Thermogravimetric Analysis-derivative Thermogravimetry Research Articles

Development of HDTMA-modified Philippine natural zeolite (PNZ) for sulfamethoxazole adsorption

Abstract The surface of Philippine natural zeolites (PNZs) was modified using the surfactant hexadecyltrimethylammonium chloride (HDTMA-Cl) to improve its adsorption capacity of sulfamethoxazole (SMX), a persistent organic pollutant and emerging contaminant. The PNZs were modified with HDTMA based on their 100% and 200% external cation exchange capacity (ECEC) to form monolayer and bilayer HDTMA–modified zeolites (MHZ & BHZ). The unmodified zeolites (UZs) and surfactant–modified natural zeolites (SMNZs) were characterized using Fourier Transform Infrared Spectroscopy, Thermogravimetric Analysis-Derivative Thermogravimetry, Scanning Electron Microscopy with Energy Dispersive x-ray Spectroscopy, and X-Ray Diffraction to confirm the modification of the PNZs using HDTMA. The SMX adsorption of UZ and SMNZs were fitted using isotherm and kinetic models. It was determined that all zeolites showed a high degree of linearity relative to the Langmuir, Freundlich, and Temkin models. The maximum SMX adsorption of MHZ and BHZ was calculated to be 3.685 mg g−1 and 13.034 mg g−1, respectively, exhibiting 1.6 times and 5.5 times more improved SMX adsorption than UZ. Kinetic models showed that UZ and SMNZ adhered to the pseudo-second order model. The results of this study highlight the promising increased SMX adsorption using SMNZs.

Synergy of Magnetic Nanoparticles and Sodium Alginate-Coated Lignin for Effective Pollutant Remediation, Simple Recovery, and Cost-Effective Regeneration.

In the pursuit of sustainable materials for environmental remediation, this study presents the development and comprehensive characterization of cobalt ferrite nanoparticles (CFNPs) incorporated in lignocellulosic-derived sodium alginate (CFNPs@LCG-SA) biocomposite beads. These biobased beads exhibit exceptional adsorption capabilities, particularly for methylene blue (MB) dyes, rendering them promising candidates for wastewater treatment. Using a comprehensive range of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis-derivative thermogravimetry (TGA/DTG), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), etc., we elucidated their structural, physicochemical, and thermal properties. Their multifunctional nature, derived from lignin and sodium alginate components, provides ample active sites for both physical interactions and chemical bonding with contaminants apart from the magnetic character attributed by the CFNPs. With a freeze-drying approach, the optimal adsorption capacity and removal rate of MB reached 97 mg/g and 99%, respectively, and no meaningful decline in their activity was noted even after six cycles. The CFNPs@LCG-SA biocomposite beads emerge as a cost-efficient and sustainable remedy for environmental cleanup, offering valuable perspectives in environmental preservation and advancing green energy technologies.

Recovery of Ni-Co-Mn Oxides from End-of-Life Lithium-Ion Batteries for the Application of a Negative Temperature Coefficient Sensor

