Thermogravimetric And Differential Thermal Analysis Research Articles

Synthesis of cationic polyacrylamide by low-pressure UV initiation for turbidity water flocculation

This work presents a preparation process and flocculation performance evaluation of a novel cationic polyacrylamide PADC synthesized by low-pressure ultraviolet (UV) initiation. Flocculant of PADC was polymerized with acrylamide (AM), diallyl dimethyl ammonium chloride (DMDAAC) and coconut diethanolamide (CDEA) in homogeneous aqueous solution under the irradiation of low-pressure UV, and 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure2959) was used as photo sensitizer. The factors that affect polymerization were investigated; these include monomer concentration, initiator dosage, mass ratio of mAM:mDMDAAC and irradiation time. Structures and morphologies were characterized by Fourier transform-infrared (FTIR) spectroscopy, nuclear magnetic resonance hydrogen (1H NMR) spectra, scanning electron microscope (SEM), and thermo gravimetric and differential thermal analysis (TG-DTA). The flocculation performance was evaluated by removing high turbidity kaolin suspension; flocculation mechanism was also correspondingly analyzed. Experimental results show that the PADC efficiently removes the suspended particles efficiently by charge neutralization and bridging effect in an environment with wide range of pH.

Thermal, spectroscopic and biological studies on solid ibuprofen complexes of heavy trivalent lanthanides and yttrium

Heavy lanthanide complexes (Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) and yttrium (III) complexes with ibuprofen ligands (Hibu) were synthesized and characterized by simultaneous thermogravimetric and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), attenuated total reflection mid-infrared spectroscopy (ATR-MIR), complexometric titration, X-ray powder diffraction (XRD) in order to determine stoichiometry, thermal stability and the ligand coordination modes of the compounds. The volatiles released were also analyzed by online coupled thermogravimetry-infrared spectroscopy evolved gas analysis (TG-EGA-MIR), to identify the main product resulting from the heating of terbium complex. In addition, ibuprofen and the synthesized compounds were tested to assess cytotoxic/proliferative and anti-inflammatory activity. The results of the cytotoxicity assays showed that compounds [Yb(ibu)3], [Lu(ibu)3] and [Y(ibu)3] decreased the cytotoxic activity of ibuprofen. Furthermore, [Yb(ibu)3] and [Lu(ibu)3] exhibited a significant anti-inflammatory profile, superior to that of ibuprofen. Under the stimulatory effect of lipopolysaccharide, these compounds displayed anti-inflammatory activity characterized by low TNF-α and H2O2 production and high IL-10 production, emerging as interesting alternatives for further biological applications.

Synthesis, structure, optical and magnetic properties of interlamellar decoration of magadiite using vanadium oxide species

A new kind of vanadium decorated magadiite was synthesized by ion-exchange and combination of the calcination. The composition and structure of the samples were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), thermo-gravimetric analysis and differential thermal analysis (TG/DTA), Fourier-transform infrared spectra (IR), Raman, ultraviolet–visible spectroscopy (UV–Vis), Electron paramagnetic resonance (EPR) and N2 adsorption/desorption. Results indicate that vanadium species tend to bond to surface and form a vanadium oxide phase that has never been observed as far as we know. A new observation is presented on the protection of VO2+ of lamellar in the process of calcination, part of the VO2+ is oxidized to V2O5. Morphology tests suggest that vanadium oxide species in the magadiite is uniformly dispersion. Measurements of fluorescence and magnetic tests show that new properties appear in the vanadium oxide species in the confined spaces of magadiite which are much different from those present in the bulk materials. Results of this study show that uniqueness of structure, optical and magnetic properties of vanadium oxide decorated magadiite render this material has the potential applications in catalysis.

Monocrystal growth, X-ray diffraction, photoluminescence, thermal and dielectric studies of cadmium thiourea acetate complex doped with l- cystine

Single crystal of l-cystine (LC) doped cadmium thiourea acetate (CTA) material has been grown by slow solution evaporation technique. The crystalline phase and structural parameters of LC doped CTA crystal has been evaluated using the powder X-ray diffraction technique. The color centered emission in grown crystal has been examined in the visible region of interest using the photoluminescence study. The thermal stability and the melting point of LC doped CTA crystal has been investigated using the simultaneous thermogravimetric and differential thermal analysis (TG/DTA) technique employed in the temperature range of 50–500°C. The dielectric properties of pure and LC doped CTA crystal has been comparatively investigated at different temperatures by means of dielectric measurement study.

