TG-DTG Analysis Research Articles

Studies on the Synthesis and Properties of Energetic Ionic Liquids Based on Imidazolium Compounds

Starting from N-methylimidazole, 1,2-dimethylimidazole and 2-chloroethanol, a series of imidazolium-based ener- getic ionic liquids were synthesized via quaternization, nitration and metathesis reactions. All the energetic ionic liquids were characterized by ultraviolet visible spectrum (UV-Vis), infrared spectrum (IR), mass spectrometry (MS), nuclear magnetic resonance (NMR) and elemental analysis. The solubility study of these ionic liquids was carried out with commonly used or- ganic solvents, which showed that the energetic ionic liquids dissolved easily in polar solvents. Moreover, the ionic liquids had good thermo-stabilities indicated by thermal gravimetric analysis (TG-DTG) and differential scanning calorimetry (DSC). TG-DTG analyses showed that N-nitrooxyethylimidazolium nitrate decomposed at about 160 ℃ and N-hydroxyethylimida- zolium ionic salts decomposed above 190 ℃. Furthermore, there was an obvious glass transition process for the energetic ionic liquids based on 1-(2-nitrooxyethyl)-3-methylimidazolium and N-hydroxyethylimidazolium during the secondary heating process of DSC, which was the unique property of ionic liquids. Their densities and standard enthalpies of formation and det- onation properties were calculated and analyzed. Keywords energetic materials; quaternary ammonium; metathesis; thermal properties; detonation properties

Interlayer configuration of ionic liquids in a Ca-montmorillonite as evidenced by FTIR, TG-DTG, and XRD analyses

Ionic liquids (ILs) have attracted much attention in the scientific community during the past two decades. However, studies of interactions between Earth materials and ILs have been limited. In this study, the uptake and interlayer configuration of ILs on a high charge Ca-montmorillonite (MMT) were systematically studied using TG-DTG, FTIR, and XRD analyses. The intercalation protected the ILs from thermal decomposition, resulted in an increase in their thermal stability in comparison to ILs adsorbed on the surfaces. The results from TG-DTG, FTIR, and XRD all pointed to a change in mechanisms and interlayer configurations as the chain length, input amounts, and initial concentrations of ILs changed. A higher decomposition temperature in TG analyses and a large blue shift of selected FTIR bands agreed well with the cation exchange mechanism at lower IL loading levels. Accompanying cation exchange the interlayer water was completely removed. Hydrophobic interactions and admicelle adsorption were responsible for IL uptake beyond the cation exchange capacity of the MMT. A pseudo-trilayer configuration was suggested based on XRD analyses for the intercalation of ILs with a chain length of 12 carbons at the sorption maximum and that of 16 carbons at medium sorption levels. A paraffin-like conformation with an almost vertical orientation was suggested for the configuration of IL with a chain length of 16 carbons in the interlayer of MMT at the sorption maximum.

In situ preparation of a magnetic composite during functionalization of poly[maleic anhydride-co-3,9-divinyl-2,4,8,10-tetraoxaspiro(5.5)undecane] with erythritol

New magnetic hybrid composites were prepared, in situ, during the functionalization of poly[maleic anhydride-co-3,9-divinyl-2,4,8,10-tetraoxaspiro(5.5)undecane] copolymer, by opening the anhydride ring with erythritol and by introducing magnetic nanoparticles into the polymeric matrix. The procedure allows for magnetic nanocomposite preparation. More than that, the new polymeric matrices owing to their suitable and specific functionalities are anticipated to be used for further link of biological molecules via the maleic anhydride moiety and the polyol presence. The hybrid composites are analyzed by infrared absorption spectrometry, dynamic light scattering (DLS), TG-DTG analysis, X-ray diffraction, SEM, TEM, and vibrating sample magnetometry. Examination of the magnetic composites by DLS analysis shows that the material consists mostly of particles with mean sizes between 295 and 342 nm, depending on the magnetite type in synthesis. The obtained results indicate the magnetite encapsulation and the interactions established with the polymeric matrix that lead to carbonyl band shifting in FTIR spectra, composite particle size decreasing, and influence on XRD and magnetic behavior data. The report of magnetization demonstrates that the prepared nanocomposites are superparamagnetic.

