Thermogravimetric Decomposition Research Articles

Ultrasound-assisted vacuum drying of limequat peels and characterization of thermal, morphological and functional properties

Ultrasound-assisted vacuum drying of limequat peels and characterization of thermal, morphological and functional properties

Synthesis of benzoic acid from catalytic co-pyrolysis of waste wind turbine blades and biomass and their kinetic analysis

Synthesis of benzoic acid from catalytic co-pyrolysis of waste wind turbine blades and biomass and their kinetic analysis

Development and characterization of enhanced urea through micronutrients and established technology addition

AbstractIt is necessary to increase the agronomic use efficiency of urea to reduce ammonia volatilization and increase crop yield. However, relying solely on urea for the enhanced efficiency technologies development could harm fertilizer integrity, resulting in reduced application quality and fertilizer storage time. The authors aimed at developing and characterizing the physical, chemical, and physicochemical quality of a novel enhanced efficiency fertilizers, synthesized from urea plus boron (B), zinc (Zn), nickel (Ni), or molybdenum (Mo) addition, with or without N‐(n‐butyl) thiophosphoric triamide (NBPT) associated. Hygroscopicity, hardness, salt index (SI), pH, and thermogravimetric decomposition were the parameters evaluated. Fertilizer quality was assessed through microscopic X‐ray fluorescence, microtomography, and scanning electron microscopy. Micronutrients were added by coating or granulation; they were homogeneously distributed over the fertilizer's granules. The fertilizers’ hardness increased up to 86% with Zn coated compared with uncoated. Granulated urea with B, Zn, Ni, or Mo had greater internal porosity, which resulted in lower hardness. Boron and Zn addition to the fertilizers increased the hygroscopicity in average 388% and 473%, respectively, compared with hygroscopicity observed for urea. Moreover, hygroscopicity was increased by an average of 56% with NBPT addition. Micronutrients addition to the urea granules increased the SI, while thermal decomposition stages of urea were unaffected by micronutrients addition. Enhanced efficiency fertilizers require characterization before agronomic efficiency tests due to changes in their physical, chemical, and physicochemical properties. Unfavorable changes could harm granules integrity and application efficiency in the field, resulting in economic losses to the industry and farmers.

Xanthan gum produced from milk permeate and deproteinized cheese whey: A comparative analysis with commercial xanthan gums

Xanthan gum produced from milk permeate and deproteinized cheese whey: A comparative analysis with commercial xanthan gums

The Flame Retardancy and Smoke Suppression Performance of Polyvinyl Chloride Composites with an Efficient Flame Retardant System

Polyvinyl chloride (PVC) is the most widely used general flame-retardant plastic worldwide; however, the large number of plasticizers added during processing significantly reduces its flame-retardant property. To prepare a new type of PVC material with highly efficient flame retardancy and smoke suppression, antimony trioxide (Sb2O3), talc powder, hydromagnesite, and zinc borate were added in different proportions to PVC to explore the flame-retardant properties, thermal weight, smoke density (Ds), and mechanical properties of the composite materials. Results showed that the limiting oxygen index value of each group was higher than 27% after adding talc powder, magnesite, and zinc borate to replace part of the Sb2O3. This value was within the refractory-grade level and indicated a good flame retardancy performance. The replacement effect was in line with the experimental expectation. The lowest Ds peak value was 656.4 when the flame retardants were added with 10 wt% Sb2O3, 50 wt% hydromagnesite, 20 wt% talc, and 20 wt% Zn3BO6. Compared with pure Sb2O3 as a flame retardant, the Ds peak value decreased by 46.7%. The thermogravimetric decomposition temperature of the composites in each group was generally higher than that of the group with pure Sb2O3 as a flame retardant, increasing by 45.3 °C. The thermal stability of the composites was improved, and the elongation at the break and tensile strength were 234.9% and 25.8 MPa, respectively, indicating good mechanical properties. The results showed that using compound flame retardants to replace most of the Sb2O3 is an effective technique for obtaining good flame retardancy and mechanical properties of PVC. This study, not only reduced the manufacturing cost of flame-retardant PVC, but also effectively reduced its smoke density and the time to reach the highest smoke density, which provided a research reference for the application and promotion of flame-retardant PVC.

