Variable Heating Rate Research Articles

Radioluminescence results, thermoluminescence analysis and kinetic parameters of Y2O3:Ln3+ (Ln: Dy, Nd, Sm) nanophosphors obtained by sol-gel method

Dy3+, Nd3+, Sm3+ doped Y2O3 nanophosphors were produced with high homogeneity at low sintering temperature using the sol-gel method. To compare the structural and optical changes of different rare-earth ions included in the crystal lattice, the dopant ratio was chosen as constant 2 mol%. In the light of X-ray diffraction (XRD) analysis, the unit cell volume and average crystallite size of the doped nanophosphors and their pure Y2O3 sintered under the same heat treatment regime were calculated and compared. Scanning electron microscopy (SEM) techniques were used to describe their structures and morphologies; an average particle size histogram of nanostructures was generated. The Radioluminescence (RL) spectra of Y2O3:Ln3+ (Ln: Dy, Nd, Sm) nanophosphors were presented for the first time. Splittings were seen in detail in the emission spectra given the 200–1100 nm range. For Dy3+4F9/2 → 6H13/2, for Nd3+; in the visible region 4H11/2-4I9/2 in the NIR region 4F3/2-4I9/2, for Sm3+; in the visible region 4G5/2-6H7/2 in the NIR region 4G5/2-6F5/2 transitions were determined to have the most vigorous emission. It was observed that the optical band gap calculated from the absorption spectrum of Y2O3 was 4.97 eV; this value changed the most with Dy contribution and decreased to 4.77 eV. The thermoluminescence (TL) behaviors of nanophosphors were compared under both UV and X-ray excitation. The kinetic parameters were calculated by applying computerized glow curve deconvolution (CGDC), and various heating rate (VHR) methods to the glow curves obtained UV excitation. The obtained E (eV) values correlated with each other are highly compatible.

Thermoluminescence glow curve analysis and kinetic parameters of Eu doped Li2MoO4 ceramic phosphors

LiMoO4: x Eu ceramic phosphors with x = 0.5, 1, 2, 3, 5, and 7 mol% were synthesized using a gel combustion method. X-ray diffraction (XRD) measurements confirmed a rhombohedral structure (space group R3) of synthesized compounds. Following irradiation with 50 Gy beta dose, the sample doped with 5 mol% Eu exhibited the highest integrated thermoluminescence (TL) intensity. In order to evaluate dose-response, samples were irradiated with beta radiation for 10–1000 Gy. TL intensity with 1000 Gy dose without saturation yielded the highest integrated value. Different methods were employed to determine the number of peaks, the trap structure, and the kinetic parameters of the thermoluminescence glow curve of Eu doped Li2MoO4: the Hoogenstraaten method, the Booth-Bohun-Parfianovitch method, the initial rise method (IR), combined with the TM-Tstop experiment, various heating rates (VHR), and glow curve fitting with two different software packages. Based on the glow curve deconvolution obtained using both software packages, the component TL glow peaks present in the complex glow curve are composed of well-isolated nine overlapping glow peaks. Two software packages have shown quite similar activation energies and frequency factors.

Errors in the Activation Energy and Thermal Quenching Parameters When Evaluated from Quenched Thermoluminescence Glow Peaks Using the Various Heating Rates Method

It is generally observed that the various heating rates (VHR) method overestimates the activation energy (E) when applied to quenched thermoluminescence (TL) peaks. Based on the analysis of numerically computed quenched TL peaks, we introduced an empirical expression that estimates the error in E. The expression correlates the error in E with the width of the peak, the luminescence efficiency and its first derivative at the lowest heating rate evaluated at the temperature of peak maximum. In addition, the expression accurately predicts the temperature shift of the peak maximum as a function of the heating rate. The VHR-based methods used to evaluate the quenching parameters (W and C) result in erroneous values. The source of error in the peak area-based method is the replacement of the unquenched peak area by the quenched peak area at the lowest heating rate as usually practiced in the literature. Accurate values of W and C were obtained when we modified the basic equation to include the luminescence efficiency at the lowest heating rate. On the other hand, we explicitly showed that the maximum intensity-based method used to evaluate these parameters is not suitable due to the lack of a reference point.