An investigation for the performance of meta-aramid fiber blends treated in supercritical carbon dioxide fluid

The physicochemical performance of meta-aramid fiber blends treated in supercritical carbon dioxide fluid was studied at different temperatures. The effects of treatment temperatures on the surface morphology, wettability, chemical and crystal structures, thermal and antistatic properties were investigated by employing Scanning electron microscopy, Dynamic wetting measurements, Fourier transform infrared spectrometry, X-ray diffraction, Thermal analysis and Static half period method, respectively. The result showed that the surface of the treated meta-aramid fiber blends was changed with the treatment temperature increasing and more mild grooves and stripes appeared. The dynamic wetting measurements showed that the water contact angles and absorption time for treated fibers were decreased with temperature increasing. The slight shifts of the characteristic bands of the treated meta-aramid fiber blends were observed in FT-IR spectra with the system temperature increasing. Meanwhile, XRD analysis showed that the diffraction intensities of treated samples were improved in the supercritical carbon dioxide fluid because some re-arrangements and re-crystallizations of the molecule chains generated. TG-DTG analysis indicated that the thermal property of meta-aramid fiber blends could be improved at various temperatures. In addition, supercritical carbon dioxide fluid had little negative influence on the physical and antistatic properties of the meta-aramid fiber blends.

Investigation of intercalation of diphenhydramine into the interlayer of smectite by XRD, FTIR, TG-DTG analyses and molecular simulation

Diphenhydramine (DPH) is one of the pharmaceuticals commonly found in the effluent stream after wastewater treatment, and the cause of its environmental persistence needs to be addressed urgently. Smectite minerals are common soil components with large surface area, expandable interlayer, and high cation exchange capacity (CEC), thus are capable of adsorbing or intercalating inorganic or organic cations on the surface or in the interlayer. In this study the intercalation of DPH in the interlayer of a Ca-smectite was characterized by X-ray diffraction, infra-red, and thermogravimetric analyses supported by molecular dynamic simulation. At the low (0.2–0.3 CEC) and high (0.6–0.7 CEC) adsorption levels, the intercalated DPH might take a horizontal monolayer or a bilayer configuration, resulting in a d001 expansion to 15 or 17Å, respectively. As the amount of DPH intercalation increased, a gradual, yet systematic, dehydration due to removal of hydrated inorganic cation Ca2+ from the interlayer was observed. In addition, the intercalated DPH had a slightly higher thermal stability due to the shield effect of the host mineral smectite against heat. The uptake of DPH by the smectite was attributed to both electrostatic interactions between the negatively charged mineral surfaces and the positively charged tertiary amine and cation exchange interactions between DPH+ and hydrated Ca2+. Thus, smectite minerals could serve as a sink to remove dissolved DPH from water on the one hand, and as a carrier to transport intercalated DPH in the environment on the other hand.

Growth, optical and thermal studies on N-benzyl-2-methyl-4-nitroaniline

In this work we present the growth, optical and thermal studies of the nonlinear organic molecular crystal, N-benzyl-2-methyl-4-nitroaniline (BNA). BNA is also a good THz electromagnetic waves emitter in 0.1 – 15 THz range. Nonlinear optical property of the crystal has been confirmed using the Kurtz powder technique and a study of its second harmonic generation efficiency in comparison with KDP has been made. Knoop hardness test was carried out and its Young's modulus was calculated. Thermal behaviour of the crystal was investigated by TG-DTG analyses.

Effects of Silane Coupling Agent/Organic Bentonite on Tea Saponin Intumescent Flame-Retardant Coatings

In this paper, silane coupling agent and organic modified bentonite were used in tea saponin intumescent flame-retardant coatings to improve the flowability, storage stability and film properties. The effects of silane coupling agent and organic modified bentonite on the flowability, storage stability and film properties were discussed, and flame resistance and pyrolysis performance of the flame-retardant coatings also were investigated. The results show that silane coupling agent can greatly improve the rheological properties, storage stability and film properties of the flame-retardant coating at the amount of 1.5%. Flame-retardant coatings have good dispersion properties and thixotropy, When bentonite modified with cetyltrimethylammonium chloride (CTAC-Bentonite) was introduced to the coatings. Fire resistance test and TG-DTG analysis showed that silane coupling agent/organic bentonite can promote the charring of the coatings and increase the amount of char, which protecting the internal substrates, reducing the thermal degradation rate. What's more, the flame retardancy of the materials was improved significantly owing to the increasing of the amount of residual carbon and the enhancing of thermal stability at a high temperature.

