Thermogravimetric Differential Thermal Analysis Research Articles

Prediction of thermal and thermo‐mechanical behavior of nano‐zirconia reinforced aluminium matrix composites

AbstractAluminium bequeaths the same benefits to medical industry as it does to other industries: it is incredibly lightweight and possesses superior strength‐to‐weight ratio. This study‘s aim is to investigate the thermal and thermomechanical behaviour of aluminium 6061 alloy reinforced with nano zirconia (0 wt. % to 15 wt. %; in 5 % steps) for medical applications. The effect of nano zirconia loading on thermal conductivity and thermo‐mechanical (thermo‐gravimetric analysis and dynamic mechanical analysis) have been systematically investigated. The thermal conductivity (128 W/m⋅K to 79 W/m⋅K) decreases with the increasing of nano zirconia particles reinforcement. The storage modulus increases with the nano zirconia particles (64 GPa to 172 GPa), whereas loss modulus indicates an increasing trend concerning the increasing temperature. The thermogravimetric analysis and differential thermal analysis result shows that composites’ decomposition temperature improved with the weight percentage of nano zirconia particles. Furthermore, representative volume element analysis is conducted to evaluate the thermal conductivity and results indicates good agreement with the experimental results within a deviation of ∼5 %.

Synthesis, Characterization, Anti-bacterial and Anti-inflammatory Activities of Bismuth(III) Complexes Based on 5-chloro-2-mercaptobenzothiazole

Bismuth, known as a heavy metal, is excluded from this class due to its low toxicity. Due to this feature, bismuth containing compounds have always been interesting compounds in the field of medicinal chemistry. For this reason, the discovery of new bismuth compounds and the investigation of their biological properties are very important for this field. In this study, three new bismuth(III) compounds formulated as [Bi(L)2X3] (L: 5-chloro-2-mercaptobenzothiazole (ClMBZT); X: Cl, Br, and I) were synthesized for the first time and, the molecular structure of them were elucidated by a series of spectroscopic techniques. Thermal stability and degradation steps of the title compounds were analyzed by Thermogravimetric-Differential Thermal Analysis (TG-DTA). The antibacterial study has been conducted against six strains bacteria, and the results indicated that bismuth(III) compounds generally showed more effective antibacterial activity than free ligand. The anti-inflammatory potential of bismuth(III) compounds was investigated through in vitro lipoxygenase enzyme inhibition studies. The results show that bismuth(III) compounds have higher anti-inflammatory potential than free ligand.

Influence of alumina modulus on formation of high-magnesium clinker and morphological evolution of MgO

This work investigates the influence of alumina modulus (AM) on the formation of high-magnesium clinker (w(MgO) > 5 %) and the morphological evolution of MgO and prepares clinkers with different MgO contents by using analytical reagents. High-temperature microscopy (HTM), thermogravimetric–differential thermal analysis (TG–DTA), X–ray diffraction (XRD), optical microscopy and backscattered electrons–energy–dispersive spectrometry (BSE–EDS) examine the clinkering mechanism. The results show that a reduced AM improves burnability of raw meal and the formation of more regular and larger alite particles. An increased AM contributes to reducing the size of the periclase and causes the shape of its particles to be round. An AM of 1.1 leads to the lowest liquidus temperature and increased tricalcium silicate (C3S) content. In this case, a maximal solid solubility and a minimal crystallinity of MgO can be obtained. The highest content of C3S and tetra-calcium aluminoferrite (C4AF) can be achieved at an MgO content of 3 %–6 %.

Synthesis, Covalency Sequence, and Crystal Features of Pentagonal Uranyl Acylpyrazolone Complexes along with DFT Calculation and Hirshfeld Analysis.

