Thermogravimetry Differential Scanning Calorimetry Research Articles

The Suppression Characteristics of NH4H2PO4/Red Mud Composite Powders on Methane Explosion

The composite powders composed of red mud (RM) and NH4H2PO4 (NH4H2PO4/RM) were successfully prepared by the anti-solvent method. The composition and structure of the NH4H2PO4/RM composite powders were characterized by the techniques of X-ray diffraction (XRD), SEM, N2 adsorption-desorption and Thermogravimetry-Differential scanning calorimetry (TG-DSC). The analysis results indicate that the as-prepared samples are composed with uniform nanoparticles and possess the porous structure. The methane explosion suppression characteristics of the NH4H2PO4/RM composite powders were tested by a 20 L spherical explosion system and a 5 L pipe test system. The results show that the NH4H2PO4/RM composite powders possess considerable suppression properties on methane explosion. When the loading content of NH4H2PO4 reached 30%, the maximum pressure and the maximum pressure rise rate of methane explosion were decreased by 35.1% and 95.8%, respectively. When comparing with no powder addition, the time to reach the pressure peak was extended from 0.07 s to 0.50 s. The NH4H2PO4/RM composite powders presented a synergistic suppression effect between NH4H2PO4 and RM, which made it exhibit considerable suppression property than that of pure NH4H2PO4 or red mud powders.

Synthesis of 4A Zeolite from Kaolinite-Type Pyrite Flotation Tailings (KPFT)

As a solid waste, kaolinite-type pyrite flotation tailings (KPFT) are a type of low-quality kaolin that contain impurities, such as iron and titanium. In this study, KPFT were calcined at 800 °C for two hours. The calcined production (CKPFT), which is mainly metakaolin, was used as the silicon and aluminum source to synthesize 4A zeolite (Na12[(AlO2)12(SiO2)12]·27H2O) via hydrothermal synthesis. The optimal hydrothermal synthesis conditions were determined from X-ray diffraction phase analysis, relative crystallinity (RC), and cation ion exchange capacity (CEC). The optimal hydrothermal synthesis conditions were determined to be a ratio of 5 g CKPFT, 6.5 g NaOH, 65 mL H2O, crystallization temperature 110 °C, and crystallization time of three hours. Under the optimal hydrothermal synthesis conditions, the RC and CEC of the synthesized 4A zeolite were 40.77% and 210.32 mg CaCO3·g−1, respectively. Further characterizations including pore size distribution, scanning electron microscopy, energy dispersive X-ray, thermogravimetry-differential scanning calorimetry, and Fourier transform infrared spectroscopy were performed. The results revealed that impurities in KPFT do not affect the synthesis of 4A zeolite. The surface morphology of the synthesized 4A zeolite was composed of chamfered-edged cubes with a particle size of one to three μm that was thermally stable up to approximately 890 °C.

Tailoring Schiff base cross-linking by cyano group toward excellent flame retardancy, anti-dripping and smoke suppression of PET

To improve the flame retardant efficiency of aromatic Schiff base (BA), and adjust the crosslinking temperature of imine groups, a cyano group, an electron-drawing group has been introduced into the chemical structure of aromatic Schiff base to obtain a third monomer for poly(ethylene terephthalate) (PET), named as dimethyl-5-[(2-cyanobenzylidene)amino]-isophthalate (CBAA). Thermogravimetry-differential scanning calorimetry (TG-DSC) and dynamic rheological results prove that the PET-based copolyester containing CBAA (CBAAnPETs) can cross-link at higher temperature than that containing BA, which will not affect the preparing and processing of PET. DSC and wide angle x-ray diffraction (WAXD) results demonstrate CBAAnPETs remain good crystallization ability. Owing to the two types of cross-linking reactions, i. e. the reactions between Schiff base (CHN-) and cyano group (-C≡N), and among -CHN- units, CBAA plays an important role in solid phase as well as gaseous phase endowing CBAAnPETs with excellent flame retardancy. With a low CBAA content (only 6.7 mol%), the copolyesters self-extinguish in 5 s with no melt drips in UL-94 vertical test, and its LOI value also increases to 31.0%. The peak heat release rate and total smoke release of the copolyesters obtained from cone calorimetry also observably decrease.

