Thermogravimetric-differential Thermogravimetric Analysis Research Articles

Preparation, Characterization and Hydrothermal Stability of Hydrophobic TiO2/SiO2 Membrane

Hydrophobic TiO2/SiO2 (TiO2/HSiO2) membrane was fabricated by sol-gel method using methyltriethoxysilane as a precursor instead of partial tetraethylorthosilicate. The thermal stability of the composites was characterized by Fourier transform infrared spectra, X-ray diffraction, thermogravimetric-differential thermogravimetric analysis and N2 adsorption-desorption measurements. The H2 permeation and H2 permselectivity of TiO2/HSiO2 membrane were investigated by single gas permeance test. Calcination at about 350 ∼ 400 °C is suitable for preserving the hydrophobicity of the TiO2/HSiO2 membrane. The H2 permeance and H2 permselectivity in TiO2/HSiO2 membranes increased significantly with growing temperatures. At 200 °C and 0.4 MPa, the H2 permeance of TiO2/HSiO2 membrane is 7.27 × 10−6 mol·m−2·Pa−1·s−1 and the H2/CO2 and H2/N2 permselectivities are 7.68 and 10.09, respectively. In comparison to the HSiO2 membrane, the H2 permeances of TiO2/HSiO2 membrane increased by 71.56%, and the H2/CO2 and H2/N2 permselectivities increased by 23.07% and 24.11%, respectively. After steam treatment, the water absorption rate of TiO2/HSiO2 materials decreased by 33.17% relative to that of HSiO2 materials. TiO2/HSiO2 membrane has better hydrothermal stability and reproducibility than HSiO2 membrane.

Syntheses, crystal structures and thermal behavior of two new Sr(II) complexes derived from tetrazole-based carboxylic acids

Metal-organic frameworks(MOFs) derived from high-energy ligands such as nitrogen-rich heterocycles bridging metal ions have been demonstrated to be the strategies to construct safety energetic materials. Here we chose two tetrazole-based carboxylic acids, 5-(2-pyrazinyl) tetrazole-2(1-methyl) acetic acid (HL1) and 3,3-di(1H-tetrazol-5-yl) pentanedioic acid (H4L2), as ligands to build two new Sr(II) complexes: [Sr(L1)2(H2O)2] (1) and [Sr8(L2)4(CH3CH2OH)2(H2O)19]·2(H2O) (2). These complexes have been characterized by elemental analysis, FT-IR and single crystal X-ray diffraction. Complex 1 displays a 1D chain, while complex 2 shows a novel 2D framework. The differential scanning calorimetry and thermogravimetric-differential thermogravimetric analyses were adopted to investigate the thermal decomposition processes of the complexes 1–2 and the thermodynamic parameters (ΔH, ΔS and ΔG) were obtained. The results show that both 1–2 may be the potential energetic materials.

Copper(II), nickel(II), zinc(II) and cadmium(II) complexes of 1,2,4-triazole based Schiff base ligand: synthesis, comparative spectroscopic, thermal, biological and molecular docking studies

Herein, a Schiff base ligand, 9-(((5-mercapto-4H-1,2,4-triazole-4-yl)imino)methyl)-anthracene and its metal complexes with copper(II), nickel(II), zinc(II) and cadmium(II) ions have been synthesized and systematically characterized by certain analytical and multispectral studies. Fourier transform infrared, proton nuclear magnetic resonance, microanalysis, mass spectra, electronic spectra, magnetic moment, powder X‐ray diffraction analysis, thermogravimetric-differential thermogravimetric analyses and electron spin resonance spectroscopy techniques have explicated the structure of the complexes. The copper complexes showed square planar geometry whereas other complexes are in an octahedral geometry. Metal complexes exhibited a remarkable fluorescence response. The electrochemical property, i.e., oxidation–reduction potential of copper complexes was enlightened by cyclic voltammetry. The activation thermodynamic parameters for the decomposition steps of complexes were documented using the Coats–Redfern method. Adverse antimicrobial activities of titled compounds have been studied against different microbes; in addition, 1,1-diphenyl-2-picrylhydrazyl assay was also used to evaluate the antioxidant activity of these compounds. Molecular docking was exercised to vaticinate the binding of the ligand with receptors of crystal structures of Escherichia coli, Bacillus subtilis and Candida albicans.