Decomposition Behavior of Stereocomplex PLA Melt-Blown Fine Fiber Mats in Water and in Compost

This study introduces systematic and comparative investigations of various PLA fine fiber mats prepared by melt blowing. A series of PLLA and PDLA melt-blown fibers from various L and D enantiomers blends were produced. Their morphological, mechanical, and thermal properties were studied, and their decomposition in water and compost was investigated. It was found that the 1:1 ratio blend with stereocomplex crystals had an 80% lower average fiber diameter, 60% higher specific strength and better thermal stability than the PLLA and PDLA fiber mats. In the case of composting, the crystalline peak melting temperature, crystallinity, and thermogravimetric decomposition temperatures marginally decreased after 14 days. The high surface of the fine fiber mats played a crucial role in fast decomposition, as they entirely disintegrated in less than only 40 days. In the case of water, the homocrystalline domains were more susceptible to hydrolysis than the stereocomplex ones. All the PLA fiber mats underwent decomposition and extensive disintegration for 70 days in water. Hydrolysis reduced the amorphous and crystalline fraction of the fibers via surface and bulk erosion, while the decomposition of stereocomplex-crystalline-rich domains mainly exhibited surface erosion. Findings revealed that high porosity and the high surface area of PLA melt-blown fine fiber mats undergo fast decomposition in compost and in water.Graphical

Synthesis, characterization, theoretical calculation, DNA binding, molecular docking, anticovid-19 and anticancer chelation studies of some transition metal complexes

The globe has recently been consumed by frightening viral pneumonia (COVID-19). The new strain of the virus, called SARS-CoV-2, belongs to the family of coronaviruses, so research is aimed at screening ligands and drugs for multimodal structure-based structure-design and then docking to the main viral protease to examine the active binding sites. The complexes of Cu(II), Ni(II) Zn(II) and Mn(II) with 3-Cyano-6-(p-chlorophenyl) azo-7-hydroxy coumarin (HL) were synthesized and characterized by elemental analyses, IR, UV-Visible, magnetic measurements and thermal analyses. The measurements of molar conductance showed that all the complexes are non-electrolyte. The IR spectra showed that the ligand (HL) acts as a monobasic bidentate ligand by coordinating via the nitrogen atom (-N = N-) and deprotonated -OH group. Analytical data showed that all complexes exhibited a ratio of 1:1 (metal-ligand). The thermal data indicate that some complexes have outside water molecule and some have within the domain of coordination water molecule, and the complexes display identical fragments of thermogravimetric decomposition that are compatible with the proposed structures. Mass spectra were also used to make the large fragments of the ligand and Ni (II) complex, with the main peaks corresponding to molecular weight using quantum chemical equations.

Study the Thermal Properties of Epoxy Resin Reinforced with Calcium Oxide Fibers

ABSTRACT Poor tensile strength and brittle nature are considered to be a major weakness in epoxy resin. Herein, thermogravimetric decomposition is used to investigate the effect of the addition of calcium oxides on the thermal degradation of the epoxy resin. Four composites with 5%, 7.5%, 10%, and 15 wt % calcium oxide are prepared with epoxy resin as a matrix substance. Arrhenius equation is used to evaluate the activation energies of the composites and the findings are tabulated. The findings indicate that the addition of calcium oxides as a filler contributes to an enhancement in the thermal stability of the components by inhibiting the process of thermal decomposition of epoxy resin. The composition with a ratio of 10% by weight of calcium oxide/epoxy shows a good and distinct stability, which is evidenced by the increasing in the thermal decomposition of the composite 10% CaO filler/epoxy at 400°C compared with other composites.