Novel Composite Electrolytes of Zr0.92Y0.08O2-α(8YSZ)-Low Melting Point Glass Powder for Intermediate Temperature Solid Oxide Fuel Cells.

In this study, Zr0.92Y0.08O2-α(8YSZ) powders were synthesized by the sol-gel method. The chemical physics changes and phase formation temperature of 8YSZ crystal were determined by thermogravimetry analysis and differential scanning calorimetry (TGA-DSC). 8YSZ-low melting point glass powder (8YSZ-glass) composite electrolytes with various weight ratios were prepared and calcined at different temperatures. The X-ray diffraction (XRD) patterns of the composite electrolytes were tested. The effects of synthesis temperature, weight ratio, test temperature, and oxygen partial pressure on the conductivities of 8YSZ-glass composite electrolytes, were also investigated at 400–800 °C. The result of the logσ ~ log(pO2) plot indicates that the 8YSZ-20% glass (700 °C) is almost a pure ionic conductor. The oxygen concentration discharge cell illustrates that the 8YSZ-20% glass (700 °C) composite electrolyte is a good oxygen ion conductor.

Selective Fabrication of Barium Carbonate Nanoparticles in the Lumen of Halloysite Nanotubes

Barium carbonate (BaCO3) materials with the controllable morphology of nanoparticles were selectively loaded into the lumen halloysite nanotubes (abbreviated as Hal) by a urease assisted catalytic implementation strategy. The Hal mineral was pre-treated through leaching by hydrochloric acid (abbreviated as A-Hal), resulting in increased defect sites and zeta potential. The negatively charged urease was loaded inside the positively charged A-Hal lumen, and then through the decomposition of urea catalyzed by urease to produce carbonate ions and ammonia. When Ba2+ diffused in, BaCO3 particles were selectively synthesized in the lumen of A-Hal, the pore channels of A-Hal effectively controlled the growth and aggregation of BaCO3 nanocrystals and their geometrical morphology. The obtained BaCO3/A-Hal-T was characterized by transmission electron microscopy, Fourier transformation infrared spectroscopy and X-ray diffraction, differential scanning calorimetry-thermogravimetry (DSC-TG). The BaCO3/A-Hal-T may provide a candidate for potential applications.

Separation of Li and Co from the active mass of spent Li-ion batteries by selective sulfating roasting with sodium bisulfate and water leaching

This paper presents a novel approach for recovering valuable metal from spent Li-ion batteries by separating Li and Co by using selective sulfating roasting with NaHSO4·H2O. This study focuses on the effects of the additive ratio of NaHSO4·H2O on the roasting mechanism. The occurrence evolution of the Li and Co elements during sulfating roasting and water leaching is studied by thermogravimetry–differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and inductively coupled plasma. The mixtures of spent LiCoO2 and NaHSO4·H2O possesses two obvious weightlessness platforms with corresponding endothermic peaks at 25–600 °C. As the proportion of NaHSO4·H2O in mixtures increases, the occurrence of the Li and Co elements evolves as follows: LiCoO2 → LiNa(SO4) and LiCoO2 → Co3O4. After being washed with deionized water, the concentrations of the Co and Li elements from the washed products in a mass ratio of 1:1.40 are 72.56% and 0.53%, respectively. The different occurrence forms of the Li and Co elements lead to their separation during sulfating roasting.