Linear thermal expansion behavior of compacted bentonite buffer materials

In a geological repository system, buffer is indispensable to ensure the safe disposal of high-level radioactive waste (HLW). Because heat generated from spent nuclear fuel in a canister is released to the surrounding buffers, thermal properties of such materials are fundamental in determining the overall disposal safety. Specifically, given that thermal expansion causes thermal stress to canisters and intact rock masses in the near-field location, it is imperative to evaluate the thermal expansion characteristics of the buffer, particularly when bentonite is used. This study investigates the linear thermal expansion properties of Kyeongju bentonite buffer, a type of Ca-bentonite produced in South Korea. The linear thermal expansion coefficient of dried bentonite was measured considering the heating rate, dry density, and temperature variation using dilatometer equipment. The linear thermal expansion coefficient values of the KJ bentonite buffers were found to be 4.0–6.2 × 10⁻⁶/°C. Based on test results, a numerical analysis was conducted, and the thermal strain values were similar between the test and numerical analysis. The overall linear thermal expansion coefficient of the KJ bentonite, considering radially confined or unconfined conditions and dried or saturated states, was predicted to be between 3.2 × 10⁻6/°C and 1.0 × 10⁻5/°C.

Thermoluminescence kinetic parameters of yttrium niobate

Yttrium niobate (YNbO4) phosphorus produced using the solid-state technique by sintering at 1200 °C investigated for thermoluminescence (TL) kinetics after irradiated with ultraviolet radiation (UV). The TL glow curve of UV irradiated yttrium niobate phosphorus recorded with a heating rate of 2 Ks−1 exhibited glow peaks at 366 and 424 K. The TL kinetic parameters belonging to main glow peak (424 K) of yttrium niobate phosphor, namely trap energy (E), frequency factor (s) and kinetic order (b) were investigated using Various Heating Rates (VHR), Computerized Glow Curve Deconvolution (CGCD), and Chen's Peak Shape (PS) methods after exposure to UV radiation. Trap energies of the phosphor by all methods were calculated as 1.09 eV. The frequency factors of the phosphor by CGCD, VHR and Chen’s PS methods were obtained as 0.96 × 1012 s−1, 1.38 × 1012 s−1 and 0.98 × 1012 s−1, respectively. The results attained by all methods are discussed and compared.

The kinetic parameters of the main thermoluminescence glow peak of Al2O3:C,Mg: A critical evaluation of different analytical methods

Carbon and magnesium co-doped aluminum oxide (Al2O3:C,Mg) is a highly sensitive luminescence dosimeter with promising use in a wide spectrum of radiation-related applications, including neutron dosimetry and as a fluorescent nuclear track detector (FNTD). The goal of this work is to critically evaluate diverse methods and approaches for the determination of the kinetic parameters using Al2O3:C, Mg as a case study. Al2O3:C, Mg was beta irradiated with doses from 0.1 to 0.6 Gy. Besides thermoluminescence (TL) peaks at 325, 350, and 375 K, the analysis of the activation energy, frequency factor and order of kinetics focused exclusively on the main TL peak at 450 K. Analysis by curve fittings used a number of freeware, namely, Glowfit, TLAnal, the Thermoluminescence Glow Curve Deconvolution (TGCD) package, and the spreadsheet TLDecoxcel. The results from the computational approaches were compared with results obtained by analyzing experimental data using conventional methods as initial-rise, whole glow peak, variable heating rate and peak shape. The performance of the computational methods is satisfactory as the values found are consistent with the ones determined by the methods listed above.

