Derivative Thermogravimetry Curves Research Articles

Multifunctional superhydrophobic coating constructed from rosin-based polymer and nano-boehmite particles for oil-water separation, flame retardancy and anti-icing

The massive release of oily wastewater poses a significant threat to ecological systems and environ mental sustainability. Superhydrophobic materials have been regarded as an effective solution for the treatment of oily wastewater. Herein, a multifunctional superhydrophobic coating (poly(DR-DMA)@BMP coating) was developed using a constructed from rosin-based polymer (poly(DR-DMA)) and nano-boehmite particles (BMP). Poly(DR-DMA) was fabricated by double-bond modified dopamine (DMA) and double-bond functionalized rosin acid (DR). The poly(DR-DMA)@BMP coating exhibited excellent superhydrophobicity with a water contact angle of up to 163°, along with self-cleaning performance. Meanwhile, the poly(DR-DMA)@BMP coating had desirable oil-water separation, with a permeation flux of 8966.67 L·m−2·h−1, and an n-heptane separation efficiency of 98.26 %. After 10 separations, the permeation flux and separation efficiency remained high. In addition, the poly(DR-DMA)@BMP coating retained excellent superhydrophobicity (water contact angle >150°) and emulsions separation after mechanical and chemical treatment. Thermo-gravimetric analysis and Derivative thermo-gravimetry curves illustrated increased thermal stability of the coating, which indicated that the poly(DR-DMA)@BMP coating exhibited a certain degree of flame retardancy. The freezing time of water droplets on the coated sample was extended to 1100 s at −20 °C, indicating that the poly(DR-DMA)@BMP coating had favorable anti-icing properties. To encapsulate, the poly(DR-DMA)@BMP coating holds promising applications in the realms of oil-water separation, flame retardancy and anti-icing.

Acoustic and thermal properties of mycelium-based insulation materials produced from desilicated wheat straw - Part B

The acoustic and thermal properties were determined for biodegradable insulation materials produced from desilicated wheat straws with two different fungi and three different incubation periods. Ganoderma lucidum (GL) and Pleurotus ostreatus (PO) fungi and wheat straw were exposed to fungal incubation for 10, 20, and 30 days to produce mycelium-based insulation materials. The sound absorption coefficients of mycelium-based insulation boards produced using PO fungus were higher than those produced with GL fungus. It was found that the acoustic absorption coefficients of insulation boards produced using PO fungus at 1,000 Hz were 87 to 99% according to the incubation periods. The sound transmission losses of mycelium-based insulation boards produced ranged from 46.4 to 59.7 dBa at 1000 Hz. The group of boards labeled as YP2 exhibited the lowest level of sound transmission loss, whereas GL2 revealed the highest degree of sound transmission loss at 1000 Hz. The lowest thermal conductivity coefficient was obtained in insulation boards produced with PO fungus and an incubation period of 20 days. The limiting oxygen index (LOI) value of mycelium-based insulation materials was considerably higher than the insulation boards commonly used today. Thermogravimetric analysis and derivative thermogravimetry curves of mycelium-based insulation materials were also determined.

Photophysical, thermal, and DFT studies on a tetraaryl-azadipyrromethene ligand and its zinc(II) complex.

An azadipyrromethene ligand (H1) and homoleptic zinc(II) (H1-Zn) complex were synthesized. The resulting structures were elucidated by NMR, FTIR, and HRMS techniques. The photophysical properties and effects of complexing the zinc(II) atom to azadipyrromethene ligands in solution were studied by means of UV-Vis absorption and fluorescence spectroscopy. Experimental findings were elucidated using density functional theory computations and interfragment charge transfer (IFCT) and electron-hole analyses. The fluorescence features were found to be negligible. The ligand molecule decayed at a rate of 3% while the complex decayed at 2% upon photoirradiation based on photostability experiments. The singlet oxygen quantum yields of the ligand and complex were calculated as 0.127 and 0.233, respectively, signifying low photodynamic activity. The charge transfer transitions were determined between reciprocal ligands responsible for the red shift of the main absorption band by IFCT and electron-hole analysis. Compounds in an inert N2 atmosphere demonstrated high thermal stability. Although the thermogravimetric analysis (TGA) and derivative thermogravimetry curves of the complexes were similar, zinc(II) coordination and homoleptic complex formation reduced the degradation temperatures. These findings suggest that azadipyrromethene and the Zn(II) class of chromophores have beneficial features for use in the development of novel photo- and thermostable materials that combine charge transfer with low energy in the visible and near infrared regions.