Effect of multilayered CoO-CoAl2O4 films on improving solar absorptance of Co-WC solar selective absorbing coatings

The multilayered CoO-CoAl2O4 solar selective films were prepared on Co-WC coatings with different mole ratio of Co and Al by sol-gel process. The thin film has high and low refractive indices, respectively. The inner layer can improve surface condition of Co-WC coating as a high absorbing film and buffer lay, annealed at 650 °C in vacuum. The outer layer was annealed at the same condition. The absorptance (α) of the multilayer structure coating increased from 0.873 to 0.932. The properties of the sols were characterized by thermogravimetry-differential scanning calorimetry (TG-DSC). The phase compositions and structure of samples annealed at 650 °C were analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The microstructure and elements distribution of thin films were investigated by field emission scanning electron microscopy (FE-SEM) and energy dispersive spectrometer (EDS), respectively. The absorptance of coatings indirectly indicate the binding force between the Co-WC substrate, durability, long-time stability and corrosion resistance are fine. The results illustrated that defects on surface of the Co-WC coating gradually decrease with the deposition of sol films. And the good element gradients in multilayer structures and the structure of thin films might be the reasons for its improvement in absorptance.

Thermal, Structural, AC Conductivity, and Dielectric Properties of Ethyl-2-amino-6-ethyl-5-oxo-4-(3-phenoxyphenyl)-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carboxylate Thin Films

Thermal, structural, alternating-current (AC) conductivity (σAC), and dielectric properties of ethyl-2-amino-6-ethyl-5-oxo-4-(3-phenoxyphenyl)-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carboxylate (HPQC) thin films have been studied. Thermogravimetry analysis and differential scanning calorimetry confirmed the thermal stability of HPQC over a wide temperature range. Fourier-transform infrared spectroscopy and x-ray diffraction analysis were carried out on HPQC in powder form and as-deposited thin film. The crystal system and space group type were determined for HPQC in powder form. The AC conductivity and dielectric properties were determined in the frequency range from 0.5 kHz to 5 MHz and temperature range from 296 K to 443 K. The AC electrical conduction of HPQC thin film was found to be governed by the small-polaron tunneling mechanism. The polaron hopping energy (WH), tunneling distance (R), and density of states (N) near the Fermi level were determined as functions of temperature and frequency. The dielectric properties of HPQC thin film were studied by analysis of Nyquist diagrams, the dissipation factor (tan δ), and real (e′) and imaginary (e″) parts of the dielectric constant.

Thermodynamics and Kinetics Parameters of Eichhornia crassipes Biomass for Bioenergy.

Eichhornia crassipes is an aquatic plant well known for its role in soil reclamation due to the containment of valuable nutrients. Moreover, its biomass is an abundant and low-cost biological resource. Pyrolysis of a biomass offers one of the cleanest methods to harness the bioenergy stored in the biomass. The present study was focused on evaluating the bioenergy potential of Eichhornia crassipes via pyrolysis. Biomass of E. crassipes was collected from a municipal wastewater pond. Oven dried powdered biomass of E. crassipes was subjected to pyrolysis at three heating rates including 10, 30 and 50 °C min-1 in a simultaneous Thermogravimetry-Differential Scanning Calorimetry analyzer under an inert environment containing nitrogen. Data obtained were subjected to isoconversional models of Kissenger-Akahira-Sunose (KSA) and Flynn-Wall-Ozawa (FWO) to understand the reaction chemistry. Kinetic parameters have shown that the pyrolysis followed first-order reaction kinetics. The average values of activation energies (129.71-133.03 kJ mol-1) and thermodynamic parameters including high heating values (18.12 MJ kg-1), Gibb's free energies (171-180 kJ mol-1) and enthalpy of reaction (124-127 kJ mol-1) have shown the remarkable bioenergy potential of this biomass. This low-cost biomass may be used to produce liquids, gases, and biochar in a costefficient and environmentally friendly way via pyrolysis or co-pyrolysis in the future.