Significance of thermal interfacing in hematite (α-Fe2O3) nanoparticles synthesized by sol-gel method and its characteristics properties

Hematite (α-Fe2O3) nanoparticles were synthesized through the cost-effective sol-gel method. The impact of temperature influenced in as-prepared and calcinated hematite nanoparticles was explored. To characterize the synthesized compounds with the help of X-ray diffraction (XRD), Thermogravimetric & Differential Thermogravimetric Analysis (TG-TDA), Fourier Transform Infrared spectroscopy (FT-IR), Ultra-Violet spectroscopy (UV-Vis), Scanning Electron Microscope with Energy Dispersive X-ray Analysis (SEM with EDAX), and Vibrating Sample Magnetometer techniques (VSM). The structural studies were confirmed rhombohedral structure with space group R-3c in C-2 NPs. The surface morphological analysis confirmed shape, size, and particle homogeneity were ensured with the arrival of temperature. The thermal analysis reported as the C-1 NPs shows excellent phase stability till reaching 1100 °C. FT-IR confirms the phase purity of the nanoparticles synthesized. The optical absorption at 534nm confirms the formation of red color α-Fe2O3 C-2 NPs and the optical bandgap values 1.92–1.97eV. The magnetometry steady was observed as a magnetic transition of paramagnetic to weak ferromagnetic magnetic behavior of NPs, which implies that several structural improvements are achieved by the thermal interfacing on the NPs surface.

Synthesis and thermal behavior of two Sr(II) compounds derived from isomeric 5-(n-pyridyl)tetrazole-2-isopropionic acid (n = 2, 3)

Isomers play a crucial role in the formation of coordination architectures. Herein we report two Sr(II) coordination compounds, mononuclear [Sr(2-pytzipa)2(H2O)4] (1) and 1D [Sr(3-pytzipa)2(H2O)2]n (2) derived from two isomers, 5-(n-pyridyl)tetrazole-2-isopropionic acid (Hn-pytzipa, n = 2, 3). Furthermore, differential scanning calorimetry and thermogravimetric-differential thermogravimetric analyses were applied to evaluate the thermal decomposition behavior of such compounds. The relevant thermodynamic parameters (ΔH, ΔS, and ΔG) of the decomposition process of 1 and 2 were calculated as well.

Preparation and properties of solid electrolyte CaxBi1.7−xW0.3O3.45−0.5x electrolyte material by sol–gel combution method

CaxBi[Formula: see text]W[Formula: see text]O[Formula: see text] (CBW) ([Formula: see text], 0.05, 0.10, 0.15, 0.20, 0.30) electrolyte material were synthesized by sol–gel self-combustion method. The samples were characterized by thermogravimetric-differential thermogravimetric analysis(TG-DSC), X-ray diffraction, scanning electron microscopy (SEM), porosity and electrochemical impedance spectroscopy (EIS). The results show the powders CaxBi[Formula: see text]W[Formula: see text]O[Formula: see text] (CBW) with fluorite crystal structure can be obtained after the precursor was calcined at 760∘C. When sintered at 780∘C for 2[Formula: see text]h, the compact ceramic sintered with relative density higher than 97% can be obtained. The electrochemical studies showed that CaxBi[Formula: see text]W[Formula: see text]O[Formula: see text] (CBW) have high ionic conductivity after 780∘C sintering. The sample Ca[Formula: see text]Bi[Formula: see text]W[Formula: see text]O[Formula: see text] exhibits a conductivity of 0.07978 S[Formula: see text][Formula: see text][Formula: see text]cm[Formula: see text] at 750∘C, and the activation energy is 0.845[Formula: see text]eV, which is expected to be applied to the electrolyte materials for intermediate temperature solid oxide fuel cells (SOFC).