Three uranyl acylpyrazolone complexes [UO2(PCBPMP)2(CH3CH2OH)] (complex I), [UO2(PCBMCPMP)2(CH3CH2OH)] (complex II), and [UO2(PCBPTMP)2(CH3CH2OH)] (complex III) were synthesized from σ-donating acypyrazolone ligands to analyze their sequence of covalent characteristics, reactivity, and redox properties (PCBPMP: p-chlorobenzoyl 1-phenyl 3-methyl 5-pyrazolone; PCBMCPMP: p-chlorobenzoyl 1-(m-chlorophenyl) 3-methyl 5-pyrazolone; PCBPTMP: p-chlorobenzoyl 1-(p-tolyl) 3-methyl 5-pyrazolone). An examination of the structure, pentagonal bipyramidal geometry, and composition of these complexes was conducted mainly through their single-crystal X-ray diffraction (XRD) data, 1H nuclear magnetic resonance (NMR) δ-values, plots of thermogravimetric-differential thermal analysis (TG-DTA), significant Fourier transform infrared (FTIR) vibrations, gravimetric estimation, and molar conductivity values. The covalency order was found to be complex II > III > I, which mainly depends on values of stretching frequencies, average bond lengths of axial uranyl bonds, values of average bond lengths on the pentagonal equatorial plane, solvent coordination on the fifth site of a pentagonal plane, and the type of aryl group on the nitrogen of the pyrazolone ring. This was confirmed by FTIR spectroscopy and single-crystal spectral characterization. To verify experimental results by comparison with theoretical results, density functional theory (DFT) calculations were carried out, which further gives evidence for the covalency order through theoretical frequencies and the gap of highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energies. Theoretical bond properties were also examined by the identification of global index parameters. Intermolecular noncovalent surface interactions were studied by the Hirshfeld surface analysis. The irreversible redox behavior of uranyl species was identified through electrochemical cyclic voltammetry-differential pulse voltammetry (CV-DPV) plot analysis.

Sol–Gel Synthesis of Iron-Doped Sepiolite as a Novel Humidity-Sensing Material

Nowadays, humidity sensors are attracting a great deal of attention, and there are many studies focusing on enhancing their performances. Nevertheless, their fabrication through facile methods at reasonable cost is a significant factor. In this article, a new magnesium silicate nanopowder was successfully synthesized using a simple and low-cost sol–gel method. Subsequently, modified sepiolite was achieved by the substitution of iron ions in the synthesized nanopowders. The specimens were then characterized by X-ray diffraction, field emission–scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric–differential thermal analysis, infrared spectroscopy, and nitrogen adsorption. Furthermore, humidity sensors were manufactured by screen printing the prepared powders on alumina substrates with interdigitated Pt electrodes. The results showed that the fabricated sensors with modified sepiolite exhibited interesting characteristics for humidity detection.

Conjugation of tetracycline and penicillin with Sb(v) and Ag(i) against breast cancer cells

AbstractTetracycline (TecH2) reacts with triphenylantimony (TPSbiii) in the presence of hydrogen peroxide to form the [Ph3Sbv(Tec)] (TecAn). The sodium penicillin G (PenH) conjugates with Ag(i) towards [Ag(Pen)(MeCN)]2(PenAcAg).TecAnandPenAcAgwere characterized by melting point, X-ray fluorescence spectroscopy, attenuated total reflectance-Fourier transform infra-red, thermogravimetric-differential thermal analysis in solid state, ultraviolet-Vis spectroscopy, and nuclear magnetic resonance (1H and13C-NMR), spectroscopies in solution. The molecular weight was determined with cryoscopy. Thein vitrocytotoxic activity ofTecAnandPenAcAgwas evaluated against the human breast adenocarcinoma cell lines: MCF-7 (positive to hormones receptor (HR+)), MDA-MB-231 (negative to hormones receptor (HR−)), and theirin vitrotoxicity and genotoxicity were tested against normal human fetal lung fibroblast cells (MRC-5). The MCF-7 cells’ morphology and acridine orange/ethidium bromide staining suggest an apoptotic pathway for cell death. The binding affinity ofTecAnandPenAcAgwith DNA was, ex vivo, studied by UV-Vis and fluorescence spectroscopy and viscosity measurements of DNA solution.PenAcAginhibits lipoxygenase (LOX) stronger than cisplatin, while no inhibitory activity has been detected forTecAn. The reduction of non-active Sb(v), ofTecAn, to active Sb(iii) by glutathione (a tripeptide over expressed in tumor cells) was also investigated.

Synthesis, characterization, and biological properties of mono-, di- and poly-nuclear bismuth(III) halide complexes containing thiophene-2-carbaldehyde thiosemicarbazones