Roasting and leaching behaviors of vanadium and chromium in calcification roasting–acid leaching of high-chromium vanadium slag

Calcification roasting–acid leaching of high-chromium vanadium slag (HCVS) was conducted to elucidate the roasting and leaching behaviors of vanadium and chromium. The effects of the purity of CaO, molar ratio between CaO and V2O5 (n(CaO)/n(V2O5)), roasting temperature, holding time, and the heating rate used in the oxidation–calcification processes were investigated. The roasting process and mechanism were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetry–differential scanning calorimetry (TG–DSC). The results show that most of vanadium reacted with CaO to generate calcium vanadates and transferred into the leaching liquid, whereas almost all of the chromium remained in the leaching residue in the form of (Fe0.6Cr0.4)2O3. Variation trends of the vanadium and chromium leaching ratios were always opposite because of the competitive reactions of oxidation and calcification between vanadium and chromium with CaO. Moreover, CaO was more likely to combine with vanadium, as further confirmed by thermodynamic analysis. When the HCVS with CaO added in an n(CaO)/n(V2O5) ratio of 0.5 was roasted in an air atmosphere at a heating rate of 10°C/min from room temperature to 950°C and maintained at this temperature for 60 min, the leaching ratios of vanadium and chromium reached 91.14% and 0.49%, respectively; thus, efficient extraction of vanadium from HCVS was achieved and the leaching residue could be used as a new raw material for the extraction of chromium. Furthermore, the oxidation and calcification reactions of the spinel phases occurred at 592 and 630°C for n(CaO)/n(V2O5) ratios of 0.5 and 5, respectively.

Mineral structure and crystal morphologies of high-iron hydrargillite

Various characterization methods, including scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller surface-area measurements, thermogravimetry–differential scanning calorimetry, X-ray diffraction, and infrared spectroscopy, were used to study the mineral structure and surface characteristics of high-iron hydrargillite. Gibbsite, goethite, and hematite were found to be the main mineral components of hydrargillite, whereas the goethite and hematite were closely clad to the surface of the multilayer gibbsite crystals. Compared with the synthetic gibbsite, the hydrargillite contained more structural micropores generated by the mineral evolution during the mineralization process. The gibbsite in hydrargillite contained less crystal water compared with the synthetic gibbsite, and it was a typical polymorphic structure. The isomorphous substitution of Al and Fe was observed in goethite. The dissolution-controlling step of hydrargillite was the ionic diffusion speed because of the goethite and hematite that closely covered and encapsulated the gibbsite crystals.

Preparation of ErMnO3 by Sol-gel Method and its Photocatalytic Activity for Removal of Methyl Orange from Water

The single phase perovskite ErMnO3 was synthesized using Er(NO3)3, manganese acetate, citric acid and urea by a facile sol-gel method. The gel of ErMnO3 precursor was kept for 36 hours in 100 °C oven to get the xerogel. Then, the xerogel was calcined at 800 °C for 12 hours in muffle furnace to prepare single phase ErMnO3. The prepared sample was characterized by thermogravimetry differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Under ultraviolet light, the photocatalytic activity of ErMnO3 was studied with methyl orange of 20 mg/L as the simulated sewage. The results show that the ErMnO3 sample particle size distribution is relatively uniform, the average grain size is mainly around 100 nm. The photocatalytic experiment demonstrates that ErMnO3 is highly photocatalytic activity for removal of methyl orange from water. When methyl orange of 20 mg/L is degraded for 120 min in the presence of ErMnO3, the degradation rate of methyl orange can reach about 95%. The degradation of methyl orange accords with first order kinetic model in presence ErMnO3 sample, and the apparent rate constant is 0.022 min-1.

Surface Nitridation of Aluminum Nanoparticles by Off-Line Operation and Its Kinetics Analysis

To improve combustion efficiency and anti-oxidation property of aluminum nanoparticles (ANs), surface nitridation of ANs was performed in a pipe furnace under the protection of nitrogen gas in a glove-operation hermetic box via an off-line nitridation process. The product was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analysis. A core-shell nanostructure with an aluminum nitride (AlN) coating on the ANs core was observed. The empirical kinetic triplets (Ea, A, and f(α)) for the nitridation of ANs, for the first time, were calculated and analyzed using five types of iso-conversional methods and a differentiation method. The effects of the kinetics of the reaction were investigated by simultaneous differential scanning calorimetry–thermogravimetry (DSC-TG) and thermal analysis using linear programmed temperature at different heating rates.

