Differential Thermogravimetric Curves Research Articles

Experimental and theoretical quantum chemical studies of 2-(2-acetamidophenyl)-2-oxo-N-(pyridin-2-ylmethyl)acetamide and its copper(II) complex: molecular docking simulation of the designed coordinated ligand with insulin-like growth factor-1 receptor (IGF-1R)

Newly synthesized ligand 2-(2- acetamidophenyl)-2-oxo-N-(pyridin-2-ylmethyl)acetamide and its copper(II) complex were characterized by elemental analyses, FT-IR, UV–Vis., ESR, 1H-NMR, and thermal analysis along with the theoretical quantum chemical studies. Combined experimental and theoretical DFT (density functional theory) studies showed the ligand to be a tridentate ligand with three coordinate bonds. The complex was suggested to be in a distorted octahedral structure with dx2-y2 ground state. The activation energy, ΔE*; entropy ΔS*; enthalpy ΔH* and order of reaction has been derived from differential thermogravimetric (DTA) curve, using Horowitz–Metzeger method. The nujol mull electronic spectrum of the ligand and Cu(II) complex have been recorded and the difference of the excited and ground state densities has also been theoretically calculated and plotted to investigate the movement of electrons on excitation. The Cu(II) complex was evaluated for its antibacterial activity against two bacterial species, namely Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Antifungal screening was performed against two species (Condida albicans and Aspergillus flavus). The complex under investigation was found to possess notable biological activity. Molecular docking investigation predicted different types of non-covalent interactions of the synthesized ligand towards Insulin-like growth factor 1 receptor (ID: 5FXR).

Synthesis, investigation of temperature and salt resistant polyacrylamide microspheres used for deep sealing and profile control and function strengthening mechanism

AbstractBased on the requirements of deep sealing and profile control for the excellent temperature and salt resistance on polyacrylamide microspheres, the Poly‐AM/AMPS was prepared depends on aqueous solution polymerization method to improving oil and gas recovery efficiency in low‐permeability and heterogeneous reservoirs resulted by water channeling. The key technical parameters were established through single‐factor experimental methods, and the chemical structure was studied by infrared spectrum analysis (FTIR), energy spectrum analysis, and x‐ray diffraction analysis, and then the thermal stability was investigated depends on the thermogravimetric (TG) and differential thermogravimetric (DTG) distribution curves, moreover, the particle size and distribution, microstructure, and surface morphology were further studied. As a result, the results confirmed that the molecular structure of Poly‐AM/AMPS meets the expected design, and the quality retention rate at 800°C is 17.4%, the median particle size of Poly‐AM/AMPS particles is 35.88 μm, and the particle size distribution range is about 1.94–497.8 μm. Further, the Poly‐AM/AMPS was modified by maleic anhydride, sodium styrenesulfonate, and dimethyl diallyl ammonium chloride through conventional functional strengthening and modification, modified by nano‐SiO2, GO, and S‐CaCO3 through nano‐functional strengthening and modification. Additionally, the functional strengthening and modification mechanism was studied depends on the FTIR, TG, and DTG methods.

Elaeis guineensisleaves for potential renewable sub‐bituminous coal: Optimization of biochar yield by response surface methodology and product characterization

AbstractPyrolysis of oil palm biomass residue can convert the rich organic matter in biomass into sustainable green energy, thereby addressing the challenge of surplus oil palm biomass residue generated during cultivation. Nonetheless, the pyrolysis of oil palm leaves (OPLs) has received limited attention. In this study, design of experiment‐response surface methodology (DoE‐RSM) was employed to identify the optimal combination of reaction temperature, residence duration, and nitrogen (N₂) flow rate for maximum biochar yield. The elemental analysis, high heating value (HHV), functional group, morphology, pore structure, and thermal behavior were assessed. By varying the operational parameters using response surface methodology, the biochar yield increased by 32.6–85.3%. TheDoE‐RSMpredicted a theoretical yield of 52.1% at 344 °C, 146 min, and 3.2 scfh N₂ flow rate. The experiment confirmed a comparable yield of 53.7% at the stated parameters. TheHHVof 24.14 MJ kg−1was recorded under optimal conditions, and was comparable to sub‐bituminous and bituminous coal. Fourier transform infrared analysis validated theOPLbiochar by weakeningO‐H, C=O,C‐OH, andC‐Hpeaks. Scanning electron microscopy images revealed enlarged pores and altered morphology in theOPLbiochar. X‐ray diffraction showed lower crystallinity of theOPLbiochar than the feedstock. Raman spectroscopy showed higherID/IG, indicating a more disordered carbon structure in theOPLbiochar. Thermogravimetric analysis confirmed higher temperature for main devolatilization ofOPLbiochar, and the differential thermogravimetric analysis curve pattern resembled that of Mukah Balingan coal. The findings are helpful for an initiative to convert a large amount of leftoverOPLsproduced during cultivation and to turn them into high value‐added material for a sustainable contribution to a circular carbon economy.

