TG-DSC Analysis Research Articles

Mechanistic insights into the structure-activity relationship of FeS for arsenic removal in strongly acidic wastewater

Sulfide precipitation is an efficient method for separation. However, its application is limited due to the significant H2S pollution caused by conventional reagents. The utilization of amorphous FeS lead to a substantial reduction in H2S escape, while concurrently enhancing the crystallization and settling characteristics of As-precipitates. Under the conditions of an initial arsenic and H2SO4 concentration in the solution of 2 g/L and 50 g/L, respectively, and a FeS dosage of 1.5 times the molar amount of S/As, the arsenic removal exhibited a significant decrease from 89.8 % to 40.8 % over a FeS aging period of 0 to 84 days. Notably, no H2S emissions were detected during the entire reaction process. XRD analysis revealed a transformation of FeS from its amorphous form to a crystalline state as it undergoes aging. This transition is primarily characterized by a reduction in interlayer spacing and FeS bond length within the FeS lattice. The lattice energy experienced a decrease from −3071 to −3688 kJ/mol, indicating the progressive stabilization of the FeS structure. FTIR and TG-DSC analyses have demonstrated the infiltration of water molecules into both the interlamellar spaces and the lattice of FeS during the process of crystallization. Additionally, As3+ ions were observed to initially adsorb onto the surface of aged FeS through the hydroxyl group, followed by their diffusion into the lattice. The products of arsenic removal undergone a transformation from As2S3 to predominantly FeAsS-like complexes, as the mechanism of arsenic removal shifted from precipitate transformation to adsorption and co-precipitation.

Introducing metal oxide as solid oxygen carrier for energy release enhancement of boron suspension fuel

Boron (B) suspension fuel is a novel high-density fuel for aerospace propulsion. However, it suffers from significant incomplete energy release of B during combustion, which seriously restricts its practical application. This study focuses on the key causes of this problem, insufficient oxygen supply, and proposes to introduce metal oxides (MOx) as solid oxygen carriers to form B-MOx and replace pure B to enhance the energy release characteristics of B suspension fuel. TG-DSC analysis is conducted to sort out CuO as the optimal additive for B oxidation enhancement and its enhancement mechanism is analyzed with thermal equilibrium calculation. It was found that CuO could generate active O atoms through two-step reduction, thus achieving efficient oxygen supply for B and reduce its initial reaction temperature from 810 °C to 661.7 °C with an optimal B-CuO ratio of 1:1. CO2 laser ignition experiment and combustion residue analysis are conducted to analyze the combustion characteristics of B-CuO/JP-10 suspension fuel. Compared with original B/JP-10 suspension fuel, B-CuO/JP-10 suspension fuel presents much higher combustion intensity with local explosion after ignition, and a second stage of intensive energy release is realized with the reignition and explosion of solid agglomerate. The oxidation of JP-10 and B are enhanced with no incomplete oxidation product found in the residue. The enhancement mechanism of CuO on B suspension fuel is proposed including the generation of active radical, efficient internal oxygen supply and enhanced external oxygen supply.

Efficient Conversion of Methyl Lactate to Methyl Acrylate over Cesium-Modified Al-Rich Beta Zeolites

Dehydration of methyl lactate (ML) obtained from biomass is a sustainable route for the production of methyl acrylate (MA). Herein, we demonstrate that cesium-exchanged Al-rich Beta zeolite (Cs-Beta) is highly efficient for the dehydration of ML to MA, exhibiting full ML conversion with 87.4% MA yield at 340 °C. In situ FT-IR spectra and kinetic studies provide evidence that the ML dehydration on the Cs-Beta zeolite follows a forward ion-exchange/dehydration/reverse ion-exchange reaction pathway. Model experiments, DFT calculations, TG-DSC analysis, and FT-IR spectra showed that coke formation competes with the dehydration of ML to MA. Kinetic studies and theoretical simulations demonstrate that cesium cations in the micropores of Beta zeolite have a strong steric hindrance, suppressing the formation of oligomers and coke. These results offer new insights for developing highly selective and stable catalysts for the dehydration of ML to MA in the future.

