Evolved Gas Analysis Research Articles

On-Line Thermally Induced Evolved Gas Analysis: An Update-Part 2: EGA-FTIR.

The on-line thermally induced evolved gas analysis (OLTI-EGA) is widely applied in many different fields. Aimed to update the applications, our group has systematically collected and published examples of EGA characterizations. Following the recently published review on EGA-MS applications, this second part reviews the latest applications of Evolved Gas Analysis performed by on-line coupling heating devices to infrared spectrometers (EGA-FTIR). The selected 2019, 2020, 2021 and early 2022 references are collected and briefly described in this review; these are useful to help researchers to easily find applications that are sometimes difficult to locate.

Elemental composition of manganese- and phosphorus-rich nodules in the Knockfarril Hill member, Gale crater, Mars

The Mars Science Laboratory rover Curiosity encountered nodules rich in manganese and phosphorus while exploring the Knockfarril Hill member of Gale crater on Mars. Deconvolution of X-ray spectroscopy data acquired by the Alpha Particle X-ray Spectrometer (APXS) at the spectral level indicate P2O5 concentrations possibly in excess of 18 wt% and MnO exceeding 8 wt%. The nodules occur intermittently in ∼mm-thick layers concordant with the sedimentary laminae, extending up to ∼10 cm laterally. Calcium sulfate associated with the nodules is interpreted as having precipitated from fluid that infiltrated between the nodule-bearing bedding planes in a separate and subsequent fluid event. Though the Mn- and P-bearing phase(s) was(were) not definitively identified by X-ray diffraction, evolved gas analyses show that the oxidation state of Mn is most likely 2+.

Pyrolysis gas chromatography mass spectrometry: A promising tool for disclosing metal-free tanning agents used in leather industry

Leather represents the principal industrial product derived from the skin of animals. Leather manufacturing has evolved from artisanal practice, making use of vegetable tannins, to industrial production, today mostly based on chromium salts. Chromium tanning accounts for the most efficient and affordable process available on the market, but the environmental pressure caused by heavy metal pollution has pushed towards the development of Metal-Free leather tanning agents. This paper aims at highlighting the potentialities and limits of analytical pyrolysis to characterise metal-free leather samples and to identify the tanning agents. To this aim, thirty-three bovine split leather samples tanned with various metal-free tanning agents (constituted by single or combined formulations of GRANOFIN® F90, glutaraldehyde, tetrakis(hydroxymethyl)phosphonium sulphate, oxazolidine and three different synthetic tannins), provided by bovine split suppliers (Tuscany, Italy) were analysed by flash Pyrolysis coupled with Gas Chromatography - Mass Spectrometry (Py-GC-MS). For most of the tanning formulations, Py-GC-MS was able to determine pyrolytic markers in reference materials, intermediates (wet-white metal-free and metal-free crust) and end-products (metal-free final products). Evolved Gas Analysis coupled with Mass Spectrometry (EGA-MS) was used to evaluate, from the molecular point of view, the thermodegradative profiles of metal-free leathers and compare them with that of chromium tanned leather.

Study of the thermal behavior, evolved gas analysis and temperature diffraction patterns of new light lanthanide complexes with niflumic acid