This study demonstrates the current advancements in battery management systems (BMSs), emphasizing the need for precise temperature monitoring within battery packs to enhance safety and performance through efficient thermal management. The increased demand for lithium-ion batteries (LIBs) has driven the development of temperature sensors with improved accuracy and stability. In particular, Ni-Co-Mn-based spinel oxides are commonly used due to their stable negative temperature coefficient (NTC) behavior. However, challenges arise in manufacturing due to the high cost and uncertain supply of critical cathode components (e.g., Co, Ni, and Mn) for LIBs. This research focuses on developing spinel-type (Ni0.6Co0.4Mn2)O4 using recycled Ni-Co-Mn oxides obtained from end-of-life (EOL) LIBs, demonstrating temperature resistance behavior suitable for temperature sensing. The oxides are prepared through hydrometallurgy, oxalate synthesis, and post-heat treatment. Successful integration into spinel-type NTC thermistors suggests broader applications in various industrial fields. A systematic investigation into the synthesis and characterization of recovered Ni-Co-Mn oxides from EOL LIB cathode materials (Li(Ni0.33Co0.33Mn0.33)O2) is presented for NTC thermistor application. Thermogravimetric analysis-derivative thermogravimetry (TGA-DTG) identifies the optimal post-heat treatment temperature. The X-ray diffraction (XRD) patterns confirm a cubic spinel structure of the Ni-Co-Mn oxides, supported by scanning electron microscope (SEM) images showing a uniform microstructure. Also, energy dispersive X-ray spectroscopy (EDS) mapping confirms homogeneous element distribution. Recovered oxide pellets from the sintering process exhibit a single spinel structure, with X-ray photoelectron spectroscopy (XPS) analysis revealing changes in the valence states for Ni and Mn. Resistivity measurements demonstrate semiconductive behavior, which shows a B value (3376.92 K) suitable for NTC thermistor applications. This study contributes valuable insights to black powder recycling from EOL LIBs and its potential in temperature-sensitive electronic devices.

Novel Hyperbranched Dialdehyde Carboxymethyl Cellulose-Grafted Gelatin Films as Potential Natural Antibacterial Materials

Carboxymethyl cellulose (CMC) has potential applications in food packaging given its good processibility and biological properties. In this research, dialdehyde carboxymethyl cellulose (DCMC) was first modified with polyamidoamine (PAMAM G0) to synthesize hyperbranched dialdehyde carboxymethyl cellulose (HPD). Then, a novel hyperbranched dialdehyde carboxymethyl cellulose-grafted gelatin (HPD/Gs) film was obtained by the “one-pot” method. The structural characteristics, degree of cross-linking, thickness, swelling behavior, water solubility, water vapor permeability, surface morphology, hydrophilicity, mechanical strength, antibacterial properties, and biocompatibility of HPD/Gs were characterized by using Fourier transform infrared (FTIR), scanning electron microscopy energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray diffractometry (XRD), thermogravimetric analysis/derivative thermogravimetry (TGA/DTG), differential scanning calorimetry (DSC), and other analysis technologies. The results revealed that the prepared HPD/Gs film showed good thermal stability and mechanical properties. In particular, when the mass ratio of HPD to G was 1:1.5, the cross-linking degree, swelling behaviors, water vapor permeability (WVP), water contact angle, tensile strength, and elongation at break of the HPD/1.5G film reached 42.757%, 109.114%, 46.71 g·mm/m2·day·kPa (1 day), 115.4 ± 4.5°, 1.77 MPa, and 320.93%, respectively. Moreover, the HPD/Gs films had good cytocompatibility and antibacterial properties against Staphylococcus aureus and Escherichia coli. The research indicated that the designed HPD/Gs are a type of green antimicrobial material with potential value.

Preparation and characterization of Ce-MOF/g-C3N4 composites and evaluation of their photocatalytic performance

In this study, unique hybrid structures were constructed between a Ce-based metal-organic framework (Ce-MOF) and graphitic carbon nitride (g-C3N4) materials. In addition, the g-C3N4 materials used for these heterostructures were prepared by five different methods, namely the conventional pyrolysis method, chemical exfoliation by a strong acid, activation by an alkaline hydrothermal treatment, melamine-cyanuric acid supramolecular assembly with a mechanochemical method, and by the solvothermally pre-treated method. The structural and morphological properties of the resulting g-C3N4 sheets and their composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), thermogravimetric analysis-derivative thermogravimetry (TGA-DTG), diffuse reflectance UV–vis spectroscopy (UV–vis DRS) and N2 sorption-desorption isotherms (BET). Finally, the photocatalytic performance of the composites was determined by following the photocatalytic degradation of methylene blue (MB) in an aqueous solution under UV–visible light irradiation. It was found that the photocatalytic efficiency of the Ce-MOF/g-C3N4‒TS composite was significantly higher than that of their counterparts (Ce-MOF or g-C3N4‒TS) for the photocatalytic degradation of MB. When employing the composite, UV light-induced degradation of MB yielded an efficiency of 96.5% after 120 min for a dye solution containing 10 mg/L MB. This corresponds to a 5-fold or 2-fold improvement of the rate constant (k) when compared to the Ce-MOF or g-C3N4, respectively.