Optimization of Three Extraction Methods and Their Effect on the Structure and Antioxidant Activity of Polysaccharides in Dendrobium huoshanense.

Dendrobium huoshanense is a famous edible and medicinal herb, and polysaccharides are the main bioactive component in it. In this study, response surface methodology (RSM) combined with a Box-Behnken design (BBD) was used to optimize the enzyme-assisted extraction (EAE), ultrasound-microwave-assisted extraction (UMAE), and hot water extraction (HWE) conditions and obtain the polysaccharides named DHP-E, DHP-UM, and DHP-H. The effects of different extraction methods on the physicochemical properties, structure characteristics, and bioactivity of polysaccharides were compared. The differential thermogravimetric curves indicated that DHP-E showed a broader temperature range during thermal degradation compared with DHP-UM and DHP-H. The SEM results showed that DHP-E displayed an irregular granular structure, but DHP-UM and DHP-H were sponge-like. The results of absolute molecular weight indicated that polysaccharides with higher molecular weight detected in DHP-H and DHP-UM did not appear in DHP-E due to enzymatic degradation. The monosaccharide composition showed that DHPs were all composed of Man, Glc, and Gal but with different proportions. Finally, the glycosidic bond types, which have a significant effect on bioactivity, were decoded with methylation analysis. The results showed that DHPs contained four glycosidic bond types, including Glcp-(1→, →4)-Manp-(1→, →4)-Glcp-(1→, and →4,6)-Manp-(1→ with different ratios. Furthermore, DHP-E exhibited better DPPH and ABTS radical scavenging activities. These findings could provide scientific foundations for selecting appropriate extraction methods to obtain desired bioactivities for applications in the pharmaceutical and functional food industries.

The effect of modified carbon-doped boron nitride on the mechanical, thermal and γ-radiation stability of silicone rubber composites

The developing nuclear technology has increased the need for radiation-resistant and shielding materials. It is crucial to study the radiation resistance of polymers in order to prevent safety incidents brought on by the degradation of polymer performance in a nuclear environment. In this work, γ-aminopropyltriethoxy silane (KH550) was successfully grafted onto carbon-doped boron (BCN) to obtain modified BCN (BCN-KH550), then BCN-KH550 was added in silicone rubber and refined and vulcanized. The elongation at break of silicone rubber composite doped with 0.3 phr BCN-KH550 can retain (54 ± 2)% of the initial value. The addition of BCN and BCN-KH550 both increases the initial decomposition temperature of the irradiated SR. The radiation caused changes in crystallinity and glass transition temperature (Tg) were measured using differential scanning calorimetry. The difference Tg of BCN-KH550/SR0.3 before and after irradiation is 0.9 °C higher than that of SR. It is supposed that BCN protects the side group of SR during irradiation through differential thermogravimetric analysis curve and gas phase infrared spectra of the irradiation-induced gas products. BCN and BCN-KH550 can lower the hydrocarbon, CO2 and CO production by side chain breakdown in both air and nitrogen atmospheres. The presence of BCN and BCN-KH550 decrease the radiation crosslinking of SR. The outcomes demonstrate that BCN-KH550 can reduce the effects of γ-radiation crosslinking on SR by declining side chain decomposition.

Synthesis, Spectral Characterization, Thermal Investigation, Computational Studies, Molecular Docking, and In Vitro Biological Activities of a New Schiff Base Derived from 2-Chloro Benzaldehyde and 3,3'-Dimethyl-[1,1'-biphenyl]-4,4'-diamine.

