrogen, atmosphere at three different heating rates of 10, 15, and 20 K per minute. The coal-waste blends were prepared in the percentage ratios of 90:10, 80:20, and 70:30. This work analyzed the synergy analysis for considered blends shown via descriptive parameters during co-pyrolysis process. According to the performed analysis, the presence of synergistic effect was identified, where strong interactions were also observed. For lignite-spent coffee ground blends, it was found that two factors which affect the synergy effect with coal are concentration of added biomass material and the heating rate. For lignite-tire rubber granulate blends, the blending ratio take on a decisive role for positive consequences of a synergistic effect (ratios below 30% of tire rubber granulate in coals are desirable). Also, in this work the influence of micro-scale condition parameters such as heating rate (as the experimental regulatory factor) was analyzed on the magnitude response of synergism during co-pyrolysis.

Despite many advantages of the utilization of biomass as a renewable energy source, certain bottlenecks during biomass plant operation can be identified. Transport and collection of biomass as well as non-uniform material characteristics are issues related to decreasing efficiency of logistics and fuel manipulation which can also cause economic problems with biomass collection, transport, and storage. Since biomass is an especially reactive fuel, this has raised concerns over its safe handling and utilization. Fires, and sometimes explosions, are a risk during all stages of fuel production as well as during handling and utilization of the product. This paper presents a novel method for assessing ignition risk and provides a ranking of relative risk of ignition of biomass fuels. Tests within this method include physical and chemical properties of biomass, thermal analysis measurements, and the calculation procedure steps which were made using characteristic temperatures from thermogravimetry recordings. The results of thermogravimetry analysis were used for determination of tangent slope of the mass loss rate curves in devolatilization zone at considered heating rates for all tested samples. Linear interpolation of the data obtained by tangent slope analysis and used heating rates may provide unique straight line for each sample in the ignition testing. Thermogravimetry index of spontaneous ignition (TGspi) is obtained for all samples based on newly established formula. By varying gradient of linear dependence of self-heating coefficient against reference temperatures, mass and heat transfer limitations for various biomasses were discussed. The proposed method is accurate as well as relatively simple and quick, enabling determination of data necessary for design and application of appropriate measures to reduce fire and explosion hazard related to operation of biomass.

Thermal decomposition of hydrous volcanic glass occurs through the release of different water species under overlapping processes over wide temperature range. Its investigation is of practical interest since it constitutes integral processing part towards its valorization as source for the production of high-quality porous material for various applications. The study presents investigation of thermal decomposition of hydrous rhyolite through the non-isothermal solid-state kinetics approach. Rhyolite decomposition occurs through three partially overlapping processes, where loosely held and chemically bound water, as well as hydroxyl release at different temperature regions and through different mechanisms. The separation of overlapped thermal curves was done through peak deconvolution method using Frazier-Suzuki equation. Subsequently, the isoconversional (model-free) Friedman, generalized master-plots and Kissinger methods were applied for the determination of apparent activation energy (Ea), reaction model (f(a)) and pre-exponential factor (A) for each individual reaction step considered. Using the kinetic triplet values of each process, the kinetic rate equations were combined allowing precise simulation of the dehydration and dihydroxylation processes. A comparison of model results with thermogravimetric (TG) data, as well as data from the literature, showed the satisfactory accuracy of the model in the simulation of the process and the successful prediction of each water type fraction, during the process evolution. Spectroscopy techniques in UV―VIS and NIR (near infra-red) spectral ranges were applied to raw rhyolite and sample with different water content allowed calculation of color coordinates and its correlation with dehydration and dehydroxylation degrees, and also identification of water species.

Thermally accelerated oxidative degradation of wolfberry pulp was kinetically monitored using model-free and model-based approaches. Kinetic calculations were performed based on simultaneous thermal analysis measurements in an air at four different heating rates. From kinetic analysis, new developed mechanistic scheme which is responsible for wolfberries anti-oxidative behavior was proposed. It was found that thermo-oxidative process proceeds through multiplestep mechanism including sum of two independent reaction sets, via consecutive and competitive steps. It was established that rutoside degradation pathway to flavonol through hydrolysis reaction is rate-determining step of considered process. Furthermore, it was found that key flavonol compound degraded by competitive reactions mechanism forming such kinetic branches, which lead to compounds responsible for wolfberries antioxidant activity. It was established that flavonol oxidative cleavage reaction and oxidative polymerization are main chemical routes which are very important in a complex antioxidant mechanism for scavenging free radicals in wolfberries oxidative stress response.

