Thermal Gravimetry Differential Scanning Calorimetry Research Articles

Hydrophobic Modification of the α‐Hemihydrate Phosphogypsum (α‐HH) Surface by Myristic Acid

AbstractPhosphogypsum is widely used as a filler. However, gypsum fillers exhibit poor water resistance, compromising the performance of subsequent products. To address this issue, we modified α‐hemihydrate phosphogypsum (α‐HH) with myristic acid (ΜΑ), a low surface energy material used to prepare super hydrophobic (SHP) surfaces. The MA concentration, temperature, and modification time were optimized using a Box‐Behnken experimental design method. The surface properties, microstructure, and thermal stability of the modified powders were characterized using contact angle measurements, X‐ray diffraction (XRD), Fourier transform infrared (FT‐IR) spectroscopy, Raman spectrum, X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy coupled with energy‐dispersive X‐ray spectroscopy (SEM‐EDS), and thermal gravimetry‐differential scanning calorimetry (TG‐DSC). Additionally, we discussed the hydrophobic modification mechanism of the modified α‐HH. The modified α‐HH/MA prepared with 11.0×10−4 mol L−1 MA at 60 °C for 60 min exhibited high hydrophobicity. During modification, MA bound to the calcium ions on the surface of α‐HH to form calcium myristate, thereby forming a hydrophobic film. The thermal stability of α‐HH was improved by MA modification. The modified powder maintained high hydrophobicity even at 250 °C.

Study of Possibility Physical Interactions Antimalarial Combination Drugs

Identification of solid state to investigate the possibility of physical interaction between Antimalarial Artemisinin Combination Treatment base Artesunate (AS) and Amodiaquine (AQ) by hot contact method Kofler, cold contact method (crystallization reaction) and binary phase diagram confirmation had been carried out. The results of hot contact method Kofler shown the formation a new crystalline habit as a long and thin needle on the contact zone (mixing zone) between AS and AQ. A different melting point was seen in its single component. Cold contact methods between two of supersaturated solution of component AS and AQ in methanol solvent also indicated the growth of crystal habit as similar as hot contact method Kofler. Confirmation by biner phase diagram shown the specific diagram for cocrystalline phase. Solid state interaction between AS and AQ was analysed by powder X-ray diffraction, FTIR (Fourier Transformed Infra Red) spectrophotometric, microscopic SEM (Scanning Electron Microscopic) and thermal DTA (Differential Thermal Analysis), TG-DSC (Thermal Gravimetry- Differential Scanning Calorimetry). Microscopic analysis by SEM showed significantly the change of habit and morphology of crystal to long and thin needle shaped. The difference of powder X-ray diffraction (PXRD) interferences peaks were observed in addition to PXRD interference peaks of each component and its physical mixtures that proved formation of cocrystalline phase. DSC Thermogram indicated a new endothermic peak corresponding to melting point of a new cocrystalline phase at temperature 160,4°C.

DSC/TG and SEM Studies of Synthesized Potassium Sulphamate (PS) and Potassium Dinitramide (KDN) Crystals

In the present paper, thermal decomposition and crystal researches of synthesized potassium sulphamate (PS) and potassium dinitramide (KDN) crystals were studied using differential scanning calorimetry/ thermal gravimetry (DSC/TG) and scanning electron microscope (SEM) techniques, respectively. Initially, PS crystals were synthesized using sulphamic acid and potassium hydroxide pellets. Afterwards, PS crystals were used for synthesizing potassium dinitramide (KDN) crystals by the nitration of PS in sulfuric and nitric acid mixture. One sample of PS was used for studying DSC/TG curves, while three samples of KDN crystals were used for the studying DSC/TG curves. The three samples of KDN crystals which were used in the present studies are, a) stored KDN (1 month), b) stored KDN (2 months), and c) washed KDN. All the obtained DSC/TG curves of three KDN crystals are dissimilar to each other, and the probable reasons for this dissimilarity are discussed in the manuscript. For further clarifications, TG curve of KN was compared with the TG curves of three samples of KDN used in the present study. It was observed that, while storage, KDN slowly converts into KN with some rate which gradually changes the physical and chemical properties of KDN.

