Thermogravimetry Curves Research Articles

Experimental study on the influence of water immersion on spontaneous combustion of anthracite with high concentrations of sulfur-bearing minerals

The influence of water immersion on the spontaneous combustion characteristics of anthracite with high concentrations of sulfur-bearing minerals was studied using simultaneous thermogravimetry–mass spectrometry (TG-MS), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction. In addition, variations in the structural parameters, mass, heat release and gas evolution processes before and after water immersion were investigated. The results showed that the coal sample contained a large amount of pyrite (FeS2). After 45 days of immersion, the pyrite content in the coal decreased, and the infrared absorption peak of Si (Al)–O at 1116 cm−1 disappeared. The TG curves did not show a mass increase. Moreover, the initial reaction temperature of immersed coal was 39 °C lower than that of raw coal, and the heat release increased by 127.3 J g−1. The gas products in the samples varied mainly in quantity but not in species. MS and FTIR analyses revealed that SO2 was the main gas produced, and the maximum SO2 gas evolution temperatures of both coal samples were similar to the peak temperatures in the differential thermogravimetry and differential scanning calorimetry (DSC) curves. Furthermore, the infrared 3D spectrogram revealed that gas generated by immersed coal was detected at a lower temperature, the peak temperature occurred earlier, and the evolved intensity was stronger.

Physicochemical Studies on Some Coordination Biopolymer Compounds: Kinetics of Thermal Degradation and Heterogeneous Chemical Equilibrium of Ion Exchange for Coordination Biopolymer Zirconium (IV)- Alginate Complex

Thermogravimetry (TG) and differential thermogravimetry (DTG) techniques have been applied for studying the kinetics of thermal degradation of coordination biopolymer zirconium (IV)- alginate complex in static air. The DTG curves indicated the presence of a series of thermal peaks associated with three distinct stages of TG curves, i.e. three stages of degradation were observed. The first stage of degradation was corresponding to the dehydration of four coordinated water molecules in the first step, followed by degradation of the formed dehydrated compound in the other two following stages. The kinetic parameters were computed by a set of different models and a tentative degradation mechanism consistent with the kinetic observations is discussed. In addition, the heterogeneous chemical equilibrium for ion exchange process of Zr4+ counter ions chelated in the biopolymer coordination complex by exchangeable H+ ions of acid electrolyte have been investigated by using both the complexometric and titrimetric techniques. The kinetic and thermodynamic parameters have been evaluated and discussed in terms of the complex stability related to the strength of chelation and geometrical structure of coordination complex.

Characterization of solid char produced from pyrolysis of the organic fraction of municipal solid waste, high volatile coal and their blends

In this study, the organic fraction of municipal solid waste (Org-MSW) was blended with high-volatile coal (HVC) in proportions of 25/75%, 50/50%, 75/25% by weight. Pyrolysis of these mixtures was then investigated in a thermogravimetric analyzer (TGA) and a horizontal tube furnace under a nitrogen environment. The mass loss rate of samples, differential thermogravimetry (DTG) curves and kinetic analysis of the samples were compared for both blended and non-blended samples. Higher gas yields were seen with increasing pyrolysis temperature for both samples. In addition, the kinetic analysis indicated that the apparent activation energy values of org-MSW samples varied from 535 to 5284 kJ/kmol (over the temperature range of 100–887 °C), while the values for HVC were 247–962 kJ/kmol. The activation energy for HVC varied with temperature and the highest value of 2036 kJ/kmol was found in the temperature range of 336–490 °C. Comparable results were obtained between the TGA and fixed bed tests on the residual char fraction. The findings of this work will be very important in developing a co-firing technology for solid waste residuals and coal for energy production.

Non-Isothermal Decomposition Kinetic of Polypropylene/Hydrotalcite Composite.