Electrochemical impedance spectroscopy evaluation on the protective properties of epoxy/DBSAdoped polyaniline-TiO2 nanocomposite coated mild steel under cathodic polarization

The dodecyle benzene sulphonic acid doped polyaniline (DBSA doped PANI) and dodecyle benzene sulphonic acid doped polyaniline-TiO2 (DBSA doped PANI-TiO2) nanocomposite were synthesized via in situ oxidative polymerization and characterized by Fourier transform infrared (FTIR) spectroscopy, ThermoGravimetric/differential ThermoGravimetric analysis (TGA/DTA), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The protective properties of epoxy/DBSA doped PANI and epoxy/DBSA doped PANI-TiO2 coated mild steel were evaluated by electrochemical impedance spectroscopy (EIS) in NaCl 3.5wt% at 65°C with and without cathodic protection (CP). Cathodic protection was applied at −500, −750, −1000, −1250 and −1500mV vs. Ag/AgCl. The application of cathodic protection at more negative potentials than −750mV affected the performance of the both coatings causing the decreasing of coating resistance (Rcoat). The coating resistance of epoxy/DBSA doped PANI and epoxy/DBSA doped PANI-TiO2 are in the order of 1×104Ωcm2 and 1×105Ωcm2, respectively. Accordingly, the coating capacitance and water uptake of epoxy/DBSA doped PANI is greater than epoxy/DBSA doped PANI-TiO2 at whole applied potentials. The protective performance of epoxy/DBSA doped PANI coating is improved in the presence of TiO2 nanoparticles under different cathodic potentials.

Facile synthesis of a symmetrical squarylium dye sensitized SnIn4S8 composites with enhanced photocatalytic activity under visible-light irradiation

A symmetrical squarylium dye, 1,3-bis[2,3,3-trimethylnaphto(1,2-d)pyrrole]squaraine (SQ) sensitized SnIn4S8 composites with different mass ratio of SQ were facilely prepared by the ultrasonic method. The resulting composites were characterized by the scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectra, UV–Vis diffuse reflectance spectroscope, photoluminescence spectra, photoelectric current and thermogravimetric-differential thermogravimetric analysis. The highest occupied molecular orbital and lowest occupied molecular orbital states of SQ were calculated by Gaussian 98 at the B3YP/6-311+G(d,p) level. The visible light photocatalytic activities of SQ/SnIn4S8 composites were evaluated using the degradation of malachite green as a photodegradation target. The results showed that the SQ/SnIn4S8 composites exhibited significantly enhanced photocatalytic activities under visible-light irradiation. The maximum photocatalytic activity of the SQ sensitized SnIn4S8 was found at a 10%-SQ/SnIn4S8 composites (mass ratio of SQ to SnIn4S8 was 1:10), and its degradation efficiency of MB reached approximately 90.5% after 25 min visible-light irradiation. Furthermore, the kapp value of 10%-SQ/SnIn4S8 composites (0.0587 min−1) was 2.37 times larger than that of bare SnIn4S8 (0.0248 min−1).

Green and efficient oxidation of benzylic alcohols with hydrogen peroxide catalyzed by an inorganic–organic hybrid catalyst

Inorganic–organic hybrid catalysts 1-POM(M) were prepared by electrostatic interaction between transition metal-substituted polyoxometalates, {[PW11MO39]4− [M = Cr(III), Fe(III)], [PW11MO39]5−, [M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II)], [PW11VO40]4−}, and branched organic polyammonium, (tris[2-(dimethylammonium)ethyl]-1,3,5-benzenetricarboxylate), and characterized by elemental analyses, UV–vis and FT IR spectroscopic techniques, XRD, SEM, and Thermogravimetric-Differential thermogravimetric analyses. The hybrid material 1-POM(Zn) was an efficient and selective heterogeneous catalyst in the oxidation of benzylic alcohols to their corresponding carbonyl compounds with hydrogen peroxide. The catalyst was reused several times without significant loss of catalytic activity.