Ethyl cellulose–graphene oxide composite dense membranes: Kinetic and thermodynamic studies of dye adsorption

Graphene oxide (GO) is extensively used in dye adsorption from wastewater. Polymer–GO composite membranes exhibits improved surface wettability and dye adsorption capacity. In this study, ethyl cellulose (EC)–GO nanocomposite dense membranes (EG membranes) are prepared by the solvent casting method. The morphology and physicochemical properties of the developed nanocomposite membranes are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction studies, thermogravimetric analysis, static contact angle measurements, and UV–visible spectroscopy. The derivative thermogravimetry curves indicate the complete degradation of the composites below [Formula: see text]C. The results confirm the homogeneous dispersion of GO in the EC matrix. The addition of GO to the EC matrix leads to a remarkable increase in surface wettability which decreases the contact angle to [Formula: see text] for the membrane with a 0.7% addition of GO. The prepared membranes are used for the separation of methylene blue from water. The adsorption properties of the prepared membranes are found to be varying in accordance with the contact angle values. The equilibrium data fit well for the Langmuir model and the adsorption follows pseudo-second-order kinetics.

Kinetic and thermodynamic study of pyrolysis of the hydrolyzed residue of rice straw and husk by subcritical water process using thermogravimetric analysis

AbstractThe use of hydrolyzed rice straw (HRS) and hydrolyzed rice husk (HRH) as feedstock for pyrolysis was evaluated through kinetic and thermodynamic studies. HRS and HRH were obtained from subcritical water hydrolysis (SWH) at different temperatures (180, 220, and 260°C). The Coats‐Redfern method was used to analyze the thermal behavior through thermogravimetry (TG) and derivative thermogravimetry (DTG) curves. TG profiles showed higher decomposition in the range of 250–400°C, especially for rice straw (RS) and HRS (80 wt %). The pyrolysis curves were well predicted by a first‐order reaction model. The kinetic analysis showed a variation in activation energy (EA) between 24.3 to 41.3 kJ mol−1 and 40.4 to 54.7 kJ mol−1 for RS/HRS and rice husk (RH)/HRH, respectively. The enthalpy (ΔH), Gibbs free energy (ΔG), and entropy (ΔS) varied from 25.9 to 39.6 kJ mol−1, 35.4 to 69.6 kJ mol−1, and −64.1 to −6.7 J mol−1 K−1, respectively, for RS/HRS, and 35 to 49.8 kJ mol−1, 43.2 to 79.3 kJ mol−1, and −53.5 to −10.2 J mol−1 K−1, respectively, for RH/HRH. These results showed that the pyrolysis reactivity using HRS is higher than HRH, which indicates the pyrolysis of HRS is more advantageous than HRH.

Antioxidative capacity evaluation of imine compounds as metal ions chelators and free radical scavengers in biodiesel