Seven new complexes of niflumic acid with light lanthanide ions (La-Gd except Pm) were obtained in solid state. With the application of chemical, elemental and thermal analysis, the minimal formulas of the complexes were established, which were different despite the fact that the syntheses of the complexes were carried out under the same conditions. The complex with La(III) ions is mononuclear and its stoichiometry is represented by the formula La(nif)3∙2.5 H2O. The remaining complexes are binuclear and their stoichiometry is expressed by the formula Ln2(nif)4(OH)2∙nH2O (where: Ln is Ce or Pr, n is equal to 4 or 5, respectively) or Ln2(nif)3(OH)3∙4 H2O (where: Ln = Nd, Sm, Eu or Gd). On the basis of the FTIR spectra, it was stated that the carboxylate groups of the ligand can coordinate metal ions in a bidentate chelating or tridentate chelating-bridging mode. XRPD analysis of the obtained compounds showed that they are amorphous. Based on the TG/DTG–DSC analysis, it was shown that the thermal decomposition of the complexes is a multistage process, depending on the metal ion and the used atmosphere. It was found that the stability of the dehydrated compounds in air atmosphere increases in the order: La < Pr < Nd < Sm < Gd = Eu < Ce, while in nitrogen atmosphere, the stability of these complexes is as follows: La < Nd < Ce = Pr < Eu < Sm < Gd. Using coupled TG-FTIR-MS techniques, the decomposition pathways of the synthesized compounds were examined and the gaseous products released during thermal oxidation and pyrolysis of the complexes were identified. The EGA analysis showed that the gaseous products contained mainly H2O, CO2, COF2, fragments from the partial decomposition of the organic ligands (both in air and nitrogen atmosphere), NO (in air) and CO (in N2). Moreover, based on the temperature diffraction patterns, it was found that the thermal degradation of most of the studied complexes, both in air and nitrogen atmosphere, did not end at 1000 °C. It has been experimentally proven that during thermal decomposition of niflumic acid complex with Nd(III) ions in an oxidizing atmosphere at approximately 440 °C NdF3 is formed as one of a solid intermediate product. At the temperature of 570 °C, the tetragonal form of this compound appears additionally in the solid residue. At 800 °C, the solid residue is a mixture of Nd2O3 and NdOF, while the final product obtained at 1000 °C is Nd2O3 and NdOF. Under pyrolysis conditions, only at a temperature of 800 °C it was possible to identify solid intermediate products and in the case of the niflumic acid complex with Nd(III) ions complex it was a mixture of NdOF and NdF3. NOF has been identified as one of the solid products of thermal degradation.

Sedimentary Organics in Glen Torridon, Gale Crater, Mars: Results From the SAM Instrument Suite and Supporting Laboratory Analyses

AbstractThe Sample Analysis at Mars (SAM) suite instrument on board NASA's Curiosity rover has characterized the inorganic and organic chemical composition of seven samples from the Glen Torridon (GT) clay‐bearing unit. A variety of organic molecules were detected with SAM using pyrolysis (up to ∼850°C) and wet chemistry experiments coupled with evolved gas analysis (EGA) and gas chromatography‐mass spectrometry. SAM EGA and GCMS analyses revealed a greater diversity and abundance of sulfur‐bearing aliphatic and aromatic organic compounds in the sediments of this Gale crater unit than earlier in the mission. We also report the detection of nitrogen‐containing, oxygen‐containing, and chlorine‐containing molecules, as well as polycyclic aromatic hydrocarbons found in GT, although the sources of some of these organics may be related to the presence of chemical reagents in the SAM instrument background. However, sulfur‐bearing organics released at high temperature (≥600°C) are likely derived from Martian sources (e.g., igneous, hydrothermal, atmospheric, or biological) or exogenous sources and consistent with the presence of recalcitrant organic materials in the sample. The SAM measurements of the GT clay‐bearing unit expand the inventory of organic matter present in Gale crater and is also consistent with the hypothesis that clay minerals played an important role in the preservation of ancient refractory organic matter on Mars. These findings deepen our understanding of the past habitability and biological potential of Gale crater.

Revealing Lithium Battery Gas Generation for Safer Practical Applications

AbstractGases generated from lithium batteries are detrimental to their electrochemical performances, especially under the unguarded runaway conditions, which tend to contribute the sudden gases accumulation (including flammable gases), resulting in safety issues such as explosion and combustion. The comprehensive understanding of battery gas evolution mechanism under different conditions is extremely important, which is conducive to realizing a visual cognition about the complex reaction processes between electrodes and electrolytes, and providing effective strategies to optimize battery performances. This review aims to summarize the recent progress about battery gas evolution mechanism and highlight the gas suppression strategies to improve battery safety. New approaches toward future gas evolution analysis and suppression are also proposed. It is anticipated that this review will inspire further developments of lithium batteries on performance, gas suppression, and safety, especially in high energy density systems.