Anomalous heating rate dependence and analyses of thermoluminescence glow curves in Gd doped ZnB2O4 phosphors

Here, we report the thermoluminescence (TL) characteristics and trapping parameters under beta ray excitations of pelletized Gd-incorporated ZnB2O4 synthesized through the gel combustion method. The chemical composition of the obtained Gd incorporated ZnB2O4 was confirmed using X-ray diffraction (XRD). The best doping concentration of Gd was 0.25 mass%, which resulted in the highest luminous efficiency. The glow curves of the pellet-formed samples exposed to β-irradiation at various doses showed glow peaks at about 79 °C, 133 °C and 276 °C with a heating rate of 2 °Cs−1. An anomalous heating rate effect was observed for the peak centered at 276 °C, but the TL intensity of the peak at 79 °C and 133 °C decreased with an increasing heating rate. The TL glow peaks were studied using Tm-Tstop, initial rise (IR), and variable heating rate (VHR) and Computerized glow curve deconvolution (CGCD) methods. In the range of 0.1–50 Gy, the total integral values of TL output increased linearly with increased dose. A complex glow curves are composed of six distinguishable peaks as revealed by the results obtained from IR and CGCD methods. The current results indicate that the ZnB2O4:Gd3+ phosphor is a suitable option in radiation dosimetry for environmental monitoring.

Luminescence characterization of Ce and Gd doped MgB4O7 phosphors

This paper presents the results of the structural and luminescence characterization of Ce3+ and Gd3+ doped MgB4O7 powders produced by the solid-state synthesis technique. The phase composition of the samples was confirmed by X-ray Diffraction (XRD) method. Morphological characterization using a Scanning Electron Microscope (SEM) revealed a regular surface morphology with spherical/cylindrical grains. The luminescent properties were examined by measuring the RL emission spectra, Optically Stimulated Luminescence (OSL) decay signal, and Thermoluminescence (TL) glow curve. The correlation between luminescence intensity and concentration quenching of the prepared phosphor was investigated. The results show a maximum luminescence efficiency when the synthesis of MgB4O7:Ce,Gd was carried out using contents of 0.1 wt% Ce3+ and 3 wt% Gd3+. The data shows that at the heating rate of 5 °C/s, MgB4O7:Ce0.1%,Gd3% exhibits five TL peaks: two rapidly decaying peaks at about 80 °C and 110 °C, a shoulder peak at 180 °C, a high sensitivity peak at 235 °C TL and another shoulder peak at 320 °C (temperatures are approximate). The step annealing patterns suggest that the origin of the OSL signal is associated with the TL traps located between 180 and 235 °C. The kinetic parameters using various heating rate (VHR) technique, Tm-Tstop assisted extended initial rise method (IRM) and computerized glow curve deconvolution (CGCD) method were obtained and compared. The phosphor showed the dose linearity up to 10 Gy beta dose with a slight supralinearity for higher doses and the minimum detectable dose value of 743.1 ± 11 μGy. Fading and reusability studies of MgB4O7:Ce0.1%,Gd3% further confirmed the phosphor suitability for radiation dosimetry.

Effect of heating rate on MgB4O7:Tm,Dy glow curve and its kinetic parameters calculated with different methods

This paper presents the results of a long experimental work carried out to study the influence of the heating rate (H.R.) on thermally stimulated light emission phenomenon, well known as thermoluminescence (TL) of MgB4O7 activated by Tm and Dy ions (MgB4O7:Tm.Dy) in pellet form. The kinetics parameters, i.e. the activation energy, E, the frequency factor, s, the kinetics order, b and the number of trapped electrons, n0, were determined using the algorithm of sequential quadratic programming glow curve deconvolution (SQPGCD). The results obtained for the kinetics parameters, were compared with those obtained by other methods like Initial Rise (IR), Chen General-Order Kinetics (PS-GOK) and variable heating rate (VHR). These results suggest that SQPGCD method gives more accurate kinetics parameters values for the experimental glow curves.