The current research involves the synthesis of a new Schiff base through the reaction between 2-chlorobenzaldehyde and 3,3'-dimethyl-[1,1'-biphenyl]-4,4'-diamine by using a natural acid catalyst and a synthesized compound physicochemically characterized by X-ray diffraction, Fourier transform infrared spectroscopy, 1H- and 13C-nuclear magnetic resonance, and liquid chromatography-mass spectrometry. Thermal studies were conducted using thermogravimetric, differential thermal analysis, and differential thermogravimetric curves. These curves were obtained in an inert nitrogen environment from ambient temperature to 1263 K using heating rates of 10, 15, and 20 K·min-1. Using thermocurve data, model-free isoconversional techniques such as Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa, and Friedman are used to determine kinetic parameters. These parameters include activation energy, phonon frequency factor, activation enthalpy, activation entropy, and Gibb's free energy change. All of the results have been thoroughly investigated. The molecule's anti-inflammatory and antidiabetic properties were also examined. To learn more about the potential of the Schiff base and how successfully it can suppress the amylase enzyme, a molecular docking experiment was also conducted. For in silico research, the Swiss Absorption, Distribution, Metabolism, Excretion, and Toxicity algorithms were used to calculate the theoretical pharmacokinetic properties, oral bioavailability, toxic effects, and biological activities of the synthesized molecule. Moreover, the cytotoxicity tests against a human lung cancer cell line (A549) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay demonstrated that the synthesized Schiff base exhibited significant anticancer properties.

Air and oxy-fuel combustion characteristics of coal gangue and weathered coal blends

Oxy-fuel combustion technology is suggested as one of the promising technologies for capturing CO2. The combustion characteristics of blends of a coal gangue and a weathered coal under air (21% O2/79% N2), oxy-fuel (20% O2/80% CO2) and oxygen-enriched oxy-fuel (40% O2/60% CO2) conditions were studied using a thermogravimetric analysis (TGA) technique operating at heating rate 10 oCmin−1 to a final temperature 900 °C, focussing on the effect of blending ratio and atmosphere. While the differential thermogravimetric (DTG) profiles of coal gangue in the three different atmospheres were very similar, the weathered coal showed a sharp peak in the temperature range 400–440 °C under oxygen-enriched oxy-fuel condition, which was different from DTG curves under air and oxy-fuel conditions. The blending of the coal gangue into the weathered coal gradually diminished this peak. The negligible deviations between the experimental DTG curves and theoretical DTG curves indicated that interactions were absent for all the coal gangue/weathered coal mixtures under air and oxy-fuel conditions. The obvious interactions between coal gangue and weathered coal were observed under oxygen-enriched oxy-fuel condition and the interaction may be related to thermal effect. The interactions increased as the increasing weathered coal ratio in blends and increasing oxygen concentration under oxy-fuel conditions.

A new, improved method to identify reaction mechanisms based on the shape of derivative thermogravimetric curves

This study firstly presents a summary of using differential thermogravimetric (DTG) data for identifying reaction mechanisms of solid-state reactions. It shows that applying features delineated in currently-used models for initial and final temperatures are problematic during the classification of reaction mechanisms. Secondly, it develops a relationship linking the number of distinct peaks in second derivative thermogravimetric (DDTG) curves for selecting reaction mechanisms. An analysis is also given discussing the maximum conversion rates and relevant values of half widths in DTG curves, and recommends modified limits of these parameters which cover a greater majority of solid-state reactions. Based on the revised parameters, a new flow chart is developed to define reaction mechanisms. This flow chart is applied to the experimental combustion of three different of coal samples for which data analyses proved to be simple and reliable, and then from which distinct reaction mechanisms were determined successfully.

A preliminary multistep combination of pulsed electric fields and supercritical fluid extraction to recover bioactive glycosylated and lipidic compounds from exhausted grape marc