Synthesis and characterization of cyclohexylammonium hydrogen maleate hemihydrate single crystal and its anti-bacterial activities

The single crystal of cyclohexylammonium hydrogen maleate hemihydrate (CYHMH) developed using slow solvent vaporization technique in distilled water solvent. The crystal structure of CYHMH was in monoclinic structure with space group C12/C. The CYHMH single crystal structure consists of an individual cyclohexylamine and an independent maleic acid molecule with all atoms placed in general positions. The prepared CYHMH single crystal was characterized by various analysis techniques such as, Fourier transform infrared (FT IR), Ultra Violet-Visible near infrared (UV–vis-NIR) spectral analysis, TG-DSC analyses, nonlinear optical studies and anti-bacterial activities. From the UV–Vis-NIR studies. The cut off wavelength of CYHMH single crystal is 328 nm with excellent translucence in complete visible region. Melting point of CYHMH was 112 °C determined from TG-DSC analysis. Nonlinear refractive index (-8.55 10 -8 cm2/W), nonlinear absorption coefficient (0.03 10-4 cm/W) nonlinear susceptibility (4.07 10-6 esu) were calculated by Z scan technique by diode pumped Continuous Wave Nd:YAG Laser. Gram negative bacteria such as Staphylococcus aureus and Escherichia coli were selected for anti-bacterial tests and it is found that CYHMH is most significant agent for bacterial strains.

Preparation of Fe2O3 porous microspheres modified pumice and its adsorption performance on phosphate removal

Fe2O3 porous microspheres modified pumice (Fe2O3@pumice) was generated in this study using a simple hydrothermal method. XRD, SEM, TEM, BET, and TG-DSC analyses were employed for characterization. The results show that the pumice is encapsulated by a large amount of Fe2O3 porous microspheres. Fe2O3@pumice exhibits good phosphate adsorption property. The adsorption process follows the Freundlich isothermal adsorption model and Pseudo-secondary adsorption kinetic model, and the adsorption capacity is more than 378.8 mg/g. It shows outstanding phosphate removal capacity throughout the pH range of 3–11. The adsorbent has fewer effects on coexisting anions and good performances of reusability. The adsorption mechanism is mainly attributed to ligand exchange. Electrostatic attraction also existed in the adsorption process. The column test indicated that the adsorption column can continuously treat 2106 bed volumes of sewage with 2 mg/L phosphate.

Study on Zinc-Modified Adsorbent for Adsorption of Trace CO2 in Electronic Special Gas BF3

Usually, the ion implantation gases used in semiconductor production are required to be extremely high in purity. Due to the presence of trace CO2 in electronic special gas BF3, the quality of the material is significantly affected, which makes it crucial to impose control on CO2 content. Unlike a series of blank adsorbents reported in other studies, the zinc-loaded adsorbents prepared in this study are intended for the adsorption of CO2 from CO2/BF3. Firstly, the materials were characterized by XRD, BET, SEM-EDS and TG-DSC analysis, etc., and the breakthrough curves of the adsorbents as obtained under different preparation conditions were investigated at 20 °C and 200 kPa. The results show that the adsorption performance reached the optimal level when the activation temperature was 450 °C and a 13X molecular sieve was impregnated by 0.15 mol/L Zn(NO3)2. Moreover, compared with the Zn-13X, the breakthrough time was reduced to 69% and 44% in two adsorption cycles, respectively. Finally, FTIR was used to reveal the adsorption mechanism of the carbonates produced by CO2 adsorption. It was found that the adsorption performance was affected by the irreversible reduction in the number of active sites due to the continuous formation of polydentate carbonate during adsorption and regeneration.