Factors affecting the oxidation stability of commercially available biodiesel were primarily investigated using the acid value (AV), peroxide value (PV), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, and thermogravimetric (TG) analysis in the presence of imine antioxidants. In this study, the imine compounds N,N′-bis-(4-octadecanate)-salicyl ethylenediamine (stearic dhben) and N,N′-bis-(4-hexadecanate)-salicyl ethylenediamine (palmitic dhben) were synthesized to evaluate their abilities as metal chelators and oxygen scavengers. The AV analysis showed a slight difference between the samples with and without copper. The PV tests demonstrated that both imines were efficient free radical scavengers and copper ion chelators at both room temperature and 50 °C, outperforming the commercial antioxidants butylhydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ). The Derivative Thermogravimetry (DTG) curves indicated that both imines were more effective compared to commercial antioxidants. In the DPPH assay, it was observed that the palmitic dhben imine exhibited the best performance, with an half maximal inhibitory concentration (IC50) of 12.4·10−5 mol L−1. Therefore, both stearic and palmitic dhben imines act as efficient biodiesel antioxidants at room temperature and 50 °C, functioning as excellent metal chelators and free radical scavengers. However, stearic dhben demonstrated better performance as a metal chelator, whereas palmitic dhben was more effective as a free radical scavenger.

Influence of hydrogen flow rate on multistep kinetics of hematite reduction

Hydrogen ironmaking is the most ideal approach to reduce industrial carbon emissions. In this study, the isothermal reaction characteristics and multistep kinetics of hematite particles with hydrogen are investigated using thermogravimetric analysis (TGA) at 650–725 °C. The two steps of Fe3O4–FeO and FeO–Fe of hematite reduction are discovered to proceed simultaneously. The reduction is divided into three stages according to the derivative thermogravimetry (DTG) curves. For the three stages, the optimal kinetic models are the phase boundary and the 2D growth of nuclei. In the range of 75–130 mL/min, there is a critical hydrogen flow rate below which the apparent activation energy increases and above which it remains constant, which is 30.44 ± 3.30, 77.33 ± 0.41, and 49.56 ± 0.49 kJ/mol, respectively. A significant linear correlation between hydrogen flow rate above the critical value and the pre-exponential factor is found.

The Catalytic Effect of Iron and Alkali and Alkaline Earth Metal Sulfates Loading Series on the Conversion of Cellulose-Derived Hydrochars and Chars.

The catalytic effect of minerals on biomass conversion was studied focusing on Fe as well as alkali and alkaline earth metals as the metallic inorganic elements typically present in minerals found in biomass. A mineral-free reference hydrochar and an analogous char material based on cellulose were systematically doped with sulfates of the different metallic inorganic elements in various amounts via impregnation, thereby excluding differences originating from the counterion and the carbon matrix. Thermogravimetric reactivity measurements were performed in diluted O2 and CO2, and the derivative thermogravimetry curves were fitted using the random pore model. This procedure enabled a quantification of the apparent activation energy decrease due to doping as well as the influence of doping on the carbon structural parameter. Fe sulfate was always among the most active minerals, and alkali metal sulfates were typically more active than alkaline earth metal sulfates. The only exception was the high activity of very small Ca sulfate loadings during gasification. A saturation behavior of the kinetic parameter upon increasing the mineral loading was observed. The Langmuir-type modeling of this dependence further revealed that catalytically influenced devolatilization results in a char with higher oxidation reactivity, whereas for gasification, thermal annealing dominates. The systematically derived parameters provide a comprehensive description of catalytic effects, taking into account the type of mineral, the applied loading, the used atmosphere, and the fuel morphology. The derived activation energies can be used to include catalytic effects into combustion models.

Experimental and theoretical study on the evolution of functional groups in cellulose char during oxidative pyrolysis