This study provides new information on the thermal stability and kinetics of pyrolysis of commonly used resins in solid-phase peptide synthesis. Pyrolysis process of 4-benzyloxybenzyl alcohol resin was monitored by simultaneous TGA-DTG measurements in a nitrogen atmosphere, at four different heating rates (5, 10, 20 and 30 K min−1). Kinetic computations included the model-free (isoconversional) and model-based methods for reliable estimation of kinetic parameters and the mechanism of investigated process. Based on the findings from applied methods, the pyrolysis process can be described by three reaction steps, where one of them encompasses the consecutive reactions. The first step (n-th order reaction, referred to Fn) is attributed to the random scission of the main chain in PS (polystyrene) solid support, where polymer radicals were formed. The second step proceeds through homolytic cleavage path of ether linkage of the resin (by the first-order reaction, referred to F1) and then via phenoxy radical (semiquinone) formation which is converted into the benzoquinone through a dehydrogenation (by autocatalysis reaction, referred to Cnm). Finally, the third step (referred to Fn reaction) was characterized by depolymerization mechanism, which takes place at higher temperatures (T > 385 °C). With determined kinetic parameters and the most probable mechanism functions, the model agrees excellently with experimental data. By applying the obtained kinetic results, isothermal life-time prediction was also performed.

This study presents the experimental results of the mechanical and thermophysical properties of wood pellet samples important for their utilization in pellet stoves and boilers for heat production. The impact of operational parameters during the production process on a single pelletizer unit for three typical domestic commercial wood pellet samples (PWP110, BWP110, and BWP140) on fuel particle mechanical characteristics and related thermal properties was analyzed. It was concluded that the changes in raw material selection, as well as related operating parameters (extrusion length, i.e., die temperature during production process), have influenced the key mechanical and thermal characteristics of tested commercial wood pellets. The presented results have indicated the existence of a thin solid layer (due to waxes and subsequently lignin coating layer behaviors depending on their glass transition temperatures) on the surface of the BWP140 pellet sample. This layer leads to increasing the thermal resistance in the considered sample which can be explained by decreasing the effective thermal conductivity. Also, the forming of this layer on the surface of the wood pellet sample was caused by the production process (high-temperature impact explained by increasing friction between the die and feedstock during pellets production). It could be related to a lower value of effective thermal conductivity and specific heat capacity for considered (Beech) wood pellet sample.

This paper provides in-depth knowledge about the evolved gas analysis interpretation via newly proposed semi-quantitative approach, arising from thermogravimetric analysis (TGA) – mass spectrometry (MS) coupled measurements, for studying pyrolysis behavior of three kinds of biomass waste materials (spent coffee grounds, beech sawdust and wheat straw). TGA – MS coupling allows accurate correlation between molecular ion peak and fragment peaks to the corresponding mass loss rates from derivative thermogravimetry curves. Within proposed semi-quantitative analysis, MS spectra were interpreted through the comparative analysis of compounds fragments and of the compound itself, where the single atomic mass unit was identified by multiple compounds exhibition. It was shown that by this procedure which involves overlapping multiple curves supervising, the identification of gases in volatiles complex scheme becomes more simplified. By setting up semi-quantitative formulas, easy and reliable calculations of gaseous products yield and syngas energy capacities are possible to achieve. The H2/CO ratio derived from the proposed method for wood waste product (sawdust) is in an excellent agreement with H2/CO ratio for sawdust syngas production, in fuel reactor for biomass gasification and H2 production. © 2021 Elsevier B.V.