Synthesis, crystal structure, thermal decomposition, and non-isothermal reaction kinetic analysis of an energetic complex: [Mg(CHZ)3](ClO4)2 (CHZ = carbohydrazide)

An energetic complex [Mg(CHZ)3](ClO4)2 was synthesized by the reaction of carbohydrazide (CHZ) with magnesium perchlorate. The product was characterized by X-ray single-crystal diffraction, elemental analysis, and IR spectroscopy. The crystal belongs to the monoclinic system with space group P2(1)/n. Cell parameters: a = 10.034(2) Å, b = 8.5069(16) Å, c = 21.285(4) Å, β = 100.901(3)°, V = 1784.1(6) Å3, Z = 4. The central magnesium is six-coordinate with three oxygen atoms of carbonyl groups and three terminal nitrogen atoms of the hydrazine groups from three CHZs to form a distorted octahedron. Differential scanning calorimetry and thermogravimetric-differential thermogravimetric analysis were applied to assess the thermal decomposition behavior. The kinetic parameters were obtained by non-isothermal reaction kinetics. The equation can be expressed as . Moreover, the values of critical temperature of thermal explosion, ΔS≠ , ΔH≠ , ΔG≠ , and the energy of combustion were obtained as 284°C, −169.76 J mol−1 K−1, 65.46 kJ mol−1, 154.27 kJ mol−1, and 6759 kJkg−1, respectively.

Structural and optical properties of electrodeposited molybdenum oxide thin films

Electrosynthesis of Mo(IV) oxide thin films on F-doped SnO 2 conducting glass (10–20/Ω/□) substrates were carried from aqueous alkaline solution of ammonium molybdate at room temperature. The physical characterization of as-deposited films carried by thermogravimetric/differential thermogravimetric analysis (TGA/DTA), infrared spectroscopy and X-ray diffraction (XRD) showed the formation of hydrous and amorphous MoO 2. Scanning electron microscopy (SEM) revealed a smooth but cracked surface with multi-layered growth. Annealing of these films in dry argon at 450 °C for 1 h resulted into polycrystalline MoO 2 with crystallites aligned perpendicular to the substrate. Optical absorption study indicated a direct band gap of 2.83 eV. The band gap variation consistent with Moss rule and band gap narrowing upon crystallization was observed. Structure tailoring of as-deposited thin films by thermal oxidation in ambient air to obtain electrochromic Mo(VI) oxide thin films was exploited for the first time by this novel route. The results of this study will be reported elsewhere.

Mild acid MCM-41 promotes para-isomer in the vapour phase alkylation of isopropylbenzene with diethyl carbonate

Ethylation of isopropylbenzene (IPB) with diethyl carbonate (DEC) was studied using Al-MCM-41 molecular sieves with Si/Al ratios of 33, 52, 75 and 114 at temperatures ranging from 200 to 350 °C. Both mono-ethylated and diethylated isomers were obtained. The products obtained were 2-ethyl-isopropylbenzene (2-EIPB), 3-ethyl-isopropylbenzene (3-EIPB), 4-ethyl-isopropylbenzene (4-EIPB), 2,4-diethyl-isopropylbenzene (2,4-DEIPB), 2,6-diethyl-isopropylbenzene (2,6-DEIPB) and ethylbenzene (EB). The Al-MCM-41 mesoporous materials were characterized using powder X-ray diffraction (XRD), nitrogen adsorption measurements (BET) and thermogravimetric-differential thermogravimetric analysis (TGA-DTG). XRD studies indicated that the calcined and as-synthesized materials had the standard MCM-41 structure. Nitrogen adsorption was used to determine specific surface area, pore volume, and pore size distribution in the Al-MCM-41 (33), Al-MCM-41 (52), Al-MCM-41 (75) and Al-MCM-41 (114) mesoporous molecular sieves. FT-IR studies showed that Al ions were incorporated into the hexagonal mesoporous structures of Al-MCM-41. The thermal stability of the as-synthesized materials was studied using TGA-DTG. The effects of reaction temperature, WHSV and feed ratios on the selectivity of 4-EIPB were studied.