Oxidative pyrolysis of biomass is a promising substitute technology for conventional pyrolysis and is also crucial to the related degradation process of biomass materials such as aging, combustion, fire hazard, etc. The intertwining of heterogeneous oxidation and homogeneous oxidation of biomass and its derivative muffles the detailed mechanism of oxidative pyrolysis. To unravel the mechanism of heterogeneous oxidation in the cellulose condensed phase, the real-time evolution of functional groups in cellulose char during oxidative pyrolysis was probed by the in situ diffuse reflectance infrared Fourier transform technology, which is further analyzed by a homemade semi-quantitative analysis program based on the perturbation-correlation moving-window two-dimensional correlation spectroscopy and two-dimensional correlation spectroscopy. The experimental results show the obvious promotion effects of O2 on the direct oxidation of hydroxyls to unconjugated CO and the cleavage of COC in the development stage between the temperatures of the initiation and the maximum rate of weight loss, resulting in the lowered thermostability and devolatilization of cellulose. At elevated temperatures, the hydroxyls and CO were further oxidized by O2 into carboxyls, and released at around 450 °C in the last decline stage, performing the second peak of the derivative thermogravimetry curve for oxidative pyrolysis. Through density functional theory calculation of the hydroxyl oxidation, a low-temperature oxidation mechanism competitive with the transglycosylation and other dehydration reactions was proposed. Its rate is determined by the initiating H abstraction, which highly depends on the spin density (population) for the transition state and pyrolysis temperature.

Hydrochar prepared from municipal sewage sludge as renewable fuels: Evaluation of its devolatilization performance, reaction mechanism, and thermodynamic property

Hydrothermal treatment (HT) of sewage sludge (SS) is a promising method to improve its dewaterability. Effect of HT on devolatilization performance, kinetic parameters, and thermodynamic property during the pyrolysis of SS was investigated by thermogravimetric analysis (TGA), isoconversional method, and master plots method. Derivative thermogravimetry (DTG) curves showed two distinct devolatilization peaks #1 at 283.21 °C and #2 at 327. 43 °C along with a shoulder between 400 and 600 °C. HT temperature influenced peak #2 more significantly as its peak devolatilization rate decreased consecutively from 4.25 % to 1.70 %∙min−1. Meanwhile it moved towards higher temperature and overlapped with the shoulder ultimately. The value of comprehensive pyrolysis index (CPI) decreased greatly from 3.37 × 10−5 to 1.24 × 10−6 %3∙°C−3∙min−2 with HT temperature. Activation energy was determined by Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Starink, and Friedman methods. It generally increased against conversion with diverse variation patterns. Its average value reduced obviously after HT. Despite HT, all samples followed identical Avrami-Erofeev model with decreased order of reaction from 7.60 to 6.56. The variation trends of enthalpy, Gibbs free energy, and entropy verified that HT improved the thermal stability of SS, which coincided with CPI. Pyrolysis process of SS evolved from ordered state to disordered state, indicating increased reactivity due to the probable catalytic effect of inorganics in the ash. The work provides guidance for the design, optimization, and upscale of pyrolysis reactors and operation parameters when SS is utilized as renewable fuels.

Thermal behaviour and inertia effect in calcium aluminate cement pastes with microsilica

The main contribution of this research is the study of the effect of thermal inertia in the activation energy in calcium aluminate cement pastes. For this, several formulations of calcium aluminate cement pastes (CACPs) with 51 wt% and 71 wt% of alumina (Al2O3) were made at 0.4 water-to-cement ratio, and with additions of 0.0 wt% and 20 wt% of silica content. The characterisation was done using X-ray fluorescence and X-ray diffraction, and the behaviour of the phases with temperature was studied using thermal gravimetric analysis, including the corresponding derivative thermogravimetry (DTG). The influence of the thermal inertia on the activation energies and its dependence on the heating rate is established. The effect of thermal inertia on peaks of DTG curves and activation energies is analysed. The activation energies for dehydroxylation of the gibbsite were calculated based on the Kissenger–Akahira–Sunose method. The activation energy values obtained, in kJ/mol, for CACP71 – 0, 20 wt% and CACP51 – 0, 20 wt% silica content were 19.9, 6.37 and 19.8, 17.2, respectively. The influence of silica on phase formation, activation energies and the effect of thermal inertia is also analysed.