In order to investigate the coordination chemistry and pharmacological applications of bismuth compounds, a series of new bismuth(III) halide thiosemicarbazone complexes were synthesized. The reactions of thiophene-2-carbaldehyde-N-substituted thiosemicarbazones with bismuth(III) halides resulted in the formation of the {[[BiCl2(η1-S-Httsc)4]+.Cl−][BiCl2(μ2-Cl)(η1-S-Httsc)2]2} (1), {[BiCl3(η1-S-Htmtsc)3].CH3OH} (2), {[BiCl3(η1-S-Htetsc)3].CH3OH} (3), {[BiBr2(μ2-Br)(η1-S-Httsc)2]2.CH3OH} (4), {[BiBr2(μ2-Br)(η1-S-Htmtsc)2]n} (5), and {[BiI2(μ2-I)(η1-S-Httsc)2]2} (6) complexes (Httsc: thiophene-2-carbaldehyde thiosemicarbazone, Htmtsc: thiophene-2-carbaldehyde-N-methyl thiosemicarbazone, Htetsc: thiophene-2-carbaldehyde-N-ethyl thiosemicarbazone). The complexes were characterized by a number of different spectroscopic techniques and the crystal structures of all bismuth(III) complexes (1–6) were determined by using single crystal X-ray diffraction study. In addition, the thermal stability of the complexes was compared using Thermogravimetric–differential thermal analysis. Crystal structures of the two free ligands, thiophene-2-carbaldehyde-N-methyl-thiosemicarbazone and thiophene-2-carbaldehyde-N-ethyl-thiosemicarbazone, were also determined by using single crystal X-ray diffraction analysis. The Hirshfeld surface of the bismuth(III) complexes and free ligands were additionally analyzed to verify the intermolecular interactions. Biological studies showed that all six bismuth(III) thiosemicarbazone complexes (1–6) exhibited biological activities against selected bacteria and the human breast adenocarcinoma (MCF-7) cell line.

Fabrication and characterization of silica ceramic compact prepared using Aloe‐Vera mucilage as a binder

AbstractIn this study, silica compacts were fabricated through a powder processing route at different compaction pressure, using Aloe‐Vera (AV) mucilage as a binder. The silica compacts were prepared at 90, 100, and 110 MPa compaction pressure using 0%–16 wt% of AV binder. The optimum amount of AV binder was 14 wt% for both 90 and 100 MPa and 12 wt% for 110 MPa. The maximum achieved green density and green strength of silica compacts at the optimum binder amount were 62.3% and 4 MPa, respectively at 110 MPa compaction pressure. The green silica compacts prepared at 110 MPa compaction pressure exhibited a minimum porosity of 21% and maximum flexural strength of 15 MPa after sintering at 1400°C. The green silica compacts with the optimum amount of binder were strong enough for machining. The Fourier transform infrared spectroscopy analysis revealed the functional groups present in AV mucilage. The binder burnout characteristic of AV mucilage in the silica compact was determined by thermogravimetric analysis and differential thermal analysis. Additionally, AV gel acted as a binder and solvent simultaneously for ceramic compaction.

Effect of nano TiO2 on the thransport, structural and thermal properties of PEMA-NaI solid polymer electrolytes for energy storage devices

Nano Titania (TiO2) added polymer electrolytes have been prepared successfully via conventional solvent casting technique using Poly (Ethyl Methacrylate) (PEMA) as the host polymer and Sodium Iodide (NaI) as salt. Different characterization techniques such as AC impedance spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), and Thermogravimetric differential thermal analysis (TG-DTA) have been employed. With the help of the AC impedance analyzer, the ionic conductivity for all samples has been calculated and higher ionic conductivity of 2.91 × 10−5 Scm−1 is achieved for the system PEMA/NaI/4 wt% TiO2 at room temperature. The shifting and disappearance of bands in FTIR spectroscopy confirm the mixing of polymer and salt in the homogeneous polymer electrolytes. The decrease in crystallinity and hence the increase in amorphous nature has been confirmed through XRD studies. The diffusion coefficient, mobility, and the number of mobile ion concentrations have been estimated for all compositions of nano TiO2 added PEMA/NaI systems. The thermal stability of the membranes has been investigated by TG-DTA analysis.

Co-incineration effect of sewage sludge and municipal solid waste on the behavior of heavy metals by phosphorus