Highly stable MWCNT-CoFe2O4 photocatalyst. EGA-FTIR coupling as efficient tool to illustrate the formation mechanism

MWCNT-CoFe2O4 nanocomposites were prepared in sequential synthesis steps by decorating CoFe2O4 nanoparticles on the surface of functionalized MWCNT. Initially, the CoFe2O4 nanoparticles were obtained by chemical precipitation and subsequently, the obtained CoFe2O4 nanoparticles were anchored on functionalized MWCNT through polymer wrapping. The thermal analysis approaches namely, evolved gas analysis (EGA) coupled with FT-IR spectra were involved in highlighting the sequential steps mechanism for obtaining MWCNT-CoFe2O4 nanocomposites. The composite formation was proved by X-ray Diffraction (XRD), Scanning Transmission Electron Microscopy (STEM), FT-IR spectroscopy, X-ray Photoelectron Spectroscopy (XPS). The influence of CoFe2O4 content on the magnetic and textural properties (surface area and porosity measurements) of the obtained nanocomposites was evidenced. Depicting the importance of thermal stability of nanomaterials in different industrial applications, the thermal behavior of MWCNT and CoFe2O4 was pointed out. Furthermore, the photocatalytic activity against organic pollutants such as Rhodamine B (RhB) and oxytetracicline (OTC) were evidenced. Additionally, it was evidenced that the MWCNTs acquired ferromagnetic behavior through spin polarized electron transfer from the CoFe2O4. The electron spin resonance spectroscopy (ESR) coupled with spin trapping technique was used to evidence the generation of reactive oxygen species (ROS). The obtained results suggest the efficient anchoring of CoFe2O4 on MWCNT through polymer linkage resulting in a thermal stable magnetic recoverable photocatalyst. The photocatalytic mechanism was discussed in terms spin polarized transitions and ROS generation. During the irradiation superoxide anion (O2-), hydroxyl (•OH) radical and nitroxide were detected.

Brewer's spent grain pyrolysis kinetics and evolved gas analysis for the sustainable phenolic compounds and fatty acids recovery potential

Within the presented paper, a thermochemical conversion via pyrolysis of spent grain from the local brewery (Alternatywa, Ruda Śląska, Poland) for phenolic compounds and fatty acids recovery is presented. Thermogravimetric pyrolysis was carried out at non-isothermal conditions (1, 2, and 4 K/min), under an inert N2 atmosphere. Deconvolution procedure for the kinetic modeling was implemented using own algorithm based on Gaussian function, using 3-stage kinetic mechanism, ascribed to the independent decomposition of the pseudo-components i.e., hemicellulose, cellulose, and bulk lignin-extractives. Released volatiles during pyrolysis was evaluated and recognized using gas chromatography-mass spectrometry and Fourier-transform infrared spectroscopy analysis, which confirmed the high content of fatty acids, phenolic compounds, and nitrogen compounds, with shares of 23.95%, 13.94%, and 25.10% respectively. Linkage of the desired product formations to the modeled kinetic stages of the BSG pyrolysis is a complex subject, and it is encouraged for future studies.

Influence of growth rates, microstructural properties and biochemical composition on the thermal stability of mycelia fungi

Mycelium fungal species exhibit fire retardant characteristics. The influence of the growth media on the fungal growth rates, biochemical composition, and microstructural characteristics and their relationship to thermal properties is poorly understood. In this paper, we demonstrate that molasses can support the growth of non-pathogenic Basidiomycota phylum fungal species producing bio-derived materials with potential fire retardation characteristics. Scanning electron microscopy and Fourier transform infrared (FTIR) spectrometry were used to interrogate the microstructural and biochemical properties of the molasses-grown mycelia species. Thermal decomposition of molasses-fed mycelia was evaluated via thermogravimetric analysis interfaced with FTIR for real-time evolved gas analysis. The morphological and microstructural characteristics of the residual char post-thermal exposure were also evaluated. The material characterization enabled the establishment of a relationship between the microstructural, biochemical properties, and thermal properties of molasses-fed mycelia. This paper presents a comprehensive exploration of the mechanisms governing the thermal degradation of three mycelial species grown in molasses. These research findings advance the knowledge of critical parameters controlling fungal growth rates and yields as well as how the microstructural and biochemical properties influence the thermal response of mycelia.