Effect of Bound Water Content on Secondary Compression of Three Marine Silty Clays

Secondary compression studies can provide insights for evaluating the engineering potential and environmental impact of soil. The objective of this research was to investigate the effect of bound water content on the secondary compression of marine silty clay. To this end, a novel method was established based on thermogravimetric analysis (TGA) to determine the contents and limits of strongly bound water and weakly bound water for three typical marine silty clays including Tianjin mucky silty clay (TJ), Qingdao mucky silty clay (QD), and Weihai silty clay (WH). A total of 17 groups of uniaxial confined compression tests were performed for reconstituted samples at different absolute water contents under the condition of multistage loading to investigate their secondary compression characteristics. The results show that the initial dehydration temperature of strongly bound water (Ts) corresponds to the peak of the derivative thermogravimetry (DTG) curve. The values of Ts for TJ, QD and WH are 112.35 °C, 109.67 °C and 118.46 °C, respectively. The initial dehydration temperatures of weakly bound water (Tw) for TJ, QD and WH are 55.26 °C, 52.56 °C and 56.56 °C, respectively. The secondary compression coefficient Cα changes little before the strongly bound water limit and increases dramatically as weakly bound water content increases at the same vertical stress. A piecewise linear model and a quadratic polynomial model are established for calculating the average secondary compression coefficient from bound water content. Weakly bound water is the determining factor controlling secondary compression. Increasing the bound water content weakens the connection force and friction force among the particles and the viscosity of weakly bound water. The results will guide decisions on long-term settlement assessment and facilitate understanding of the secondary compression mechanism of marine silty clays affected by bound water.

Effect of Pyrolysis Atmosphere on the Gasification of Waste Tire Char

The aim of the study is to assess the influence of the atmosphere during pyrolysis on the course of CO2 gasification of a tire waste char. Two approaches were used: the pyrolysis step was carried out in an inert atmosphere of argon (I) or in an atmosphere of carbon dioxide (II). The examinations were carried out in non-isothermal conditions using a Rubotherm DynTherm thermobalance in the temperature range of 20–1100 °C and three heating rates: 5, 10 and 15 K/min. Based on the results of the gasification examinations, the TG (Thermogravimetry) and DTG (Derivative Thermogravimetry) curves were developed and the kinetic parameters were calculated using the KAS (Kissinger-Akahira-Sunose) and FWO (Flynn-Wall-Ozawa) methods. Additionally, the CO2 gasification of tire chars reaction order (n), was evaluated, and the kinetic parameters were calculated with the use of Coats and Redfern method. Tire waste char obtained in an argon atmosphere was characterized by lower reactivity, which was reflected in shift of conversion and DTG curves to higher temperatures and higher mean values of activation energy. A variability of activation energy values with the progress of the reaction was observed. For char obtained in an argon atmosphere, the activation energy varied in the range of 191.1–277.2 kJ/mol and, for a char obtained in an atmosphere of CO2, in the range of 148.0–284.8 kJ/mol. The highest activation energy values were observed at the beginning of the gasification process and the lowest for the conversion degree 0.5–0.7.

Thermal Decomposition of Brominated Butyl Rubber.

The thermal decomposition of brominated butyl rubber under air atmosphere was investigated by thermogravimetry (TG) and derivative thermogravimetry (DTG) at various heating rates. The kinetic parameters were evaluated by TG and the isoconversional method developed by Ozawa. One prominent decomposition stage was observed in the DTG curves at high heating rates, while an additional small peak was observed at low heating rates. The apparent activation energy determined using the TG method ranged from 219.31 to 228.13 kJ·mol−1 at various heating rates. The non-isothermal degradation was found to be a first-order reaction, and the activation energy, as determined by the isoconversional method, increased with an increase in mass loss. The kinetic data suggest that brominated butyl rubber has excellent thermal stability. This study can indirectly aid in improving rubber pyrolysis methods and in enhancing the heat resistance of materials.