Investigating the heat stability, calorimetric degradations and chromatographic polyphenolic profiling of edible macerated hog-tree apple leaf (Morinda lucida Benth)

The increasing demand for food-based bio-products has necessitated screening characterizations and microstructural elucidation. In this study, different analytical techniques were employed to investigate the thermal stability, morphological changes and phenolic profile of macerated hog-tree apple leaf. TGA peak heights from the thermo-gravimetric decomposition curve could be attributed to mass evaporation and simultaneous removal of residual moisture from the sample accounting for 0.9239 mg mass loss from 5.825 mg of the total sample. The TGA results suggest that the 87 polyphenolic metabolites recovered from the sample occurred between 71.94 °C and 243.55 °C with 3.871 mg mass loss from 5.825 mg from the total sample loading. In this region eighty-seven compounds were identified which include mainly the phenolic and flavonoids viz: isochlorogenic acid, trans-ferulaldehyde, 10-O-methylprotosappanin, moracin G, terchebin, geraniin, albaspidin AA. These has been reported in previous studies as strong antioxidant compounds. Moreover, the SEM monograph generated further elucidated the morphological changes and surface degradation of Morinda lucida Benth which resulted in the exudation of phenolic constituents. The result of this investigation could, therefore, be used as blueprints for storage and post-harvest processing of edible M. lucida Benth.

Urea derived deposits in diesel exhaust gas after-treatment: Integration of urea decomposition kinetics into a CFD simulation

Abstract Formation of solid urea by-products in mixing sections of SCR systems is a well-known problem in development and design of exhaust gas after treatment systems. Spray impingement induces liquid film formation on mixer blades and tailpipe walls, from which urea by-products can be derived in dependence on temperature and residence time. This work presents a comprehensive modeling approach for prediction of by-product formation. An existing kinetic model for urea decomposition is integrated into CFD simulations by user coding. Implementation is evaluated by 3D simulations of thermogravimetric decomposition of urea and its by-products. Results are compared to experimental data and simulation results from a 0D model. Furthermore, the procedure is applied to simulations of a flow setup including urea injection for demonstration of the model capabilities.

Novel copper(II) and palladium(II) complexes with 4-aroyl-5-pyrazolone ligands: Synthesis and characterization

Abstract Novel bidentate 4-aroyl-5-pyrazolone ligands were synthesized and reacted with copper(II) and palladium(II) salts in 1:2 (metal:ligand) equimolar ratio leading to the formation of eight new coordination compounds. All synthesized compounds were characterized by FTIR, UV–Vis, ESI-Mass, 1H NMR, 13C-APT and also, in the case of the paramagnetic palladium(II) complexes, by ESR spectral studies. Additionally, elemental and thermogravimetric analyses (TG/DTG) were applied to all prepared complexes. These complexes are mononuclear and the copper(II) complexes have distorted square-planar geometry as determined by ESR. Spectral studies confirm the coordination of 4-aroyl-5-pyrazolone ligands through the carbonyl moieties to the metal. All the copper(II) complexes coordinated to the metal by enolization and the palladium(II) complexes showed ‘Type B’ coordination. The ligand which has 1-(4-methoxy)phenyl-substituted pyrazolone ring gave copper(II) complexes with a water molecule outside the coordination sphere. The proposed structures of the complexes agree well with the thermogravimetric decomposition results.

Synthesis, characterization and biological properties of oxovanadium(IV) complexes

