Thermal stability of ionic liquids (ILs) is of great significance for their applications in dissolving cellulose at elevated temperature. A novel ionic liquid, 1-allyl-3-methylimidazolium chloride ...(AmimCl), was found to be a powerful solvent for cellulose. However, the study about long-term isothermal stability, thermal decomposition mechanism and decomposition products of AmimCl are scarce. Herein, we studied the thermal stability and degradation mechanism of AmimCl using isothermal thermogravimetric analysis (TGA) experiments and density functional theory (DFT) calculations. The weight loss of AmimCl at 100
°C under air atmosphere within 15 days was only 1.9% and AmimCl after long-term heating also had dissolving capability of cellulose, indicating that AmimCl has high thermal stability and can be long-term used at the dissolving temperature of cellulose. Both TGA experiments and DFT calculations revealed AmimCl decomposed along two channels and the main pyrolysis products of the proposed mechanisms were detected using thermogravimetric technique coupled with mass spectrometry (TGA–MS).
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
This research explores the structural effect of phosphoramidates as flame retardants (FRs) for cotton cellulose. Flame retardant (FR) and thermal decomposition actions of phosphate such as triethyl ...phosphate (TEP), primary phosphoramidate such as diethyl phosphoramidate (DEPA) and secondary phosphoramidates such as phosphoramidic acid, N(2-hydroxy ethyl) diethylester (PAHEDE), diethyl ethyl phosphoramidate (DEEP) and diethyl 2-methoxyethylphosphoramidate (DEMEP) on cotton cellulose were investigated. Limiting oxygen index (LOI) of treated cotton cellulose showed that all phosphoramidates exhibited better flame retardant properties as compared to TEP. Secondary phosphoramidate PAHEDE had better flame retardant properties as compared to DEMEP and DEEP which indicate that flame retardancy of secondary phosphoramidates is structure related. Test performed on pyrolysis combustion flow calorimeter (PCFC) for treated cellulose showed higher reduction in heat of combustion for efficient FRs (PAHEDE, DEPA). Evolved gas analysis using thermogravimetric analyzer–Fourier transform infrared spectroscopy (TGA–FTIR) and thermogravimetric analyzer–mass spectrometer (TGA–MS) of treated cellulose showed that phosphoramidates could catalyze the dehydration and char formation of cellulose at a lower temperature. The enhanced flame retardant action of phosphoramidate may be due to the catalytic thermal decomposition of the phosphoramidate structure to produce acidic intermediates which could react with cellulose to alter its thermal decomposition.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•HF showed interesting results on EFB (empty fruit bunches) and PMF (palm mesocarp fibre) deashing.•HCl indicated maximum ash removal from PKS (palm kernel shell).•Significant pyrolysis reactions ...took place at ∼250°C to ∼400°C.•Inorganics played a considerable catalytic role during the biomasses pyrolysis.•Acid pretreatment introduced some impacts on the biomasses structure.
To eliminate the negative impacts of inorganic constituents during biomass thermochemical processes, leaching method by different diluted acid solutions was chosen. The different palm oil biomass samples (palm kernel shell (PKS), empty fruit bunches (EFB) and palm mesocarp fiber (PMF)) were pretreated by various diluted acid solutions (H2SO4, HClO4, HF, HNO3, HCl). Acids with the highest degrees of demineralization were selected to investigate the dematerialization impacts on the biomass thermal characteristics and physiochemical structure. Thermogravimetric analysis coupled with mass spectroscopy (TGA-MS) and Fourier transform infrared spectroscopy (TGA-FTIR) were employed to examine the biomass thermal degradation. TGA and DTG (Derivative thermogravimetry) indicated that the maximum degradation temperatures increased after acid pretreatment due to the minerals catalytic effects. The main permanent evolved gases comprising H2, CO2, CO were detected online during analysis. The major permanent gases produced at the temperature range of 250–750°C were attributed to the condensable vapors cracking and probably some secondary reactions. The physiochemical structure change of the acid-treated biomass samples was examined by using Brunauer Emmett Teller (BET) method, Scanning Electron Microscope (SEM) and FTIR. The pyrolysis kinetics of the different palm oil biomasses were investigated using first order reaction model.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
•The thermal characteristics of DNZTO were studied by TG–DTA and ARC.•TG–DTA tests at six different heating rates below 10°Cmin−1 were employed.•The thermal decomposition products of DNZTO were ...studied by FTIR–TGA–MS.