This article reports the first multistep combination of pulsed electric field (PEF; 3 kV/cm, 100 kJ/kg, 2 Hz, 100 ms) and supercritical fluid extraction (SFE) with CO2 (10–20 MPa, 25 mL/min [10% EtOH], 50 °C, 60 min) for exhausted grape marc (EGM). This current protocol was mainly created to recover bioactive glycosylated and lipidic compounds. In this regard, total antioxidant capacity (TAC) was enhanced up to 68% after PEF treatment compared to conventional soaking. However, re-extracting PEF-treated EGM after the application of SFE (PEF + SFE) boosted the efficiency by up to 87%. Several polyphenols (kaempferol, luteolin, scutellarin, and resveratrol, among others), together with other glycosylated structures, were identified by liquid chromatography coupled with mass spectrometry analysis. The bioactive lipidic compounds extracted by SFE, along with the carbohydrate fraction (free sugars) favourably extracted by PEF pre-treatment (mainly glucose, but also fructose and sucrose), were concurrently detected by nuclear magnetic resonance. The remaining solid fraction after treatment was also characterised. Different microscopic morphology was observed by scanning electron microscopy (SEM) on untreated, PEF, and PEF + SC–CO2–treated EGM. Differential thermogravimetric (DTG) curves determined by thermogravimetric analysis (TGA) also suggested alternative and potential means for the valorisation of this matrix.

Oxidative Conversion of Chars Generated from the Fixed-Bed Pyrolysis of Wood Torrefied at Different Temperatures and Holding Times

Fixed-bed pyrolysis of torrefied spruce wood, for a heating temperature of 800 K, results in char yields between about 27–57 wt% (versus 23 wt% for untreated wood), depending on both pre-treatment temperatures (533–583 K) and holding times (8–25 min). In this study char oxidation behavior and kinetics are investigated by means of thermogravimetric analysis. The differential thermogravimetric curves always showed a low-temperature zone of slow rates (oxidative devolatilization), followed by a high-rate zone with a well-defined peak (oxidation). As the torrefaction severity increases, the temperature range of the oxidative devolatilization enlarges. Moreover, the oxidation rates become slower (both burning and burnout temperatures tend to increase). As already found for untreated wood chars, the two stages are well described by a linear and a power-law rate reaction, respectively. Volatiles released from the devolatilizations are approximately around 20 wt%, but torrefaction causes lower activation energies (66–92 kJ/mol versus 117 kJ/mol). The oxidation activation energies also decreas (170–168 kJ/mol versus 193 kJ/mol), accompanied by small variations in the reaction order.

Thermal decomposition study of cadmium telluride (CdTe)

Pure CdTe crystalline material is synthesized at 1073 K temperature in a closed tube under vacuum in horizontal tubular furnace. The synthesized material is found to be stoichiometric having atomic % of Cd: 49.31 and Te: 50.69 as determined by energy dispersive analysis of X-ray. The material is CdTe phase with cubic unit cell structure possessing lattice parameters of a = b = c = 6.48 Å as determined by X-ray diffraction. The morphology of the as-synthesized material is studied by scanning and transmission electron microscopy. The morphology showed clusters of varying sizes ranging from sub-micron to nano having stacked layers. The Raman spectroscopy showed three peaks positioned at 91, 120 and 140 cm−1, corresponding to CdTe. The thermogravimetric, differential thermogravimetric and differential thermal analysis curves of synthesized CdTe are recorded in the temperature range of ambient to 1233 K for three heating rates of 10, 15 and 20 K⋅min−1. The thermocurves demonstrated one-step decomposition of the as-synthesized CdTe material. The thermodynamic parameters, such as activation energy (Ea), activation enthalpy change (ΔH*), Gibb’s free energy change (ΔG*), activation entropy change (ΔS*) and phonon frequency factor (A) are calculated by model-free isoconversional methods. The obtained data and outcomes are discussed thoroughly.

Thermal exploration of sonochemically achieved SnS2 nanoparticles: Elemental, structural, and morphological investigations of TG residual SnS2

The nanoparticles (Nps) of tin disulfide (SnS2) are synthesized by sonochemical route. The Nps are characterized by dispersive analysis of X-ray energy (EDAX) and X-ray photoelectron spectroscopy (XPS) to get the chemical composition. The diffraction of X-ray (XRD) is used for determination of phase and crystal structure. The as-synthesized Nps are polycrystalline and possess hexagonal structure. The surface morphology of the as-synthesized Nps is examined by electron microscopy in scanning (SEM) and high-resolution transmission modes. The residual sample after the thermal analysis is characterized by EDAX, XPS, XRD, SEM and Fourier transformed infra-red spectroscopy. The obtained results of the post-thermal analyzed and as-synthesized SnS2 Nps samples are compared. The thermal analysis of the Nps is carried out by recording the thermogravimetric and differential thermogravimetric curves. These simultaneous thermo-curves are recorded in the temperature range of ambient to 850 K in inert nitrogen atmosphere for three heating rates of 5, 10, 15 and 20 K·min−1. The thermal curves data are analyzed by the isoconversional Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa, and Friedman methods, and the thermodynamic parameters; activation energy (Ea), change in activation entropy (ΔS*), change in activation enthalpy (ΔH*) and change in activation Gibb's free energy (ΔG*) are determined. All the obtained outcomes are discussed in detail.