This paper provides insights into understanding the physical and chemical changes that take place during re-heating process of Poplar fluff bio-char derived by carbonization at high operating temperature (850 °C). Bio-char re-heating experiments were performed by simultaneous TGA-DTG-DSC techniques in N2 atmosphere at 5, 10, 15 and 20 °C min−1. Kinetic modeling of the process was done through implementation of model-free and model-based approaches. It was identified that re-heating process contains two stages. The first was described by single consecutive reaction step (up to 200 °C) which is attributed to removal of physisorbed moisture at surface and in pores of carbonized material, while second was described by multiple reactions, including one consecutive step and two competitive steps. In the last, consecutive pathway includes reduction of PAH compounds (400–600 °C) into smaller ones, changing degree of condensation of carbon structure continuously. Competitive steps encompass competition between C10H8 (naphthalene) (700–780 °C) and C9H8 (indene) (700–750 °C) molecules decomposition. It was found that used heating rates have great influence on regulating the amount of gaseous (combustible) products from these reactions. It was established that internal heat and mass transfer processes control the release of products. Changing the pyrolysis mechanism with temperature of carbonized bio-char is the main factor for occurrence of true kinetic compensation effect, which is also discussed by applied isothermal life-time analysis. © 2021 Elsevier Ltd

The efficient utilization of waste from food industry is possible after thermal treatment of the material. This treatment should be economically feasible and compromise the energy efficient drying process. The main goal of this investigation is to determine drying characteristics of nectarine pomace as a waste from food industry. The measurements were performed in an experimental dryer by combined conductive-convective drying method with disk-shaped samples of 5, 7, and 10 mm thickness and 100 mm in diameter at the air temperatures of 30, 40, 50, 60, and 70°C, hot plate temperatures of 50, 60, and 70°C and air velocity of 1.5 m/s. The drying curves were compared to a few semi-theoretical mathematical models. The Logarithmic model showed the best correlation. On the basis of experiments, it is determined that the drying process takes place in a falling rate period and it is accepted that the main mechanism of moisture removal is diffusion. The effective coefficient of diffusion was determined using experimental results by calculating the slope of the drying curves. Drying time and equilibrium moisture are determined for each experiment. Analysis of drying curves showed that the conductive-enhanced drying method reduces drying times and increases the diffusivity coefficient. The character of drying rate curves for conductiveenhanced drying was analysed and compared with pure convective drying of nectarine pomace.

As waste biomass from fruit processing industry, apricot kernel shells have a potential for conversion to renewable energy through a thermo-chemical process such as pyrolysis. However, due to major differences of biomass characteristics as the well-known issue, it is extremely important to perform detailed analysis of biomass samples from the same type (or same species) but from different geographical regions. Regarding full characterization of considered biomass material and to facilitate further process development, in this paper, the advanced mathematical model for kinetic analysis was used. All performed kinetic modeling represents the process kinetics developed and validated on thermal decomposition studies using simultaneous thermogravimetric analysis (TGA) – differential thermal analysis (DTA) – mass spectrometry (MS) scanning, at four heating rates of 5, 10, 15 and 20 °C min−1, over temperature range 30–900 °C and under an argon (Ar) atmosphere. Model-free analysis for base prediction of decomposition process and deconvolution approach by Fraser-Suzuki functions were utilized for determination of effective activation energies (E), pre-exponential factors (A) and fractional contributions (φ), as well as for separation of overlapping reactions. Comparative study of kinetic results with emission analysis of evolved gas species was also implemented in order to determine the more comprehensive pyrolysis kinetics model. Obtained results strongly indicated that the Fraser-Suzuki deconvolution provides excellent quality of fits with experimental ones, and could be employed to predict devolatilization rates with a high probability. From energy compensation effect properties, it was revealed the existence of unconventional thermal lag due to heat demand by chemical reaction. © Springer Nature Switzerland AG 2020.

The combustion reactivity of plane tree seeds biomass feedstock was studied using the thermogravimetry. The effects of atmosphere (O2/Ar) and different oxygen concentrations (O2/Ar = 20:80% and O2/Ar = 50:50%) on the combustion characteristics were investigated. When combustion atmosphere changes from O2/Ar = 50:50% to O2/Ar = 20:80% (reducing oxygen concentrations), the burnout temperature increases by 29.50 °C for tested biomass. Obtained results demonstrate the ease of ignition of investigated lignocellulosic material for O2/Ar = 50:50% ratio compared with O2/Ar = 20:80% ratio, and the actual trend is maintained under the condition when the heating rate increases. The reducing of oxygen concentration strongly influenced the amount of final residue products, particularly at higher heating rates (beyond 10 °C min−1). Kinetic analysis applied to investigated process shows strongly dependencies of both the apparent activation energy (E) and pre-exponential factor (logA) with conversion (α), especially in devolatilization and combustion of volatiles reaction stages. Large variation in E is attributed to existence of multiple parallel reactions. In order to solve this problem, the deconvolution technique that uses Fraser–Suzuki function was applied. It was shown that Fraser–Suzuki function fits successfully kinetic rate curves of entire combustion process, assuming the best selected nth-order reaction model.