P₃O5-10 pillared Mg/Al hydrotalcite (HTs) as a functional fire-retarding filler was successfully prepared by impregnation-reconstruction, where the HTs was used to prepare polypropylene (PP) and HTs composite (PP/HTs). Thermal decomposition was crucial for correctly identifying the thermal behavior for the PP/HTs, and studied using thermogravimetry (TG) at different heating rates. Based on single TG curves and Málek method, as well as 41 mechanism functions, the thermal decompositions of the PP/HTs composite and PP in nitrogen atmosphere were studied under non-isothermal conditions. The mechanism functions of the thermal decomposition reactions for the PP/HTs composite and PP were separately "chemical reaction F₃" and "phase boundary reaction R₂," which were also in good agreement with corresponding experimental data. It was found that the addition of the HTs increased the apparent activation energy Ea of the PP/HTs comparing to the PP, which improved the thermal stability of the polypropylene. A difference in the set of kinetic and thermodynamic parameters was also observed between the PP/HTs and PP, particularly with respect to lower ΔS≠ value assigned to higher thermal stability of the PP/HTs composite.

Novel solid-state compounds of heavy rare-earth (III) picolinates. A pyrolytic study using: TG-DSC-IR, HSM-MS and GC-MS

Heavy trivalent lanthanides and yttrium picolinates were synthesized by complexation of basic rare-earth metal carbonates with an aqueous solution of picolinic acid. The novel compounds were obtained with the general formula Ln(L)3∙nH2O, where L is picolinate and n = 1.5 H2O (Dy, Ho, Yb, Lu and Y), 2 H2O (Tb and Tm) and 2.5 H2O (Er). The stoichiometry of the complexes was calculated through mass losses found using thermogravimetry (TG), complexometry and elemental analysis (EA). The thermal behavior in oxidative and pyrolytic atmospheres of the compounds was analyzed by simultaneous thermogravimetry - differential scanning calorimetry (TG-DSC). The gaseous products of the pyrolysis were determined throughout by monitoring the evolved species using TG-DSC couple to Fourier transform infrared spectroscopy (TG-DSC-IR), hot-stage microscopy mass spectrometry (HSM-MS), and gas chromatography-mass spectrometry (GC-MS). The obtained results validated mass loss assignments made using the TG curves. However, gaseous product analysis indicates the degradation processes are more complex than the thermoanalytical techniques suggest alone. This study used a GC-MS technique to identify the condensed gaseous products obtained during the second step of thermal degradation of the picolinate complexes. The analysis of the symmetric and asymmetric stretching frequencies of the carboxylate group in the IR spectra showed a monodentate bonding mode. The compounds were obtained in the amorphous state, as indicated by the powder x-ray diffractometry (PXRD) data.

Influence of ultrasonic pretreatment on the co-pyrolysis characteristics and kinetic parameters of municipal solid waste and paper mill sludge

In this study, through orthogonal experiments design, the influences of ultrasonic pretreatment (frequency, power and treatment time) on co-pyrolysis and catalytic pyrolysis of municipal solid waste and paper mill sludge were explored. The differential thermogravimetry curves became steeper and the peak values were larger after pretreatment, which made the pyrolysis reaction rapidly and the volatile separated out timely. However, the change of pyrolysis characteristics was not obvious after adding MgO. The catalytic effect of MgO increased with the increase of sludge ratio. After pretreatment, the average activation energy of the samples had an overall increasing trend, but the change was small. MgO had a decreasing effect on activation energy, and with the increasing proportion of sludge the degree of reduction became significant. In addition, high ultrasonic frequency had a negative effect on reducing activation energy.

Thermal decomposition, kinetics and electrical measurements of Poly(3-Acetamidopropyl Methacrylate)/graphite composites

