TGA DTA Research Articles

Thermal behaviour of TiOy/HAp nanocomposites

The structural and microstructural characteristics and thermal behaviour of TiOy/HAp nanocomposite materials used for tissue engineering have been studied by differential and thermal gravimetric analyses (DTA–TGA), X-ray diffraction (XRD) phase analysis and scanning electron microscopy (SEM) methods. Substoichiometric TiO0.92 and superstoichiometric TiO1.23 were used in amounts of 10 and 20 wt %, respectively, to reinforce HAp. When the temperature increased as a result of interactions between the matrix and the introduced nanoparticles, titanium monoxide was oxidized to titanium dioxide. Comparing the DTA–TGA and XRD results allowed us to determine the temperature intervals of the beginning of the titanium valence variation and phase transitions occurring in the nanocomposites. The onset temperatures of HAp decomposition and TiOy oxidation depend on the initial stoichiometry of titanium monoxide and the composition of the reinforcing additive. The TiOy additives have a stabilizing effect on HAp. The effect of the additive stoichiometry on the interactions between the matrix and nanoparticles in the whole temperature range is shown.

In-situ fabrication of ternary (3D/2D/2D) prism‒like structures with dramatically enhancement on degradation of profenofos: A systemic study

In the present work, a novel (3D/2D/2D) prism-like ZGO‒MOF hybrid nanocomposite was successfully prepared via two-pot hydro-thermal process and employed as a catalyst for the degradation of organic persistent pesticide such as profenofos (PF). Due to more toxicity, the removal of such organic compounds are necessary in environmental aspects. The prepared nanocomposites were characterized and well explained using FT‒IR, XRD, UV‒DRS, SEM‒EDX, TEM, TGA‒DTA, PL and BET surface area measurements. The OH and O2− radicals was benign effective oxidative species involved in the ZGO‒MOF system for the mineralization of organic pollutants. Besides, ZGO‒MOF showed excellent photo-stability over five repetitive runs for the removal of organic pesticides with minimal drop on catalytic activity. Eventually, the intended photocatalytic mechanisms and degradation pathways of PF are readily determined in detail based on experimental results. The catalyst achieves excellent efficiency of about 94 %. Possible PQ oxidative pathways and their reaction intermediates were observed by LC–MS. Therefore, the pollutant which primarily oxidize into ring-ruptured components into innocuous products like H2O, CO2 and a few in-organic salts. With the concern of its environmental friendly, low‒cost, and benign simple synthesis, ZGO‒MOF was expected to be a promising choice for applications in wastewater management.

Sinterability of macrocrystalline and cryptocrystalline magnesite to refractory magnesia

AbstractThe purpose of this paper is to present the results of an investigation aiming at obtaining high quality sintered magnesia from two well‐known Chinese magnesite. Two types of natural magnesite have been considered, one macrocrystalline, from Liaoning, with the grain size of 60‐100 µm and one cryptocrystalline, from Tibet, with 2‐4 µm grains. Calcining characteristics to transform the two magnesite to caustic magnesia have been studied at first. Subsequently, the calcining‐sintering characteristics using a two‐ and a three‐step process for both raw materials at different temperatures have been determined. A DTA–TGA study reveals that the minimum endothermic peak during the calcining step differs by 28°C (624 vs 652°C between the crypto‐ and macrocrystalline magnesite). It has also been observed that by using a two‐step sintering process, it is possible to obtain a magnesia with a bulk density of 3.26 and 3.14 g/cm3, respectively, for cryptocrystalline and macrocrystalline, while with a three‐step process, it is possible to reach a bulk density of 3.48 g/cm3, even at a temperature <1750°C.