Pyrolysis of apricot kernel shell in a fixed-bed reactor: Characterization of bio-oil and char

The pyrolysis of apricot kernel shell was studied for determining the main characteristics and quantities of liquid and solid products. Experiments were carried out in a static atmosphere with heating rates of 10°C/min and 50°C/min, pyrolysis temperatures of 400, 450, 500 and 550°C and sweep gas flow rates of 50–200cm3/min. The maximum bio-oil and char yields were 26.3 (500°C) and 35.2% (400°C), respectively. The TG-DTG analyses were applied on the raw material to investigate the thermal degradation of apricot kernel shell. The elemental analysis and heating value of the bio-oils were determined, and then the chemical composition of the bio-oil was investigated using chromatographic and spectroscopic techniques such as column chromatography, 1H NMR, and FTIR. In addition, the char was characterized by elemental, BET and scanning electron microscopy (SEM) analyses. According to the experimental results the liquid products can be used as liquid fuels and the solid product seems to be suitable for adsorption purposes due to its high surface area.

Characterization and environmental application of iron-modified zeolite from the Zlatokop deposit

In this paper, characterization of iron-modified zeolite (IMZ) from the Zlatokop deposit and its potential environmental application has been described. The modification procedure includes treatment of natural zeolite (NZ) with Fe(NO3)3 in an acetate buffer at pH = 3.6 followed by treatment with NaOH and NaNO3. The properties of NZs and IMZs have been determined by analysis of their chemical composition, specific surface area and by X-ray powder diffraction method (XRPD), scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDS), TG-DTG and FTIR analyses. The chemical behaviour of modified zeolite has been examined in the zeolite-ultrapure water system at adjusted initial pH values in the range of 1.71–5.08, and also by determining the zero-point charge. The NZ and IMZ samples have been tested relative to the uptake of zinc ions. The results have shown that the capacity of IMZ samples for zinc ions is three-to-four times higher compared to the NZs. The balance of exchangeable ions before and after zinc uptake confirms an almost complete stoichiometric relation for both zeolite samples indicating ion exchange as the main process. However, in IMZ samples ion exchange takes place inside the zeolite particle and on activated zeolite particle surface.

Bis-pyridinium dibromides modified organo-bentonite for the removal of aniline from wastewater: A positive role of π–π polar interaction

Aniline removal is of great importance for water treatment, and adsorption is an efficient treatment method. Hexamethylene bis-pyridinium dibromide modified bentonite (HEMBP-B) was firstly prepared and characterized by XRD, FT-IR, BET, SEM, TEM and TG–DTG analysis. Adsorptive experiments of aniline on the organo-bentonite were carried out using batch method as a function of the length of linking carbon chain (n), concentration of HEMBP (C), contact time (t), temperature (T) and pH. The optimal conditions for aniline removal on HEMBP-B were as follows: n of 5 or 6, C of 1.0CEC, t of 120min, T of 298K, and natural pH of 6.6. The π–π polar interaction existed between the aromatic rings of aniline and HEMBP has successfully explained the main adsorption mechanism. The equilibrium data of aniline removal on HEMBP-B followed Freundlich and D-R isothermal models precisely, which indicated a less favorable and physical process of aniline adsorption. The kinetic data could be best described by the pseudo-second-order model. Besides, the thermodynamic study revealed that aniline adsorption on HEMBP-B was non-spontaneous, exothermic and physical.