Characterization, theoretical computation, DNA‐binding, molecular docking, antibacterial, and antioxidant activities of new metal complexes of (E)‐1‐([1H‐1,2,4‐triazol‐3‐yl]diazenyl)naphthalen‐2‐ol

AbstractComplexes of (E)‐1‐([1H‐1,2,4‐triazol‐3‐yl]diazenyl)naphthalen‐2‐ol with manganese (II), cobalt (II), nickel (II), and zinc (II) have been constructed. Elemental analyses, molar conductance, magnetic moment measurements, spectral (IR, 1H, 13C NMR, EI‐mass, and UV–Vis), XRD, and thermal studies have all been used to determine the structure of complexes. Except for Ni (II), which has a tetrahedral geometry, the results demonstrated that all complexes have octahedral geometry. The molecular mechanic calculations used in the hyper chem. 8.03 molecular modeling program were used to determine the potential structures of metal complexes. To confirm the geometrical geometries of the investigated metal complexes, the bond lengths, bond angles, LUMO, HOMO, and dipole moments of the listed complexes were determined. At varied heating rates, the thermal analysis (TG) measurements are also investigated. Different integral equations were used to compute the kinetic and thermodynamic characteristics of the thermal degradation processes. UV–Vis absorption titration was used to study the complexes' DNA binding mechanisms. The results revealed that the complexes attach to DNA in either intercalative or non‐intercalative manner. Azodye and its metal complexes were tested in vitro against Gram positive bacteria (Staphylococcus aureus), Gram negative bacteria (Escherichia coli and Pseudomonas aeruginosa), fungi (Aspergillus flavus, Candida albicans, and Mucor), and yeast (Malassezia furfur). The azodye and its metal chelates have shown potent antioxidant activities. The molecular docking analysis has been tested with Topoisomerase II protein code: 4CHT model.

Thermoluminescence characteristics of a novel Li2MoO4 phosphor: Heating rate, dose response and kinetic parameters

Lithium molybdate (Li2MoO4) phosphor was synthesized by a gel combustion method and its thermoluminescence properties were studied with the irradiation of beta. Various Heating Rate (VHR), Initial Rise (IR), and Computerized Glow Curve Deconvolution (CGCD) methods were used to determine the kinetic parameters (activation energy E (eV), frequency factor s (s−1), and kinetic order b) of the visible glow peaks. According to the kinetic study, the TL glow curve is made up of seven separate peaks with activation energies of 1.05, 0.76, 0.40, 0.60, 0.78, 1.81 and 1.25 eV and these peaks follow general-order kinetics. The results clearly showed that undoped Li2MoO4 has a potential to be considered in dosimetric applications where high doses have to be monitored as in the case of clinical dosimetry.

Structural, thermal and thermoluminescence response of transition and alkaline earth metals activated on aluminium borate [Al2(B4O7)3:Mn, Mg

Aluminium borate doped with manganese (Mn) and magnesium (Mg) at different concentrations are studied. The samples were synthesized by solid state sintering. The structure, morphology and crystallite size of the aluminium borate are affected by the dopants used. The crystallite size values calculated for different concentrations of manganese and magnesium used in doping of aluminium borate are within a range of 32.5–35.1 nm and 21.3–28.7 nm respectively. The particle size obtained using a scanning electron spectroscopy for Mn and Mg-doped aluminium borate are in the range of 30–40 nm and 20–30 nm respectively. A loss in weight from the thermal analysis performed for Mn and Mg-doped aluminium borate are observed to be 10.43% and 20.06%. The thermoluminescence glow peaks from all the samples measured at 1 °C.s−1 following irradiation to 50 Gy showed a prominent glow peak at 96 °C with minor peak observed at higher temperature (178 °C) region of the glow curve. The activation energy for Mn and Mg-doped aluminium borate were determined to be approximately 0.78 ± 0.30 eV and 0.76 ± 0.25 eV by using the initial rise, glow curve deconvolution and variable heating rate method. The dose responses were considered from 1 to 300 Gy for Mn (0.4%) and Mg (0.3%) doped aluminium borate and were further studied by using the g(D) and f(D) functions.