The Structural Influence of Airborne Particles on their Toxicity

This paper studies human exposure to microplastics in real-life situations. The concentration of the polyamide nano/microplastics in the proximity of textile workplaces was made by the device Laser Aerosol Spectrometer. The descriptive statistical analysis was elaborated for: variables TSC (total concentration µg/m3), PM10 (µg/m3), PM2.5 (µg/m3), PM1 (µg/m3) and TC (total number of particles, 1/l). The histograms of each variable highlight the asymmetry of the distribution, with the predominance of frequencies or variables; representation of level indicators (average, median) and dispersion-box-plot graphs were obtained. Collection of the particle made with TECORA-SKYPORT PM-HV and GilAirPlus pumps, by using Quartz and Nucleopore filters with different diameters highlighted that the highest mass (683µg) was collected by using GilAir Plus pump and Quartz filter 37mm. A strong correlation was obtained between the variable: "Collected mass/ Air concentration": r = 0997775 ÷ 0,999477 and "Collected mass/ Air volume", r = -0,97473 ÷ 0.80064. The prediction of the value of the collected mass as a function of the diameter of the filters, particle concentration, airflow, and total air volume was made by obtaining the regression equations. Optic microscope analyses highlighted the dimension of microfibres (50% are <10µm) and SEM the dimension: 25% < 68.47 nm and the spherical shape of particles. FT-IR, µRaman and TG-DSC analyses showed the presence of PA particles in the collected particles.

Mechanical properties, impact initiation characteristics and energy release effect of Al/PTFE reactive materials enhanced by Fe particles

AbstractAluminum/polytetrafluoroethylene (Al/PTFE) composites are a promising category of reactive structural materials. In order to improve the mechanical properties and reactivity, Fe particles were introduced into Al/PTFE. Quasi-static and dynamic compression tests for Al/PTFE/Fe reactive materials were conducted, and significant strain and strain rate hardening phenomena were observed. The compression strength of Al/PTFE with Fe content of 30 wt.% reached 191.8 MPa at the strain rate of 5000 s−1, increased by 39% compared to Al/PTFE. The oriented PTFE nano-fibers could effectively prevent the propagation of micro-cracks. The impact reaction processes under SHPB and drop-weight conditions were observed by high-speed photography technology, and the reactivity was qualitatively characterized by a newly-designed device. Based on the results of TG-DSC and XRD analyses, the reaction involving Al/PTFE and Al/Fe was clarified. The Johnson−Cook constitutive model was established and the model results agreed well with experimental data. Under impact loading, the reactivity was speculated to be the result of multiple actions.

In-situ constructing nano ternary Ni-P-Cu alloy shell on the micro-aluminum surface: Enhancing its ignition and combustion performances

To improve the combustion efficiency of widely used micro-aluminum (μAl) particle, enhancing its ignition and combustion performances is a critical issue via breaking through the intrinsic Al2O3 layer covering the Al-core. This study proposed a facile in-situ ‘one-pot’ electroless plating method to functionalize the surface of μAl particles with ternary-shelled nickel-phosphorus-copper alloy coating and furthermore investigated the thermochemical and ignition/combustion behaviors of energetic core–shell composites (defined as Al@Ni-P-Cu). The microstructure characterization results of Al@Ni-P-Cu demonstrated that a spherically distributed triple-shell Ni-P-Cu alloy with the thickness of 129 nm was tightly coated on μAl particle surface. Through TG-DSC analysis, the Al@Ni-P-Cu composites exhibited improved heat release (7597.7 J/g) and decreased initial oxidation temperature (814.3 °C) in comparison to that of μAl particle with 949.2 J/g and 960.1 °C, respectively. The Al@Ni-P-Cu exhibited extremely shorter laser ignition delay time of 36.3 ms under 1 MPa O2 atmosphere, reducing by 86.86% compared with that of raw μAl particles (276.3 ms); and its maximum flame temperature could reach up to 1588.93 °C, increasing by 243.36 °C compared with that of μAl (1345.57 °C). The drastic improving performances were attributed to the synergistic effects of surface/interfaces reactions along with heat release in the core–shell structure, resulting in enhanced mass and heat transfer to facilitate the combustion of internal Al-core.