Biopolymer-Grafted, Magnetically Tuned Halloysite Nanotubes as Efficient and Recyclable Spongelike Adsorbents for Anionic Azo Dye Removal.

The quest for sustainable development and green chemistry had led to the design and synthesis of advanced adsorbent materials for efficient removal of pollutants in industrial effluents. Magnetic halloysite nanotubes with chitosan nanocomposite sponges were prepared by combining solution-mixing and freeze-drying. Magnetic@chitosan/halloysite (Fe3O4–HNT/CS) and spongelike chitosan/halloysite (HNT/CS) were used as adsorbents for the removal of Congo red dye in aqueous solution in a batch process. The as-prepared composites were characterized using scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, vibrating-sample magnetometry, thermal gravimetry–differential scanning calorimetry, and Fourier transform infrared spectroscopy. Data from kinetic study were analyzed with pseudo-first-order and pseudo-second-order models, whereas the mechanism was analyzed using Bangham’s, Elovich’s, intraparticle, and double-exponential diffusion models. The equilibrium data were evaluated using Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models. The adsorption kinetics of dye removal followed the pseudo-first-order model with average rate constants of 0.260 and 0.196 min–1 for Fe3O4–HNT/CS and HNT/CS, respectively. The Langmuir adsorption isotherm best fitted the equilibrium data with R2 > 0.9 with maximum adsorption capacities of 41.54 and 54.49 mg g–1 obtained for HNT/CS and Fe3O4–HNT/CS, respectively. Negative values of ΔG° obtained from thermodynamic studies revealed that the adsorption process was spontaneous. The values of ΔH° and ΔS° obtained for Congo red dye removal were 69.46 and 39.54 kJ mol–1 and 240.5 and 145.1 J mol–1 K–1 for HNT/CS and Fe3O4–HNT/CS, respectively. The results indicated that CS–HNT is an excellent adsorbent; however, its magnetic modification further improved its recyclability and enhanced the performance for the removal of Congo red dye from aqueous solution.

Synthesis and Characterization of Photosensitive Ionic Liquid Surfactant 4-Butylazobenzene-4′-(Oxyethyl)Methylimidazolium with Br− and BF4− Counterions

AbstractThe photo-responsive ionic liquid surfactants 4-Butylazobenzene-4′-(oxyethyl)methylimidazolium with Br− (AZMIMBr) and BF4− (AZMIMBF4) counterions were synthesized, and their structures were characterized by means of 1H NMR. Their properties for pre- or post-UV irradiation were investigated by employing tensiometry, electrical conductance, thermal gravimetry-differential scanning calorimetry (TG-DSC) and small-angle X-ray scattering (SAXS). The effect of UV irradiation time on photoisomerization of two surfactants solutions was evaluated, which showed the photoisomerization efficiency decreases with an increase of their concentrations. After UV irradiation, the CMC value of the two surfactants increased, whereas, the surface tensions at CMC (γCMC) and the fraction of counterion binding (β) were approximately the same. SAXS coupled with polarized optical microscopic studies (POM studies) confirmed that the liquid crystal textures of AZMIMBr could be affected by UV-irradiation. The detailed analysis of thermodynamic parameters revealed that the micellizaton of AZMIMBr was entropy-driven, and the micellization of AZMIMBF4 was enthalpy-driven.