Kinetic study and thermal analysis of the pyrolysis of non-edible oilseed powders by thermogravimetric and differential scanning calorimetric analysis

This work reports the kinetic study of the pyrolysis of four non-edible oil seeds such as Mahua, Karanja, Niger and Linseed conducted at a heating rate of 5, 10 and 15 °C min−1 under nitrogen atmosphere. The relation between kinetic parameters and degradation rate was observed with respect to temperature and heating rate. The results indicated that the kinetic parameters were very close to each other and directly proportional to temperature and heating rate. The comparison of kinetic parameters related to heating rate concluded that heating rate had a direct affinity towards activation energy and pre-exponential factor. The TG-DTG analysis indicated three stages of thermal degradation during pyrolysis of the oil seeds whereas DSC analysis point towards the endothermic and exothermic pathway of pyrolysis. The presence of hemicelluloses, cellulose and lignin was determined on the basis of degradation temperature and their respective functional groups in the seeds observed by FTIR analysis.

High permittivity ofBa(Ti1-xZrx)O3-basedY5V-type nanopowders and ceramics synthesized using a one-step sol–gel method

We synthesized Ba ( Ti1-xZrx) O3-based (BTZ) nanopowders modified with Cu and Nb , and sintered ceramics using a one-step sol–gel process. Characterization using TG-DTG, XRD, SEM, and TEM analysis methods revealed that the powders formed at a nanometer scale. The process was controlled by the composition and calcining temperature. BaZrO3formed earlier than BaTiO3during the calcining, then a Ba ( Ti1-xZrx) O3solid solution formed incompletely, resulting in ceramics with huge permittivity and good temperature stability. Moreover, the maximum dielectric constant (εmax) first increased and then decreased as the Curie temperature (Tc) shifted to a lower temperature. When the Zr concentration was 5.4 mol%, εmaxwas greater than 24,000 and the dielectric loss (25°C) was only 0.005; this meets the Electronic Industries Alliance Y 5 V specifications. These nanopowders would permit a significant reduction in the thickness of multilayer ceramic capacitors and the huge permittivity of the ceramics will help meet the current demand for device miniaturization in the electronics industry.

Growth, spectral, thermal and dielectric studies on a new semiorganic NLO material: Di-N-methylanilinium tetrachlorocadmiate(II)

A new semiorganic nonlinear optical material, di-N-methylanilinium tetrachlorocadmiate(II) was grown by slow evaporation solution method at ambient temperature. The absorption of the compound was studied by UV–vis absorption spectral analysis. The suitability of the optical property was ascertained through optical transmittance study. The sharp and well defined Bragg peaks in the powder X-ray diffraction pattern confirm its crystallinity. Thermal stability and decomposition pattern of the compound were studied by using TG-DTG and DTA analyses. The different kinds of protons and carbons were assigned through nuclear magnetic resonance (NMR (13C and 1H)) spectroscopic techniques. The Fourier infrared spectrum (FTIR) characterizes the vibration frequencies due to NC, CCl, CdCl42− and other chemical bond vibrations. The second harmonic generation (SHG) efficiency of the compound was measured by suing Kurtz–Perry powder techniques and it shows that the compound has SHG efficiency one and a half times greater than of potassium dihydrogen phosphate (KDP). The dielectric constant and dielectric loss of the compound decrease with increases in frequencies.

Thermal stability and hot-stage Raman spectroscopic study of Ca-montmorillonite modified with different surfactants: A comparative study

Three long chain cationic surfactants were intercalated into Ca-montmorillonite through ion exchange and the obtained organoclays were characterized by X-ray diffraction (XRD), high resolution thermogravimetric analysis (TG) and Raman spectroscopy. The intercalation of surfactants not only changes the surface properties of clay from hydrophilic to hydrophobic but also greatly increases the basal spacing of the interlayers based on XRD analysis. The thermal stability of organoclays intercalated with three surfactants (TTAB, DTAB and CTAB) and the different arrangements of the surfactant molecules intercalated into Ca-montmorillonite were determined by TG-DTG analysis. A Raman spectroscopic study on the Ca-montmorillonite modified by three surfactants prepared at different concentrations provided the detailed conformational ordering of different intercalated long-chain surfactants under different conditions. The wavenumber of the antisymmetric stretching mode is more sensitive than that of the symmetric stretching mode to the mobility of the tail of the amine chain. At room temperature, the conformational ordering is more easily affected by the packing density in the lateral model. With the increase of the temperature, the positions of both the antisymmetric and symmetric stretching bands shift to higher wavenumbers, which indicates a decrease of conformational ordering. This study offers new insights into the structure and properties of Ca-montmorillonite modified with different long chain surfactants. Moreover, the experimental results confirm the potential applications of organic Ca-montmorillonites for the removal of organic impurities from aqueous media.