3-Acetamidopropyl methacrylate [AAPMA] (monomer) were synthesized. The homopolymer of AAPMA was prepared by free radical polymerization method. Novel composites based on poly(3-acetamidopropyl methacrylate) [PAAPMA] containing graphite nanoparticles were prepared using ultrasonic bath. The decomposition behavior of PAAPMA before and after adding graphite to PAAPMA was thermally investigated through thermogravimetric analysis measurements (TGA). Flynn-Wall-Ozawa method for thermal decomposition kinetics of poly(AAPMA) was applied to thermogravimetry curves. The activation energies for the first stage of poly(AAPMA), poly(AAPMA)/1.5% by wt graphite and poly(AAPMA)/6.0% by wt graphite are found to be 115 kJ/mol, 76.7 kJ/mol and 58.7 kJ/mol for conversion of 0.40, respectively. The activation energies in the second step are found to be 116 kJ/mol and 57 kJ/mol at the different conversion of 0.75, respectively. The thermal degradation of both poly(AAPMA) and poly(AAPMA)/graphite 6.0% by wt showed that monomer produced by main chain breaking. And also, in case of composite with graphite 6.0% by wt of poly(AAPMA) was observed that the more amount of monomer revealed at lower temperatures during degradation of composite. 1H, 13C-NMR, FT-IR and GC-MS analyses results showed that as major component of products formed during degradation of the pure polymer (to 365 °C) and poly(AAPMA)/graphite 6.0% by wt (to 265 °C) was AAPMA (monomer). Electrically conductivity of graphite-based poly(AAPMA) composites were investigated. So, dc and ac electrical conductivity and dielectric properties, i.e., real and imaginary parts of the permittivity of pure polymer and polymer composites were revealed. The ac dielectric measurements of poly(AAPMA) were investigated at room temperature between 100Hz and 2kHz depending on the alternating current conductivities. The dipolar functional groups (C-O, C = O and N-C = O) of the AAPMA segment showed that possess significantly effect on the dielectric constant. Also, the activation energy profile of different poly(AAPMA)/graphite composites was revealed by measuring dc conductivity of individual composite material.

Principles of the Construction of Polymer Structures, Heteronuclear (13C, 15N) CP-MAS NMR, and Thermal Behavior of Heteroleptic Bismuth(III) Complexes of the General Composition [Bi(S2CNR2)2X] (X = NO3, Cl)

The crystalline heteroleptic bismuth(III) complexes, [Bi{S2CN(iso-C4H9)2}2(NO3)] (I) and [Bi{S2CN(C3H7)2}2Cl] (II), are isolated in preparative yields. Both compounds form 1D polymer structures and are characterized by X-ray diffraction analysis (CIF files CCDC nos. 1877115 (I) and 1876364 (II)) and (13C, 15N) CP-MAS NMR spectroscopy. The coordination mode of each of the dialkyldithiocarbamate ligands is S,S′-anisobidentately terminal. The inorganic anions performing the μ2-bridging function participate in the binding of the adjacent metallic atoms to form zigzag polymer chains. A new mode of bismuth(III) binding involving all oxygen atoms (O,O'-anisobidentate coordination to each adjacent bismuth atom) is found for the bridging nitrate groups in compound I. The bismuth atoms in the studied compounds are characterized by the eightfold [BiS4O4] (I) or sixfold [BiS4Cl2] (II) environment. The thermal behavior of the synthesized complexes is characterized by the data of simultaneous thermal analysis, using parallel recording of thermogravimetry and differential scanning calorimetry curves. In both cases, Bi2S3 is the only final product of the thermal transformations of compounds I and II.

Surface characteristics of a recyclable and efficient adsorption material

Abstract Magnetized biochar materials (MCs) were prepared through magnetization of biochar (C) by Fe3O4-loaded coprecipitation method and coating the MCs with different ratios of the amphoteric modifier, dodecyl dimethyl betaine (BS-12), for C recycling and simultaneous adsorption of various pollutants. The MC and BS-12-coated MCs (BS-MCs) were subjected to characterization methods, such as scanning electron microscopy (SEM), thermogravimetry (TG), vibrating sample magnetometry (VSM), and Fourier transform infrared (FT-IR) spectroscopy. Results indicated the following. (1) With increased BS-12 coating ratio, the pH, cation exchange capacity (CEC) and specific surface areas (SBET) of each BS-MC decreased gradually. (2) BS-MCs exhibited good magnetic separation performance, and their infrared spectra showed that Fe3O4 and BS-12 had been loaded on the C surface. The TG curves showed that the weight loss rate of BS-MC increased with increasing BS-12 coating ratio. (3) According to SEM results, Fe3O4 was evenly distributed on C, and no evident agglomeration was observed. After BS-12 coating, BS-MCs presented lower surface roughness and higher concentration of particles, which confirmed that BS-12 coated the MCs organically.