The Use of Hybrid Genetic Algorithm in the Kinetic Analysis of Thermal Decomposition of [Ni(C2H8N2)3](ClO4)2 with Overlapping Stages.

This work describes the mathematical modeling of the thermal decomposition of the complex compound [Ni(En)3](ClO4)2 (En = C2H8N2 = ethylenediamine) in an inert atmosphere under non-isothermal conditions. This process is characterized by several simultaneous and intense stages: elimination of ethylenediamine from the nickel coordination sphere, decomposition of perchlorate anions, and explosive-like oxidation of free or bound ethylenediamine. These stages overlap and merge into a one step on the differential thermogravimetric curve. Typically, this curve is modeled as a one-stage process during kinetic analysis. In this paper, for the first time, the data from the dynamic mass-spectral thermal analysis and thermogravimetric analysis were modeled using the hybrid genetic algorithm, and the results were compared. A two-stage scheme of [Ni(En)3](ClO4)2 thermolysis was proposed and the kinetic parameters for each stage were obtained. It was shown that the decomposition of [Ni(En)3](ClO4)2 begins with the elimination of one molecule of ethylenediamine (stage A), then the perchlorate anions quickly decompose with the evolution of oxygen (stage B). We believe that the resulting ClO4-x- (x = 1-3), as stronger oxidizing agents, instantly start an explosive-like exothermic process of ethylenediamine oxidation (stage B).

Investigation of Thermal Decomposition and Gases Release from Pre-Drying Municipal Solid Waste (PMSW) Via Pyrolysis Technology

Abstract Present study investigates the thermal decomposition and syngas potential of pre-drying municipal solid waste (PMSW) via pyrolysis using thermo-gravimetric (TGA) analyzer coupled with the mass spectrometer (MS). The experiments were performed at the heating rates 5 and 15°C/min. Differential thermo-gravimetric (DTG) curves exposed four conversion phases at lower heating rate and two conversion phases at higher heating rate. MS analysis of the evolved gases H2, CO, and CH4 revealed that the devolatilization phase played a major role during the processes. Higher H2 generation was observed at a lower heating rate due to more contact among PMSW and process temperature. Higher CO and CH4 were also favored at lower heating rate. Total yield of gases was found higher due to higher CO generation. For the estimation of activation energy (Ea), Flynn-Wall-Ozawa (FWO) kinetic model was applied at the conversion rates (α) ranged from 5–35. In overall, the lower heating rate supported the higher WMSW conversion as well as higher gas released during the process. Hence, this study will help to evaluate the H2 potential of the PMSW using pyrolysis thermal technology.

Engineered UIO-66 metal-organic framework for delivery of curcumin against breast cancer cells: An in vitro evaluation