Pyrolysis behaviors of iodine vapor cured fine-diameter polysilazane fibers for the preparation of SiCN ceramic fibers

Polymer-derived SiCN ceramic fibers have been developed as a new ultrahigh-temperature material that can be an alternative to the binary system of SiC and Si3N4 due to the preservation of its amorphous phase at high temperatures. In this work, a novel strategy of iodine vapor curing has been employed to cure the fine-diameter PSZ fibers. The pyrolysis behaviors of the cured PSZ fibers at various temperatures were investigated. The as-prepared fibers were characterized by TG-DSC, PY/GC/MS, FT-IR, FE-SEM, and XRD analysis. The results revealed the fine-diameter amorphous SiCN ceramic fibers have a high tensile strength of 1.08 ± 0.26 GPa after pyrolysis at various temperatures. During the process of pyrolysis, the unstable chemical bonds and active groups (i.e., N-I, Si-I, N-H, Si-H, and Si-CH3) transformed into Si3N structure with the release of iodine, CH4, NH3, cyclotrisiloxane at 300 °C. The dehydrogenation and transamination reactions occurred between the Si-H, N-H, and N-H bonds at the pyrolysis temperature of 400 °C. At the higher temperature (500─600 °C), a rearrangement reaction occurs to form some complex compounds (i.e., 3TMS and 4TMS derivative melamine and other higher molecular weight compounds) and inorganic fibers were attained at temperature ≥ 700 °C. This work revealed an important guiding significance for the pyrolysis of PSZ ceramic precursor polymer fibers.

TG-DSC and TG-FTIR analysis of heavy fuel oil and vacuum residual oil pyrolysis and combustion: characterization, kinetics, and evolved gas analysis

TG-DSC and TG-FTIR analysis of heavy fuel oil and vacuum residual oil pyrolysis and combustion: characterization, kinetics, and evolved gas analysis

Nonaqueous amino-phenolic dual-functionalized ionic liquid absorbents for reversible CO2 capture: Phase change behaviors and mechanism

In order to improve the recycling capacity, regenerability and energy efficiency of ionic liquid (IL) based CO2 capture technology, a series of nonaqueous phase change solvents comprising amino-phenolic dual-functionalized ILs and polyethylene glycols (PEGs) were proposed for CO2 capture in this research. The capture performance results demonstrated that the 20 wt% diethylenetriamine-2-bromophenolate(D2Br)-PEG200 and diethylenetriamine-4-bromophenolate(D4Br)-PEG200 solutions with slight phase change could realize high CO2 loading of 1.923 and 1.859 mol/mol IL and CO2-rich phase constituted volume fractions lower than 70%. The absorption ability kept stable at relatively high temperature and the two systems could be rapidly regenerated at 363 K with cyclic regeneration rate above 85% after ten consecutive cycles. The weak thermal stability of the absorption products was proved by TG-DSC analysis, contributing to improved regeneration performance. ATR-IR and 13C NMR analysis confirmed that the amino groups of IL reacted with CO2 to form carbamates, and phenol groups through 1:1 mechanism to form alkyl carbonates, guaranteeing enhanced recycling capacity and regenerability. Spectroscopic analysis and theoretical calculation results revealed the different phase change behaviors presented in PEGs solutions were mainly derived from the product-solvent interaction, which was more influenced by hydroxyl content. The interactions between the product ion pairs could be the main cause of the unstable state of the solutions and phase separation. The different patterns of hydrogen bonding established between IL and PEG molecules could maintain a relatively strong product-solvent interaction in the reacted solution, which would partially overcome the interactions between protonated amine and carbamate, thus delaying the phase transition formation and forming a slight solid–liquid phase change, potentially beneficial for CO2 capture. The two systems experienced a low reaction heat of 1.315 and 0.782 GJ/t CO2, which could significantly reduce regeneration heat load. Therefore, the amino-phenolic dual-functionalized IL solutions are proposed to be a competitive and reversible CO2 trapping agent.

An approach of pectin from Citrus aurantium L. for superabsorbent resin with superior quality for hygiene products: Salt resistance, antibacterial, nonirritant and biodegradability