Thermal properties of simulated Hanford waste glasses

AbstractThe Hanford Tank Waste Treatment and Immobilization Plant will vitrify the mixed hazardous wastes generated from 45 years of plutonium production at the Hanford Site in Washington State. The molten glasses will be poured into stainless steel containers or canisters and subsequently cooled for storage and disposal. For appropriate facility design and operations to handle such highly energy‐consuming processes, knowledge of the material properties is required. The thermal properties (heat capacity, thermal diffusivity, and thermal conductivity) of representative high‐level and low‐activity waste glasses were studied as functions of temperature in the range of 200°C‐800°C (relevant to the cooling process). Simultaneous differential scanning calorimetry‐thermal gravimetry (DSC‐TGA), Xe‐flash diffusivity, pycnometry, and dilatometry were implemented. The study showed that simultaneous DSC‐TGA would be a reliable method for obtaining the heat capacity of various glasses in the temperature range of interest. Accurate thermal properties from this study were shown to provide a more realistic guideline for capacity and time constraints of the heat removal process when compared to the original conservative design‐basis engineering estimates. The estimates, though useful for design in the absence of measured physical properties, can now be supplanted and the measured thermal properties can be used in design verification activities.

Synthesis of mesoporous alumina microfibres by ammonium carbonate precipitation

Mesoporous alumina microfibres were successfully synthesised through a facile ammonium carbonate precipitation route. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectrometry, thermal gravimetry–differential scanning calorimetry, N2 adsorption and desorption as well as transmission electron microscopy were used to characterise the samples. It was observed that the phases of the samples transformed from gibbsite into ammonium aluminium carbonate hydroxide with an increase in aging time from 0 to 18 h, while the molar ratio of ammonium carbonate to aluminium nitrate nonahydrate was 3. At the same time, well dispersed ammonium aluminium carbonate hydroxide microfibres with a layer by layer packing structure were obtained. The fibrous morphology was maintained after the calcination. The calcined alumina microfibres possessed wormhole-like mesopores with a pore diameter of ∼4 nm. The Brunauer–Emmett–Teller surface area of the alumina microfibres was 298·7 m2 g−1, and the pore volume was 0·36 cm3 g−1.

Chemo-mechanical effects in kaolinite. Part 2: exposed samples and chemical and phase analyses

Continuing from part 1 of this paper, the results of laboratory tests on chemo-mechanical interactions in kaolinite subjected to the diffusion of inorganic, salt, acid and base solutions under an applied stress state are presented. Chemical analyses on the surnatant and analyses on X-ray diffraction patterns, high-temperature differential scanning calorimetry thermal gravimetry scans and transmission electron microscopy micrographs led to the conclusion that the bulk of kaolinite mineral is probably only slightly affected by the chemical interactions, the chemical attack being concentrated mainly at the particle edges, where it induces a change in the shape of the edges, which become irregular and less sharp. The mechanical behaviour of kaolinite is not affected by pore fluid salinity, but it is significantly affected by pore fluid pH: both acid or base solutions under an applied stress cause significant volumetric compression. Such strains are irreversible and probably related to the particle rearrangement induced mainly by the degradation of the particle edges, in addition to the decrease in basal friction angle (described in the companion paper) and the change of strength at edge-to-face contact points. The mechanical effects are slightly related to the dielectric constant of the pore fluid and this is consistent with the general conviction that interactions between kaolinite particles are mostly mechanical.

Stabilization and phase transformation of CuFe 2O 4 sintered from simulated copper-laden sludge

The feasibility of stabilizing copper-laden sludge by high-temperature CuFe 2O 4 ferritization process is investigated with different sintering temperature, and the prolonged leaching test. The thermal behavior, structural morphology, phase composition, and phase transformation of the stabilized sludge were investigated by using thermal gravimetry-differential scanning calorimetry, scanning electron microscopy and X-ray diffraction. The leaching behavior of the stabilized sludge under acidic environment was evaluated by modified Toxicity Characteristic Leaching Procedure (TCLP). The results indicated that CuFe 2O 4 could be effectively formed at around 800 °C by the iron oxide precursor with a 3 h of short sintering. The transformation was discovered on crystallographic spinel structures: the low-temperature (800–900 °C) tetragonal phase (t-CuFe 2O 4) and the high-temperature (∼1000 °C) cubic phase (c-CuFe 2O 4). At higher temperatures (∼1100 °C), the formation of cuprous ferrite delafossite phase (CuFeO 2) from the dissociation of CuFe 2O 4 was also noticed. Both CuFe 2O 4 spinel and CuFeO 2 delafossite phase have a better intrinsic resistance to acidic environment when compared to that of CuO phase by the modified TCLP test. The sintering strategy designed for copper-laden sludge is proven to be beneficial in stabilizing copper.

