Thermogravimetric Analysis Methods Research Articles

Adsorption of Cu2+, Cd2+ and Pb2+ in wastewater by modified chitosan hydrogel

ABSTRACT Heavy metal pollution is extraordinary critical, so it is urgent to develop an effective adsorbent to dispose of such pollution. Modified chitosan was combined with polyacrylic acid to form N-carboxymethyl chitosan hydrogel (NCS-hydrogel) adsorbent. The morphology and structure of NCS-hydrogel were analyzed and identified by infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis and other characterization methods. NCS-hydrogel adsorption was used to treat water pollution of Cu, Cd and Pb ions, and the influencing factors of adsorption performance were studied. The intrinsic mechanism of adsorption process was discussed by thermodynamic, kinetic and isotherm models. The results show that the adsorption process of metal ions by NCS-hydrogel meets the spontaneous monolayer chemisorption, and the adsorption process is accompanied by heat release.

Molybdenum Carbonyl Grafted on Amine-Functionalized MCM-22 as Potential Catalyst for Iso-Eugenol Oxidation

Different concentrations of molybdenum carbonyl were incorporated on the surface of amine-functionalized MCM-22. The obtained samples were thoroughly characterized by Fourier-transform infrared spectroscopy (FTIR), powder X-Ray diffraction (XRD), high-resolution transition electron microscopy (HRTEM), N2-sorption and thermo-gravimetric analysis (TGA) methods. HRTEM images confirmed the uniform distribution of active molybdenum species on the functionalized MCM-22. The resultant materials were explored for liquid-phase oxidation of iso-eugenol at ambient reaction conditions. The catalyst with 6 wt% Mo(CO)6 loaded materials showed comparable conversion (87%) with vanillin as the major product (selectivity of 61%) for the chosen reaction. The better catalytic activity of MCM-22-DA-Mo catalyst having 6 wt% loading of Mo carbonyl could be due to the uniform distribution of molybdenum species on MCM-22-DA surface. Importantly, the catalyst retained its activity even after several runs. Molybdenum carbonyl were incorporated on the surface of amine-functionalized MCM-22 by the post-synthesis method. The resultant MCM-22-DA-Mo showed promising activity on iso-eugenol oxidation with a conversion of 87%.

Thermogravimetric Analysis of Fuel Blends of Biomass and High-Ash Coal-Containing Waste

An investigation of co-combustion characteristics of the two-component mixed fuel was carried out using methods of thermogravimetric analysis. As feedstock, there were used two types of biomass and the high-ash coal-containing waste, which were ash-slag waste from a coal-fired power plant and coal concentrate obtained by their enrichment. The experiments were carried out in an inert (nitrogen) and oxidizing (air) medium. It is shown, that in the temperature range characteristic for biomass burning the additivity principle cannot be used for evaluation of combustion characteristics of the blends. The presence of a coal-containing component in the mixture leads to a disproportionate decrease in the mass loss rate both in the temperature range characteristic for yield and oxidation of biomass volatile products, and in the temperature range in which its solid residue is oxidized. The effect of biomass on the oxidation rate of the coal-containing component was not found.

The Effect of Ammonium Chloride on the Structure of Hydroxyapatite Nanoparticles and the Proliferative Activity of Mesenchymal Stromal Cells

Synthetic hydroxyapatite nanoparticles that contain ammonium chloride crystals are obtained. The X-ray diffraction, thermogravimetric analysis, and BET methods show that ammonium chloride crystals are decomposed in argon in the temperature range of T = 220–270°C. The heat treatment at T = 300°C gives thermal stability to the nanoparticles. The presence of ammonium chloride in the culture medium has a substantial effect on the biocompatibility of nanoparticles. An increase in its content reduces the proliferative activity of mesenchymal stromal cells.