Abstract The complexes of oxovanadium(IV) with bidentate heterocyclic azo pyrazolone were synthesized and characterized by elemental analyses, IR, UV–Visible, EPR and magnetic measurements as well as thermal analysis and X-ray diffraction. Reaction of [VIVO(acac)2] (where acac = acetylacetonate) in methanol with azo pyrazolones (HLn) produced mononuclear vanadium(IV) oxo complexes with general formula [VO(Ln)2]H2O. The molar conductance measurements proved that all the complexes are non-electrolytes. IR spectra showed that the ligands (HLn) acts as a monobasic bidentate ligand by coordinating via the nitrogen atom of the pyrazole ring ( HN N = ) and deprotonated hydroxyl O, thereby forming a square pyramidal chelating ring. Analytical data revealed that all the complexes exhibited 1:2 (metal-ligand) ratio. The thermal data confirm that the complexes have water molecule outside the coordination sphere and the complexes show similar thermogravimetric decomposition fragments which are consistent with the proposed structures. The thermodynamic parameters of VO(II) complexes are calculated using Coats–Redfern and Horowitz-Metzger methods. The optimized bond lengths, bond angles and the calculated quantum chemical parameters for VO(II) complexes (1–3) were investigated. Their interactions with calf thymus DNA were investigated by absorption spectra and viscosity measurements. The results suggest that these complexes bind to DNA in an intercalative mode (Kb = 4.58–8.96 × 105 M−1). All VO(II) complexes (1–3) were evaluated against human cancer cell lines, MCF-7 and HepG-2 as compared with the positive controls in the viability assay of colchicine and vinblastine. Complex 2 (IC50 = 30.5 ± 2.3 and 20.1 ± 1.9 μg/ml) exhibit moderate activities against the two cell lines MCF-7 and HepG-2, respectively as compared to the Colchicine (IC50 = 17.7 ± 0.03 and 10.6 ± 0.01 μg/mL). The antimicrobial activities of VO(II) complexes were tested against gram negative bacteria (Escherichia coli), gram positive bacteria (Staphylococcus aureus) and fungal (Candida albicans).

Thermal Reduction of NOx with Recycled Plastics.

This study develops technology for mitigation of NOx formed in thermal processes using recycled plastics such as polyethylene (PE). Experiments involve sample characterization, and thermogravimetric decomposition of PE under controlled atmospheres, with NOx concentration relevant to industrial applications. TGA-Fourier transform infrared (FTIR) spectroscopy and NOx chemiluminescence serve to obtain the removal efficiency of NOx by fragments of pyrolyzing PE. Typical NOx removal efficiency amounts to 80%. We apply the isoconversional method to derive the kinetic parameters, and observe an increasing dependency of activation energy on the reaction progress. The activation energies of the process span 135 kJ/mol to 226 kJ/mol, and 188 kJ/mol to 268 kJ/mol, for neat and recycled PE, respectively, and the so-called compensation effect accounts for the natural logarithmic pre-exponential ln (A/min-1) factors of ca. 19-35 and 28-41, in the same order, depending on the PE conversion in the experimental interval of between 5 and 95%. The observed delay in thermal events of recycled PE reflects different types of PE in the plastic, as measurements of intrinsic viscosity indicate that, the recycled PE comprises longer linear chains. The present evaluation of isoconversional activation energies affords accurate kinetic modeling of both isothermal and nonisothermal decomposition of PE in NOx-doped atmosphere. Subsequent investigations will focus on the effect of mass transfer and the presence of oxygen, as reburning of NOx in large-scale combustors take place at higher temperatures than those included in the current study.

Synthesis and structural characterization of new oxovanadium(IV) complexes derived from azo-5-pyrazolone with prospective medical importance

Abstract Four novel o-hydroxy substituted aryl-(m H, Cl, Br, CH 3 ) azo-5-pyrazolone compounds ( 2a–d , respectively) were synthesized as azo-group containing ligands by diazotization of aryl amines then coupled with 1-(4-chlorophenyl)-3-isopropyl-1 H -pyrazol-5(4 H )-one ( 1 ) and the structures were confirmed by FTIR, UV-Visible, GC-MS or ESI-LCMS and NMR spectroscopic techniques. As a result, the first synthesis of azo-5-pyrazolone based oxovanadium(IV) complexes ( 3a–d ) was achieved by interaction of 2a–d with half equivalent of vanadyl sulphate pentahydrate in a methanolic medium with moderate to high yields (67, 74, 60, 71 for 3a–d , respectively). The resulting complexes were characterized using FTIR, UV-Visible, ESI-LCMS and EPR spectroscopic techniques as well as with thermogravimetric (TG/DTG) analysis. They have the composition [VO(L) 2 ]·H 2 O; ( 3a–c ) or [VO(L) 2 ]·CH 3 OH; ( 3d ) where LH is an azo-5-pyrazolone compound as the ligand ( 2a–d ). The electronic spectra of the complexes are typical of oxovanadium(IV) complexes showing a low intensity band near 500 nm. Spectroscopic results have shown that azo-5-pyrazolone compounds have acted bidendate and the coordination sites are hydroxyl-substituent on the -azo phenyl-aromatic ring and the pyrazolone carbonyl-moiety. The thermal data confirm that the complexes have methanol ( 3a–c ) or water ( 3d ) molecule outside the coordination sphere and the complexes show similar thermogravimetric decomposition fragments which are consistent with the proposed structures. A distorted octahedral geometry has been proposed for these complexes mainly with EPR and the other spectral techniques.