Detection of Organic Carbon in Mars‐Analog Paleosols With Thermal and Evolved Gas Analysis

AbstractAncient, buried soils, or paleosols, may have been preserved in the geological record on Mars, and are considered high‐priority targets for biosignature investigation. Studies of paleosols on Earth that are similar in composition to putative martian paleosols can provide a reference frame for constraining their organic preservation potential on Mars. However, terrestrial paleosols typically preserve only trace amounts of organic carbon, and determining what carbon is original is complicated by diagenesis and additions of modern carbon. The objectives of this study were (a) to determine whether organic carbon in Mars‐analog paleosols can be detected with thermal and evolved gas analysis, and (b) constrain the age of organic carbon using radiocarbon (14C) dating. Oligocene (33 Ma) paleosols from Oregon were examined with an instrument similar to the Sample Analysis at Mars Evolved Gas Analysis instrument onboard the Mars Science Laboratory Curiosity rover. Trace amounts of organic carbon and fragments of organic molecules were observed in all samples. Total organic carbon (TOC) ranged from 0.002 to 0.032 ± 0.006 wt. %. The near‐surface horizons of paleosols had significantly higher TOC relative to subsurface layers. Radiocarbon dating of four samples revealed an organic carbon age of ∼6,200–14,500 years before present and a fraction modern ranging from 0.16 to 0.46. Modeled abundances of modern carbon in bulk samples ranged from 0.41%–3.1% ± 0.11%, which were consistent with additions of small amounts of modern organic carbon. This work demonstrates that martian paleosols are a potential high priority location for in‐situ biosignature investigation.

반응성 필러로써 Aluminum Fumarate을 이용한 Dicyanate Composites의 물성 강화: 열역학적 특성 연구

In this work, the synthesized nanoporous aluminum fumarate (Al_FA_A) metal organic framework (MOF) has been used as reactive filler for the bisphenol-A dicyanate (BADCy) resin system. The use of Al_FA_A is interesting due to the involvement of double bonds (fumarate) in triazine during polymerization. The thermal properties of the polymers formed with and without reactive filler were evaluated under different curing temperatures, prepolymerizations and post-polymerizations conditions. All the samples were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD) and Evolved gas analysis. On the contrary, the cure chemistry was determined by non-isothermal model free kinetic methods. This study provides a new path to utilize the MOFs as reactive nanoparticle fillers to obtain multifunctional materials.

Characterization and modeling of chemical reactions taking place during the vitrification of high level nuclear waste

Several chemical reactions take place during the vitrification of high-level nuclear waste. The integration of these chemical aspects in process numerical simulation tools is one of the key points in the approach of improving the prediction capabilities of numerical tools today. In this study, based on simultaneous differential scanning calorimetry-thermogravimetry (DSC-TGA) and the run/rerun method, we propose a modeling of the kinetics of chemical reactions taking place when nuclear glass precursors are subjected to constant heating. For the mathematical modeling, a weighted sum of nth order reactions was used to describe the overall mechanism. A hybrid approach coupling the Kissinger and least squares methods was performed to identify the apparent kinetic parameters. Along with the thermal characterization, we also provide some information about the nature of the main reactions through microstructural evolution and evolved gas analyses.

"INVESTIGATION OF OLIVE STONES PYROLYSIS VIA COUPLED THERMOGRAVIMETRIC ANALYSIS-MASS SPECTROMETRY: THERMAL BEHAVIOR AND KINETIC PARAMETERS"