PET/CLOISITE 15A composite fibers - studies on the structure and the flame inhibition mechanism

The improvement of poly(ethylene terephthalate) (PET) fibers flame retardancy is usually achieved by using antipyrenes, which may be incorporated into polyester molecules during polycondensation or are physically mixed with polymer in the fiber formation process. In this article we present an alternative method to reduce the flammability of PET fibers and fabrics which is analogous to dyeing them with a dispersed dyes in a high temperature bath. We have tested this method many times using various modifiers so far. This time, we applied a commercial organophilized montmorillonite Cloisite®15A (C15A). In the presented work, using Limited Oxygen Index (LOI) flammability tests and the thermogravimetric analysis (TGA) method, the effectiveness of the modification used was demonstrated and its optimal variant was determined. Based on Fourier Transform-Infrared Spectroscopy (FT-IR) studies, the existence of interactions between PET macromolecules and the C15A modifier in the entire temperature range of the oxidative degradation was confirmed. Using the Wide-Angle X-ray Scattering (WAXS) and Small-Angle X-ray Scattering (SAXS) methods, the basic parameters of the nanostructure of the studied fibers were determined, and their nanocomposite nature was confirmed. The most important goal, which was successfully achieved, was to explain the mechanism of flame inhibition by the applied modifier C15A.

Reduced-order model for CaO carbonation kinetics measured using micro-fluidized bed thermogravimetric analysis

A reduced-order model was developed to describe the CaO carbonation kinetics by simplifying the detailed one-dimensional rate-equation-based grain model. The reduced-order model was derived using the Thiele modulus method and is an analytical model, which can be easily used in the reactor scale model or computational fluid dynamics (CFD) simulation. In the reduced-order model, physical/chemical steps occurring during the carbonation process were considered, including external diffusion of gas around the particle, intraparticle diffusion, surface reaction, product islands growth and product layer diffusion. This model can be used to investigate the complex kinetic behaviors such as reaction controlled steps, kinetics transition from chemical reaction to product layer diffusion, and the effect of particle structure change on intraparticle diffusion, such as pore plugging phenomenon. The prediction accuracy of reduced-order model was verified by the detailed one-dimensional model. In order to demonstrate the application of the reduced-order model for reactor scale analysis, the CaO carbonation kinetics under different temperatures (600–750 °C), CO2 concentrations (25–75 vol%) and particle sizes (0.2–3 mm) were measured using a novel micro-fluidized bed thermogravimetric analysis (MFB-TGA) method, which is based on real-time mass measurement of CaO sample in a fluidizing state. The reduced-order model was implemented into a K-L two-phase bubbling bed reactor model to analyze the experimental data of a micro-fluidized bed reactor. Results indicated that the two-stage behavior of carbonation kinetics can be described successfully using the model, and the effect of particle structure change on pore plugging and intraparticle diffusion can be well predicted and explained. The carbonation is first-order reaction when the CO2 partial pressure is within 75% (1 bar). The effect of particle size on carbonation kinetics shows three-zone characteristics of reaction/diffusion combined controlling mechanism, and was discussed in detail. The reduced-order model provides a promising application for describing multiscale mechanisms (surface, particle and reactor) of carbonation kinetics.

Fast redox kinetics of a perovskite oxygen carrier measured using micro-fluidized bed thermogravimetric analysis