Performance of cement-bonded wood particleboards produced using fly ash and spruce planer shavings

The aim of this research was to investigate the physico-mechanical, thermal, and morphological properties of cement-bonded wood particleboards produced by using fly as has a partial cement replacement and spruce planer shavings. Experimental single-layer cement-bonded wood particleboards produced using a target density of 1200 kg/m3, 1/3 wood-cement ratio, a dimension of 460x460x10 mm3 and 5%, 10%, 15%, 20% fly ash as cement replacement were tested for physical and mechanical properties in accordance with EN and ASTM standards. Moreover, morphological and thermal properties of the cement-bonded wood particleboards were analysed by using the scanning electron microscope and thermogravimetric analysis-derivative thermogravimetry. Test results indicated that the fly ash enhanced both the bending strength and water-resistance of the cement-bonded wood particleboards. Internal bond and screw withdrawal strengths tended to decrease as the fly ash content increased in the cement-bonded wood particleboards, but this decrease was not statistically significant. As the fly ash increased, the weight loss of the cement-bonded wood particleboards decreased in the thermogravimetric analysis because of the pozzolonic reaction of the fly ash with calcium hydroxide. In the scanning electron microscope, it was observed that calcium silicate hydrate gel increased, whereas calcium hydroxide decreased as the usageratio of the fly ash increased in the cement-bonded wood particleboards.

Thermal decomposition mechanism and pyrolysis products of waste bischofite calcined at high temperature

The thermal behavior of bischofite waste and MgCl2•6H2O was investigated by thermogravimetric analysis–derivative thermogravimetry (TGA-DTG) and X-ray diffraction (XRD). TGA-DTG results showed that the pyrolysis behavior and weight loss of bischofite were different from those of MgCl2•6H2O due to large number of impurities. The effects of temperature, atmosphere, and heating rate on the pyrolysis mechanism and products of bischofite were studied in detail by using XRD. The pyrolysis temperature remarkably affected the pyrolysis products. The mixture of MgO and Mg(OH)Cl coexisted at high temperatures of 550 and 600 °C. However, the presence of MgCl2 was confirmed by calcination at 650 and 700 °C for 0.5 h except MgO. Through calcination at 700 °C for up to 2.0 h, the pyrolysis products of bischofite and MgCl2•6H2O were predominantly MgO, and the atmosphere had no effect on the content of MgO. Low heating rate was favorable for pyrolyzing bischofite into MgO, and the content of MgO reached 94.1% at the heating rate of 5.0 °C/min. After further purification by washing, the content of MgO in the final product increased to 99.0%. This study provided an effective route for the comprehensive utilization of bischofite resources in salt lakes.

Preparation of hydrophobic carbon aerogel using cellulose extracted from luffa sponge for adsorption of diesel oil

Carbon aerogel (CA) was prepared using the cellulose extracted from luffa sponge (LS). Trichlorosilane was employed to modify CA to enhance the adsorption capacity for diesel oil. The physical and chemical properties of aerogel, CA and modified CA were analyzed using XRD (X-ray diffraction), XPS (X-ray photoelectron spectroscopy), FTIR (Fourier Transform infrared spectroscopy), SEM (scanning electron microscope) and TGA/DTG (Thermogravimetric analysis/Derivative Thermogravimetry). Modified carbon aerogel (MCA) had better adsorption capacity for diesel oil (49.62 g/g) than aerogel (5.2 g/g) and CA (32.34 g/g). In addition, the adsorption capacity of MCA for other organics was also investigated, which indicated the abroad application scope for MCA. The reuse method (burning, suction filtration and pyrolysis) for diesel oil adsorption using MCA was investigated and pyrolysis shown the optimal effect for MCA regeneration. The cycle times of MCA for diesel oil adsorption was studied using pyrolysis to regenerate MCA and MCA still had good adsorption capacity for diesel oil (45.14 g/g) in the sixth use. This paper provides a novel strategy for resource utilization of LS and a fast and green method for diesel oil treatment.