"The pyrolysis of olive stones was investigated by thermogravimetric analysis-mass spectrometry in nitrogen atmosphere under non-isothermal conditions, at heating rates of 5, 10, 20, and 30 °C/min. According to gas evolution analysis, the thermal degradation of olive stones under inert atmosphere can be divided into four stages. There was only dehydration in the first stage (&lt;200 °C). Most of gas products (CO2, CO, CH4, C2H6 and H2O) were evolved in the second stage in the temperature range 210-407 °C, simultaneously with main mass degradation. Only H2 was produced in the fourth stage at high temperatures (&gt;550 °C). Thermogravimetric analysis results have been utilized to determine kinetic parameters by using a composite procedure involving the iso-conversional method (Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose) and the master-plots method. The activation energy values estimated by the Ozawa-Flynn- Wall and the Kissinger-Akahira-Sunose methods are very close, with values of 229.20 kJ/mol and 232.55 kJ/mol, respectively. The master-plots method shows that the most probable reaction mechanism was described by an order n (On) model. The frequency factor was estimated to be A = 5.6x1021 min-1, the kinetic exponent was n = 6.2, and the reaction model function was f( ) = (1- )6.2."

Partially disordered pyrochlore: time-temperature dependence of recrystallization and dehydration

Abstract The comparison of the evolution of the mechanical properties (elastic modulus and hardness) after step-wise thermal annealing for 1 and 16 h up to 900 K of a radiation-damaged pyrochlore (∼35% amorphous fraction; 1.8 wt% ThO2) provides insights to the time-temperature dependence of the recrystallization behavior. Especially the elastic modulus, directly related to interatomic bonding, enables the correlation with the amount of amorphous fraction. From this a pronounced effect of the annealing time on percolation behavior could be deduced. Evolved gas analysis indicate dehydration in the course of the structural reorganization process.

On-Line Thermally Induced Evolved Gas Analysis: An Update-Part 1: EGA-MS.

Advances in on-line thermally induced evolved gas analysis (OLTI-EGA) have been systematically reported by our group to update their applications in several different fields and to provide useful starting references. The importance of an accurate interpretation of the thermally-induced reaction mechanism which involves the formation of gaseous species is necessary to obtain the characterization of the evolved products. In this review, applications of Evolved Gas Analysis (EGA) performed by on-line coupling heating devices to mass spectrometry (EGA-MS), are reported. Reported references clearly demonstrate that the characterization of the nature of volatile products released by a substance subjected to a controlled temperature program allows us to prove a supposed reaction or composition, either under isothermal or under heating conditions. Selected 2019, 2020, and 2021 references are collected and briefly described in this review.

Characterization of textile fibers by means of EGA-MS and Py-GC/MS

Textile fibers have represented an important resource for mankind throughout all human history. In fact, ancient cultures employed them not just to produce clothes, but also for expressing their habits and traditions. Based on the chemical composition, textile fibers are classified as natural, artificial, and synthetic. The analysis of textile fibers can be very challenging, so it is crucial to find new analytical tools capable of identifying them and studying their behavior in the environment. The collected information can be transferred in many different fields, such as the industrial sector, forensic science, environmental science, and heritage science. In the present study, the capability of Pyrolysis coupled to Gas Chromatography and Mass Spectrometry (Py-GC/MS), and Evolved Gas Analysis coupled to Mass Spectrometry (EGA-MS) to discriminate textile fibers was tested. The first part of the study was addressed to the analysis of pure samples to build a detailed database by highlighting the main differences in the chromatographic profiles. Then, three textile blends of known composition were investigated, and the results compared with those acquired by Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR). Eventually, the information obtained from the reference materials was exploited for the study of textile samples collected from the stage costumes of the lyrical opera ‘I Puritani’ directed by Franco Zeffirelli in 1961. The EGA-MS and Py-GC/MS results, integrated with those obtained by optical microscopy, allowed us to deepen the characterization of the historical samples.

Product specific thermal degradation kinetics of bisphenol F epoxy in inert and oxidative atmospheres using evolved gas analysis–mass spectrometry