Characterization and application of MgAl layered double hydroxide for methyl orange removal from aqueous solution

Layered double hydroxide (LDH), also known as hydrotalcite or anionic clays, have attracted attention in recent years due to their applications in various fields, particularly in the water treatment sector. In this work, the MgAl layered doublehydroxidewas synthesized byureamethod and used for the removal of methyl orange dye (MO) from aqueous solutions.The MgAl-LDH adsorbent was then characterized using different techniques such as; Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric and differential thermal analyses (TGA–DTA).The effect of some environmental parameters (contact time, adsorbent mass, initial dye concentration, ionic strength) on the removal of MO has been also investigated. The adsorption kinetic of methyl orange on the surface of MgAl-LDH material was best fitted by pseudo-second-order model. The maximum experimental adsorption capacity was fond to be 197.62 mg.g−1. According to the results of this study, it can be concluded that MgAl-LDH adsorbent can be used effectively for the removal of anionic dyes fromindustrial wastewater.

Synthesis, spectroscopic properties, crystal structures, antioxidant activities and enzyme inhibition determination of Co(II) and Fe(II) complexes of Schiff base

Considering the importance of metal complexes in the development of medical science, two different Schiff base Fe(II) and Co(II) metal complex compounds were synthesized with Schiff base obtained through the condensation of 1-(4-aminophenyl)ethanone with 2-hydroxy-3-methoxybenzaldehyde. The reactions of the ligand with Co(II) and Fe(II) metal ions enabled six coordination compounds with octahedral geometries. The novel metal complexes were characterized by IR, elemental analyses, magnetic susceptibility, mass spectra, UV–Vis, thermogravimetry–differential thermal analysis (TGA–DTA) and X-ray diffraction analysis. The antioxidant properties of the new compounds were investigated using different in vitro assays. Moreover, enzyme inhibition of derivatives complexes against carbonic anhydrase I and II isoenzymes (CA I and II) and acetylcholinesterase (AChE) was evaluated. The best inhibitor complex for CA I and II isoenzymes was the Fe(II) complex with Ki values of 52.83 ± 11.52 and 63.34 ± 8.88, respectively.

The synthesis of rGO/RuO2, rGO/PANI, RuO2/PANI and rGO/RuO2/PANI nanocomposites and their supercapacitors

In this work, reduced graphene oxide (rGO) was obtained by chemical reduction of graphene oxide (GO) using sodium borohydride (NaBH4). Four different nanocomposites rGO/ruthenium oxide (RuO2), rGO/polyaniline (PANI), RuO2/PANI and rGO/RuO2/PANI were chemically synthesized. In addition, PANI-based nanocomposites were synthesized by in situ polymerization technique. Nanocomposites were examined by different methods such as Fourier transform infrared spectroscopy–attenuated transmission reflectance, UV–Vis spectrophotometer, scanning electron microscopy–energy-dispersive X-ray analysis, thermal analysis (TGA–DTA) and transmission electron microscopy. TGA–DTA results show that the decomposition of rGO/RuO2/PANI nanocomposite (27.2% at 788.8 °C) was less than that of rGO (1% at 779.7 °C), which confirms the successful synthesis of nanocomposites. These nanocomposites can be used in supercapacitor applications. Supercapacitor device performances were taken by cyclic voltammetry (CV), galvanostatic constant current and electrochemical impedance spectroscopy (EIS) via two-electrode configuration. Ragone plots were drawn to observe energy and power densities of supercapacitor devices. Stability tests were taken by CV method for 1000 cycles. A ternary rGO/RuO2/PANI nanocomposite yields higher specific capacitance as Csp = 723.09 F g−1 than rGO/RuO2 (Csp = 347.28 F g−1), rGO/PANI (Csp = 159.62 F g−1), RuO2/PANI (Csp = 40.2 F g−1) and rGO (Csp = 37.5 F g−1) at 2 mV/s by CV method. A new electrical circuit model of LR(C(R(CR))) was used to analyze EIS data for rGO, rGO/PANI, rGO/RuO2, RuO2/PANI and rGO/RuO2/PANI nanocomposites. These nanocomposites demonstrate remarkable properties for use as electroactive materials for supercapacitor applications.