Hydrogen production via CO2-reforming of methane over Cu and Co doped Ni/Al2O3 nanocatalyst: impregnation versus sol–gel method and effect of process conditions and promoter

In this study, Cu and Co doped Ni/Al2O3 nanocatalyst was synthesized via impregnation and sol–gel methods. The physiochemical properties of nanocatalyst were characterized by XRD, field emission scanning electron microscopy (FESEM), particle size distribution, BET, fourier transform infrared spectroscopy (FTIR), TG–DTA and energy dispersive X-ray (EDX) analysis. The samples were employed for CO2-reforming of methane in atmospheric pressure, temperature range from 550 to 850 °C, under various mixture of CH4/CO2 and different gas hourly space velocity. XRD patterns besides indicating the decline of the peaks intensity in sol–gel method, proved the potential of this procedure in diminishing the crystal size and preventing the NiAl2O4 spinel formation. Moreover, high surface area might derive of smaller particle size and uniform morphology of sol–gel prepared ones, confirmed by FESEM and BET analysis. TG–DTG analysis as well supported the higher surface area for sol–gel made ones, represented the proper calcination temperature (approximately 600 °C). Also, presence of the active phases and elemental composition of nanocatalysts determine via EDX analysis. Promoting the basicity and the adsorption rate of CO2, is attributed to the higher amount of OH groups for sol–gel prepared samples, proved by FTIR. Ni–Co/Al2O3 due to the synergetic effect of sol–gel method and cobalt addition depicted excellent characterization such as higher surface area, smaller particle size, supplying more stable support and enhanced morphology. Therefore, this nanocatalyst represented the best products yield (H2 = 98.21 and CO = 95.64), H2/CO close to unit (0.92–1.05) and stable conversion during 1,440 min stability test. So, Ni–Co/Al2O3 among all of the prepared nanocatalysts demonstrated the best catalytic performance and presented it as a highly efficient catalyst for dry reforming of methane. Despite of the stable yield of Ni–Cu/Al2O3, it depicted the lower catalytic activity and H2/CO ratio than the unprompted nanocatalysts.

English

The methods of bio-control have diversified resulting in study of new fighting measures.  Studies on Euphorbia cyparissias active compounds as well as their in vivo and in vitroactivity revealed a significant pharmacologic activity, encouraging design of a complex original conditioning. Encapsulation techniques can be of considerable help in this endeavour, being a means to protect sensitive active components (such plant’s active compounds) from the environment and from other excipients used. The aim of the present study was to evaluate E. cyparissias extracts inclusion in β-cyclodextrine complexes and thermo gravimetric (TG-DTG) analysing of Euphorbia’s extracts complexes, as a GMP pharmaceutic step, in the study of thermal behaviour of a future finite conditioning destined to demodectic mange treatment, a zoonotic ectoparasitic disease. TG-DTG analysis of pure β-cyclodextrine revealed a mass loss of 11.7%, which actually represent the β-cyclodextrin decomposition. In crude Euphorbia extract complexes T5 / β-CD case, the mass loss was corresponding probably to the encapsulated bioactive decomplexing phase of Euphorbia extracts’ compounds. A similar behaviour to heating was recorded in case of crude Euphorbia extract T10 / β-CD complexes. In case of Euphorbia concentrated extracts T5 / T10 - β-CD complexes, the loss can be translated as a degradation / loss of complexes’ bioactive compounds.   Key words: Euphorbia cyparissias, β-cyclodextrine, complexes, TG-DTG analysis.