In this paper, a kind of superabsorbent resin (SAR) with superior quality for hygiene products was developed using Fructus Aurantii Immaturus pectin (FAIP) from Citrus aurantium L.. FAIP-g-AM/AMPS SAR was established by free radical graft co-polymerization with FAIP as skeleton structure, N, N′-Methylene-bis (acrylamide) (MBA) as the cross-linker. Meanwhile, the functional monomers of acrylamide (AM) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) were introduced. The structure and morphology of FAIP-g-AM/AMPS were characterized by FTIR, 13C NMR, XRD, SEM and TG-DSC analysis. The results confirmed that the AFIP-g-AM/AMPS SAR was successfully prepared, which exhibited a three-dimensional (3D) network structure and an excellent thermal stability. The absorption and retention capacity of FAIP-g-AM/AMPS was comparable to or even better than commercial diapers and sanitary napkins. Significantly, FAIP-g-AM/AMPS itself exhibited excellent antibacterial and safety. FAIP-g-AM/AMPS has an inhibition ratio of 97.1 % for Escherichia coli (E. coli) and 98.5 % for Staphylococcus aureus (S. aureus), and was non-irritating and non-allergic to the skin. In addition, FAIP-g-AM/AMPS presented amazing biodegradability and a weight loss reached 37.1 % after 30 days by soil burial test. The research provides a safe and high-performance SAR, which expected to be used in hygiene products such as baby diapers, adult incontinence pads and sanitary napkins.

Structural Features and Thermal Behavior of Ion-Exchanged Clinoptilolite from Beli Plast Deposit (Bulgaria)

The structural features and the thermal behavior of natural, Na-, Ca-, K-, Mg-, and Cd-exchanged clinoptilolite from the Beli Plast deposit (Bulgaria) were studied. Purified clinoptilolite sample was preliminary prepared and ion-exchanged at 100 °C for six days. DSC-TG analyses were performed for all studied forms. The effects in the DSC curves show differences with temperature due to release of weakly bound H2O molecules and strongly bound ones. The endotherm minima temperatures were between 78 and 115 °C decreasing in the sequence K- &lt; Na- &lt; Natural- &lt; Ca- ≤ Mg- &lt; Cd-clinoptilolite. The hydrate complexes around the exchanged cations also influenced the DSC curves. The cation-coordinating H2O molecules and the non-coordinating ones were determined by XRD structural refinement for all exchanged samples. The H2O molecules of the cation–hydrate complexes are released at higher temperatures than weakly bound ones and affected the DSC curves differently. The structural adjustments made by the Rietveld method, as well as the applied EDS analyzes for the chemical composition of the samples, allowed us to correlate these data to the thermal characteristics of the studied clinoptilolite samples.

Preparation and characterization of La2-xSmxMo1.8Al0.2O8.7 as electrolyte for solid oxide fuel cells

Solid oxide fuel cells (SOFCs) have been regarded as promising eco-friendly power sources in recent years owing to their high energy conversion efficiency and fuel flexibility. La2Mo2O9-based ceramics draw researchers’ attention due to their good performance as electrolyte materials for SOFCs. In this study, the Sm and Al co-doped La2Mo2O9, La2-xSmxMo1.8Al0.2O8.7 (x=0.1,0.2,0.3 and 04, LSMAO), are successfully synthesized by the sol-gel method as electrolyte materials for SOFCs. The phase evolution, sintering, the microstructural and electrochemical performance of LSMAO were observed by TG-DSC, XRD, SEM, and impedance analyses, respectively. The results show that the highly phase-pure cubic LSMAO nanopowders can be obtained after calcining at 600 °C for 2 h. The as-synthesized LSMAO powders exhibited a better sintering activity. All these samples were found to have a relative density above 94.5% after sintering at 950 °C for 5 h. The electrical performance study shows that higher doping concentrations of Sm caused a decrease in ionic conductivity and an increase in activation energy. La1.9Sm0.1Mo1.8Al0.2O8.7 exhibited the highest oxide ionic conductivity (σ800 °C=0.033 S/cm) and lowest electrical activation energy (Ea=0.85 eV). This shows that LSMAO could be used as a potential electrolyte for intermediate temperature SOFCs (IT-SOFCs).

A long-acting hygroscopic and antibacterial composite filler: A new approach to phytoextraction solid residues from Citrus aurantium L.