Redox kinetics of oxygen carrier in chemical looping combustion (CLC) is important for reactor design and its oxidation enthalpy is important in order to establish auto thermal demonstration. Most published redox kinetics of oxygen carrier has been measured by thermogravimetric analysis (TGA) which can include additional diffusion limitations and thus underestimate the overall kinetics. In this study, the redox kinetics of a new perovskite oxygen carrier (CaMn0.375Ti0.5Fe0.125O3-δ) was measured by a novel micro-fluidized bed thermogravimetric analysis (MFB-TGA) method which can achieve real-time weight measurement of oxygen carrier in a fluidizing state with similar mass and heat transfer characteristics as in a CLC reactor. The experimental data from MFB-TGA were analyzed with a reactor model. The redox kinetics was described by a two-stage model of gas-solid reaction. The effect of temperature, O2 concentrations and reducing gas type (H2 and CH4) on the redox kinetics in MFB-TGA was investigated and compared with other oxygen carriers such as natural manganese ore and ilmenite. It is observed that the oxidation of both manganese ore and ilmenite can be divided into two stages, a fast initial stage followed by a second slower stage, resulting in slower total oxidation rates. A very interesting finding is that there is only the fast initial stage for the oxygen carrier of CaMn0.375Ti0.5Fe0.125O3-δ, and the full oxidation of CaMn0.375Ti0.5Fe0.125O3-δ can be finished within ∼4 s which is ∼7.5 and ∼30 times faster than that of manganese ore and ilmenite. The reduction kinetics of CaMn0.375Ti0.5Fe0.125O3-δ by H2 is also ∼5 and ∼2.2 times faster than that of manganese ore and ilmenite, respectively. The kinetic parameters of three oxygen carriers were compared and the redox mechanism of CaMn0.375Ti0.5Fe0.125O3-δ was discussed.

Investigation of the Effect of Diisocyanate on the Thermal Degradation Behavior and Degradation Kinetics of Polyether-Based Polyurethanes

Low molecular weight polyether (PE) or polyester polyols can produce novel elastomeric urethane products when cured with diisocyanate which are then utilized for formation of castable energetic composites in addition to many more applications. In this work four different kinds of diisocyanates, isophorone diisocyanate (IPDI), methylenediphenyl diisocyanate (MDI), 2,2,4-trimethyl hexamethylene diisocyanate (TMDI), and toluene diisocyanate (TDI), were used to react with a PE to form PE-based polyurethanes (PUs); they were denoted PE/IPDI, PE/MDI, PE/TMDI, and PE/TDI, respectively. The effect of the four diisocyanate groups in the PE-based PUs on the thermal degradation behavior, thermal degradation kinetics, reaction model, and thermodynamic parameters of the PE/IPDI, PE/MDI, PE/TMDI, and PE/TDI samples were investigated by thermogravimetric analysis (TGA) and derivative thermal gravimetric analysis (DTGA) methods. On the basis of the degradation peak temperature at a high heating rate, the thermal stability of the PU followed the order PE/TDI > PE/TMDI > PE/MDI > PE/IPDI. The activation energy for the thermal degradation was derived using the Flynn–Wall–Ozawa (FWO) method from the TGA data and the average values of the PE/IPDI, PE/MDI, PE/TMDI, and PE/TDI samples were found to be 136.9, 148.0, 132.3, and 155.7 kJ mol‒1, each at various conversions from 0.05 to 0.95, respectively. In addition, the results of the activation energies obtained from the Kissinger–Akahira–Sunnse (KAS) method were in good agreement and consistent with those obtained the FWO method. The reaction models of the degradation reaction were investigated through the Coats–Redfern method and all PUs samples were probably best described by the Avarami–Erofeyev (A 2) and reaction order (F 1) models. The kinetic and thermodynamic parameters for formation of the activated complex of all PUs, such as the activation energy (Ea ), enthalpy of activation (ΔH #), Gibbs free energy of activation (ΔG #), and entropy of activation (ΔS #), were investigated. The investigated thermal kinetic and thermodynamic parameters indicated that there was significant variation in the properties of the PUs containing the different diisocyanate groups.

Thermal degradation kinetics of calcium stearate/PVC composite

Thermogravimetric analysis (TGA) and non-isothermal multiple scan rate method were used to study the effect of calcium stearate on the thermal degradation of PVC. The results show that the thermal decomposition process of calcium stearate/PVC composite includes two stages, which occur at 361–402 ​°C and 552–585 ​°C, respectively. The apparent activation energy of the 1st stage calculated by Kissinger, Starink, Friedman and Flynn-Wall-Ozawa method is 93.22, 87.18, 94.81 and 92.13 ​kJ ​mol−1, respectively. The decomposition reaction in the 1st stage is controlled by the F1 mechanism, of which differential and integral equation is f(α) ​= ​1/(2α), g(α) ​= ​α2, respectively. This work provides a way to study the effect of heat stabilizers on the thermal stability of PVC.