The influence of calcium lignosulphonate addition on non-isothermal pyrolysis and gasification of demineralised bituminous coal fines

• Coal fines were demineralised using acid de-ashing treatment. • CaLS added to the coal fines and demineralised coal in different proportion showed an increase in compressive strength. • CaLS blended samples showed higher reactivity when compared to the demineralised coal and coal fines. • 5% CaLS addition did not influence coal gasification rate significantly. • An increase in CaLS blends correlates with an increase in reactivities. Amorphous calcium lignosulphonate (CaLS), a by-product of the paper industry, was evaluated as an adhesive to bind demineralised bituminous coal fines in various weight percentage ratios. Sequential acid (HCl, HF, HCl) leaching was used to reduce mineral matter content in the coal fines. The pyrolysis and gasification of the samples were investigated in laboratory-scale experiments to determine the effect of the CaLS addition on the pyrolysis and gasification reactivities. Coal-CaLS blends consisting of 5, 10, and 15% calcium lignosulphonate were prepared, compressed into pellets, and characterised using proximate, X-ray diffraction, and X-ray fluorescence analyses. An increase in binder concentration increases the mechanical strength of the pellets due to the increased interparticle contact area. The relative coal gasification reaction reactivity (1/T max and 0.5/T 50 ), which was determined from the derivative thermogravimetry curves, increases with CaLS addition. The experimental results revealed that these wastes (coal fines and calcium lignosulphonate) could be utilised in thermochemical processes. Utilising these wastes will reduce the environmentally unfriendly volumes of amorphous calcium lignosulphonate and coal fines particles.

Comparative Study of the Synergistic Effects of Blending Raw/Torrefied Biomass and Vietnamese Anthracite Using Co-pyrolysis.

Biomass can be upgraded via torrefaction, and torrefied kenaf (TK) is a fuel that allows blending with coal at high ratios. In the present study, raw kenaf (Hibiscus cannabinus L.) (RK) was torrefied at 523 K for 30 min and then mixed with Vietnamese anthracite (NinhBinh, NB) before co-pyrolysis. Thermogravimetric (TG) analysis was used to evaluate the behavior of RK, TK, and blended RK/TK during co-pyrolysis at biomass blending ratios (BBRs) of 0, 25, 50, 75, and 100 wt %. The TG and derivative thermogravimetry curves of a mixture of NB and RK (NBRK) were similar to those of RK. The decomposition curves of a mixture of NB and TK (NBTK) depended on the mass fraction of TK. Based on weight loss differences between the experimental and calculated data for the fuel blends, no interaction between the RK and anthracite was observed for all BBRs, whereas anthracite involving 50 and 75% TK exhibited synergistic effects. The temperature range for synergy and degree of synergy for NB and TK depended on the heating rate and mass ratio of TK. Kinetic parameters were calculated using the Friedman–non-isothermal free kinetic method at heating rates of 10, 20, and 40 K/min. The results showed that the activation energy (E) values of the NBRK at conversion ratios of 0.2–0.5 were equal to those of the RK, whereas they were superior at NB decomposition ratios of 0.6–0.8. NBTK1-1 (BBR of 50%) showed E values higher than those of NB at some conversion ratios, thus demonstrating a negative impact of blending. Further, NBTK1-3 (BBR of 75%) and NBTK3-1 (BBR of 25%) exhibited E values between those of NB and TK. The present study suggests that a high TK mass fraction (75%) in the blend for co-pyrolysis is optimal for the activation energy and volatile matter yield.

Pyrolysis of Tropical Agricultural Crop Waste (Pineapple Residue and Banana Pseudo-Stem): Kinetics, Mechanism and Valorization of Bio-Char