Synthesis of CoxMg1−xAl2O4 nanospinel pigments by microwave combustion method

The aim of the work is optimizing the calcined temperature for CoxMg1−xAl2O4 nanospinel pigment formation after microwave treatment. The powders were prepared by the microwave combustion method (MCM), using Magnesium chloride hexahydrate (Mg(Cl)2·6H2O), cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and Aluminum chloride hexahydrate (Al(Cl)3·6H2O), as starting materials and starch as a fuel. The powder precursors were calcined at different temperatures; 400°C, 550°C and 800°C to optimize the nanospinel formation. The properties of products were characterized using differential thermal analysis and thermogravimetric analysis (DTA/TGA), X-ray diffraction (XRD), scanning electron microscope (SEM), infrared spectra (IR) and transition electron microscope (TEM). Finally, determination of the magnetic properties of nanocrystalline CoxMg1−xAl2O4 spinel powders was performed by means of Mössbauer spectroscopy, using a vibrating sample magnetometer (VSM). The results revealed that CoxMg1−xAl2O4 compositions exhibited crystal size below 35nm except for the powders containing high level of the cobalt content. The particle size was below 100nm except for the MgAl2O4. The diffuse reflectance spectra of the CoxMg1−xAl2O4 pigments confirmed the presence of tetrahedrally coordinated Co2+. Magnetic measurements revealed that the nanocrystalline CoxMg1−xAl2O4 have ferromagnetic behavior. Therefore, the present experiment succeeds in synthesis of nanospinel blue compositions in short time based on microwave combustion method to be applied in various applications such as in the fields of pigment, ceramic and magnetic applications.

Internal-curing efficiency of cold-bonded coal bottom ash aggregate for high-strength mortar

Herein is reported the results of a study on the internal-curing efficiency of cold-bonded bottom ash aggregates (CBBA) used in high-strength mortar. The flow and compressive strength of high-strength mortar with CBBA were measured. To evaluate the internal curing efficiency of CBBA, the autogenous deformation and internal relative humidity of mortar with pre-wetted CBBA were observed at an early age. In addition, the degree of hydration was measured, and then differential thermal and thermogravimetric analyses (DTA/TGA) were carried out to understand the hydration kinetics of the mortar. The experimental results of mortar with CBBA were compared with those of mortar with raw bottom ash, and with artificial lightweight aggregates. Compared with raw bottom ash, CBBA showed greater mitigation of autogenous shrinkage, meaning that a lower volume proportion of CBBA was sufficient to eliminate autogenous shrinkage in the high-strength mortar.

Sulfonium cation based ionic liquid incorporated polymer electrolyte for lithium ion battery

Polymer electrolyte (PE) composed of poly(vinylidene fluoride-co-hexafluoropropylene) P(VdF-co-HFP) and triethylsulfonium bis(trifluoromethylsulfonyl)imide (SEt3TFSI) ionic liquid (IL) had been evaluated in lithium ion battery for the first time in order to improve its performance and cycle life. X-ray diffraction analysis (XRD) reveals that incorporation of the IL (20 and 25 wt%) into the polymer matrix results in the change of state of the material from semi-crystalline to amorphous nature. Thermo-gravimetric and differential thermal analysis (TG/DTA) of the PE sample with 25 wt% of the IL shows high thermal stability. The nature of functional groups present in the PE was investigated by Raman spectrum. Surface morphological characteristics indicate that increase in the loading of the IL into the polymer matrix leads to maximum number of pores with good interconnected network. Polymer/IL electrolyte (wt. ratio of 75:25) having a maximum ionic conductivity of 6.93 × 10−5 S/cm at 303 K with an activation energy of 0.23 eV shows excellent electrochemical potential stability of 4.4 V vs Li, as revealed by cyclic voltammetry (CV). Charge–discharge characteristics of the coin cell containing the above optimized ratio of PE with LiFePO4 cathode and Li anode shows a discharge capacity of 133 mAh/g, which is stable up to ten cycles.

High surface area mesoporous alumina nanosheets and nanorolls from an aluminum based metal organic framework

High surface area mesoporous γ-alumina was prepared from aluminum fumarate metal organic framework (MOF A520)by calcination at 750°C and characterized by Fourier Transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TGA-DTA), BET surface area measurement, scanning electron microcopy (SEM) and transmission electron microscopy (TEM). The XRD pattern of products derived by calcination of MOF A520 at 450, 550 and 650°C showed a very low degree of crystallinity or amorphous materials, and by raising temperature to 750°C a well crystallized mesoporous γ-alumina developed with surface area of 205m2g−1 and narrow pore size distribution. SEM analysis demonstrated that warm-like morphology of the MOF A520 maintained and did not collapse during calcination; it is just shrunk and transferred to γ-alumina. TEM study showed a one dimension fibrous morphology, in which fibers curled and produced scrolls.