A promising new composite filler with hygroscopic and antibacterial properties was developed based on the Fructus Aurantii Immaturus solid residues (FAIR) from Citrus aurantium L. , a typical bulk forest industrial crops. FAIR@AM-APTAC composite filler was established using FAIR as substrate, allyl glycidyl ether (AGE) as the cross-linker, while functional monomers of acrylamide (AM) and (3-acrylamidopropyl) trimethyl ammonium chloride (APTAC) were introduced. The structure of FAIR@AM-APTAC was characterized by FTIR , SEM, BET and TG–DSC analysis. The results confirmed that the FAIR@AM-APTAC composite filler was successfully prepared, which exhibited a three-dimensional(3D) network structure with a specific surface area of 0.1758 m²/g and exhibited excellent thermal stability. The equilibrium percent moisture absorption of FAIR@AM-APTAC (63.0%) was higher than that of FAIR (15.7%) under RH= 80% at 25 ℃ for 48 h, and much better moisture adsorption was achieved. The moisture adsorption process of FAIR@AM-APTAC followed a type III moisture adsorption isotherm and conformed to GAB, Peleg and pseudo-second order kinetics model. The moisture adsorption process of FAIR@AM-APTAC was a multi-layer adsorption process with enthalpy driven non-spontaneous and endothermic, which was dominated by chemical adsorption simultaneous existing physical adsorption, and the adsorption force was the synergy of both hydrogen bond and van der Waals force. The inhibition ratio of FAIR@AM-APTAC was 97.1% for E. coli and 95.4% for S. aureus . The antimicrobial efficacy of FAIR@AM-APTAC was enormously improved compared with that of FAIR due to the introduction of quaternary ammonium groups. The antibacterial mechanism of FAIR@AM-APTAC may be that the surface contact between bacterial and FAIR@AM-APTAC leads to inactivation. Significantly, FAIR@AM-APTAC showed long-acting hygroscopic and antibacterial properties, with little weakness even after 120 times cycle of wetting-drying. It is expected to be applied to an indoor air purifier or filter. • A new approach to phytoextraction solid residues from Citrus aurantium L. • Establishment of 3D structure long-acting hygroscopic and antibacterial composite. • Superior hygroscopic properties. Percent moisture absorption: 63.0% (25 ℃，RH=80%). • Superb antibacterial properties. Inhibition ratio: 97.1% ( E. coli ) and 95.4% ( S. aureus ). • A promising new filler: expected to be applied to indoor air purifier or filter.

Synthesis, characterization, DFT and biological studies of Fe(II), Cu(II), and Zn(II) complexes of keto-imine chelators

Three naphthoquinone-based chelators, 2-(pyrimidin-2-ylamino)-2,3-dihydronaphthalene-1,4-dione (HLa) 2-((4,6-dihydroxypyrimidin-2-yl)amino-2,3-dihydronaphthalene-1,4-dione (HLb), and 2-((4,6-dimethylpyrimidin-2-yl)amino-2,3-dihydronaphthalene-1,4-dione (HLc), have been synthesized by the reaction of 2-hydroxy-1,4-napthoquinone with 2-aminopyrimidine, 2-amino-4,6-dihydroxypyrimidine, and 2-amino-4,6-dimethypyrimidine respectively. Reaction of the chelators with Fe2+; Cu2+ and Zn2+ sulphate; and acetate salts; plus 2,2′-bipyridine(B) gave the resultant heteroleptic M2+ complexes, which were characterized by analytical, 1H-and 13C NMR, FT-IR, UV–vis, ESI-MS, and TG-DSC analyses. The FT-IR and NMR results showed that the chelators are bidentate and chelated with the M2+ ions via their ketonic oxygen (>CO) and secondary amine nitrogen (HN) atoms. The μeff data and UV–vis spectral evaluations of the complexes provided credence to the 6-coordinate octahedral geometries of the complexes. DFT calculations were performed to understand the mode of complex formation as well as their geometry around the metal centers. Compared to the chelators, the heteroleptic complexes have improved antimicrobial actions attributed to the extra 2-nitrogenous atoms in the 2,2′-bipyridine moiety and the presence of active metal ions. The CuLc complexes displayed the best antibacterial performance with inhibitory effects of 34.0 mm. However, the ZnLb complexes recorded the best antifungal activity (33.0 mm), due to the absorption of Zn2+ ions on the surface of the fungiform cell walls. The antioxidant assays with ferrous ions show that all the keto-imine chelators showed good chelating abilities. HLc showed values of 78.76 plus 74.5 % separately at concentrations of 200 and 100 mg/mL, which are higher than that of the standard ascorbic acid. The DPPH radical scavenging activities of the heteroleptic complexes indicate that they can be used for the synthesis of drugs for the treatment of pathological diseases arising from oxidative stress.