Effect of coconut coir and regenerated silk microparticles as blends and natural binders for construction and demolition waste (CDW) wood on the mechanical, thermal, and structural properties of biomicrocomposites prepared by hot-pressing

This study aims to utilize the thermosetting behavior of native lignin and the self-assembly of silk in coconut coir (CC) and regenerated silk (RS) microparticles used as blends and natural binders for construction and demolition waste (CDW) wood and their effect on the mechanical, thermal, and structural properties of CDW wood/CC, RS/CC, and CDW wood/RS biomicrocomposites. The obtained biomicrocomposites were prepared by hot-pressing blended microparticles at weight ratios of 80:20, 60:40, 50:50, 40:60, and 20:80 in the temperature range of 170–180°C. The obtained biomicrocomposites were characterized by bending strength, water resistance, scanning electron microscopy (SEM), thermogravimetric analysis/derivative thermogravimetry (TGA/DTG), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) measurements. Findings showed that the incorporation of RS displayed superior enhancement in the mechanical properties and water resistance in CDW/RS. The incorporation of CC slightly improved these properties in CDW/CC and RS/CC but offered greater thermal stability, as shown by thermogravimetric analysis (TGA/DTG). The addition of RS and CC showed good interfacial adhesion, as revealed by SEM. FTIR data revealed strong reactivity among CC, RS, and CDW wood.

Use of magnesium-silicate-hydrate (M-S-H) cement mixes in 3D printing applications

This study focused on the development of 3D printed building components incorporating MgO–SiO2 binders. The effects of parameters such as MgO/SiO2 and water/binder ratios and superplasticizer dosage were evaluated to produce 3D printable MgO–SiO2 binders. The assessment of rheological and mechanical properties, which led to an optimum mix that satisfied the printability criteria, was supported by microstructural characterization. The best-performing mix in terms of printability and mechanical performance was characterized via x-ray diffraction (XRD), thermogravimetric analysis/derivative thermogravimetry (TG/DTG) and field emission scanning electron microscopy (FESEM) with energy dispersive spectroscopy (EDS). The selected mix exhibited thixotropic behaviour with an ability to recover ~80% of its original viscosity within 60 s of extrusion and a shape retention factor of ~1. The extrudability, shape retention and buildability aspects were successfully demonstrated by printing a 5-layered 3D structure without any deformations. The final product contained brucite and M-S-H as hydration products, which were the main contributor to mechanical performance and microstructural densification.

Analytical investigation of archaeological pottery fragments excavated from Porunthal, Tamil Nadu, India

Abstract Within the framework of a technological study of pottery production of Porunthal, Dindigul district of Tamil Nadu, India, the chemical composition and mineralogy of the 7 potteries of different varieties from that archaeological site were studied using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis-derivative thermogravimetry (TGA-DTG), and scanning electron microscopy coupled with energy dispersive spectrometer (SEM-EDS). The analytical data obtained from several analyses were used to determine the mineral transformations during firing, such as quartz, feldspar, and iron oxides (hematite and magnetite), firing temperature, and firing conditions. The results of all the techniques confirmed that all the samples were manufactured by the artisans locally with the same raw materials and also were fired at the same temperature.