Curcumin (Cur) is a traditional herb with known anticancer properties against various malignancies such as breast cancer. In this study, a metal-organic framework (MOF) based on UIO-66 with excellent water stability was prepared to deliver Cur into MDA-MB-231 and SKBR3 human breast cancer cell lines. The size of the fabricated UIO-66 ranged from 100 to 150 nm with a spherical shape and triangular base pyramid morphology. Favorable adsorption of Cur on the UIO-66 was approved by Fourier transform infrared spectroscopy (FTIR). The release profile exhibited a slow pH-dependent release of Cur from UIO-66 with significant enhancement in the acidic microenvironment (50, 55, and 70% Cur release from UIO-66-Cur in pH values of 7.4, 6.5, and 5.4 in 72 h test), showing UIO-66-Cur versatile releasing capacity in the acidic milieu of breast cancer. The characterization and structural elucidation of nanoparticles were evaluated by N2 adsorption–desorption, thermogravimetric analysis (TGA), differential thermogravimetric (DTG), Brunauer Emmett-Teller (BET), Barrett-Joyner Halenda (BJH), and adsorption kinetics that showed promising results. Particularly, the UIO-66-Cur exhibited the highest adsorption capacity for Cur. The kinetics of drug adsorption were investigated by three well-known kinetic models, and the result indicated that the adsorption of the drug into the synthesized MOFs followed the pseudo-second-order model. TGA and DTG curves of UIO-66 demonstrated a three-step weight reduction. The N2 adsorption/desorption isotherms and pore size distribution characteristics of UIO-66. The BET surface area and total pore volume of UIO-66 were computed to be 910.58 m2/g and 0.49 cm3/g. The size and entrapment efficacy (EE) of nanoparticles were more stable at 4 °C compared to 25 °C. Furthermore, the cytotoxic effects of UIO-66-Cur against MDA-MB-231 and SKBR3 cell lines were demonstrated using MTT assay, flow cytometry, gene expression profile, migration assay, and DAPI staining. The MTT assay revealed the high biocompatibility of UIO-66 with MCF10A healthy breast cell line (95% viability at a concentration of 200 μg/ml), whereas UIO-66-Cur showed cytotoxicity toward MCF10A at high concentrations (78% viability at concentration of 200 μg/ml). Furthermore, loading of Cur into UIO-66 notably increased its anticancer activity as the IC50 of UIO-66-Cur was significantly lower than Cur (72.2 vs. 159.3 against SKBR3 and 109.3 vs. 269.1 against MD-MBA-231 in 72 h test). It was shown that loading of Cur into UIO-66 profoundly promotes its anticancer activity as UIO-66-Cur significantly induced caspase 3 and caspase 9 and inhibited MMP-2, MMP-9 and cyclin E/D expression in cancer cell lines.

Thermal and electrical transport property study of direct vapour transport grown Cu2SnS3 single crystals

Copper tin sulphide (Cu2SnS3) (CTS) single crystals are grown by vapour transport technique of direct (DVT) type. The stoichiometric compositional analysis; Cu: 40.78 % (37.21 %), Sn: 31.09 % (34.35 %) and S: 28.13 % (28.15 %); showed the crystals to be slightly copper rich and tin deficient, bracket values are standard data. The X-ray diffraction showed the CTS to possess cubic unit structure having lattice parameter of 5.43 Å. The high resolution transmission electron microscopy substantiated the crystalline character. The thermal analysis are carried out by recording simultaneous thermogravimetric, differential thermogravimetric and differential thermal analysis curves. These analysis are done in inert atmosphere for three heating rates of 10, 15 and 20 K⋅min−1 in the range from ambient to 1023 K. The thermocurves are analyzed by two standard methods of Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The thermodynamic parameters like activation energy, changes of entropy, enthalphy and Gibbs free energy are determined using KAS and FWO methods. These determined thermodynamic parameters of as-grown CTS single crystals matches each other stating the validity of the analysis. Temperature variation of electrical transport properties like dc electrical resistivity (ρ) and Seebeck coefficient (S) are measured in the temperature range of 323 K to 473 K. The values of ‘ρ’ decreases with temperature, stating semiconducting nature of crystals. The observed ‘S’ values are found to be positive in entire temperature range, stating crystals to be of p-type semiconducting nature.

Comparison and characterization of torrefaction performance and pyrolysis behaviour of softwood and hardwood

ABSTRACT In this study, the torrefaction and pyrolysis behaviors of softwood (pinewood) and hardwood (teakwood) were experimentally explored. Three different torrefaction temperatures (i.e. 210, 240, and 270°C) and two different residence times (20 and 40 min) were adopted. Various property indicators, for example, solid and energy yields, enhancement factor of higher heating value (HHV), and torrefaction severity index, were used to characterize the torrefaction performance. The principal component analysis (PCA) demonstrated the correlation among different torrefied samples with the help of chemical composition, solid yield, and HHV. Moreover, slow pyrolysis experiments were conducted at three different heating rates (i.e. 15, 30, and 40°C/min) to investigate the thermal degradation behavior of the torrefied biomass samples. Both thermogravimetric and differential thermogravimetric curves shifted to a higher temperature as the pyrolysis heating rate increased. The activation energies E a were estimated by using three isoconversional methods, that is, Kissinger-Akahira-Sunose (KAS), Starink and Flynn-Wall-Ozawa (FWO) methods. The E a broadly increased with torrefaction severity. When using the FWO method, the average E a values ranged from 97.51 to 168.68 kJ/mol and 120.73 to 180.25 kJ/mol for torrefied pinewood and teakwood samples, respectively. Scanning electron microscopy (SEM) images revealed that at higher torrefaction conditions, the samples experienced severe structural damages, leading to crack formation and augmentation. All these observations not only reveal that torrefaction can turn raw biomass into fuel with improved properties but also help to clarify the differences between soft and hardwood for energy utilization purpose.