Rheological phase synthesis of nanosized α-LiFeO2 with higher crystallinity degree for cathode material of lithium-ion batteries

In this paper, rheological phase method has been successfully applied to synthesize nanosized α-LiFeO2, a promising cathode material of lithium-ion batteries. The formation, structure and morphology of the as-prepared powder were characterized by Thermogravimetric and differential thermal analyses (TGA/DTA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Scanning electron microscopy (SEM). The particle size of the obtained α-LiFeO2 ranged from 100 to 300 nm. It exhibited an initial discharge capacity 169 mAh g−1 at 0.1 C between 1.5 and 4.3 V, especially excellent cycling retention from the 10th to the 50th cycle (96.8%) between 1.5 and 4.3 V. The higher crystallinity degree might be responsible for the cyclability improvement.

A systematic study on electrical and physical properties of calcium bis-thiourea chloride crystal

In present investigation crystal of calcium bis thiourea chloride (CBTC) material has been grown by slow evaporation solution technique. The grown CBTC crystal has been characterized by dielectric, laser damage threshold, thermal and photoconductivity studies. The laser damage threshold of CBTC crystal has been determined using the Nd:YAG laser operative in pulse mode at 1064nm. The thermal stability of CBTC crystal has been determined by means of simultaneous thermogravimetric and differential thermal analysis (TG/DTA). The CBTC crystal is found thermally stable up to 190°C. The frequency dependent response of dielectric constant and dielectric loss of CBTC crystal has been studied by means of dielectric measurement studies. The origin of photo current and dark current in CBTC crystal has been investigated by employing photoconductivity study.

High-Solid Anaerobic Codigestion of Horse Manure and Grass in Batch and Semi-continuous Systems

This study investigated high-solid codigestion of horse manure (HM) and grass in batch and semi-continuous systems. After 28 days, the cumulative methane yield of HM was 298.7 mL/g of volatile solids (VS). When the ratio of HM/grass was 80:20, on a percent VS basis, with the C/N ratio of 20.42, the highest methane yield of 382.3 mL/g of VS was achieved. The methane concentration of fresh HM was higher than that of codigestion and that of grass as a result of the high volatile fatty acid concentration. The semi-continuous codigestion of HM and grass was carried out in a high-solid system with an organic loading rate (OLR) of 1.25, 1.88, and 2.50 g of VS L–1 day–1, which resulted in an average methane productivity of 152.9, 149.6, and 141.1 mL g–1 of VS day–1, respectively. The optimal OLR of semi-continuous codigestion was 1.88 g of VS L–1 day–1, with the hydraulic retention time (HRT) of about 14 days. Thermogravimetric and differential thermal analysis (TG/DTA) revealed that more than 80% of the fraction...

Synthesis of high surface area MgAl2O4 spinel as catalyst support via layered double hydroxides-containing precursor

Magnesium aluminate spinel (MgAl2O4) was synthesized via layered double hydroxides (LDHs)-containing precursor by co-precipitation method. The precursors and the calcined powders were characterized by various techniques including N2 physical adsorption, powder X-ray diffraction (XRD), 27Al nuclear magnetic resonance (NMR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The characterization results suggested that the as-synthesized precursor was mainly composed of MgAl LDHs and gibbsite Al(OH)3. Upon calcination of the LDHs-containing precursor at 600~700°C, MgAl2O4 spinel was formed and a high BET specific surface area of ~193m2g−1 was achieved at 700°C, demonstrating the effectiveness of LDHs-containing precursor for the preparation of high surface area MgAl2O4 spinel. It was suggested that the poorly crystalline Mg(Al)O solid solution resulted from the thermal decomposition of MgAl LDHs might facilitate the formation of MgAl2O4 spinel. The precipitation procedure had significant effect on the textural property of spinel. The MgAl2O4 prepared by constant pH precipitation exhibited much higher BET specific surface area than those prepared by decreasing pH precipitation and increasing pH precipitation. This high-surface area MgAl2O4 appeared a promising catalyst support. The prepared MgAl2O4-supported Ni catalyst possessed well-dispersed Ni nanoparticles and exhibited stable activity for the carbon dioxide reforming of methane.