Characterization of particle emission from thermoplastic additive manufacturing

Abstract Particle emission from fused-deposition modelling (FDM) desktop 3D printer has raised concerns regarding indoor personal health due to the increased accessibility of printers. This study characterises the size, number and morphology of the emitted particles to understand particle formation processes and propose guidelines for their abatement. The effects of extruder temperature, layer height, filament colour and shape of printing object on particle characteristics emitted from a desktop 3D printer have been investigated. For first time, a novel thermogravimetric analysis (TGA) method is developed to emulate printing process, which offers an insight into particle formation during extruder heating, standing-by and during the printing process. Printing temperature and printing layer height demonstrate a major effect on the ultra-fine particles (UFP) emitted, while ABS filament colour shows a minor effect on the nanoparticle emissions. Local temperature and concentration of volatile organic material emitted from the filament play an important role on the number of particles formed, while printing duration and air change rate (ACH) affect particle size, morphology and emission rate. The results provide guidelines to develop printing settings that will lead to lower UFP emissions for improved indoor air quality. The developed TGA method demonstrates the qualitative behaviour of particle emissions from a material under heating, which is approximately proportional to an FDM printers’ particle emissions; facilitating increased repeatability, time and cost efficiency for printing material assessment.

Study on the Oxidation Kinetics and Microreactivity of Water-Immersed Coal.

Both the macroscopic reaction and microscopic characterization of water-immersed coal have been studied. The methods of thermogravimetric analysis via Fourier transform infrared spectroscopy (TG-FTIR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) are used. The apparent activation energy of water-immersed coal was significantly lower than that of raw coal. For the same coal sample, the production of CO in water-immersed coal is significantly higher than that in raw coal. The analysis shows that after water immersion, the content of hydroxyl and aromatic hydrocarbons in the coal increases significantly and the temperature at which fat-based and oxygen-containing functional groups participate in the reaction decreases. This indicates that the functional groups are unstable after water immersion and react violently. When the immersion time is 60 days, the activation energy is the lowest, the production of CO reaches its maximum, and the variation of each functional group is most obvious.

Novel Methotrexate-Ciprofloxacin Loaded Alginate-Clay Based Nanocomposite as Anticancer and Antibacterial Co-Drug Delivery System.

Purpose: In last decades, by increasing multi-drug resistant microbial pathogens an urgent demand was felt in the development of novel antimicrobial agents.Methods: Promising nanocomposites composed of clay/alginate/imidazolium-based ionic liquid, have been developed via intercalation of calcium alginate and ionic liquid by ion exchange method. These tailored nanocomposites were used as nanocarriers to simultaneously deliver methotrexate (MTX), and ciprofloxacin (CIP), as anticancer and antibacterial agents, respectively to MCF-7 breast cancer cells. Nanocomposites were fully characterized by scanning electron microscopy studies (SEM), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA) methods. The in vitro antimicrobial potential of the mentioned nanocomposites in free and dual-drug loaded form was investigated on Pseudomonas aeruginosa and Escherichia coli bacteria. The antitumor activity of nano-formulations was evaluated by both MTT assay and cell cycle arrest.Results: The dual drug-loaded nanocomposites with exceptionally high loading efficiency (MTX: 99 ±0.4% and CIP: 98 ±1.2%) and mean particle size of 70 nm were obtained with obvious pH-responsive MTX and CIP release (both drugs release rate was increased at pH 5.8 compared to 7.4). The antibacterial activity of CIP-loaded nanocomposites was significantly higher in comparison with free CIP (P <0.001). The antitumor activity results revealed that MTX cytotoxicity on MCF-7 cells was significantly higher in nano-formulations compared to free MTX (P <0.001). Both MTX-loaded nanocomposites caused S-phase arrest in MCF-7 cells compared to non-treated cells (P ˂ 0.001). Conclusion: Newly developed smart nanocomposites are potentially effective pH-sustainable delivery systems for enhanced tumor therapy.