Thermal stability of several polyaniline/rare earth oxide composites

Polyaniline/rare earth oxide composites (PANI/La2O3 and PANI/Sm2O3) were synthesized by in situ polymerization at the presence of sulfosalicylic acid (as dopant). The composites obtained were characterized by Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thermal stability of the composites was investigated by thermogravimetry (TG) and derivative thermogravimetry (DTG). The electrochemical performance of the composites was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results of FTIR, XRD, SEM, CV, and EIS show that the structure of composite has changed greatly when rare earth oxide content is >0.7 g (PANI/La2O3[w/w(92.7/7.3)] and PANI/Sm2O3[w/w(96.2/3.8)]) and the PANI in the composite has transformed into pernigraniline base (non-conducting state) from emeraldine base (conducting state). TG-DTG analysis indicates that the thermal stability of composite was higher than pure PANI, which is attributed to the interaction between PANI and rare earth oxide.

Poly(Lactic Acid)-co-Aspartic Acid Copolymers: Possible Utilization in Drug Delivery Systems

The synthesis and characterization of poly(lactic acid)-co-aspartic acid copolymers (PLA-co-Asp) were presented. Subsequently, the synthesized PLA-co-Asp copolymers were tested as biodegradable carriers in drug delivery systems. PLA-co-Asp copolymers were synthesized by solution polycondensation procedure, using different molar ratios PLA/l-aspartic acid (2.33/1, 1/1, 1/2.33), manganese acetate and phosphoric acid as catalysts and N,N′-dimethyl formamide (DMF)/toluene as solvent mixture. The copolymers were characterized by FT-IR and 1H-NMR spectroscopy, gel permeation chromatography (GPC), DSC and TG-DTG analyses. Diclofenac sodium, a non steroidal anti-inflammatory drug was subsequently loaded into PLA-co-Asp copolymers. The in vitro drug release experiments were done by dialysis of the copolymer/drug systems, in phosphate buffer solution (pH = 7.4, at 37 °C) and monitored by UV spectroscopy.

Effective removal of Ni(II) from aqueous solutions by modification of nano particles of clinoptilolite with dimethylglyoxime

In this work an Iranian natural clinoptilolite tuff was pre-treated and changed to the micro (MCP) and nano (NCP) particles by mechanical method. Modification of micro and nano particles and also their Ni-exchanged forms were done by dimethylglyoxime (DMG). The raw and modified samples were characterized by XRD, FT-IR, SEM, BET, TG-DTG and energy dispersive analysis X-ray spectroscopy (EDAX). Removal of Ni(II) by modified and unmodified samples was investigated in batch procedure. It was found that NCP-DMG has higher capacity for removal of Ni(II). The effects of analytical parameters such as pH, dose of DMG, concentration of nickel solution, contact time and selectivity were studied and the optimal operation parameters were found as follows: pHPZC: 7.6, CNi(II): 0.01M, contact time: 360min and DMG dosage: 5mM. The results of selectivity experiments showed that the modified zeolite has a good selectivity for nickel in the presence of different multivalent cations. Langmuir and Freundlich isotherm models were adopted to describe the adsorption isotherms. Adsorption isotherms of Ni(II) ions could be best modelled by Langmuir equation, that indicate the monolayer sorption of Ni(II). Comparison of two kinetic models indicates that the adsorption kinetic can be well described by the pseudo-second-order rate equation that indicates that the rate limiting step for the process involves chemical reaction. The negative ΔH and ΔG indicate an exothermic and spontaneously process. The negative ΔS indicates that the adsorption of nickel cations from solution occurs with lower amount ion replacement, thus chemisorptions due to complex formation are dominant process in nickel removal.

Spectral and Thermal Degradation of Melamine Cyanurate

Melamine cyanurate, an organic crystalline complex was, synthesized by evaporation of an aqueous solution containing equimolar quantities of melamine and cyanuric acid. The synthesized compound has been subjected to various characterizations like Powder XRD, FT-IR, TG-DTG, SEM, and SHG. The presence of sharp diffraction peaks in the XRD confirms that the products are highly crystalline. The average particle size was calculated using the Debye-Scherrer formula, and it was found to be 3.067 μm. Thermal behavior of the grown crystal has been studied by TG-DTG analysis. From TG-DTG, it is found that the title crystal possesses good thermal stability. The activation energy was calculated using the Broido, Coats-Redfern, and Horowitz-Metzger methods. A sharp peak exothermic peak at 405.40°C was assigned as the melting point of the title material. SEM reveals the morphology of the synthesized salt. No detectable signal was observed during the Kurtz-Perry technique.