Hydrothermal syntheses, crystal structures and characterization of two new 1-D and 2-D inorganic–organic hybrid polyoxomolybdates [H2dap]2[x-Mo8O26]·2H2O and [Cu(dap)2]2[β-Mo8O26

Abstract Two new 1-D and 2-D inorganic–organic hybrid polyoxomolybdates [H2dap]2[x-Mo8O26]·2H2O (1) and [Cu(dap)2]2[β-Mo8O26] (2) (dap = 1,2-propanediamine) have been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectra, powder X-ray diffraction and single-crystal X-ray diffraction. The most remarkable structural differences between them are that 1 displays a 1-D chain constructed from [x-Mo8O26]4 − clusters through two terminal O atoms from adjacent [x-Mo8O26]4 − clusters whereas 2 demonstrates the 2-D extended layer made up of [β-Mo8O26]4 − clusters via [Cu(dap)2]2 + connectors. To our knowledge, the [x-Mo8O26]4 − cluster in 1 is reported for the first time. The thermogravimetric (TG) curve of 1 shows a two-step weight loss whereas the TG decomposition of 2 only proceeds in one stage. Additionally, their electrochemical behaviors and their photocatalytic degradation properties towards rhodamine-B are also investigated.

Impact of the content of ETBE, EtOH and polybutylene-succinate additives on the propensity of E10 petrol to form deposits in combustion chambers

Abstract This paper presents the results of research on the propensity of E10 petrol (defined by EN 228 standard as a petrol with a maximum oxygen content of 3.7 wt.%) to form deposits in combustion chambers by using the method of determining the unwashed gum content EN ISO 6246 and by thermography TGA FLTM BZ-154-01. The aim of this is study was to examine samples of unleaded petrol 95 containing ethanol (EtOH) and/or ethyl tert-butyl ether (ETBE) improved with three different packages containing detergent additives derived from poly-succinic acid. The additive D3 containing imido-amid of polybutylene-succinate exhibited the best efficiency in reducing the propensity for fuel deposit formation in combustion chambers. Clear differences were found in how the presence of various oxygenating compounds can affect the efficiency of the thermogravimetric decomposition of gums. In the case of petrol containing ETBE as the only oxygenate, for the same levels of additives used, there was a reduced tendency to form deposits (CCD) than for the same type of petrol fuel with ethanol content.

Tuning the Moisture and Thermal Stability of Metal–Organic Frameworks through Incorporation of Pendant Hydrophobic Groups

An isostructural series of NbO-type porous metal–organic frameworks (MOFs) with different dialkoxy-substituents of formula Cu2(TPTC-OR) (TPTC-OR = 2′,5′-di{alkyl}oxy-[1,1′:4′,1″-terphenyl]-3,3″,5,5″-tetracarboxylate, R = Me, Et, nPr, nHex) has been synthesized and characterized. The moisture stability of the materials has been evaluated, and a new superhydrophobic porous MOF has been identified. The relationship between pendant side chain length and thermal stability has been analyzed by in situ synchrotron powder X-ray diffraction, showing decreased thermal stability as the side chain length is increased, contradictory to thermogravimetric decomposition studies. Additionally, the four materials exhibit moderate Brunauer–Emmett–Teller (BET) and Langmuir surface areas (1127–1396 m2 g–1 and 1414–1658 m2 g–1) and H2 capacity up to 1.9 wt % at 77 K and 1 bar.