Improvement in the electrochemical stability of Li[Ni0.5Co0.2Mn0.3]O2 as a lithium-ion battery cathode electrode with the surface coating of branched oligomer

Although layered Li[Ni0.5Co0.2Mn0.3]O2 (LNCM 523) is one of the most promising cathode materials for lithium-ion batteries, large capacity losses during charging and discharging, due to poor surface stability, have limited its application. Surface modifications can be effective at improving the electrochemical performance of cathode materials. In this study, an oligomer polymer, named LIVING, was synthesized from bisphenol A diglycidyl ether diacrylate and barbituric acid and then used it as a coating material for LNCM 523 particles. Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, and electrochemical methods were employed to investigate the structure, surface properties, thermal stabilities, and electrochemical properties of the electrodes. Both coated (LIVING@LNCM 523) and uncoated (LNCM 523) electrodes were tested for their battery performance. A cathode material coated with 0.5 wt.% of LIVING (0.5% LIVING@LNCM 523) at a layer thickness of approximately 10 nm showed enhanced cycle stability, with over 80.7% of the capacity retained after 100 cycles at a rate of 0.2C; in comparison, the LNCM 523 electrode retained no more than 66.2% of its capacity under the same conditions. The coated electrode (0.5% LIVING@LNCM 523) also exhibited a better rate capability, retaining about 91% of its initial capacity after applying various current loads, whereas LNCM 523 retained only 79% after applying the same current loads under the same conditions. The improved electrochemical performance of the modified electrode is attributed to the chemical interactions between LNCM 523 and LIVING providing a uniform and stable oligomer layer on the LNCM 523 surface, thereby preventing the LNCM 523 surface from deeper electrolyte ion intercalation and suppressing the growth of interfacial resistance. The coating material (LIVING) appears to have great potential for improving the electrochemical performance of layered structure cathode materials, with promising applications in highly energy demanding lithium-ion batteries.

High-Impact Promotional Effect of Mo Impregnation on Aluminum-Rich and Alkali-Treated Hierarchical Zeolite Catalysts on Methanol Aromatization.

A systematic change of HZSM-5 (HZ5) as a catalyst of the methanol to aromatics (MTA) reaction was undertaken by employing a fixed-bed tubular-type reactor under ambient pressure, applying a weight hourly space velocity (WHSV) of 2 h–1 at 375 °C, as the first report on the application of low-Si/Al-ratio alkaline-[Mo,Na]-HZSM-5 in the MTA process. To characterize the surface and textural properties of the catalysts, powder X-ray diffraction (PXRD), nitrogen adsorption/desorption, temperature-programmed desorption of ammonia (NH3-TPD), pyridine-infrared spectroscopy (Py-IR), thermogravimetric analysis (TGA), and energy-dispersive X-ray (EDX) methods were employed. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) measurements demonstrated a selectivity of up to 86 wt % (65.7 wt % for benzene, toluene, and xylene (BTX)) over 2[Mo]HZ5. NH3-TPD and Py-IR results indicated a sensible decrease of strong acid sites on the impregnated samples, while the surface analyses revealed the highest Lewis acid sites (LAS) together with the largest mesopore surface area for 2[Mo]alk-HZ5, supporting the migration of Mo species to the bulk of the catalysts. Mo impregnation had a minor effect on the observed coke formation in the promoted catalyst.

Study on performance enhancement of self-compacting concrete incorporating waste foundry sand

Large amounts of waste foundry sand (WFS) is being generated worldwide every year and it is necessary to re-use it for valuable cause. WFS is reported suitable up to a certain extent for replacement of fine aggregate in concrete. Answering the doubt on the issue of workability and durability properties can enhance its potential use. This study investigates the usability of waste foundry sand in self-compacting concrete (SCC). Fine aggregate was replaced with WFS with ratios ranging from 0 to 40%. The properties of WFS were characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and X-ray fluorescence (XRF) methods. The effect of WFS was observed for the workability, mechanical behaviour and durability of the resulting SCC. The WFS showed distinct effects on workability with each level of replacement. At 90 days, SCC containing 10% WFS showed better mechanical and durability properties as compared to the control mix. Beyond 10% replacement level, strength and durability of concrete specimens started to show degradation. But WFS was observed as an excellent alternative for reducing the segregation especially in SCC. SCC with up to 20% WFS also showed acceptable levels of key performance parameters.