Optimisation of operation conditions and thermal analysis kinetics of roasting nickel-chromium mixed oxidised ore by ammonium sulphate

ABSTRACT The operation conditions of roasting nickel-chromium mixed oxidised ore using (NH4)2SO4 were optimised by an orthogonal test. The optimised conditions were concluded as a molar ratio of (NH4)2SO4 to mixed oxidised ore of 1.7:1, the roasting temperature of 475°C and the roasting time of 2 h at an ore particle size of 74 μm. The molar ratio was the most significant factor affecting the nickel, magnesium and iron extraction, followed by roasting time and temperature. Under optimal operation conditions, the extraction ratios of nickel, magnesium and iron are 94.3%, 84.9% and 88.7%, respectively. The reaction process, during roasting, was analysed based on the XRD study of specimens roasted at different temperatures and the TG-DTA curves obtained at varied heating rates. Each TG-DTA curve has five endothermic peaks. The first and third endothermic peaks are important and selected for thermal analysis kinetics using Doyle-Ozawa and Kissinger methods. The kinetic parameters, including the apparent activation energy, reaction order and frequency factor, are calculated corresponding to the two peaks before drawing the kinetic equations. Finally, the kinetic equations are obtained.

Thermal quenching and evaluation of trapping parameters of thermoluminescence glow-peaks of beta irradiated NaBaBO3: Tb3+ for TLD applications

Here, we report the thermoluminescence (TL) characteristics and trapping parameters under beta ray excitations of pelletized Tb incorporated NaBaBO3 synthesized through the gel combustion method. The chemical composition of this new phosphor was confirmed using X-ray diffraction (XRD). The best doping concentration of Tb was 2 mass%, which results in the highest luminous efficiency. The glow curves of the pellet-formed samples exposed to β irradiation at various doses showed glow peaks at about 188 °C, and 288 °C with a heating rate of 2 °Cs−1. The trapping parameters (E, b, s) related with the prominent the TL glow peaks were determined using Tm-Tstop, initial rise (IR), computerized glow curve deconvolution (CGCD), and variable heating rate (VHR) methods. In the range of 0.1–40 Gy, the total integral values of TL output enlarge linearly with increased dose. The GCD approach was also used to calculate the number of the glow peaks necessary to ensure an appropriate match to the TL response of the phosphor sample and seven TL glow peaks were estimated for all doses (FOM 1.75%), similar to the analysis of Tm-Tstop. The thermal quenching parameters of Tb activated NaBaBO3 for the 1st and 2nd peaks are measured to be W = 0.39 ± 0.04 eV, C = 3.11 × 102, and W = 0.31 ± 0.03 eV, C = 3.11 × 102, respectively. The current results indicate that the NaBaBO3:Tb3+ phosphor is a suitable option in radiation dosimetry for environmental monitoring.

Pyrolysis of agricultural waste in a thermogravimetric analyzer: Studies of physicochemical properties, kinetics behaviour, and gas compositions

Biomass is employed in pyrolysis to generate a substance that can be employed as a feedstock for speciality chemicals as well as a source of energy. Since the oil crisis in the middle of the 1970s, significant progress has been made to transform biomass into liquid fuels and chemicals. To make the process more efficient and optimized, kinetic understanding is required before moving on to applied pyrolysis. Thus, the present study explored the pyrolysis kinetics of low-value agricultural waste biomass at varied heating rates in a thermogravimetric analyzer (TGA). Six model-free methodologies were utilized to analyse the kinetics parameters (Kissinger-Akahira-Sunose (KAS), Ozawa-Flynn-Wall (FWO), Distributed Activation Energy Model (DAEM), Coats-Redfern (CR), Vyazovkin model (VZ), and master plot). In addition, a TGA-FTIR analyzer was employed to investigate the gas composition online. The physicochemical study’s findings suggested that it could be used as a feedstock for pyrolysis in the bioenergy sector. Furthermore, TGA-FTIR analyzer established the highest discharge of CO2 (28.73 and 33.14 %) and carbonyl products (20.60 and 29.35 %) for WS and CS, respectively. The average apparent activation energies (AAAE) for KAS, OFW, DAEM, and VZ are also determined to be 237.12, 186.40, 170.50, and 163.63 kJ mol−1 for WS and 176.37, 170.51, 196.12, and 194.91 kJ mol−1, for CS respectively. Further, the master plot and thermodynamic study of biomass exposed that pyrolysis passed through many multifaceted reaction mechanisms (Diffusion, nucleation, phase boundary-controlled etc.) during pyrolysis. Overall, pyrolysis techniques can be used to increase the energy density of lignocellulosic residues in an environmentally friendly manner.