Controllable fabrication and characterization of porous C/TiO2 nanocomposite films as solar selective absorber

Abstract Porous C-TiO 2 nanocomposite films prepared by photopolymerization-induced phase-separation method (PIPS) exhibited three dimensional interconnected pores structure. Scanning electron microscopy (SEM), atomic force microscope (AFM), thermo-gravimetric and differential thermal analysis (TG-DTA), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, UV–Vis-NIR spectrophotometer are employed to characterize the structure and optical properties. The results illustrated that the photomonomer pentaerythritol triarylate (PETA) directly affects the relative molecular weight of polymer formed by photopolymerization to regulate the morphology and residual carbon of C-TiO 2 nanocomposite films, and ultimately affects the solar selective absorption properties. The single layer of as-prepared porous C-TiO 2 nanocomposite films exhibits high solar absorptance (α = 0.766–0.863) with low thermal emittance (e = 0.06–0.12), yielding an optimized photothermal conversion efficiency η = α-e of (0.706–0.762) corresponding to a wide redundancy PETA concentration 0.3–0.9 (molar ratio to Ti precursor). The proportion of residual carbon contributed by PVP, PETA and poly-PETA, and other substances of the sol is 40.2%, 56.2% and 3.6%, respectively, which might be regulated by a suitable annealing process. Based on these results, porous C-TiO 2 nanocomposite films are proved to be a novel candidate material for mid-temperature solar selective absorber coatings.

Optical properties and crystallization behaviour of some MnO and/or Fe2O3-containing silicate glasses and glass-ceramics

Glass and glass-ceramics with the compositions 1Fe2O3-99SiO2 (1Fe), 2Fe2O3-98SiO2 (2Fe), 1MnO-99SiO2 (1Mn), 2MnO-98SiO2 (2Mn), 1MnO-1Fe2O3-98SiO2 (2MnFe), 2MnO-2Fe2O3-96SiO2 (4MnFe) (mol%) were prepared using the sol-gel method. The gel samples were heat treated between 120 and 1000°C. Thermogravimetric and differential thermal analysis (TG-DTA), ultraviolet, visible and near infrared spectrophotometry (UV–Vis-NIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (SEM-EDS) were used to study the structural changes that occur during the gel to glass and glass-ceramic conversions. Many of the prepared glass and glass-ceramics present brown or black colorations. These dark colorations are due to the presence in the samples of maghemite-C, magnetite, hematite, Mn3O4 (bixbyite) and Mn2+(Mn3+)14SiO24 (braunite) or simultaneously more than one of these crystalline phases. These nanoparticles give to the samples very interesting magnetic and optical properties of great importance in several medical fields. Furthermore, the study contributed to understanding the formation mechanism of some MnO and/or Fe2O3-containing silicate glasses and glass-ceramics prepared by the sol-gel method.

On thermal stability and catalytic reactivity of Zr-based metal–organic framework (UiO-67) encapsulated Pt catalysts

Pt nanoparticles (NPs, 0.5wt.%) encapsulated in a zirconium-based metal–organic framework (UiO-67 MOF) were synthesized via a linker design method. Thermal behavior of Pt in UiO-67 composite materials was compared with UiO-67 using thermogravimetric and differential thermal analysis (TG-DTA). The results showed that Pt insertion can impair the thermal stability of bulk UiO-67, resulting in a ca. 14% drop in the critical temperature of the thermal decomposition. Temperature-programmed oxidation of materials showed that calcination at 450K was essential to provide a clean framework. Temperature-programmed reduction of materials revealed that the chemisorption of H2 on UiO-67 (at 323K) was evidently enhanced owing to the incorporation of Pt NPs, thus making PtNP@UiO-67 suitable for hydrogenation reactions and hydrogen storage. PtNP@UiO-67 catalyst was evaluated by the oxidation and hydrogenation of 5-hydroxymethylfurfural in aqueous solutions at 363K, showing improved activity and selectivity in hydrogenation reactions.

Preparation and characterisation of perovskite La0.8Sr0.2Ga0.83Mg0.17O2.815 electrolyte using a poly(vinyl alcohol) polymeric method

The perovskite La0.8Sr0.2Ga0.83Mg0.17O2.815 (LSGM) fuel cell electrolyte was prepared by a polymeric method using poly(vinyl alcohol) (PVA). The LSGM precursor powder was examined by thermogravimetric and differential thermal analysis (TG/DTA) and Fourier transform infrared (FTIR) spectroscopy. It was found that thermal decomposition of the LSGM precursor powder occurs in a number of different stages, and complete decomposition of the precursor is obtained at 1000 °C. X-ray diffraction (XRD) showed that calcined powder contains three secondary phases, namely La4Ga2O9, LaSrGa3O7, and LaSrGaO4, even after calcination at 1100 °C. Furthermore, the fraction of secondary phases decreases with increasing calcination temperature. Single phase perovskite LSGM pellets with a relative density of 97% were obtained after sintering at 1450 °C for 10 h. It was therefore shown that the powder prepared by the simple PVA method is fine, highly reactive, and sinterable. The electrical properties of LSGM pellets were characterised by impedance spectroscopy. The conductivity of the LSGM pellets sintered at 1450 °C for 10 h was 8.24×10-2 S/cm at 800 °C.