Change of some characteristics of HDPE pipes tested in Nghe An province seawater

AbstractThis paper focuses to study on change of some characteristics of high density polyethylene (HDPE) pipes testing in Nghe An province seawater. The investigated characteristics of HDPE pipe before and after testing are structural, morphological, crystal, thermal property and stability. Infrared (IR) spectroscopy, scanning electron microscope (SEM), X‐ray diffraction (XRD), thermogravimetric analysis (TGA) and differential thermal analysis (DTA) methods were used to evaluate the change in characteristics of PE pipes after 10 testing months in Nghe An province seawater. In addition, the change in weight and tensile properties of PE pipes after testing was also investigated. The obtained results showed that the Nghe An province seawater had an influence on the structural, morphological, tensile, crystal and thermal characteristics of PE pipes.

Effect of organo-mineral additives on physical-mechanical properties and corrosion resistance of sand-cement mortars

Introduction. TConstruction of large-scale offshore structures in the coastal area of Vietnam requires new compositions of binders for hydraulic concretes, advanced concrete mixing technologies, and concrete transportation to depositing sites. Materials and methods. The binder, containing sulfate resistant Portland cement and finely dispersed mineral additives, including low calcium fly ash of TPP “Vung Ang” and silica fume SF-90 (SF-90), was added to the mortar mix, and the same about SR 5000F superplasticizer and quartz river sand. Powder particle shape and size were measured using laser granulometry; X-ray diffraction was employed to identify the mineral composition of sulfate-resistant cement; the effect of multi-component organo-mineral additives on the phase composition of the cement stone was studied using methods of thermogravimetric analysis; the absolute volume method was employed to analyze the composition of the mortar. Results. The co-authors have analyzed the application of new compositions of multi-component organic-mineral additives whose content, if taken as a percentage of the cement weight, reaches 1.1–1.45 % of SF 5000F superplasticizer, 10–15 % of SF-90, and 30 % of fly ash. New additives accelerate compressive and tensile strength development by 1.4–1.9 times, and that’s been confirmed by bending early-age and 28-day cement-sand mortar specimens, that have sulfate-resistant cement, and their benchmarking against control specimens. It’s been identified that SF-90 and fly ash, if added to the mix, reduce the Portlandite content in the cement stone by 1.27–3.29 % at the age of 28 days in comparison with the benchmark composition due to their high pozzolanic activity Conclusions. Testing results enable co-authors to recommend the application of multi-component organo-mineral additives to increase the resistance of cement-sand compositions to sulfate corrosion due to the denser structure and lower porosity of the cement stone, caused by the lower value of the water/binder ratio and the packing of pore spaces with active mineral fillers. Therefore, new additives are recommended for use in the production of corrosion resistant concretes suitable for construction of offshore hydraulic structures in Vietnam.

Comparative study on the carbon–carbon composites developed from petroleum pitch, coal tar pitch, and their mixture

Carbon–carbon composites, as developed from various pitch precursors and chopped carbon fiber reinforcement, have been characterized and compared on the prime basis of the precursor materials used as the matrix. Evaluation of the properties and characterization have been carried out by various techniques such as thermal analysis by thermogravimetric analysis, thermomechanical analysis, and flame ablation method, microstructural characterization by scanning electron microscopy and optical microscope, mechanical characterization by Universal Testing Machine (UTM), IZOD impact, and hardness and frictional characterization by a pin on disc tribometer were carried out. Petroleum pitch, coal tar pitch, and the mixture of both the kinds of the pitch have shown a difference in the ultimate properties on the finished composite materials. The presence of volatiles, quinoline insoluble content, and various softening point have proved to impart differences in behavior for different systems. Composites developed to form the three systems have shown robust characteristics with superior mechanical and thermal behavior. Microstructural analysis has shown good compatibility between the reinforcement and matrix, while it is also evidence of a uniform distribution of the reinforcement. The fiber–matrix interaction in all the three systems is appreciably weak, which is favorable for non-catastrophic failure.