Knowledge of the degradation kinetics for polymer materials is important for understanding thermal stability. Here, evolved gas analysis–mass spectrometry and pyrolysis gas-chromatography-mass spectrometry were evaluated for the potential to deliver additional insight into thermal degradation kinetics of diglycidal ether of bisphenol F (DGEBF) epoxy thermoset under inert and oxidative atmospheres. Degradation products of selected precursor ions were evaluated for their uniqueness to the specific precursor using extracted ion thermographs. Unique mass peaks, solely attributed to a single reaction pathway of a specific product, were determined from extracted ion thermographs and used to determine both activation energy (Ea) and pre-exponential factors for the specific primary reaction pathways. These primary reaction pathways for DGEBF epoxy degradation were then evaluated in the context of transition state theory (TST) and related transition state enthalpies (ΔH‡) and entropies (ΔS‡) of activation to further elucidate the degradation process. It was determined under pyrolysis conditions, as suggested by the Ea, the formation of bisphenol F monomer was the rate-limiting step toward the formation of xanthene and phenol. In contrast, under thermo-oxidative conditions, reactions involving oxygen containing species were identified as the rate-limiting step for all observed products based on the large negative ΔS‡ calculated from TST. This work demonstrates a powerful combination of technique and theory that can provide new insight into the degradation of polymer materials.

Thermal characteristics and combustion reactivity of coronavirus face masks using TG-DTG-MS analysis.

The presented paper deals with the influence of the heating rate on combustion characteristics (reactivity and reactivity evaluation, ignition index (Di), burnout index (Df), the combustion performance index (S), and the combustion stability index (RW)) of the protective coronavirus face masks. Two types of commonly used face masks in different state (new and exploited) were investigated by TG-DTG analysis in an air atmosphere, directly coupled with mass spectrometry (MS). Based on the experimental results, the impact of ultimate and proximate analysis data on the evolved gas analysis (EGA) was discussed. Also, the derived values from thermo-analytical (TA) data were compared with the literature reports, related to individual constitutive face mask materials. According to the performed research, it was established that different maximal reaction rate values at various heating rates indicate the complex nature of coronavirus face mask thermo-oxidative degradation, which is stimulated with carbon oxidation reactions and volatile matter (VM) release. By detailed analysis of obtained TG-DTG profiles, it was established that process takes place through the multiple-step reaction pathways, due to many vigorous radical reactions, causes by polymers degradation. The performed research was done to evaluate the possible utilization of coronavirus waste to energy production and sustainable pandemic environmental risk reduction.

Pyrolysis and thermal degradation studies of silane-carbosilane transformation using hyphenated thermal analysis

Pyrolysis process accompanying polydimethylsilane to polycarbosilane transformation and the decomposition behaviors of polydimethylsilane (PDMS), polycarbosilanes (PCS Mk-I/II and III) were investigated applying evolved gas analysis and pyrolysis–gas chromatography-mass spectrometry. Volatile fractions evolved during the reactions were recorded as specific pyrograms. The degradation of the polymer skeleton under argon leads to the evolution of methyl silane and higher linear oligomers in the molar mass range 42 ̶ 348 Da; the escape of hydrogen starts simultaneously. Based on the results, specific pyrolysis patterns and decomposition behavior of PDMS, PCS Mk-III were established. Mass spectral data revealed the structural and compositional identification of molecular moieties evolved during the pyrolysis reactions. Thermal data confirmed and complemented the pyrolysis data.

Giant Permittivity of Confined Water on Nanodiamonds

The Dielectric permittivity (ε) of hydrated detonation nanodiamonds (HDNDs) with variable water content (W) was measured at 1 kHz to 1 MHz frequencies, using a capacitor cell with bare or blocked electrodes. At low frequencies, HDNDs show a giant ε of 104 to 106, i.e., 105 to 107, for the confined water (CW) itself, probably due to microcapacitors formed at particle surfaces. At higher frequency, ε decreases but even at 1 MHz is up to 103 for hydrates and 104 for CW (cf. 78 for bulk water), probably due to disruption of hydrogen bonds. ε as a function of W peaks at W = 6 to 16% and declines on further hydration, while the conductivity continued to increase. CW density, measured by pycnometry, near the surface is ca. 1.5 g/cm3 for nanodiamonds with low hydrogen content but ca. 0.5 g/cm3 for other types, in each case converging to 1 g/cm3 in further layers. Evolved gas analysis of HDND reveals two types of adsorbed water with distinct peaks at 150–180 and 230–300 °C. In view of these and earlier results, the decreased ε of CW determined by atomic force microscopy must be taken with caution.