The effects of sewage sludge phosphorus (P) content on heavy metal behavior during co-incineration of sewage sludge and municipal solid waste (MSW) were evaluated. Thermogravimetric differential thermal analysis revealed that MSW incineration was mainly caused by organic matter and fixed carbon, while sewage sludge incineration was caused by volatile matter. During co-incineration, the peak weight loss at 460 °C shifted to slightly higher temperatures and the sludge ratio increased, indicating that interaction effects during co-incineration delayed pyrolysis and polymer/fixed carbon incineration. The residual heavy metal ratios after mono-incineration of sewage sludge were higher than those after MSW mono-incineration. The Cl content of MSW (0.757%) was much higher than that of sewage sludge (0.068%), which resulted in the conversion of heavy metals into metal chlorides and then volatilized during MSW mono-incineration. A synergistic effect of co-incineration was evident for Cu, but not for lead (Pb) or cadmium (Cd). X-ray absorption fine structure (XAFS) measurement revealed that Cu in MSW ash was in the form of CuO(s), but was Cu3(PO4)2 in sewage sludge and co-incineration ashes. CuO(s) is relatively unstable and may be transformed to CuO(g) or CuCl(s) before volatilizing at high temperature or in the presence of Cl. Phosphorus has the effect of stabilizing Cu in sewage sludge during co-incineration.

Hierarchical self-assembly of 0D/2D β-Bi2O3 crossandra flower morphology exhibits excellent photocatalytic activity against bromophenol dyes

Crossandra flower shape morphology of β-Bi2O3 nanoflakes was achieved successfully by the solvothermal method. Synthesized β-Bi2O3 nanoflakes were characterized using various characterization techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectra, Ultraviolet–Visible diffuse reflectance spectroscopy (UV-DRS), X-ray photoelectron spectrometer (XPS), N2 adsorption-desorption isotherms (BET), liquid chromatography with mass spectrometry LCMS, Dynamic light scattering (DLS) and Zeta potential (ZP). Moreover, thermal stability and phase change were studied using thermogravimetric analyzer (TGA) and differential thermal analyzer (DTA). The size, shape, and extent of growth was studied using transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX), and field emission scanning electron microscopy (FESEM). The crossandra flower shape morphology was achieved due to the effect of temperature (350 °C); this was due to the uniform shifting of heat throughout the material during calcination, which allows material growth along the c-axis. The obtained material was partially in de-agglomerated and agglomerated form, and agglomeration was due to electrostatic forces of attraction. Besides this, the synthesized β-Bi2O3 was utilized to investigate photocatalytic activity for the degradation of bromophenol blue (BPB) and bromocresol purple (BCP). β-Bi2O3 shows the effective catalytic activity as it degrades the phenolic dyes effectively. The degradation was 96% (160 min) and 94% (200 min) for BPB and BCP, respectively. Overall, β-Bi2O3 nanoflakes were more responsive as a photocatalyst for BPB, which took minimal time as compared to BCP.

Oxidation behavior and damage mechanism of SiCf/SiC minicomposites with multilayered (BN/SiC)n interfacial coatings at 1200 ℃

ABSTRACT SiCf/SiC minicomposites with multilayered (BN/SiC)n interfacial coatings were fabricated via chemical vapor infiltration and precursor infiltration pyrolysis methods. Oxidation behavior, mechanical properties, and interfacial self-healing mechanism of minicomposites at 1200°C were comparatively studied. In dry air, SiC matrix at edges of composites was oxidized to glassy SiO2, thereby sealing the pores between fibers and matrix, healing microcracks, and preventing the diffusion of oxygen into the material. Results of thermogravimetric–differential thermal analysis proved that glassy borosilicate formed at 910°C and 1050°C in minicomposites with BN/SiC and multilayered (BN/SiC)2 coatings. In water/oxygen atmosphere at 1200°C, there existed an equilibrium between the generation of SiO2 and gaseous Si(OH)4. Uncoated sample and minicomposite with single BN coatings were simultaneously eroded by oxidizing atmosphere in directions perpendicular and parallel to fiber axis. Microholes formed due to BN volatilization were gradually healed by glassy borosilicate in minicomposites containing SiC layers, improving interface self-healing capability of composites. After oxidation in water/oxygen atmosphere for 100 min, minicomposites with multilayered (BN/SiC)2 coatings retained relatively high fracture strength and strain, which were 499.0 MPa and 1.05%, respectively.

Study on luminescent properties of orange phosphor NaCaPO4 :Eu3.

The NaCaPO4 :Eu3+ phosphor was synthesized by the sol-gel method. The structure and luminescence properties of the phosphor were analyzed by thermogravimetric-differential thermal analysis (TG-DTA), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and fluorescence spectroscopy. TG-DTA results show that NaCaPO4 phase can be formed after 700°C. FTIR spectra confirmed the existence of PO4 units. XRD results show that the sample is a pure NaCaPO4 orthorhombic crystal phase. The TEM diagram shows that the sample has good uniformity. The NaCaPO4 :Eu3+ emits orange light under 394 nm excitation. The optimal doping concentration is 3mol%. The reason for concentration quenching is caused by multipolar interaction. Through further analysis of the charge transfer band and the spectrum at 5 D0 → 7 F0 transition of the NaCaPO4 :Eu3+ phosphor, the reason for the orange light of the phosphor is owing to the different Eu3+ occupancy which is explained in detail.