Thermogravimetric Kinetic Study of Automobile Shredder Residue (ASR) Pyrolysis

The separated and sorted combustibles from automobile shredder residue (ASR) can be pyrolyzed and used as a heat source or liquefied to produce materials with added value. In this study, the thermal decomposition properties of ASR were determined and thermal kinetic studies were performed. Four types of raw materials were separated from ASR and mixed at a constant ratio: 38.5 wt.% of plastic; 31.6 wt.% of fiber; 17.3 wt.% of sponge; and 12.3 wt.% of rubber. Pyrolysis kinetics analysis was carried out using the Thermogravimetric analysis-derivative thermogravimetry (TGA-DTG) technique and activation energy were calculated by differential and integral isoconversional model methods, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Friedman. Thermogravimetric analysis was performed under nitrogen with four temperature rate conditions from room temperature to 800 °C. In the thermal degradation profile, peaks representing mass loss rates were observed for each sample at different temperature ranges. It was observed that the final mass reduction temperature in the mixed samples was lower than in the individual samples. The activation energies of plastics and rubbers were 105.39 kJ/mol and 115.20 kJ/mol respectively. The sponge foams and fibers were 172.59 kJ/mol and 160.30 kJ/mol respectively. The mixed sample had an activation energy value of 159.56 kJ/mol. The basic physicochemical and pyrolysis characteristics of ASR were examined to be used as basic data for the recycling of ASR for future pyrolysis.

Greener adhesives based on UF/soy protein reinforced with montmorillonite clay for wood particleboard

AbstractThere is a global concern about the types of adhesives used for the binding of wood particles, most of which include formaldehyde in their formulation. The aim of this work is to study the effect of raw montmorillonite (Mt) particles on blended urea formaldehyde (UF)/soy protein (SP) adhesives for the manufacture of wood particleboards to reduce the use of this carcinogenic component. Rheology showed that Mt does not alter the viscosity of adhesives at high shear rates, so they can be applied by spray. Thermogravimetric analysis/derivative thermogravimetry (TGA/DTG) analysis revealed an enhancement of their thermal stability due to the presence of clay particles. Polymer–Mt interaction was studied by small amplitude X‐ray scattering and scanning electron microscopy. According to these results, the exfoliated structure of the clay particles was achieved. Wood particleboards were manufactured with UF/SP/Mt adhesives in order to study their mechanical properties. The three‐point bending test showed that Mt particles improved the modulus of both rupture and elasticity. UF/SP/Mt resins proved to be a prominent product for the development of environmentally friendlier particleboards with desirable mechanical properties.

The assessment of spontaneous ignition potential of coals using TGA–DTG technique

During the utilization of coal in large power plants, one of the major logistical issues is related to spontaneous ignition of the coal. This characteristic of coal depends on the rank and type of the coal, the content of the moisture and volatile matter as well as particle size distribution. This paper presents the novel approach for determination of spontaneous ignition potential of the coal developed as the internal laboratory experimental method. The experimental tests were performed by thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) of tested samples at five different heating rates: 3, 5, 7, 10 and 20 K min−1 under an air atmosphere. The TGA results were used for determination of tangent slope of the mass loss rate curves in the zone of the release of volatiles at considered heating rates for all coal samples. The linear interpolation of the data obtained by performed tangent slope analysis and heating rates provides the straight line unique for each tested sample. According to the standard method, the slope of the obtained straight line is defined as thermogravimetric index of spontaneous ignition (TGspi). In addition, a new formula for determination of TGspi index was provided. Three different coal samples were analyzed and classified according to the spontaneous ignition potential, based on the obtained values for TGspi by standard procedure and also using a newly proposed method. By varying the gradient of linear dependence of self-heating coefficient against reference temperatures (Tref,i), the mass and heat transfer limitations for different coals were discussed.