Thiocyanate precursor impact on the formation of cobalt complexes: Synthesis and characterization

Two new thiocyanate complexes have been synthesized with two different thiocyanate anion sources using 1-(2-pyrimidyl)piperazine and CoCl2·H2O. These compounds were characterized by single X-ray diffraction, FTIR, UV–Vis and TGA–DTA. The antibacterial activity was also examined. The XRD showed that compounds 1 and 2 crystallized into monoclinic and orthorhombic systems, respectively. In compound 1, cobalt is surrounded by two isothiocyanate anions and two nitrogen-amides, while in compound 2 it is surrounded by four isothiocyanate ligands and a separate protonated amide. Different interactions packed the system through NH⋯S, NH⋯O and OH⋯S hydrogen bonds forming a ring. Gap energy determination revealed two diverse behaviors, the first being characteristic of a semiconductor and the second of an insulator. In the 10–500 °C range, the thermal behaviors were investigated and showed the decomposition of the two complexes with metal complexes residues. The antibacterial analysis presented a weak performance.

Synthesis of Isobutylene from Ethanol in the Presence of Catalysts Containing Zinc Oxide and Zirconia

Synthesis of isobutylene from ethanol in the presence of ZnO/ZrO2 catalysts has been studied. The samples have been synthesized by incipient wetness impregnation of zirconium hydroxide derived from zirconyl chloride with zinc nitrate and subsequent calcination at 550°C. The synthesized samples have been studied by low-temperature nitrogen adsorption, SEM, XRD, IR spectroscopy of adsorbed CO, and TGA–DTA. Studies of the effect of the catalyst composition and the test conditions have revealed that, during the synthesis of isobutylene from ethanol, an optimum Zr : Zn molar ratio providing the production of isobutylene with a selectivity of 45–50% is 8–20 and optimum conditions for ethanol conversion to isobutylene are 500°C, a feed space velocity of 3 g/(g h), and a feedstock in the form of a 50% ethanol solution in water. According to thermogravimetric analysis, an increase in the zinc content in the samples leads to a decrease in the amount of coke deposits.

An improvised method for the synthesis of ZnAl2O4/ZnO nanocomposite and its use as a photocatalyst

Nanocomposite material ZnAl2O4/ZnO was prepared via layered double hydroxides co-precipitation method in the presence of triblock copolymer, Pluronic F127 as the template with different concentrations at pH 7. The material was characterized by XRD, N2 adsorption/desorption, UV–Vis diffused reflectance, TGA–DTA and SEM. XRD and SEM results reveal that ZnAl2O4/ZnO was highly ordered nanocrystalline material. N2 adsorption/desorption studies indicate that the pore size and pore volume increased significantly with the increase in concentration of F127 copolymer template, while the surface area is slightly decreased with increase of F127 template. TGA–DTA results reveal that the thermal stability of material increased after adding F127 template. The material was tested for its photocatalytic activity for a solution containing methyl orange dye and the 95.6% decolorization was achieved within 1 h. The intensive absorption light observed by UV–Vis reflectance of the catalyst confirmed high activity of the catalyst and suggest the probable photocatalytic degradation mechanism.

Enzymatic synthesis optimization of a cosmetic ester catalyzed by a homemade biocatalyst prepared via physical adsorption of lipase on amino-functionalized rice husk silica

This study aimed to optimize the synthesis of a cosmetic ester (decyl oleate) catalyzed by immobilized lipase from Thermomyces lanuginosus (TLL) on amino-functionalized rice husk silica (Amino–SiO2), i.e. a homemade biocatalyst prepared via ionic adsorption. Functionalized support has been characterized by ATR–FTIR, TGA–DTA, and TEM analyses. The effect of important parameters on ester synthesis has been evaluated through a full factorial design in Central Composite Rotatable Design (CCRD) mode. Under optimal experimental conditions, maximum ester conversion percentage of 87% was observed after 105 and 180min of reaction time in iso-octane and solvent-free systems, respectively. However, similar reaction rates of around 10mM/min were obtained for both reaction systems. Ester synthesis in a solvent-free system is a kinetically controlled process, which has been confirmed by calculating its Damköhler number (Da=7.63×10−5). Reusability tests showed that the biocatalyst retained all of its original activity after eight successive reaction cycles in a solvent-free system. These results show that this homemade biocatalyst can be successfully used in cosmetic ester synthesis through a clean technology process due to its high catalytic activity and reusability.