Pyrolysis Kinetics of Lignocellulosic Waste Biomass (Cicer arietinum) using Iso-conversional Methods

A study on kinetic analysis of Bengal gram stalk (BGS), an agricultural waste biomass, was carried out using thermogravimetric analyser in an inert atmosphere. Thermogravimetric (TG) and Derivative thermogravimetric (DTG) curves were obtained by varying heating rates at 10°C.min−1, 20°C.min−1, 30°C.min−1, and 40°C.min−1. Three iso-conversional methods viz. Flynn- Ozawa-Wall, Kissinger-Akahira-Sunose, and Starink were applied to determine the kinetic properties and simultaneously obtained the effective activation energies for BGS pyrolysis. The average activation energy (Eα) calculated for BGS was 113.37 kJ.mol-1 for FWO; 109.47 kJ.mol-1 for KAS, and 112.36 kJ.mol-1 for Starink method, respectively. The results showed that the effective activation energies for the pyrolysis of BGS varied with the degree of conversion (α) in the range of 0.1 to 1.0. The experimental analysis revealed the correlation between activation energy and conversion factor.

Thermoluminescence properties and trapping parameters of TlGaS2 single crystals

TlGaS2 layered single crystals have been an attractive research interest due to their convertible characteristics into 2D structure. In the present paper, structural, optical and thermoluminescence properties of TlGaS2 single crystals were investigated. XRD pattern of the crystal presented five well-defined peaks associated with monoclinic unit cell. Band gap and Urbach energies were found to be 2.57 and 0.25 eV, respectively, from the analyses of transmittance spectrum. Thermoluminescence measurements were carried out above room temperature up to 660 K at various heating rates. One TL peak with peak maximum temperature of 573 K was obtained in the TL spectrum at 1.0 K/s. Curve fitting, initial rise and variable heating rate methods were used for analyses. All of those resulted in presence of a deep trapping level with activation energy around 0.92 eV. Heating rate dependence of the TL peak was also studied and it was indicated that peak maximum temperature shifted to higher temperatures besides decreasing TL intensity as the higher heating rates were employed.

Reduction Reactivity of Low Grade Iron Ore-Biomass Pellets for a Sustainable Ironmaking Process

Currently, fossil fuels are still the primary fuel source and reducing agent in the steel industries. The utilization of fossil fuels is strongly associated with CO2 emissions. Therefore, an alternative solution for green steel production is highly recommended, with the use of biomass as a source of fuel and a reducing agent. Biomass’s growth consumes carbon dioxide from the atmosphere, which may be stored for variable amounts of time (carbon dioxide removal, or CDR). The pellets used in this study were prepared from a mixture of low-grade iron ore and palm kernel shells (PKS). The reducing reactivity of the pellets was investigated by combining thermogravimetric analysis (TGA) and laboratory experiments. In the TGA, the heating changes stably from room temperature to 950 °C with 5–15 °C/min heating rate. The laboratory experiments’ temperature and heating rate variations were 600–900 °C and 10–20 °C/min, respectively. Additionally, the reduction mechanism was observed based on the X-ray diffraction analysis of the pellets and the composition of the reduced gas. The study results show that increasing the heating rate will enhance the reduction reactivity comprehensively and shorten the reduction time. The phase change of Fe2O3 → Fe3O4 → FeO → Fe increases sharply starting at 800 °C. The XRD intensities of Fe compounds at a heating rate of 20 °C/min are higher than at 10 °C/min. Analysis of the reduced gas exhibits that carbon gasification begins to enlarge at a temperature of 800 °C, thereby increasing the rate of iron ore reduction. The combination of several analyses carried out shows that the reduction reaction of the mixture iron ore-PKS pellets runs optimally at a heating rate of 20 °C/min. In this heating rate, the reduced gas contains much higher CO than at the heating rate of 10 °C/min at temperatures above 800 °C, which encourages a more significant reduction rate. In addition, the same reduction degree can be achieved in a shorter time and at a lower temperature for a heating rate of 20 °C/min compared to 10 °C/min.