Influence of flue gas torrefaction on the fuel properties and pyrolysis characteristics of real components of corn stalk

The aim of this study was to identify the changes in fuel properties and pyrolysis characteristics of the torrefied real components of corn stalk. The isolated components were torrefied with simulated flue gas and nitrogen in a thermogravimetric analyzer at 230, 260 and 290 °C for 30 min. The ultimate analysis indicated that flue gas atmosphere was beneficial to improving the fuel properties of isolated components. Compared to non-oxidative atmosphere, the flue gas had a greater impact on the initial pyrolysis temperature and char yield of the isolated components. The results of mathematical deconvolution analysis (MDA) demonstrated that the pyrolysis weight losses of native mixture could be quantitatively represented by the linear summation of isolated components. The differential thermogravimetric (DTG) characteristic curves could be used to qualitative analyze the changes in relative contents of the structural components of the torrefied biomass.

Dual effect of CaO on waste PVC plastics pyrolysis: A kinetics study using Fraser-Suzuki deconvolution

Green and sustainable treatment of waste plastics emerged as one of the greatest challenging matters facing the world. In this work, the pyrolysis of chlorine-contained PVC plastics was investigated from a kinetic study perspective. The dual effects of calcium oxide (CaO) additive were examined. The Fraser-Suzuki deconvolution function was adopted to fit the differential thermogravimetric (DTG) curves into three pseudo-reactions. The apparent activation enegry (Ea), pre-exponential factor (A) and reaction mechanism models (f(a)) for each pseudo-reaction were identified. The results show that the use of CaO increased significantly the Ea value of the dehydrochlorination reaction but lowered that of the tar cracking reactions, indicating an apparent HCl release mitigation as well as tar compounds decomposition. The mechanism models of the three pseudo-reactions kept identical with or without CaO addition, which were A4 Avrami-Erofeev: ƒ(α)=4(1-α) [-ln(1-α)]3⁄4 for pseudo-reactions 1 and 3 and B1 Prout-Trompkins: ƒ(α)=α(1-α) for pseudo-reactions 2. The kinetic models of the pyrolysis of waste PVC and the mixtures were thus established. The obtained results could be used as a theoretical basis for the development and application of clean and efficient waste PVC plastics pyrolysis technology.

The Potential Application of Natural Clinoptilolite-Rich Zeolite as Support for Bacterial Community Formation for Wastewater Treatment.

The aim of this study was to investigate the use of natural zeolite as support for microbial community formation during wastewater treatment. Scanning electron microscopy (SEM), thermal decomposition and differential thermogravimetric curves (TGA/DGT) techniques were used for the physicochemical and structural characterization of zeolites. The chemical characterization of wastewater was performed before and after treatment, after 30 days of using stationary zeolite as support. The chemical composition of wastewater was evaluated in terms of the products of nitrification/denitrification processes. The greatest ammonium (NH4+) adsorption was obtained for wastewater contaminated with different concentrations of ammonium, nitrate and nitrite. The wastewater quality index (WWQI) was determined to assess the effluent quality and the efficiency of the treatment plant used, showing a maximum of 71% quality improvement, thus suggesting that the treated wastewater could be discharged into aquatic environments. After 30 days, NH4+ demonstrated a high removal efficiency (higher than 98%), while NO3+ and NO2+ had a removal efficiency of 70% and 54%, respectively. The removal efficiency for metals was observed as follows (%): Mn > Cd > Cr > Zn > Fe > Ni > Co > Cu > Ba > Pb > Sr. Analysis of the microbial diversity in the zeolite samples indicated that the bacteria are formed due to the existence of nutrients in wastewater which favor their formation. In addition, the zeolite was characterized by SEM and the results indicated that the zeolite acts as an adsorbent for the pollutants and, moreover, as a support material for microbial community formation under optimal conditions. Comparing the two studied zeolites, NZ1 (particle size 1–3 mm) was found to be more suitable for wastewater treatment. Overall, the natural zeolite demonstrated high potential for pollutant removal and biomass support for bacteria community growth in wastewater treatment.