Layered double hydroxide of cobalt-zinc-aluminium intercalated with carbonate ion: preparation and Pb(II) ion removal capacity

ABSTRACTTernary layered double hydroxide (Co–Zn–Al LDH) intercalated with carbonate was synthesised via a simple co-precipitation method at pH ≥10. It was characterised using the Fourier transform infrared (FTIR) spectrometer, X-ray diffractometer (XRD), surface area and porosity analyser, Thermo-gravimetric/differential thermal analysis (TGA–DTA), and Scanning Electron Microscope (SEM). The Pb(II) adsorption properties, mechanism, and possible reuse of the LDH were also investigated by the batch technique. The characterisation results showed the presence of hydroxyl group as well as the intercalated carbonate anions within the well-defined LDH crystal structure. The TGA-DTA results confirmed the presence of these anionic groups which were liberated from the structure at ≈200 and 300°C, respectively. The LDH-specific surface area, pore diameter and width are 54.0 m2/g, 41.3 and 25.1 nm, respectively. Adsorption results showed that Pb(II) equilibrium could be achieved in 120 min, and adsorption increased with concentration and temperature. A Pb(II) adsorption capacity of 130.34 mg/g was reached for this LDH, and the adsorption process was spontaneous, endothermic and mainly electrostatic with most of the adsorption occurring within the pores. Desorption test suggested that approximately 90% of the adsorbed Pb(II) could be desorbed; hence, the Co–Zn–Al–CO3 LDH may be reused.

The effect of Ce, Zn and Co on Pt-based catalysts in propane dehydrogenation

The effect of the addition of different promoters, such as, Ce, Zn and Co (0.3, 0.5 and 0.7 wt%) to the trimetallic Pt–Sn–K/Al2O3 catalyst in order to enhance performance of propane dehydrogenation was investigated and characterized with several analytic techniques, including, TPR, XRF, UV analysis, SEM and TGA–DTA. The catalysts were prepared by sequential impregnation of γ-Al2O3 technique. It was found that suitable addition of Zn (0.7 wt%), Ce (0.5 wt%) and Co (0.3 wt%) to the Pt–Sn–K/γ-Al2O3 catalyst can improve the catalytic performance more than the commercial Pt–Sn/γ-Al2O3 catalyst. The best results on Sn reduction was obtained by adding Zn (0.7 wt%) and Co (0.3 wt%) to the trimetallic Pt–Sn–K/Al2O3 catalyst. Ce (0.5 wt%) due to its ability on Pt reduction peak temperature was able to reveal better result. The performance of Pt–Sn–K–Ce0.5–Zn0.7/γ-Al2O3 and Pt–Sn–K–Co0.3–Zn0.7/γ-Al2O3 catalysts were improved by a suitable amount of Ce, Zn and Co Pt–Sn–K–Co0.3–Zn0.7/γ-Al2O3 showed better performance in terms of conversion and propylene selectivity. The synergic effect of Co and Zn can enlarge the Pt reduction peak areas than Pt–Sn–K–Co0.3/γ-Al2O3 and Pt–Sn–K–Zn0.7/γ-Al2O3, so can suppress the coke formation and improve the catalyst performance.

Preparation of inorganic\u2013organic nanohybrid compound based on NiII, MoO3 and p-phenylenediamine by hydrothermal method and its photoluminescence property

The new nanocrystalline composition was synthesized using NiSO4 and MoO3 and PPDA (p-phenylenediamine) via the hydrothermal method. The structure, morphology and photoluminescence property of nanocrystal were studied using X-ray diffraction (XRD), Fourier transform infra red (FT-IR) spectroscopy, scanning electron microscopy (SEM), photoluminescence (PL) spectra, thermogravimetric analysis (TGA–DTA) and energy-dispersive X-ray spectroscopy (EDX). The effect of factors such as type and concentration of initial materials, pH values, temperature and reaction duration on the structure and morphology of nanocrystals was investigated in the preparation of composition. The results show that the pH of the initial solution affects the size of the prepared nanocrystals; the size of the crystals is increased and the morphology of the nanostructures is changed with the increment in pH value. According to the obtained results, neutral or low alkaline conditions of pH are more favorable for the formation of the nanocrystals. The obtained nanocrystal shows an intense PL emission at room temperature with a maximum peak at 461 nm and excitation at the wavelength of 300 nm. TGA and DTA analysis display a total weight loss of 13.42%.