Study of the kinetic behaviour of biomass and coal during oxyfuel co-combustion

In this study, the thermogravimetric analysis (TGA) method has been used to evaluate the kinetic behavior of biomass, coal and its blends during oxyfuel co-combustion. The thermogravimetric results have been evaluated by the Coats–Redfern method and validated by Criado's method. TG and DTG curves indicate that as the oxygen concentration increases the ignition and burn out temperatures approach a lower temperature region. The combustion characteristic index shows that biomass to coal blends of 28% and 40% respectively can achieve enhanced combustion up to 60% oxygen enrichment. In the devolatilization region, the activation energies for coal and blends reduce while in the char oxidation region, they increase with rise in oxygen concentration. Biomass, however, indicates slightly different combustion characteristic of being degraded in a single step and its activation energies increase with rise in oxygen concentration. It is demonstrated in this work that oxygen enrichment has more positive combustion effect on coal than biomass. At 20% oxygen enrichment, 28% and 40% blends indicate activation energy of 132.8 and 125.5 kJ·mol−1 respectively which are lower than coal at 148.1 kJ·mol−1 but higher than biomass at 81.5 kJ·mol−1 demonstrating synergistic effect of fuel blending. Also, at char combustion step, an increase in activation energy for 28% blend is found to be 0.36 kJ·mol−1 per rise in oxygen concentration which is higher than in 40% blend at 0.28 kJ·mol−1.

Thermogravimetric Analysis and Mass Spectrometry Allow for Determination of Chemisorbed Reaction Products on Metal Organic Frameworks.

Thermogravimetric analysis (TGA) is a technique which can probe chemisorption of substrates onto metal organic frameworks. A TGA method was developed to examine the catalytic oxidation of S-nitrosoglutathione (GSNO) by the MOF H3[(Cu4Cl)3(BTTri)8] (abbr. Cu-BTTri; H3BTTri = 1,3,5-tris(1H-1,2,3-triazol-5-yl)benzene), yielding glutathione disulfide (GSSG) and nitric oxide (NO). Thermal analysis of reduced glutathione (GSH), GSSG, GSNO, and Cu-BTTri revealed thermal resolution of all four analytes through different thermal onset temperatures and weight percent changes. Two reaction systems were probed: an aerobic column flow reaction and an anaerobic solution batch reaction with gas agitation. In both systems, Cu-BTTri was reacted with a 1 mM GSH, GSSG, or GSNO solution, copiously rinsed with distilled-deionized water (dd-H2O), dried (25 °C, < 1 Torr), and assessed by TGA. Additionally, stock, effluent or supernatant, and rinse solutions for each glutathione derivative within each reaction system were assessed by mass spectrometry (MS) to inform on chemical transformations promoted by Cu-BTTri as well as relative analyte concentrations. Both reaction systems exhibited chemisorption of glutathione derivatives to the MOF by TGA. Mass spectrometry analyses revealed that in both systems, GSH was oxidized to GSSG, which chemisorbed to the MOF whereas GSSG remained unchanged during chemisorption. For GSNO, chemisorption to the MOF without reaction was observed in the aerobic column setup, whereas conversion to GSSG and subsequent chemisorption was observed in the anaerobic batch setup. These findings suggest that within this reaction system, GSSG is the primary adsorbent of concern with regards to strong binding to Cu-BTTri. Development of similar thermal methods could allow for the probing of MOF reactivity for a wide range of systems, informing on important considerations such as reduced catalytic efficiency from poisoning, recyclability, and loading capacities of contaminants or toxins with MOFs.