Mineralization process of ferrous ions from ZnSO4-FeSO4 solution at a temperature range of 368.15–423.15 K

The abiotic mineralization of ferrous ions for ZnSO4-FeSO4 solution at temperatures of 368.15–423.15 K was investigated. The effect of kinetic factors including oxygen partial pressure, temperature, agitation speed, with presence of a neutralizer or not, and seeding on the ferrous oxidation process was evaluated in detail. Also, the rate constants for the ferrous oxidation process were calculated by a second-order kinetic curve of the partial concentration of [Fe2+] with time to realize the effect of the different kinetic factors as variables. Furthermore, the morphology of the minerals was identified using scanning electron microscopy electron dispersive spectroscopy measurements (SEM-EDS), and the phase composition was characterized by the X-ray diffraction (XRD), the thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The research indicated that the ferrous oxidation process was accelerated by elevating temperature, increasing agitation speed, and adding a neutralizer. Conversely, increasing oxygen partial and seeding both decrease the rate constant of the oxidation process. The iron-rich precipitates produced comprise a wide range of chemical compositions, structures, sizes, and morphologies. They consisted primarily of goethite and hematite, with goethite being dominant below 403.15 K, and hematite above 403.15 K. Moreover, the iron-rich products were successfully obtained by abiotic mineralization of industrial ZnSO4 solution at 423.15 K, containing 59% of Fe and 1% of Zn, while the resultant ZnSO4 solution after removal of iron contained less than 1 g/L of iron ions. Thus, abiotic mineralization of ferrous ions for ZnSO4 is clean and energy-saving, and the iron-rich products can be used as raw materials for ironmaking.

A novel approach to band gap engineering of Nano-Ca(OH)2: Nanocomposites with Ag2O

Band gap engineering (BGE) is an important tool to tune the energy band gap of wide band gap semiconductors e.g., Ca(OH)2 which promises to show many wonderful functional applications e.g., solar blind photodetectors. The current work reports about the successful reduction in optical energy band gap (Eg) through BGE of chemically synthesized Ca(OH)2 nano particles (CHNPs) by microstructural tuning achieved through in-situ Ag2O incorporation to achieve the formation of the Ca(OH)2–Ag2O nanocomposites. The CHNPs and (3–15 atom%) Ag2O-incorporated CHNPs nanocomposite powders are characterized by the conventional x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), energy dispersive x-ray (EDX) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermo-gravimetric analysis-differential thermal analysis (TGA-DTA) and ultraviolet–visible (UV–Vis) UV–Vis spectroscopy techniques. The results reveal that systematic incorporation of nano Ag2O can very effectively reduce the magnitude of direct optical band gap energy values (Eg) by as much as 33%. These results are explained in terms of microstructural variables e.g., nanocrystallite size, lattice strain, lattice parameters, dislocation density, presence of Ag0, Ag+ states present on the surfaces of the nanocomposite powders, variation in microstructure, presence of surface functional groups, thermal stability, and optical absorption characteristics. The possible mechanisms active behind the reduction in the (Eg) values are suggested. Further, a schematic model of the band gap reduction mechanism is presented. Furthermore, the implications of the present results for designing CHNPs for futuristic applications e.g., optoelectronics are also presented.

Evaluation of Physiochemical Properties, Thermal Behavior and Phytopharmaceutical Potential of Citrus aurantium’s Essential Oil

The study investigates the therapeutic potential of the Citrus aurantium var. amara essential oil extracted from the blossoms of the bitter orange plant by examining its chemical composition, thermal stability, and potency against infectious disease-causing pathogens. Initially, the volatile components of the essential oil were evaluated by obtaining a chromatographic fingerprint using HPTLC and FTIR spectrum identification. Furthermore, a thermal profile of the essential oil was obtained using the thermogravimetric-differential thermal analysis and differential scanning calorimetric analysis. A predetermined set of antibiotic-resistant microorganisms were used to examine the antibacterial activity of the essential oil. Lastly, its anti-inflammatory activity was assessed using the albumin denaturation assay. The research concluded that the Citrus aurantium var. Amara essential oil exhibits potential therapeutic characteristics which can be further explored through in vivo studies.