Critical analysis of micro-thermogravimetry of CuSO4·5H2O crystals using heatable microcantilevers

Micro/nano thermogravimetry (TG) employing MEMS has significant potential to improve the minimum sample mass and mass resolution as compared to commercial TG instruments. Although there have been a few previous reports on MEMS TG, none of them have critically analysed the obtained TG curve in detail. In this work, we have designed and fabricated a microelectromechanical thermogravimetric device (MMTG) with integrated microheaters and temperature sensors. The mass sensitivity of the device was estimated to be 0.89 pg Hz−1 which outperforms the standard TG approaches. We tested the MMTG performance with CuSO4·5H2O crystals. The final mass loss ratio corresponds to the theoretically expected value, although the obtained TG curve deviated from the standard TG curve of CuSO4·5H2O obtained from commercial TG instruments. We attributed the deviation to the inherent temperature non-uniformity, non-isothermal conditions and temperature gradients of metallic-wire based microheaters. Finite element (FE) simulations were carried out in order to confirm and gain insights into the non-uniform heating phenomena of microheater and sample. Based on the simulation results, we propose designs that can be realized to make MEMS TG a successful enterprise.

Impact-resistant polypropylene/thermoplastic polyurethane blends: compatible effects of maleic anhydride on thermal degradation properties and crystallization behaviors

In this study, impact-resistant polypropylene (MPP), thermoplastic polyurethane (TPU) and polypropylene-grafted maleic anhydride (MA) are made into MPP/TPU/MA blends using melt-compounding and injection methods. The blending morphology, crystallization behavior, and melting and thermal behaviors of the blends are evaluated in terms of the content of TPU and MA, examining the influences of the parameters. The scanning electron microscope (SEM) observation shows that 1wt% of MA can effectively enhance the interfacial adhesion and compatibility between MPP and TPU. The differential scanning calorimetry (DSC) results show that the crystallization temperature and melting temperature of the blends are not dependent on the content of TPU or MA. However, using TPU and MA adversely affect the crystalline and melting enthalpy of the blends. The thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) curve both show that the higher the MPP, the greater the thermal stability of TPU. Likewise, using MA as compatibilizer also has a positive influence on the thermal stability of the blends. The X-ray diffraction (XRD) analyses confirm that the addition of TPU decreases the diffraction intensity of MPP, but does not harm the crystalline structure of MPP. Moreover, the addition of MA improves the compatibility between MPP and TPU. MA marginally decreases the peak value and does not influence the crystallinity degree of MPP. It is expected that the results of SEM, DSC, TGA, DTG, and XRD can serve as a valuable reference for the design of composites with improved thermal and crystallization behaviors.

Aqueous extraction of organic amaranth starch and their by-products

The aim of this study was to characterise the organic amaranth flour (Amaranthus caudatus), native starch and by-products generated after its aqueous extraction (bagasse, post-sieving and post-centrifugation residues) and to evaluate the influence of lipids on the thermal, structural and pasting properties of these samples. The analyses performed were: thermogravimetry (TG), differential scanning calorimetry, viscographic analysis, scanning electron microscopy with field emission gun and Fourier-transform infrared spectroscopy (FTIR). After aqueous extraction, the amaranth starch presented low protein and lipid content, which were retained together with inorganic material mainly in the post-sieving and post-centrifugation residues. TG curves showed three mass losses, associated with dehydration, macronutrients decomposition and oxidation of organic matter. These losses were consecutive for flour, bagasse and residues, resulting in a stability period after degreasing, which increased for the sample of defatted starch. About gelatinisation, the presence of lipids, fibre or proteins hinders the starch gelatinisation and the increase of viscosity, requiring higher energy. By microscopy, it was possible to identify different characteristics according proximal composition in each studied fraction. Three regions were identified by FTIR (lipid, protein and carbohydrates), and the spectral bands corroborated with the proximal analysis. The results obtained encourage the aqueous extraction of starch from organic sources, as well as future studies to evaluate the use of the generated residues in food formulations or starch films. The lipids removal process becomes interesting for the amaranth starch, favouring the occurrence of the gelatinisation process, property of greater industrial interest.