Rhyolite is an extrusive, igneous rock of aluminosilicate composition that upon rapid cooling forms obsidian. Obsidian is amorphous and contains limited water portions (< 2 mass%); however, secondary hydration turns it either to perlite (H2O ≈ 2–5 mass%) or pitchstone (> 5 mass%). In the current study, kinetics of hydrous rhyolite dehydration were investigated by thermogravimetry up to 1000 °C, at heating rates of 2.5, 5, 10 and 20 °C min−1 and under inert atmosphere. The mass loss is approx. 7.6 mass%, occurs along wide temperature range (100–800 °C) and is solely attributed to the release of molecular water ((H2O)m) and hydroxyl groups (OH). Rhyolite dehydration was considered as a solid-state reaction, and the apparent activation energy (Ea) of dehydration was calculated throughout the whole conversion range (a) by applying the isoconversional Friedman and advanced Vyazovkin methods. Both methods revealed inverse sigmoid trend in Ea values versus conversion degree, possessing almost stable value of 61 ± 5 kJ mol−1 for Friedman method and 59.44 kJ mol−1 for Vyazovkin method on conversion range between 0.25 and 0.75, and sharp increase at higher conversion degree. The intensive change in Ea during dehydration progression is attributed to the change in releasing species (from (H2O)m to OH). Raman and FT-IR spectroscopy analyses of raw and partially dehydrated samples at different stages revealed that up to 300 °C mainly (H2O)m is diffused out of the material causing sample enrichment in OH groups. OH release, which occurs at relatively higher temperature, is accompanied by increase in apparent Ea value of dehydration. Concerning microstructure of raw rhyolite, it exhibits a network of micro-fractures which serve as water release routes. Upon heating, more and wider fractures are created. At 600 °C, fractures merging occurs creating voids, which constitute forerunners of the expansion phenomenon. Further temperature increase causes material softening allowing local p

In order to clarify relationship between apricot kernel shell biomass slow pyrolysis mechanism and its main constituents (viz. hemicelluloses, cellulose and lignin), the reactivity effects of main constituents on pyrolysis characteristics were determined by the non-isothermal simultaneous thermal analysis. It was found that four-step (parallel) reaction model is suitable for studying the slow pyrolysis process, within the semi-global model which excludes the strong interaction between biomass constituents (pseudo-components). The application of the proposed model was allowed by the results obtained from KAS iterative isoconversional (model-free) approach. The valorization of the model was confirmed by the process optimization. The complex (cumulative) apricot kernel shell pyrolysis rate curves at different heating rates are successfully resolved into the individual decomposition rate curves (arising from thermal conversion of hemicelluloses, cellulose, and primary/secondary lignin fragments) by four-parameter Fraser–Suzuki function. Besides hemicelluloses and cellulose pyrolyses, the proposed model distinguishes primary and secondary lignin reactions, which enhance the gaseous products releasing (primarily CO and CO2 gases) and charification of the solid residue (increased the bio-char yield). © 2020, Akadémiai Kiadó, Budapest, Hungary.

Slow pyrolysis characteristics of agricultural residue feedstocks (corn brakes, wheat straw, and hazelnut shell) were investigated by simultaneous thermal analysis (STA–TG–DTG–DSC), coupled with mass spectrometry (MS). Thermal decomposition of agricultural residues was divided into three stages, corresponding to removal of water, devolatilization, and formation of bio-char. It was found that differences in thermal behavior of samples are due to differences in their composition. The MS results showed that H2, CH4, H2O, CO2 (C3H8), CO, and C2H6 were the main gaseous products released during pyrolysis. It was shown that hazelnut shells could be a good combustion fuel, since during its pyrolysis at high temperature, more gaseous products compared to other systems are very favored. For hazelnut shell pyrolysis, the CO2 can be used on the large scale for the production of CO-rich syngas. © 2019, Akadémiai Kiadó, Budapest, Hungary.