Thermogravimetric–differential thermal analysis (TG–DTA) and accelerating rate calorimetry (ARC) were performed to understand thermal characteristics and kinetics of energetic N,N′-dinitro-4,4′-azo-Bis(1,2,4-triazolone) (DNZTO). A single sharp and narrow exothermic decomposition occurred at 143.3, 150.3, 156.4, 157.4, 159.8 and 160.3°C at different heating rates (0.5, 1, 2, 3, 4, and 5°Cmin−1) suggesting that DNZTO composition was vulnerable to thermal hazard. The FTIR–TGA–MS results revealed that the decomposition product was made up of H2O, NO2, NO, CO2, CO, HCN, and N2O. ARC studies depicted onset temperature at 116.6°C with temperature step of 5°C and phi factor of 41.46, and a sharp rise in exothermic reaction at 127.69°C within the time span of 49.04min with the maximum heat release rate of 0.47°Cmin−1. The exothermic activity resulted in adiabatic pressure rise of the sample up to 300kPa by the sample pyrolysis into gas. In addition, the kinetic parameters of DNZTO were estimated for the thermal process by TG–DTA and ARC.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Display omitted
•Comparison of Municipal solid waste pyrolysis and combustion.•TGA-MS technique was used to evaluate synergistic effects of MSW mixture.•Positive and negative synergistic effects were ...observed during pyrolysis of mixture.•Negative synergistic effect in first stage was due to presence of plastic component.•Mostly positive synergistic effects were detected during MSW mixture combustion.
A thermogravimetric methodology was developed to investigate and semi-quantify the extent of synergistic effects during pyrolysis and combustion of municipal solid waste (MSW). Results from TGA-MS were used to compare the pyrolysis and combustion characteristics of single municipal solid waste components (polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), branches (BR), leaves (LV), grass (GR), packaging paper (PK), hygienic paper (HP) and cardboard (CB)) and a mixture (MX) of PP, BR and CB. Samples were heated under dynamic conditions at 20°C/min from 25°C to 1000°C with the continuous record of their main evolved fragments. Synergistic effects were evaluated by comparing experimental and calculated weight losses and relative areas of MS peaks. Pyrolysis of the mixture happened in two stages, with the release of H2, CH4, H2O, CO and CO2 between 200 and 415°C and the release of CH4, CxHy, CO and CO2 between 415 and 525°C. Negative synergistic effect in the 1st stage was attributed to the presence of PP where the release of hydrocarbons and CO2 from BR and CB was inhibited, whereas positive synergistic effects were observed during the 2nd degradation stage. In a second part of the study, synergistic effects were related to the dependency of the effective activation energy (Eα) versus the conversion (α). Higher Eαs were obtained for MX during its 1st stage of pyrolysis and lower Eαs for the 2nd stage when compared to the individual components. On the other hand, mostly positive synergistic effects were observed during the combustion of the same mixture, for which lower Eαs were recorded.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Synthesis of Egyptian Blue and mechanisms Kiss, Agoston; Stretz, Holly A.; Ueda, Akira ...
The Journal of physics and chemistry of solids,
August 2022, 2022-08-00, Volume:
167
Journal Article
Peer reviewed
Open access
Egyptian Blue (EB, Cuprorivaite, CaCuSi4O10) is a novel candidate for nanomaterial-based sensors in water, as its infrared (IR, 910 nm) emission has high quantum yield in comparison with current ...commonly-used IR reporters. IR signals for bioimaging and environmental sensing penetrate biological matrices (i.e. tissues) deeper and with less scattering than visible light. This work reports the effects of heating rate on the solid state synthetic yield of EB and formation mechanism is discussed. EB synthesis was investigated with thermogravimetric analysis coupled with mass spectrometry and in-situ high temperature X-ray diffraction. A reproducible maximum in EB yield was observed at a heating rate of 7 °C/min with samples containing CaCO3 precursor. We report the optimized reaction conditions, yields, and the photoluminescent response of the synthesized EB layered materials. The precursor content (O2, CaCO3, CuO and SiO2) also had a subtle effect on EB yield.
Display omitted
•Maximum in EB yield at 7 °C/min heating rate for CaCO3 precursor.•Egyptian Blue synthesis in 5 min instead of 16 h at 1050 °C.•Cristobalite (SiO2) is not a precursor to Egyptian Blue synthesis.•O2 is essential for EB synthesis, Cu + formed instead under N2.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•More than 80% of the total hydrogen generation comes from the coke dehydrogenation reaction.•Coke is mainly generated in the pyrolysis stage and the quantity and quality of coke is mainly determined ...by asphaltenes.•A heavy oil gasification kinetic model is proposed based on the TGA-MS experiments.