Importance of the interlayer orientation in borate-intercalating layered double hydroxides

Thermal decomposition kinetics and mechanism of layered double hydroxides (LDHs) intercalating different amounts and types of borate ions were studied using Coats–Redfern integral and Achar differential methods. The results revealed that the Coats–Redfern integral method is more appropriate than the Achar differential method for evaluation of the nonisothermal thermogravimetric decomposition data. The first-order Avrami-Erofe’ev A1 mechanism was found to be the best fitting kinetic model for almost all samples. In addition to the amount and type of the intercalated borate ion, interlayer orientation was also of importance in determining the chemical and thermal stabilities and hence the decomposition kinetics of the studied compounds.

Elemental Characterization of Trifala Powders and Tablets by Instrumental Neutron Activation Analysis, Thermal Analysis and Spectral Studies of Gallic Acid

Trifala is one of the most popular herbal formulations, marketed either as powder or a tablet and is used in all parts of India. It is an effective laxative, antioxidant, anticancer and antidiabetic agent, and is used to refresh the eyes. In order to understand the therapeutic uses of trifala, the powder and tablet forms from Zandu Pharmaceuticals, Mumbai, were analyzed for six minor (Na, K, Mg, Ca, Cl and P) and 23 trace (Al, Ba, Br, Cd, Co, Cr, Cs, Cu, Fe, Eu, Hf, Hg, La, Mn, Ni, P, Pb, Rb, Sb, Se, Th, V and Zn) elements. The elements were determined by employing instrumental neutron activation analysis (INAA) and atomic absorption spectrophotometry (AAS). A comparison of the elemental contents in the powder and tablets showed wide variations. The powder was rich in Cr, Fe, Se and Zn, whereas the tablet contained a four-fold higher Mn compared to the powder. Column and thin layer chromatography (TLC) in ethyl acetate/methanol (7:3) were used for the separation of gallic acid in ethanolic extract. It was further confirmed by elemental analysis and spectral methods and quantitatively estimated to the extent of approximately 2%. Thermogravimetric decomposition studies show a three stage process, first a slow process with approximately 20% wt loss at temperatures up to 200 degrees C followed by a fast process losing another 30-35% wt at approximately 300 degrees C for both the powder and tablets. At 700 degrees C metal oxide residue of 7.5 and approximately 16% were left for powder and tablets, respectively.

Elemental Characterization of Trifala Powders and Tablets by Instrumental Neutron Activation Analysis, Thermal Analysis and Spectral Studies of Gallic Acid

Trifala is one of the most popular herbal formulations, marketed either as powder or a tablet and is used in all parts of India. It is an effective laxative, antioxidant, anticancer and antidiabetic agent, and is used to refresh the eyes. In order to understand the therapeutic uses of trifala, the powder and tablet forms from Zandu Pharmaceuticals, Mumbai, were analyzed for six minor (Na, K, Mg, Ca, Cl and P) and 23 trace (AI, Ba, Br, Cd, Co, Cr, Cs, Cu, Fe, Eu, Hf, Hg, La, Mn, Ni, P, Pb, Rb, Sb, Se, Th, V and Zn) elements. The elements were determined by employing instrumental neutron activation analysis (INAA) and atomic absorption spectrophotometry (AAS). A comparison of the elemental contents in the powder and tablets showed wide variations. The powder was rich in Cr, Fe, Se and Zn, whereas the tablet contained a four-fold higher Mn compared to the powder. Column and thin layer chromatography (TLC) in ethyl acetate/methanol (7:3) were used for the separation of gallic acid in ethanolic extract. It was further confirmed by elemental analysis and spectral methods and quantitatively estimated to the extent of −2%. Thermogravimetric decomposition studies show a three stage process, first a slow process with −20% wt loss at temperatures up to 200°C followed by a fast process losing another 30-35% wt at ∼300°C for both the powder and tablets. At 700°C metal oxide residue of 7.5 and −16% were left for powder and tablets, respectively.