Pineapple residue and banana pseudo-stem are waste from tropical agricultural production. Kinetics, thermodynamics, mechanism during pyrolysis of them and valorization of bio-char were explored. Both biomass decomposed rapidly at 150-500°C and there was a significant mass loss peak for banana pseudo-stem at 650 °C, which indicated that degree of lignification apparently affect pyrolysis characterization of biomass. Activation energy of pineapple residue and banana pseudo-stem was 159-292 and 169-321 kJ/mol based on multi-heating rate method. Whereas based on Gaussian multi-peak fitting method, derivative thermogravimetry (DTG) curves of pineapple residue and banana pseudo-stem were simulated with three or four fitting peaks, corresponding to decomposition of hemicellulose, cellulose and lignin and deep degradation. Interaction between these components intensified complexity of kinetic parameters. The main carbon number of organic volatiles during pyrolysis was C 4 and C 5 for pineapple residue, and that was C2 and C3 for banana pseudo-stem. High content of cellulose and hemicellulose in biomass (pineapple residue) intensified volatilization of volatiles. Porous carbon sourced from pineapple residue and banana pseudo-stems had specific capacitance of 375 F/g and 297 F/g at current density of 0.5 A/g, respectively. Pineapple residue and banana pseudo-stem were potential feedstock for electrochemical materials.

Thermal and Kinetic Properties of Brazilian Coffea Arabica Beans

The chemical composition of green coffee beans depends on the number of parameters, such as coffee cherry processing methods, used. The quality of roasted coffee is related to the certain substances that developed during the roasting process and that are responsible for the organoleptic properties. The main objective of this study was an investigation of the thermal behaviour and the fatty acids profile of green and roasted Brazilian Santos coffee beans. The glass transition temperature was measured using modulated differential scanning calorimetry (MDSC). The thermal behaviour of coffee samples was evaluated by means of thermogravimetry (TG) and first derivative thermogravimetry (DTG). The oxidative stability and kinetic parameters were characterized with the use of differential scanning calorimetry (DSC). According to the TG and DTG curves, coffee samples showed different behaviour of thermal degradation in the atmosphere of oxygen and nitrogen. Our research shows that the thermal properties and fatty acids profile did not change during the roasting process.

Chemometric Comparison of Data Files Using Several Thermal Analytical Techniques for Dating Fossil Bones from Two Old Burial Sites

Background:: The possibility of estimating the age of fossil bones using only classic thermogravimetry, on the basis of proper % mass loss ratio values, has been widely considered in the past years. Objective:: Our research has brought some innovations to the previous background, by using chemometric methods and by processing the numerical files of whole thermogravimetric curves. The objective of this paper is the selection, among the main thermal analysis methods available, i.e., thermogravimetry (TG), derivative thermogravimetry (DTG), differential thermal analysis (DTA) and thermal dilatometry analysis (TDA), of the most suitable one, in order to evaluate the age of fossil bones. Methods:: Fossil bone samples from two ancient cemeteries in Sudan were analyzed using different thermal methods (TG, DTG, DTA, and TDA). Data of whole recorded thermal curves have been processed by PCA analysis. Results:: A systematic comparison of several thermal analytical techniques allowed to conclude that TG or DTG curves can provide more appropriate information to determine how old fossil bones of different ages are, as evidenced by PCA processing of the entire file set of TG or DTG curves. Conclusion:: It can be concluded that the chemometric processing of TG or DTG curves data files is the best method; however, discussing other thermal analytical curves (DTA and TDA) can complete the information found by means of chemometric processing of whole TG and DTG curves.

Kinetic study of heating pinewood sawdust with different methods using thermogravimetric analysis

A kinetic study based on pinewood (Pinus montezumae) was carried out at heating rates of 5, 10, 15, and 20 °C min−1. The Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Friedman methods were used to analyze the thermal behavior of samples. Thermogravimetry (TG) and derivative thermogravimetry (DTG) curves were obtained at non-isothermal conditions. Ultimate and proximate analyzes from pinewood were obtained and the greater decomposition was in the range of 250 to 380 °C. Mean values of activation energy (Ea) and frequency factor (A) by FWO method were 192.4 kJ mol−1 and 2.73 × 1014 min−1, respectively, whereas the aforementioned values by KAS method were 181.8 kJ mol−1 and 3.32 × 1013 min−1. Lower value of mean activation energy (174.1 kJ mol−1) was obtained with Friedman method.