Thermogravimetric analyses of oxy-fuel co-combustion of semi-coke and bituminous coal

Semi-coke is blended with bituminous coal in oxygen-enriched atmospheres to be efficiently used as an energy source. Combustion characteristics and kinetic behavior of blends under oxygen-enriched atmosphere are studied with thermogravimetric analysis. The ignition temperature of each sample in 21%O2/79%CO2 atmosphere is about 15 °C higher than that in air. The burnout behavior of semi-coke is significantly improved when N2 is replaced by CO2 at the same oxygen concentration. Increasing oxygen concentration can improve ignition and burnout behaviors further. Differential thermogravimetry (DTG) curves of semi-coke show quite different behaviors in air and 21%O2/79%CO2 atmospheres. There are two distinct peaks in air, while in 21%O2/79%CO2, there is only one. Activation energies of blends are obtained by Starink method at four heating rates. These activation energy values are, then, used to determine the most probabilistic mechanism function of each stage by Malek method. The results show that the activation energy usually decreases with the increase of the conversion degree and the proportion of bituminous coal. The average activation energy in air atmosphere is slightly smaller than that in 21%O2/79%CO2 atmospheres. It is worth noting that the activation energies of the blends increase with the increase of oxygen concentrations.

Nano Graphene-Reinforced Bio-nanocomposites Based on NR/PLA: The Morphological, Thermal and Rheological Perspective

Bio-based graphene-reinforced thermoplastic elastomers (TPE) based on natural rubber (NR), and poly lactic acid (PLA) were successfully prepared via melt blending. The effect of graphene nanosheets (GNS) content and coupling agent were investigated on morphological, thermal and rheological properties of the PLA/NR/GNS bio-nanocomposites. More stable morphology of uniformly dispersed NR phase in the continuous PLA matrix with a relatively narrower diameter-size distribution was achieved in the presence of a compatibilizer. Moreover, transmission electron micrographs showed more improved dispersion of GNS with predominantly exfoliated morphology in the case of ENR-compatibilized PLA/NR/GNS bio-nanocomposites. Crystallization/melting studies revealed that, as the GNS content increased, the cold-crystallization peak, melting peak and glass-to-rubber transition temperature values shifted to higher temperatures and the crystallinities of blends slightly decreased (about 7%) which might be attributed to the reduction of polymeric segments mobility by the restricting effect of GNS. Dynamical mechanical investigation showed that the storage modulus (E′) increased about 25% by the introduction of GNS due to the inherent stiffness of GNS and the occurrence of compatibility in the PLA/NR blend in the presence of ENR. The presence of ENR shifted the $$ T_{g} $$ of the NR phase and the PLA matrix towards each other which is a characteristic of higher miscibility and compatibility. The thermogravimetry (TGA) and derivative thermogravimetry (DTG) curves revealed higher thermal stability of the compatibilized-PLA/NR blends due to the enhanced interfacial adhesion and the homogenous dispersion of GNSs as direct effects of the presence of ENR. Rheological studies indicated that the formation of the effective GNS-polymer networks by the presence of ENR increased the storage modulus (G′) and complex viscosity (η*) value due to the effectiveness of the GNS in taking loads and restricted molecular motion, respectively.

A study of coke and char formation during pyrolysis of rice husk

The present study about pyrolysis of the rice husk (RH) was carried out to evaluate indicated operating conditions to obtain chars with adsorbent properties. Initially, thermogravimetry (TG), derivative thermogravimetry (DTG) and differential thermal analysis (DTA) were performed in order to obtain the TG and DTA RH coke formation curves and to evaluate the formed products (chars) at different selected pyrolysis temperatures. For the thermal analyses, 10 mg samples were used at a heating rate of 10 °C min−1, from ambient temperature to 1000 °C, in alumina crucibles, under air and N2 atmosphere. The coke formation curves, which were obtained subtracting RH TG and DTA curves in air from respective curves in N2, show that there are two types of coke formation, being the second the most stable and more suitable for adsorption, with maximum formation at 500 °C. Then, pyrolysis products obtained at selected temperatures of 400, 500 and 600 °C, respectively, named RHC400, RHC500 and RHC600, were characterized by thermal analysis in air and by other instrumental analyses in order to evaluate their chemical composition and adsorbing properties. The results of char TG and DTG curves, based on the original rice husk initial mass, allow to estimate and to compare contents of residual organic components during pyrolysis. The characterization by XRF, SEM and BET showed that RH and RHCs have silica in greater quantity in their chemical composition, with mainly carbon, silicon, calcium and oxygen distributed on their surfaces, which present a low surface area (16–26 m2 g−1). The analyzed chars show, by proximate analysis, a progressive concentration of fixed carbon from 400 to 600 °C. BET data show that they are mesoporous and potential adsorbents for large molecules as dyes, being RHC600 the most suitable for this purpose, as shown by preliminary results of blue methylene adsorption.