Ethylethanolammonium 4-nitrobenzoate

The demand for corrosion inhibitors with low toxicity has increased in the last years in a wide range of sectors. Our study presents the synthesis, X-ray structure, thermal and kinetic investigation of ethylethanolammonium 4-nitrobenzoate (EEA4NB) as corrosion inhibitor for iron in 3% NaCl solution. Proton transfer and hydrogen bonding in the organic salt were elucidated and confirmed by infrared spectroscopy and single-crystal X-ray diffraction. Simultaneous TGA–DTA and heat flow analysis were used to study the thermal and kinetic behavior of EEA4NB. The results provided useful information about thermal stability and thermal decomposition. The non-isothermal kinetic parameters were estimated by using three different kinetic methods. Electrochemical corrosion measurements show corrosion inhibitor efficiency of EEA4NB for iron in 3% NaCl solution higher than 92% and a decrease of corrosion current and corrosion rate as a result of adsorption of EEA4NB molecules at the metal/solution interface.

Preparation of TiO2–(B) by microemulsion mediated hydrothermal method: effect of the precursor and its electrochemical performance

Synthesis of TiO2–(B) bronze was carried out by hydrothermal method using different precursors: (a) commercial anatase, (b) amorphous TiO2 prepared by O/W microemulsion method and (c) oil-in-water (O/W) microemulsion with freshly prepared amorphous TiO2. It is important to highlight this is the first report of the preparation of TiO2–(B) using an O/W microemulsion as a precursor. The effect of precursor type on the resulting TiO2 nanostructures, namely, their structural and morphological features were studied using X-ray diffraction, thermal analysis (TGA–DTA), Brunauer–Emmett–Teller, Raman spectroscopy and scanning electron microscopy (SEM–EDX). From commercial anatase powder, amorphous TiO2 ME and O/W microemulsion ME238 (NaOH/TiO2 molar ratio 238), biphasic nanoribbons were obtained: TiO2–(B) (88–92%) and anatase (8–12%). While from the O/W microemulsion ME30 (NaOH/TiO2 molar ratio 30) only anatase phase was obtained. The material with higher TiO2–(B) phase content, showed an increase in its reversible capacity, thus the crystalline nature of the precursor as well as the textural properties contribute to the electrode performance. Materials synthesized from commercial anatase and amorphous TiO2 ME exhibited similar charge retention (86–87%) despite the slight difference in reversible capacity, 210 and 180 mAh/g, respectively. It is noticed that TiO2–(B)–AME (prepared from amorphous TiO2 ME) exhibited the lowest capacity loss, e.g. the highest reversibility.

The syntheses, molecular structure analyses and DFT studies on new benzil monohydrazone based Schiff bases

Benzil monohydrazone based Schiff bases were synthesized and characterized by 1H NMR, 13C NMR, HRMS as well as by single crystal X-ray diffraction. The geometries of the compounds was optimized by the DFT method and the results were compared with the X-ray diffraction data. The HOMO and LUMO energy gap and also related parameters (electronic chemical potential (μ) and global hardness (η), global electrophilicity index (ω) and softness (s)) were obtained from ground state calculations. In addition, the thermal properties of the compounds were investigated by DTA–TGA. The results showed that the compounds have good thermal properties for practical applications as optic dye.

Structural Analysis of Nano Ferrites Synthesized by Combustion and Microwave Methods

We suggest a new approach to synthesis of nano nickel ferrites via combustion synthesis in electric and microwave ovens. The oxidation of organic compounds, decomposition of salts, and their degradation were explored by TGA–DTA. As-prepared nanopowders were characterized by X-ray powder diffraction. Structures of both ferrites were slightly different. Detailed material parameters such as crystallite size (D), lattice constant (a), micro strain (e), X-ray density (ΔX), dislocation density (ρX), hopping lengths (LA and LB), bond lengths (A–O and B–O), ionic radii (rA and rB), texture coefficient [TC(hkl)], and mechanical properties were measured and comparatively analyzed.