Synthesis and beta particle excited thermoluminescence of BaSiF6 phosphor

BaSiF6 phosphor was synthesized by a gel combustion method. The crystalline size was found to be 54.17 ± 4.36 nm using Williamson-Hall (W–H) approximation. The TL data collected by means of a combination of a commercial BG39 and HC575/25 filters was studied to evaluate basic kinetic parameters. Three TL glow peaks of BaSiF6 phosphors are centered at around 84, 190 and 322 °C. Tm-Tstop, various heating rate (VHR) and computerized glow-curve deconvolution (CGCD) method were utilized to analyse collected data. Our findings indicate that luminescence process in scrutinized material may obey second order kinetics. The TL dose response of the TL glow peaks exhibits a linear characteristic up to 100 Gy. Deconvolution of the glow curve reveals that the number of the component TL glow peaks in the complex glow curve is composed of well-isolated six overlapping glow peaks. The FOM value is 2.32.

Evaluation of Non-Isothermal Kinetic Parameters for Pyrolysis of Teak Wood using Model-Fitting Techniques

Teak wood is one of the prominently used raw material in the construction industry, thus contributing extremely to the biomass waste available in Nigeria. These wastes are usually used for energy generation that requires upgrade into better fuel before application. Hence, the present study evaluates the non-isothermal kinetic parameters for pyrolysis of teak wood using model-fitting techniques. Teak wood dust was subjected to proximate, ultimate and calorific value analyses based on different ASTM standards. The thermal degradation and decomposition behaviour of the teak wood dust was examined using a thermogravimetric analyzer. Pulverized teak (6.5 mg) was heated from 30 to 800 ºC at varying heating rates (5, 10 and 15 ºC) in an environment where 100 mL/min of nitrogen gas was charged in continuously to maintain an inert condition. Avrami-Erofeev, Ginstling-Broushtein (GB) and Mampel models were used to evaluate the kinetic parameters of the pyrolysis of teak wood dust. The teak wood dust contained 7.25 % moisture, 79.26 % volatile matter (VM), 1.74 % ash and 11.75 % fixed carbon. The calorific value of the wood dust was 18.72 MJ/kg. The results of the thermogravimetric analyses depicted that heating rate has no effect on weight loss during the reactive drying zone. However, as the thermal treatment progressed into the active pyrolysis and passive pyrolysis zones, the weight loss decreased with increase in heating rate. The devolatilization parameters also increased with heating rates except for the maximum conversion. The results of the kinetic parameters evaluation revealed that the GB model was best fit to evaluate the kinetic parameters of teak in the active pyrolysis zone while GB and Mampel models were considered most appropriate for the evaluation of the kinetic parameters in the passive pyrolysis zone. Model-fitting method has the capacity to capture a wide range of fractional conversion at a glance.
 HIGHLIGHTS
 
 Arrhenius parameters in terms of activation energy and pre-exponential factor for the pyrolysis of teak wood while comparing 4 different model-fitting techniques were obtained
 The α-temperature plot for solid state reaction of teak wood dust was a bell-shape (sigmoidal model)
 The Avrami-Erofeev and SSS models were unable to capture the overlapping multiple reactions that took place simultaneously at the active pyrolysis zone
 Higher energy input is needed for devolatilization of teak wood dust to give 10 - 80 % conversion due to higher activation energy at the active pyrolysis zone
 Ginstling-Broushtein was found to be the best model for evaluating the kinetic parameters at the active pyrolysis zone as it had the highest R2 value
 
 GRAPHICAL ABSTRACT