Thermo-oxidative degradation of mollusk shells to CaO through intermediate phase of CaCO3 has been investigated using various analytical techniques. Powders of shells species (Dosinia exoleta and Ostrea edulis), with particle size fractions of 0.045 – 0.125 mm, 0.125–0.2 mm, and 0.2–1 mm, were subjected to degradation at the various heating rates (5, 10, 15 and 20 °C min−1). Degradation pathway of this carbonate-rich waste material has not yet been analyzed in detail at particulate level. Understanding transformation process in air should lead to control over yield and morphology of final product. Thermogravimetric analysis (TGA) and X-ray diffraction (XRD) techniques were used to benchmark transformation steps at different heating rates and final decarbonation temperatures, while scanning electron microscope (SEM) was used to analyze the effect of temperature on evolution of morphological changes for particles of different fractions. It was found that sintering in the presence of carbon dioxide (CO2) could be triggered by agglomeration of CaO crystals, enhanced by CO2 adsorption that increases surface energy. © 2020 Elsevier B.V.

Thermo-analytical characterization of selected biomasses (agricultural waste and wood biomass feedstock) through the pyrolysis process was performed under dynamic conditions. Slow pyrolysis (carbonization) regime (with a heating rate below 50 °C min−1) was selected because it favours the residual solid (bio-carbon/bio-char) in the higher yields (change in the surface area of bio-char with pyrolysis conditions was dependent on the type of biomass feedstock). Comparison of results and discussions related to obtained percentage pyro char yields from thermo-chemical conversion of biomass feedstocks were generated from simultaneous thermal analysis (STA) (TGA-DTG-DTA apparatus). The analysis of gaseous products of pyrolysis was carried out using mass spectrometry (MS) technique. Releasing of the light gaseous compounds (mainly CO, CO2, CH4, and H2 non-condensable gases) was monitored simultaneously with TGA measurements. Discussion related to this issue was performed from the aspect of the syngas production, as well as the versatility of selected biomasses in the gasification process where the various gasifying agent may be in use. © Springer Nature Switzerland AG 2020.

During the utilization of coal in large power plants, one of the major logistical issues is related to spontaneous ignition of the coal. This characteristic of coal depends on the rank and type of the coal, the content of the moisture and volatile matter as well as particle size distribution. This paper presents the novel approach for determination of spontaneous ignition potential of the coal developed as the internal laboratory experimental method. The experimental tests were performed by thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) of tested samples at five different heating rates: 3, 5, 7, 10 and 20 K min−1 under an air atmosphere. The TGA results were used for determination of tangent slope of the mass loss rate curves in the zone of the release of volatiles at considered heating rates for all coal samples. The linear interpolation of the data obtained by performed tangent slope analysis and heating rates provides the straight line unique for each tested sample. According to the standard method, the slope of the obtained straight line is defined as thermogravimetric index of spontaneous ignition (TGspi). In addition, a new formula for determination of TGspi index was provided. Three different coal samples were analyzed and classified according to the spontaneous ignition potential, based on the obtained values for TGspi by standard procedure and also using a newly proposed method. By varying the gradient of linear dependence of self-heating coefficient against reference temperatures (Tref,i), the mass and heat transfer limitations for different coals were discussed. © 2019 The Combustion Institute

Dielectric relaxation spectra of three representatives of the class of hydroxyethylammonium carboxylate protic ionic liquids (PILs), namely 2-hydroxyethylammonium formate [2-HEAF], 2-hydroxyethylammonium propionate [2-HEAP] and 2-hydroxyethylammonium butanoate [2-HEAB], were recorded over a wide frequency range (0.05 ≤ ν(GHz) ≤ 50) at 25 °C. The thermal decomposition kinetics of these ionic liquids derived from organic acids was studied by thermogravimetry (TG) using nonisothermal experiments. For the purpose of kinetic analysis, the thermal behavior of the samples was studied in the temperature interval from ambient temperature up to 420 °C at different heating rates (5, 10, 15 and 20 °C min−1). Isoconversional kinetic analysis was performed using Friedman's (FR) differential method and the integral Kissinger–Akahira–Sunose (KAS) method. The dependence of the apparent activation energy (E) on the conversion fraction (α) for the investigated decomposition processes was analyzed. It was found that the molecular structure of the involved anion significantly influences the dielectric properties of the studied PILs. It was also established that a change in the anion structure drastically affects the shape of the thermo-analytical curves. Among the considered PILs [2-HEAF] has the highest thermal stability. However, considering kinetic properties, certain deviations were observed and referred to hydrogen bonding development and steric impediment effects. © 2018 Elsevier B.V.