Mineralization and Cementation of Fugitive Dust based on the Utilization of Carbon Dioxide and Its Characterization

Fugitive dust was cemented, forming larger particles bond in the calcite-consolidation-layer by microbial method. The particular composition, the morphology, and thermal decomposition properties of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry-thermogravimetry (DSC-TG). The characterization data obtained showed that loose fugitive dust particles could be bonded and formed the consolidation-layer under the effect of calcite obtained by microbial method successfully. Meanwhile, the sample obtained by microbial method had superior wind-erosion resistance.

Preparation, quantitative surface analysis, intercalation characteristics and industrial implications of low temperature expandable graphite

Expandable graphite is widely used as a new functional carbon material, especially as fire-retardant; however, its practical application is limited due to the high expansion temperature. In this work, preparation process of low temperature and highly expandable graphite was studied, using natural flake graphite as raw material and KMnO4/HClO4/NH4NO3 as oxidative intercalations. The structure, morphology, functional groups and thermal properties were characterized during expanding process by Fourier transform infrared spectroscopy (FTIR), Raman spectra, thermo-gravimetry differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope (SEM). The analysis showed that by oxidation intercalation, some oxygen-containing groups were grafted on the edge and within the graphite layer. The intercalation reagent entered the graphite layer to increase the interlayer spacing. After expansion, the original flaky expandable graphite was completely transformed into worm-like expanded graphite. The order of graphite intercalation compounds (GICs) was proposed and determined to be 3 for the prepared expandable graphite, based on quantitative XRD peak analysis. Meanwhile, the detailed intercalation mechanisms were also proposed. The comprehensive investigation paved a benchmark for the industrial application of such sulfur-free expanded graphite.

Supramolecular arrangement and photophysical properties of a dinuclear cyanophenylboronic acid ester.

Boronic esters are useful building blocks for crystal engineering and the generation of supramolecular architectures, including macrocycles, cages and polymers (one-, two- and three-dimensional), with potential utility in diverse fields such as separation, storage and luminescent materials. The novel dinuclear cyanophenylboronic ester described herein, namely 4,4'-(2,4,8,10-tetraoxa-3,9-diboraspiro[5.5]undecane-3,9-diyl)dibenzonitrile, C19H16B2N2O4, was prepared by condensation of 4-cyanophenylboronic acid and pentaerythritol and fully characterized by elemental analysis, IR and NMR (1H and 11B) spectroscopy, single-crystal X-ray diffraction analysis and TG-DSC (thermogravimetry-differential scanning calorimetry) studies. In addition, the photophysical properties were examined in solution and in the solid state by UV-Vis and fluorescence spectroscopies. Density functional theory (DFT) calculations with ethanol as solvent reproduced reasonably well the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) of the title compound. Hirshfeld surface and fingerprint plot analyses are presented to illustrate the supramolecular connectivity in the solid state.

Purification of Algal Calcium-Chelating Peptide and Its Physical Chemical Properties

ABSTRACTThe Schizochytrium protein, extracted from byproduct of Schizochytrium sp. after lipid extraction, was isolated and hydrolyzed. A specific calcium-binding peptide was purified from the hydrolysate through Sephadex G-25 gel filtration chromatography and C18 reversed-phase high-performance liquid chromatography (RP-HPLC). The calcium-binding capacity of the specific peptide reached up to 136.68 ± 4.6 μg/mg. The amino acid sequence was confirmed as Ser-Ser-Val (SSV) with a molecular weight of 291.15 Da by liquid chromatography electrospray ionization tandem mass spectrometry (LC–ESI–MS/MS). Fourier transformation infrared spectroscopy showed that the major binding sites included oxygen atom from carbonyl group and nitrogen of amino group or imino group. SSV-Ca chelate was confirmed to be a neutral molecular by Zeta potential analysis, and the calcium ion was surrounded by the functional chelating sites of SSV. In addition, thermogravimetry-differential scanning calorimetry (TG-DSC) and calcium releasing assay revealed that the SSV-Ca chelate exhibited excellent thermal stability and solubility in both acidic and basic conditions, which was in favor for calcium absorption in the gastrointestinal tracts of humans. The findings indicate the by-product of Schizochytrium sp. is a promising source for making peptide-calcium chelate as a dietary functional supplement.