Preparation and characterization of a bis thiourea sodium iodide (BTSI)

A semi-organic nonlinear optical single crystal of bis thiourea sodium iodide (BTSI) has been successfully grown from aqueous solution using the slow evaporation solvent technique (SEST) at room temperature. Obtained crystals using the SEST method were characterized by using different characterization techniques. Structural studies of the grown crystals have been carried out by single-crystal XRD to confirm the crystal system and functional groups by FT-IR spectroscopy. Single-crystal XRD reveals orthorhombic structure of semi-organic BTSI single crystals and its unit cell parameters. Metal complex coordination of the single crystal is studied by FT-IR spectroscopy. The optical absorption study revealed excellent optical transparency of BTSI crystal in the entire visible region with a sharp lower cutoff wavelength 298 nm. The energy band gap of BTSI is found to be 4.16 eV. Thermal stability and thermal decomposition of BTSI single crystals were investigated by TGA–DTA and DSC analysis. The surface appearance of BTSI crystals by scanning electron microscopy reveals the formation of layer growth pattern. The structural perfection and growth features of the grown crystal were analyzed by wet chemical etching studies. The above studies reveal the effect of incorporation of sodium iodide into the lattice of thiourea crystals. The as-grown BTSI single crystals can be used as a potential candidate for NLO material as well as in electronic and optoelectronic devices.

Experiments on torrefaction of Dichrostachys cinerea wood: two-level factorial design and thermogravimetric analysis

The aim of this study was to determine the effect of the temperature and reaction time variables on the solid yield and the increment of heating values and composition of torrefied Dichrostachys cinerea wood by using a factorial experiment design and thermogravimetric analysis. The significant factors were identified by means of a two-level factorial design type (22), for which the statistical software Design Expert version 10 was used. Torrefaction and thermogravimetric experimental runs were carried out in a fixed-bed reactor and thermobalance TGA–DTA, respectively. Torrefaction temperature, residence time and their interaction have a significant effect on solid yield, whilst the effect of the temperature was the only statistically significant factor on increment at a high heating value (HHV). The R-Squared values for both response variables were greater than 95% in each case. An increase in torrefied biomass was achieved at HHVs of 14.92 and 30.31% under the conditions of 120 min at 250 and 290 °C, respectively. Thermogravimetric characterisation and DTG–TG curves of the torrefied material suggest that the pre-treated material has been modified chemically and structurally.

DTA–TGA and XRD study of the formation of LISICON-type Li1+xCrxZr2−x(PO4)3 ceramic using ZrOCl2·8H2O as precursor

This contribution is devoted to thermoanalytical investigation of the mechanism of the formation of solid solutions of Li1+xCrxZr2−x(PO4)3. The samples were prepared by high-temperature solid-state reaction in the reaction mixtures of (0.5 + x/2)Li2CO3–(2 − x)ZrOCl2·8H2O–(x/2)Cr2O3–3(NH4)2HPO4. Thermal behaviour of the mixtures was characterised using STA analysis (RT-1200 °C); evolution of the phase composition during heating was analysed using powder XRD analysis. It is shown that with increase in substitution degree x from 0 to 2, the mechanism of the formation of the solid solutions changes dramatically. In general, it is influenced by the content of ZrOCl2·8H2O because its interaction with (NH4)2HPO4 is the dominant feature of the thermal transformation of the mixtures. However, with decrease in ZrOCl2·8H2O content and the corresponding increase in x, the indicated process becomes less dominant. On the other hand, unreacted amount of (NH4)2HPO4 is increased and the corresponding effect of elimination of its ammonia becomes more and more prominent. The mixture with x = 2 can be characterised with typical behaviour of the mixtures of (NH4)2HPO4 with oxides or carbonates. In general, the formation of solid solutions required calcination at 1200 °C during 6–12 h.