Thermal and kinetics behaviors of the low-rank coals from different annual periods (Kolubara (2015)/(2018) and TENT A (2015)/(2018)) during combustion process in air atmosphere, using simultaneous TGA-DTG-DTA-MS measurements were investigated. The FTIR spectroscopy was used to gain additional information on coals structures. Kolubara and TENT A coals from (2015)/(2018) annual periods show differences in reactivity, where the reason for this demeanor lies in differences in decomposition kinetics of these coals. The conclusions made on the basis of model-based analysis clearly indicate that differences in combustion reaction pathways (especially in transitions from primary to secondary combustion stages) arise from continual changes in physical structure of the coals. It was found that the mineral matter significantly influences on the reactivity of coal during combustion, where this is particularly pronounced for TENT A coal particles. © 2019 Elsevier B.V.

This paper investigates the ability of waste apricot (Prunus armeniaca) kernel shells (AKS) bio-char prepared by single-step carbonization process at 850 °C (residence time of 1 h) for possible removal of toxic elements and organic micro-pollutants. The experiment that was performed as well as parameters used proved to be optimal for bio-char production as adsorbing medium, where last issue is validated by multiform material characterization techniques. It has been shown that the produced bio-char possess highly-porous morphology features, with large specific surface area (328.570 m2 g−1). The obtained product was characterized by various pore sizes (including super-micropores and mesopores with maximum pore size of 2.24 nm) structures. Preliminary results are indicated that obtained bio-char can shows increased affinity to possible adsorption of the small organic molecule contaminants upgraded by its physico-chemical properties. Cost estimation of AKS bio-char production substantiated its cost effectiveness and its good physical and chemical properties for future design in batch adsorption and regeneration tests. It was established that AKS produced bio-char was 2.5 times cheaper than the commercially available activated carbon. Bio-char exhibits promising removal performances for potential adsorption of heavy metal and organic micro-pollutants from wastewaters systems, as indicated by material textures and spectroscopy measurements. © 2019 Elsevier Ltd

This paper describes the pyrolysis of Poplar fluff (from Populus alba) using on-line apparatus, and carbonization process at 850 °C using the fixed bed reactor. Characteristics of pyrolysis products were examined. Elemental and chemical analyses were shown that Poplar fluff has higher energy content characterized by increased content of fibrous structure (particularly cellulose). Independent parallel reactions model very well describes devolatilization process. It was found that increased amount of extractives can significantly affect on increased release of light gaseous products, but declining hydrocarbons, mostly the alkanes. Liquid product is mainly composed of phenolics, aldehydes, acids, esters and ketones. The carbonization process produces the great abundance of polycyclic aromatic hydrocarbons (PAH's), where naphthalene is the most abundant. Mechanism for PAH's formation was suggested. This study represents the first step in a much wider and more comprehensive way in thermal conversion processes of this type of fuel. © 2018 Elsevier Ltd

The pyrolysis process of various types of biomass (agricultural and wood by-products) in non-isothermal conditions using simultaneous thermal analyses (STA) was investigated. Devolatilization kinetics was implemented through combined application of model-free methods and DAEM (distributed activation energy model) using Gaussian distribution functions of activation energies. Results obtained were used in the curve prediction of the rate of mass loss against temperature at various heating rates by numerical optimization. The possible calculation of biomass samples behavior under pyrolytic conditions as the summation of their pseudo-components, hemicelluloses, cellulose, and lignin is also explored. The differences between experimental and calculated data are less than 3.20% offering a quality test of applicability of proposed model on the kinetic studies of a wide range of biomass samples. It seems that the most physically realistic model is the decomposition of biomass in three reactions, depending on the composition of the biomass regarding hemicelluloses, cellulose, and lignin. Kinetic model applied here may serve as a starting point to build more complex models capable of describing the thermal behavior of plant materials during thermochemical processing.