Tri-Metallic Catalyst for Mass Production of Quasi-Aligned Carbon Nanotubes by Thermal Chemical Vapor Deposition

In this paper, mass production of quasi-aligned CNTs was achieved with a new tri-metallic catalyst (Fe-Ni-Mo/MgO) by thermal CVD method, using methane as carbon precursor. The growth process was in-situ monitored by thermal gravimetry/differential scanning calorimetry (TG-DSC) technique, and the yield of CNTs over 2200% was attained under the mixture atmosphere of CH4 and H2 with flow rate about 25 ml/min and 5 ml/min respectively at 900°C for 30 min. The as-prepared products were characterized. Raman spectrums showed that the CNTs are multi-wall structure. The diameter of the CNTs was estimated to be 20-30 nm. We think the synergism of FeNi3 alloy and Mo is the main reason for the high catalytic activity of tri-metallic catalyst.

Formation of Al 2O 3–Bi 4Ti 3O 12 nanocomposite oxide films on low-voltage etched aluminum foil by sol–gel processing

A water-based bismuth titanate Bi 4Ti 3O 12 (BTO) sol was synthesized by mixing bismuth nitrate, tetra- n-butyl titanate, lactic acid, acetic acid and distilled water. The sol was applied to low-voltage etched aluminum foil by dip-coating. The crystallization process of Bi 4Ti 3O 12 on low-voltage etched aluminum foil was measured by thermal gravimetry–differential scanning calorimetry (TG–DSC) and high-temperature X-ray diffraction (HT-XRD). It was found that Bi 4Ti 3O 12 sol first converted into intermediate phase Bi 1.74Ti 2O 6.624, then transformed into perovskite phase Bi 4Ti 3O 12. After annealed at 600 °C for 30 min in air, the low-voltage etched aluminum foil covered with Bi 4Ti 3O 12 sol was anodized galvanostatically in 15 wt.% ammonium adipate solution. The voltage–time variation during anodizing was monitored and recorded. The structure and composition of samples were investigated by field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDAX). Results showed that the anodic composite oxide film was composed of an inner Al 2O 3 layer and an outer Bi 4Ti 3O 12 layer. The specific capacitance and the product of specific capacitance and withstanding voltage of samples with a BTO coating were about 56.64% and 43.77% larger than that without a BTO coating.

Thermal oxidative degradation of bicomponent PP/PET fiber during thermal bonding process

AbstractThe effects of the thermal bonding temperature, dwell time, and the type of mold materials on the thermal oxidative degradation of the PP sheath of bicomponent fibers were investigated using the Fourier Transform Infrared Spectra (FTIR) and Thermal Gravimetry/Differential Scanning Calorimetry (TG‐DSC) techniques. The samples were prepared on a new 3D nonwovens process based on air‐laying and through‐air thermal bonding. The fiber material was a commercial polypropylene (PP)/polyester (PET) (sheath/core) bicomponent staple fiber. The results reveal that ketone developed following β‐scission in the thermally bonded nonwovens. The level of thermal oxidative degradation increases with increase in the bonding temperature, dwell time, and the thermal conductivity of the mold material. Such thermal oxidative degradation led to the slight widening of the melting peaks of the fiber PP sheath in the thermally bonded nonwovens, and a slight decreasing of melting point compared with those of the as‐received fiber. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 391–397, 2007