Thermogravimetric, Devolatilization Rate, and Differential Scanning Calorimetry Analyses of Biomass of Tropical Plantation Species of Costa Rica Torrefied at Different Temperatures and Times

We evaluated the thermogravimetric and devolatilization rates of hemicellulose and cellulose, and the calorimetric behavior of the torrefied biomass, of five tropical woody species (Cupressus lusitanica, Dipteryx panamensis, Gmelina arborea, Tectona grandis and Vochysia ferruginea), at three temperatures (TT) and three torrefaction times (tT) using a thermogravimetric analyzer. Through a multivariate analysis of principal components (MAPC), the most appropriate torrefaction conditions for the different types of woody biomass were identified. The thermogravimetric analysis-derivative thermogravimetry (TGA-DTG) analysis showed that a higher percentage of the hemicellulose component of the biomass degrades, followed by cellulose, so that the hemicellulose energy of activation (Ea) was less than that of cellulose. With an increase in TT and tT, the Ea for hemicellulose decreased but increased for cellulose. The calorimetric analyses showed that hemicellulose is the least stable component in the torrefied biomass under severe torrefaction conditions, and cellulose is more thermally stable in torrefied biomass. From the MAPC results, the best torrefaction conditions for calorimetric analyses were at 200 and 225 °C after 8, 10, and 12 min, for light and middle torrefaction, respectively, for the five woody species.

Thermal Characteristics and Kinetic Calculation of Castor Oil Pyrolysis

To investigate the thermal characteristics of castor oil pyrolysis, the fatty acid composition was firstly analyzed via gas chromatograph (GC). Then, the thermal characteristics was evaluated through the thermogravimetric analysis-derivative thermogravimetry (TGA-DTG) under nitrogen atmosphere at 5, 10, 15, and 20 K min-1 from 298.2 K to 873.2 K. Based on the iso-conversional method, pyrolysis kinetic parameter of the activation energy was calculated by the free model approaches of Kissinger-Akahira-Sunose method (KAS) and Flynn-Wall-Ozawa method (FWO). In addition, the reaction order was calculated through Avrami theory. The average activation energy values were calculated as 202.88 kJ mol-1 and 203.66 kJ mol-1 for KAS method and FWO method, respectively. And the average value of reaction order is 1.02.

Fabrication of starch‐g‐poly(l‐lactic acid) biocomposite films: Effects of the shear‐mixing and reactive‐extrusion conditions

ABSTRACTIn this study, we developed a new approach for the fabrication of a green poly(l‐lactic acid)‐grafted starch (St‐g‐PLA) copolymer and nanocomposite (St‐g‐PLA/organoclay)‐based films via shear‐mixing and reactive‐extrusion systems. The chemical and physical structures, thermal behavior, and morphology of the synthesized blends and some other parameters were examined by Fourier transform infrared spectroscopy and 13C cross‐polarization/magic angle spinning NMR spectroscopy, X‐ray diffraction, thermogravimetric analysis–derivative thermogravimetry, and scanning electron microscopy, respectively. Significant increases in the mechanical and permeability properties were evident in the high value of grafted poly(lactic acid) molar percentages and high exfoliation of organoclay. The biodegradability of films were investigated under aerobic composting conditions through the measurement of the temperature, moisture, pH, consumed O2 value, and carbon dioxide produced. This new strategy mainly improved the good adhesion between both phases, and it was an interesting method for the production of environmentally friendly biocomposites that could easily be scaled up for commercial production with the potential for replacing petroleum‐based plastics. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44490.