Thermal characterization and microbiology assay of Annona muricata L. leaves

Annona muricata L., Annonaceae, popularly known as soursop, has anticancer and antidiabetic pharmacological properties. This work aims the characterization by thermoanalytical technique and determination of antimicrobial activity of different A. muricata L. leaves particle sizes. The leaves were dried, knifed, and separated by particle size. Samples were characterized by scanning electron microscopy (SEM) and thermogravimetry (TG) using the Ozawa kinetics model in two atmospheres (nitrogen and synthetic air). The antimicrobial activity and minimum inhibitory concentration of infusions were performed by the broth microdilution method to Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae. SEM analysis suggests heterogeneous distribution in the observed particle sizes. TG curves were able to differentiate the degradation events and the residue contents in the samples analyzed in the nitrogen and synthetic air atmospheres. In nitrogen atmosphere curves, the different particle sizes presented four mass loss events, and residue ranged from 20.90 to 26.80% at the end of the analysis. In synthetic air atmosphere, the different particle sizes presented three mass loss events, and residue ranged from 7.80 to 10.42%. Ozawa model showed reaction order equal to zero for all samples assayed, and the activation energy (Ea) ranged from 121.36 to 135.42 and 115.50 to 141.00 kJ mol−1 for the nitrogen and synthetic air atmospheres, respectively. Antibacterial activity was confirmed for all particle sizes, in special to AM4 with S. aureus, E. coli, and K. pneumoniae. These results indicate that leaves from A. muricata L. have great potential for a variety of medicinal applications.

Thermal characterization of Aspidosperma pyrifolium Mart. plant drugs

Aspidosperma pyrifolium Mart. is an endemic plant from Brazilian northeastern, which is widely used in folk medicine to treat dermatitis, gastritis, and malaria due to its anti-inflammatory activity. Thus, the aim of this work was to characterize by analytical techniques A. pyrifolium in different particle sizes to use in the production of tea. For characterization, thermal analysis, optical microscopy, and near-infrared spectroscopy (NIR) techniques were used. After sieving, five samples, named AP01 (> 355 μm), AP02 (≥ 180 μm), AP03 (≥ 155 μm), AP04 (≥ 75 μm), and AP05 (≥ 38 μm), were obtained. Thermogravimetry curves showed three steps of decomposition, with different percentages of mass loss. The second step of decomposition showed the highest mass loss for the five samples. DTA curves of five samples showed a first endothermic peak at 91.70, 96.22, 96.29, 91.09, and 86.32 °C for AP01, AP02, AP03, AP04, and AP05, respectively. Decomposition of all particles occurred from 200 °C. The activation energy obtained through kinetic models showed significant differences between the two methodologies employed. NIR spectra were treated using chemometric tools, including principal component analysis and two PC were necessary to properly separate the samples. The analytical techniques used in this study allowed us to properly characterize the powders and could be used in the production of tea.

Investigation of thermal and kinetic behavior of the Stryphnodendron adstringens dry extract with antimicrobial activity