Experimental investigation on heat transfer rate of Co–Mn ferrofluids in external magnetic field

AbstractManganese substituted cobalt ferrite (Co1–xMnxFe2O4with x = 0, 0.3, 0.5, 0.7 and 1) nanopowders were synthesized by chemical coprecipitation method. The synthesized magnetic nanoparticles were investigated by various characterization techniques, such as X-ray diffraction (XRD), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM) and thermogravimetric and differential thermal analysis (TG/DTA). The XRD results confirmed the presence of cubic spinel structure of the prepared powders and the average crystallite size of magnetic particles ranging from 23 to 45 nm. The VSM results showed that the magnetic properties varied with an increase in substituted manganese while SEM analysis showed the change in the morphology of obtained magnetic nanoparticles. The TG/DTA analysis indicated the formation of crystalline structure of the synthesized samples. The heat transfer rate was measured in specially prepared magnetic nanofluids (nanoparticles dispersed in carrier fluid transformer oil) as a function of time and temperature in presence of external magnetic fields. The experimental analysis indicated enhanced heat transfer rate of the magnetic nanofluids which depended upon the strength of external magnetic field and chemical composition.

Transesterification of rapeseed oil to biodiesel over Zr-dopped MgAl hydrotalcites

Zr-dopped Mg–Al hydrotalcites with different Zr/Mg molar ratios were prepared and characterized by powder X-ray diffraction (XRD), Fourier-transform infrared spectra (FTIR), thermogravimetric and differential thermal analysis (TGA-DTA) and scanning electron micrograph (SEM). It was confirmed by XRD that the materials had a similar to Mg-Al hydrotalcite structure. The hydrotalcite catalyst calcined at 773K. In the study of the selected reaction conditions such as the reaction time and the amount of added catalyst were evaluated. It was found that modification of double layered structure of MgAl hydrotalcite with tetravalent cation Zr4+ resulted in significant increase in catalytic activity in transesterification of rapeseed oil as compared to described in the literature results for MgAl hydrotalcites. The highest conversion of oil 99.9% was obtained for hydrotalcite with molar ratio of Zr: Mg: Al=0.45: 2.55: 1.00.

Selected heavy metal biosorption by compost of Myriophyllum spicatum—A chemometric approach

In this study adsorption characteristics of lead, copper, cadmium, nickel and zinc ions onto the compost of Myriophyllum spicatum were examined. The effects of sorbent dose, duration of sorption and solution concentration on the sorption of heavy metals have been investigated. Scanning electron microscope (SEM) and thermogravimetric and differential thermal analysis (TG-DTA) were used for the characterization of this biosorbent. Low coefficients of variation have been obtained for each applied assay, which confirmed the high accuracy of measurements. Principal component analysis (PCA) was applied for differentiation of samples. Mathematical models (form of second order polynomials) were developed for prediction of adsorption. Score analysis is being useful for accessing the effect of process parameters and the tool for determination of sorption quality. On the basic of experimental results and model parameters, it can be concluded that compost has a high biosorption capacity can be utilized for the removal of selected metals from wastewater.

Enhanced Visible-Light Photocatalytic Activity of C/Ce-Codoped ZnO Nanoellipsoids Synthesized by Hydrothermal Method

C/Ce-codoped ZnO nanomaterial has been synthesized by a hydrothermal method and its physical properties and characterization investigated using thermogravimetric and differential thermal analysis (TG-DTA), x-ray diffraction (XRD) analysis, Fourier-transform infrared (FTIR) spectroscopy, energy-dispersive x-ray (EDX) spectroscopy, UV–Vis diffuse reflectance spectroscopy, and scanning electron microscopy (SEM). The photocatalytic activity of the nanomaterial was examined using methylene blue as organic dye under visible-light source. The results show that the C/Ce-codoped ZnO nanomaterial exhibited higher photocatalytic activity under visible-light irradiation compared with undoped ZnO, Ce-doped ZnO or C-doped ZnO nanomaterials. Such enhancement of the photocatalytic activity of C/Ce-codoped ZnO under visible-light irradiation suggests that these nanoparticles might have good applications in optoelectronics and wastewater treatment.