Evaluation of Physical, Thermal and Spectral Parameters of Biofield Energy Treated Methylsulfonylmethane

The methylsulfonylmethane (MSM) is an organosulfur compound having sulfonyl functional group. It is occurred naturally in some primitive plants and used in disease related to chronic pain, inflammation, and arthritis. This study was attempted to evaluate the impact of biofield energy treatment on the physical, thermal, and spectral properties of MSM. The study was performed in two groups viz. the control group was remained as untreated, while the treated group was subjected to Mr. Trivedi’s biofield energy treatment. After that, both the control and treated samples were analyzed using surface area analyzer, X-ray diffraction (XRD), thermogravimetric analysisderivative thermogravimetry (TGA-DTG), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. The surface area analysis exhibited a significant decrease in the surface area of treated sample by 22.96% as compared to the control. The XRD analysis showed the significant increase in average crystallite size by 49.20% in the treated sample with respect to the control. The DSC analysis showed the significant increase (67.20%) in latent heat of fusion of treated sample with respect to the control. The TGA analysis showed the onset temperature of thermal degradation at 170°C in the control sample that was slightly decreased to 168.05°C after biofield treatment. Moreover, the Tmax (maximum thermal degradation temperature) was also decreased slightly from 186.66°C (control) to 183.38°C (treated). This indicated the early phase of vaporization in treated sample as compared to the control. The FT-IR spectroscopic study exhibited the alteration in wavenumber of S=O group that suggests the effect of biofield treatment on force constant and bond strength of MSM molecules.

Characterization of Physical, Thermal and Spectroscopic Properties of Biofield Treated Ortho-Toluic Acid

Toluic acid isomers are widely used as a chemical intermediate in manufacturing of dyes, pharmaceuticals, polymer stabilizers, insect repellent and other organic synthesis. The aim of present study was to evaluate the impact of biofield treatment on physical, thermal and spectroscopic properties of ortho isomer of toluic acid (OTA). The OTA sample was divided into two groups, served as control and treated. The treated group received Mr. Trivedi’s biofield treatment. Subsequently, the control and treated samples were evaluated using X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis/ derivative thermogravimetry (TGA/DTG), Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-Vis) spectroscopy. XRD result showed 26.66% decrease in crystallite size in treated OTA sample as compared to control. Furthermore, DSC analysis result showed that latent heat of fusion was considerably reduced by 6.68% in treated OTA sample as compared to control. However, an increase in melting point was observed in treated sample. The melting point of treated OTA sample was found to be 107.96°C as compared to control (105.47°C) sample. Moreover, TGA/ DTG studies showed that Tmax (temperature, at which sample lost its maximum weight) was decreased by 1.21% in treated OTA sample as compared to control. It indicates that vaporisation of treated OTA sample might increase as compared to control. The FT-IR and UV-Vis spectra did not show any significant changes in spectral properties of treated OTA sample as compared to control. These findings suggest that biofield treatment has significantly altered the physical and thermal properties of OTA, which could make it more useful as chemical intermediate.

Structural Evolution under Reaction Conditions of Supported (NH4)3HPMo11VO40 Catalysts for the Selective Oxidation of Isobutane

When using heteropolycompounds in the selective oxidation of isobutane to methacrolein and methacrylic acid, both the keeping of the primary structure (Keggin units) and the presence of acidic sites are necessary to obtain the desired products. The structural evolution of supported (NH4)3HPMo11VO40 (APMV) catalysts under preliminary thermal oxidizing and reducing treatments was investigated. Various techniques, such as TGA/DTG (Thermo-Gravimetric Analysis/Derivative Thermo-Gravimetry), H2-TPR (Temperature Programed Reduction), in situ XRD (X-Ray Diffraction) and XPS (X-ray Photoelectron Spectroscopy), were applied. It was clearly evidenced that the thermal stability and the reducibility of the Keggin units are improved by supporting 40% APMV active phase on Cs3PMo12O40 (CPM). The partial degradation of APMV takes place depending on temperature and reaction conditions. The decomposition of ammonium cations (releasing NH3) leads to the formation of vacancies favoring cationic exchanges between vanadium coming from the active phase and cesium coming from the support. In addition, the vanadium expelled from the Keggin structure is further reduced to V4+, species, which contributes (with Mo5+) to activate isobutane. The increase in reducibility of the supported catalyst is assumed to improve the catalytic performance in comparison with those of unsupported APMV.