Synthesis, characterization, antimicrobial activity and DFT studies of 2-(pyrimidin-2-ylamino)naphthalene-1,4-dione and its Mn(II), Co(II), Ni(II) and Zn(II) complexes

A pyrimidine-based ligand, 2-(pyrimidin-2-ylamino)naphthalene-1,4-dione (L), has been synthesized by the reaction of 2-aminopyrimidine with 2-hydroxy-1,4-napthoquinone. Reaction of the ligand with Ni(II), Co(II), Mn(II) and Zn(II) acetate gave the corresponding metal complexes which were characterized by spectroscopic techniques, (infrared, electronic), elemental analysis, room-temperature magnetometry, conductance measurements and thermogravimetry-differential scanning calorimetry (TG-DSC) analyses. The room-temperature magnetic data and electronic spectral measurements of the complexes gave evidence of 4-coordinate square planar/tetrahedral geometry. The thermal analyses values obtained indicated the monohydrate complexes. The antimicrobial screening of the compounds showed mild to very good results. The Mn(II) complex showed the best result within in the range of 11.5–29 mm. The electronic, structural and spectroscopic properties of the complexes were further discussed using density functional theory. Molecular docking studies showed significant binding affinity with the drug targets and the metal complexes have potentials to be used as drugs.

Mineralogy and Physico-Chemical Data of Two Newly Discovered Halloysite in China and Their Contrasts with Some Typical Minerals

We report in this article the systematical acquisition of physico-chemical parameters for two newly discovered halloysite (Hal) minerals from Shiyan and Tongling in China. As the comparative reference, the data from Hal in Linfen, Chenxi, and the salt lake in Australia (samples were abbreviated as Hal-AU, Hal-SY, Hal-LF, Hal-CX and Hal-TL, respectively) were also investigated using X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), Fourier transformation infrared spectroscopy (FTIR), differential scanning calorimetry-thermogravimetry (DSC-TG), X-ray fluorescence, surface zeta potential measurements and N2 adsorption-desorption isotherms. The newly found minerals were probably formed in hydrothermal leaching and sedimentary circumstances. The Hal-SY contains 7 Å-halloysite and dickite, while Hal-TL contains 10 Å-halloysite with some alunite (similar with Hal-CX). Other impurities found in the samples include quartz, gibbsite, iron oxide and anatase. All of them showed tubular morphology with diameter in the range of 30–90 nm and a length of 300–2500 nm, while the Hal-SY has the largest inner diameter to about 150 nm. Specific surface areas varied from 26.0~59.0 m2·g−1. In addition, maximum CEC (cation exchange capacity) of the newly found Hal was about 40 cmol/kg, while that of Hal-AU was relatively low (8 cmol/kg) due to the sedimentary nature of Salt Lake circumstances. The surface charge was predominantly negative over most of the relevant pH range (>2.0). It can be concluded that the different morphology and impurity content of halloysite will greatly affect the surface area, pore volume, and cationic exchange capacity (CEC) of the minerals.

H2S selective sensitivity of Cu doped BaSrTiO3 under operando conditions and the associated sensing mechanism

Nanostructured Cu mol. 5% doped perovskite material Ba0.75Sr0.25TiO3 was synthesized under hydrothermal conditions and further on deposited via RF sputtering technique onto commercial Al2O3 substrates provided with Au interdigital electrodes and Pt heater. The obtained thin films have been analyzed by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM), X-ray photoelectron spectroscopy (XPS), Differential Scanning Calorimetry-Thermogravimetry (DSC-TG) and electrical investigations. The H2S (5–90 ppm) gas-surface interaction at moderate operating temperature (Top = 250 °C) associated with the interplay between the pre-adsorbed oxygen species and surface dipolar hydroxyl groups, has been highlighted by simultaneous work function and electrical resistance measurements. By correlation with the XPS spectra, the dominant role of surface hydroxylation was revealed and the subsequent gas sensing mechanism under operando conditions has been addressed.