Stryphnodendron adstringens Coville (Fabaceae), popularly known as “barbatimao,” is a Brazilian Cerrado tree, rich in tannins. It is used as antinociceptive, in the treatment of vaginal inflammations and infections in general. The objective was to investigate the thermal, kinetic behavior and the antimicrobial activity of the dry extract of S. adstringens. The dry extract was obtained from the leaves of S. adstringens and submitted to the thermal characterization by thermogravimetry (TG), at different atmospheres and heating rates, and by kinetic degradation by Ozawa model. Furthermore, in order to evaluate the antimicrobial activity, the minimum inhibitory concentration of the dry extract against pathogenic microorganisms was obtained. The TG curves of the sample presented six stages of thermal decomposition in both atmospheres with the beginning of decomposition of compounds in the third stage, reaching up to 16.55% of mass loss, and the fourth step achieved a maximum decomposition of 45% mass loss under inert atmosphere. The DTA curve profile of the extract presented two exothermic events with a higher enthalpy in the first event. Thermal decomposition was shown to be a zero-order reaction by the Ozawa method. The extract was presented to be sensitive to all strains tested, thus showing potent antibacterial and antifungal action (minimum inhibitory concentration < 12.5 mg mL−1). Thus, it is concluded that the characterization was done by appropriate analytical techniques and the dry extract was shown to be an active agent against all microorganisms tested, prospecting a new herbal medicine with antimicrobial activity.

Pyrolysis study of Huainan coal with different particle sizes using TG analysis and online Py-PI-TOF MS

The pyrolysis behaviors of Huainan coal (HN coal) with three particle sizes, i.e., <40 μm (HN-S), 224–500 μm (HN-M) and 1600–2000 μm (HN-L), were investigated by thermogravimetry (TG) and online pyrolysis photoionization time-of-flight mass spectrometry (Py-PI-TOF MS) using a krypton discharge lamp (10.6 eV) and synchrotron radiation vacuum ultraviolet light (SVUV) (14.2 eV and 15.5 eV) as the ionization sources. The fragment-free mass spectra of coal pyrolysis products were obtained at 600 °C in real time. The released organic volatiles were characterized as alkenes, phenols and aromatics, and their evolved profiles were measured as a function of time in fixed temperature mode and as a function of temperature in programmed-temperature mode. A higher weight loss ratio of the TG curves was obtained when the particle size was increased. The intensities of the individual volatiles in the mass spectra were all enhanced following the increase in the particle size of HN coal. With regard to the time-evolved profiles, by increasing the particle size, the appearance times of volatiles were delayed. Tricyclic aromatics showed multireleasing processes in both time-evolved and temperature-programmed profiles. The release of the guest molecules lagged within the higher temperature region as the coal particle size increased. To explain the evolution trends of most organic volatiles, a mechanism combining intraparticle and interparticle mechanisms is presented.

The Sodium (Iso)Cyanurates Nax[H3–xC3N3O3]·yH2O (x = 1–3, y = 0, 1): A Key‐Series for Understanding the Crystal Chemistry of Metal (Iso)Cyanurates

The (iso)cyanurates Na[H2C3N3O3]·H2O, Na2[HC3N3O3]·H2O, Na2[HC3N3O3], and Na3[C3N3O3] were synthesized phase pure from Na2CO3·10H2O, NaOH, and cyanuric acid, respectively, in aqueous solution by carefully adjusting the crystallization conditions. The crystal structures of all compounds were determined by single‐crystal X‐ray diffraction {Na2[HC3N3O3]·H2O: P1, a = 3.51660(10) Å, b = 7.8300(3) Å, c = 11.3966(4) Å, α = 86.4400(10)°, β = 85.5350(10)°, γ = 85.0720(10)°, Z = 2, R1 = 0.030, wR2 = 0.078; Na2[HC3N3O3]: Pnma, a = 6.3409(6) Å, b = 12.2382(13) Å, c = 6.5919(7) Å, Z = 4, R1 = 0.045, wR2 = 0.079; Na3[C3N3O3]: R3c, a = 11.7459(3) Å, c = 6.5286(3) Å, Z = 3, R1 = 0.039, wR2 = 0.066}. The structures show ribbons (Na[H2C3N3O3]·H2O), dimers (Na2[HC3N3O3]·H2O), chains (Na2[HC3N3O3]), or columns (Na3[C3N3O3]) of hydrogen‐bonded and parallel stacked (iso)cyanurate anions. These motifs are shown to be characteristic for certain degrees of protonation and hydration, and all (iso)cyanurate crystal structures found so far were classified accordingly. X‐ray powder patterns, thermogravimetry curves, IR and UV/Vis spectra were measured for all compounds.