Crystal Growth, Structural and Thermal Studies of FeC4H4O6·2.5H2O

Single crystals of iron(II) tartrate hemi-pentahydrate, FeC4H4O6·2.5H2O, were grown by the gel method using silica gels. Differential scanning calorimetry, thermogravimetric-differential thermal analysis, and X-ray diffraction measurements were performed on the single crystals. The space group symmetry (orthorhombic P212121) and structural parameters were determined at room temperature. The crystal structure consisted of slightly distorted FeO6 octahedra, C4H4O6 and H2O molecules, C4H4O6–Fe–C4H4O6 chains jointed by Fe–O bonds, and O–H···O hydrogen-bonding frameworks between adjacent molecules. Weight losses due to thermal decomposition of the crystal were found to occur in the temperature range of 300–1060 K. We inferred that the weight losses were caused by the evaporation of bound water molecules and the evolution of H2CO, CO, and O2 gases from C4H4O6 molecules, and that the black residue after decomposition was composed of triiron tetraoxide (Fe3O4) and carbon.

Mn3O4 Catalysts for Advanced Oxidation of Phenolic Contaminants in Aqueous Solutions

Water-soluble organic pollutants, such as phenolic compounds, have been exposed to environments globally. They have a significant impact on groundwater and surface water quality. In this work, different Mn3O4 catalysts were prepared for metal oxide activation of peroxymonosulfate (PMS) to remove the phenolic compound from the water environment. The as-prepared catalysts were characterized using thermogravimetric-differential thermal analysis (TG-DTA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analysis. Furthermore, the effect of temperature and reusability of the as-prepared Mn3O4 catalysts is also investigated. The Mn3O4 nanoparticles (NPs) catalyst reveals an excellent performance for activating PMS to remove phenol compounds. Mn3O4 NPs exhibits 96.057% efficiency in removing 25 ppm within 60 min. The kinetic analysis shows that Mn3O4 NPs fitted into pseudo-first order kinetic model and exhibited relatively low energy activation of 42.6 kJ/mol. The reusability test of Mn3O4 NPs displays exceptional stability with 84.29% efficiency after three-sequential cycles. The as-prepared Mn3O4 NPs is proven suitable for phenolic remediation in aqueous solutions.

A smectic T phase in hexadecyltrimethylammonium bromide

ABSTRACT To date, a very unique smectic phase having a two-dimensional tetragonal symmetry in molecular packing in the layers (smectic T phase) has been found in a few thermotropic ionic liquid crystals. This phase is relatively very rare and was found at first on dialkyldimethylammonium bromides, by the Skoulios group in 1993. On the other hand, Iwamoto et al. reported in 1981 that hexadecyltrimethylammonium bromide (CTAB) shows two solid phases. However, the higher temperature solid phase remains a possibility of mesophase. Since they did not clarify the mesomorphism, we have reinvestigated this phase in this work, by using polarising microscopic observations, thermogravimetric analysis-differential thermal analysis (TGA−DTA) and the temperature-dependent X-ray diffraction technique. As a result, we have established that this phase is the first phantom example of a smectic T phase.

Extruded monolith MnOx-CeO2-TiO2 catalyst for NH3-SCR of low temperature flue gas from an industry boiler: Deactivation and recovery

The selective catalytic reduction (SCR) of NOx with NH3 (NH3-SCR) technology has been widely applied for reducing NOx emissions from stationary and mobile sources. In this work, the extruded monolith MnOx-CeO2-TiO2 catalyst was installed in a cement kiln for NH3-SCR of NOx, where the flue gas temperature was 110–140 ℃. It is found that the monolith catalyst is severely deactivated after operating for about 200 h with almost no NOx conversion at 160 ℃ under GHSV of 50000 h−1, while the fresh monolith catalyst remains 60% NOx conversion. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of SO2 (SO2-TPD) and thermogravimetric-differential thermal analysis (TG-DTG) experiments reveal that both MnOx and CeO2 oxides in monolith are severely sulfated to manganese sulfate and cerium sulfate, and the external monolith walls are covered by massive ceria sulfate and little ammonium nitrate. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis demonstrates that the formation of nitrates at low temperatures is inhibited due to the occupation of active sites in MnOx-CeO2-TiO2 by sulfates, resulting in the decrease of low temperature activity. After washing with water, the activity of deactivated monolith catalyst can be partially recovered, together with significant loss of manganese and cerium from monolith.