Improving the Properties of Magnetite Green Pellets with a Novel Organic Composite Binder.

A novel composite binder (humic acid modified bentonite, HAMB) and two other binders (bentonite and Modified humic acid, MHA) were used to explore the effects of binders on the properties of magnetite green pellets in this study. The results of green pellet properties and drying tests show that the low doses of a humic substance-based binder can achieve the same effect as high doses of bentonite binder. A humic substance-based binder could be a promising organic binder to replace bentonite. Meanwhile, the influence mechanism of adding different binders on the strength of green pellet was discussed, and the relationship between moisture content in the pellet and the compression strength of three binders was determined. A TG-DSC analysis found that the novel composite binder (HAMB) was not a simple mix of humic acid and bentonite, in which a humic substance could change the structure of bentonite and reduce the thermal stability of bentonite, causing the HAMB composite binder to have a high decomposition temperature.

Effects of pre-oxidized temperature and pre-oxidized oxygen concentration on burning characteristics of pre-oxidized coal

The secondary oxidation of residual coal during re-mining in goaf will seriously endanger mine safety production. To investigate the influence of the formation process of PC(pre-oxidized coal) in goaf on the secondary oxidation of coal, This paper utilized the TG-DSC analysis method to study the burning characteristics of PC under different pre-oxidized temperatures and different pre-oxidized oxygen concentrations. The results showed that both PT(pre-oxidation temperature) and POC(pre-oxidation oxygen concentration) have effects on the burning process of oxidized coal, and there is an optimal POC and the best PT. Both PT and POC only have significant effects on the characteristic temperatures before ignition temperature, and fewer effects on the ignition temperature and the characteristic temperatures after ignition temperature, and thus PT and POC only have effects on the first three stages of the secondary oxidation process of PC, i.e., water evaporation and gas desorption stage, oxygen absorption stage of weight gain, and thermal decomposition stage. The effects of PT and POC are different from each characteristic temperature, thus the effects of PT and POC are different in the first three stages. In general, the secondary oxidation process of PC Y-18 %-100 is the most dangerous when re-mining the residual coal in the goaf. However, different pre-oxidized coals have different risks in different stages of the secondary oxidation process, because the types of active structures mainly involved in the coal-oxygen reaction in each stage are different, and the PT and POC during the formation of pre-oxidized coals will affect the number of active structures involved in the coal-oxygen reaction during the secondary oxidation of pre-oxidized coals. The DSC curves of PC at 300 °C showed no obvious plateau of heat uptake, which was because the too high PT would decompose the steady aromatic ring structures in the coal samples. The research results can be used as the theoretical basis for the re-mining of goaf, and ensure the safety of workers and the smooth progress of re-mining.

In-Situ Synthesis of Layered Double Hydroxide/Silica Aerogel Composite and Its Thermal Safety Characteristics.

To adjust the thermal safety of hydrophobic silica aerogel, layered double hydroxide (LDH)/silica aerogel (SA) composites were prepared by an in-situ sol-gel process at ambient pressure. This study found the physical combination of SA and MgAl-LDH based on the FTIR spectra and phase composition of LDH/SA. The N2 sorption analysis confirms that the introduction of MgAl-LDH does not change the mesoporous attribution of LDH/SA significantly. With the increase in MgAl-LDH addictive content, the low density (0.12–0.13 g/cm3), low thermal conductivity (24.28–26.38 mW/m/K), and large specific surface area (730.7–903.7 m2g) of LDH/SA are still maintained, which can satisfy the requirements of thermal insulation. The TG-DSC analysis demonstrates that the endothermic effects and metal oxides formed during the MgAl-LDH decomposition are beneficial to the improvement of the thermal stability of LDH/SA composites. In addition, it was found that the gross calorific values of LDH/SA composites decrease with an increase in MgAl-LDH addictive content, all of which are lower than that of the pure SA. The research outcomes indicate that the thermal safety of LDH/SA composites is enhanced significantly by doping MgAl-LDH without impairing too many of the excellent properties, which benefits their expansion in the thermal insulation field.