Heavy oil in-situ gasification technology (ISG) produces hydrogen by injecting air and water into the formation and chemically react with the heavy oil, which can efficiently exploit oil and gas resources in the form of clean energy. The pyrolysis reaction of crude oil is particularly important for this technology regarding hydrogen generation. In this research, the mechanisms of hydrogen generation from heavy oil pyrolysis were investigated based on the thermogravimetric analyzer (TGA) and mass spectrometer (MS). The experimental results show that the weight loss of heavy oil under 25–900 °C can be divided into two stages. The first stage is mainly the evaporation of light fractions, which corresponds to the physical stage. The second stage contains pyrolysis and coke dehydrogenation reactions, which is considered as the chemical stage. Also, the study indicates that the hydrogen generation occurs in both pyrolysis and coke dehydrogenation reactions, and 80% of hydrogen is generated from the coke dehydrogenation reaction with corresponding reaction temperature range of 528–820 °C. Furthermore, the kinetic parameters of heavy oil pyrolysis were obtained based on the distributed activation energy model (DAEM), where the apparent activation energy of the coke dehydrogenation reaction is greater than 350 kJ/mol, and the reaction frequency factor (k0) is greater than 2.83 × 1023 s−1. The reaction kinetic parameters obtained in this paper and the established law of hydrogen generation by heavy oil under thermal effect lay the foundation for further research on ISG technology.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Pyrolysis and gasification processes of three types of lignocellulosic biomass (Eucalyptus wood, fir wood and pine bark) and biomass main components (cellulose, xylan and lignin) were studied by ...thermogravimetric-mass spectrometric analysis. Biomass samples were pyrolyzed between 30 °C and 1000 °C obtaining a solid fuel (char) that was later gasified using steam as the reacting agent (5% vol.). The gasification temperature was set at 900 °C. Biomass samples reactivity profiles showed a catalytic effect at high conversion values, which was correlated with their ash composition. Three models were used to reproduce the gasification process. Cellulose and pine bark samples were the only ones that properly fitted to these models. This fact was attributed to their low ash content. This way, a semi-empirical model for predicting the gasification rates including the catalytic effect of ashes was proposed, which highly improved the obtained fitting. H2, CO and CO2 were the main products obtained. Furthermore, the detection of CH4 indicated the existence of methanation reactions. NOx were also observed, indicating that nitrogen was retained in the char after the pyrolysis process.
•Gasification process of lignocellulosic biomass was studied by TGA-MS (thermogravimetric analysis-mass spectrometry).•The effect of ashes in biomass played a major role in the gasification process.•Reactivity of biomass was correlated with the amount of active catalytic species.•A semi-empirical model was proposed to reproduce the gasification of biomass.•H2, CO and CO2 were the main products obtained along with CH4.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The present study aimed to investigate the pyrolysis characteristics and kinetics of spent coffee waste (SCW) at different heating rates (5-40 °C/min) at a temperature ranging from 30 to 800°C in a ...thermogravimetric analyzer (TGA). First, the physicochemical properties of the SCW were characterized using X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy, and elemental analysis. Then, the thermal decomposition kinetic profiles were modeled using the Coats-Redfern, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Starink models. All the tested models provided accurate fits of the thermogravimetric analysis data with acceptably high R
2
values. The mean activation energy of the coffee waste was 101.8, 96.7, and 97.1 kJ/mol for the FWO, KAS, and Starink models, respectively. Finally, the evolved gases detected during the decomposition by TGA coupled with a mass spectrometer (MS) primarily consisted of water, methane, and carbon dioxide.
Full text
Available for:
BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
► Analytical pyrolysis of wastes using TGA-MS and TGA-FTIR techniques are compared. ► TGA-MS and TGA-FTIR produced a broad spectrum of qualitative data. ► Kinetic parameters determined by TGA-MS and ...TGA-FTIR show good comparability. ► Careful interpretation of the complex TGA-MS and TGA-FTIR spectra is required.
Pyrolysis of waste materials, biomass wood waste, waste tyre, refuse derived fuel (RDF) and waste plastic was performed using two thermogravimetric analysers (TGA). One TGA was coupled to a mass spectrometer (MS) and the other to an infrared spectrometer (FTIR). The kinetic parameters of the pyrolysed waste materials obtained for TGA-MS and TGA-FTIR were compared using a model based on first-order reactions with a distribution of the activation energies. A further comparison of the volatile species evolved by thermal degradation (TGA) and the subsequent characterisation by the MS and FTIR spectra was performed. The first-order reaction pathways and subsequent activation energies calculated from the differential TGA data presented good repeatability between the TGA-MS and TGA-FTIR. The TGA-MS and TGA-FTIR produced a broad spectrum of qualitative data characterising the volatile gaseous fraction of the waste materials pyrolysed. TGA-MS and TGA-FTIR are shown to be valuable techniques in corroborating the respective thermograms and spectrograms of the volatile species evolved during the pyrolysis of waste materials. However both techniques are prone to interference and careful interpretation of the spectra produced is required.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
PDF
