Thermogravimetric Analysis Methods Research Articles

Application of thermogravimetric analysis method for the characterisation of products from triglycerides during biodiesel production

In this present work, thermogravimetric analysis (TGA) was used to study the thermal degradation of a range of lipids and lipid-derived compounds associated with the production of biodiesel. Thereafter, the procedure was used to successfully quantify the compounds of three process streams from a biodiesel plant. Relevant organic chemicals involved in biodiesel production chemistry, including glycerol, oleic acid (fatty acid), palmitic acid (fatty acid), rapeseed oil (model triglyceride) and fatty acid methyl esters (FAMES) have been studied to determine their volatilisation/thermal degradation patterns. The developed method was then applied for the quantitative characterisation of three samples from a 3-stage biodiesel production plant, including two in-process samples and the final biodiesel product. The method was able to clearly distinguish between two main sets of compounds namely, early - mid volatiles (glycerol, fatty acids and fatty acid methyl esters) and late volatiles (incompletely converted and unreacted triglycerides). In addition, the FAMES in the industrial samples were extracted into petroleum ether and analysed by gas chromatography - mass spectrometry (GC/MS), with good agreement between the two analytical methods. For instance, GC/MS analysis showed that the three industrial samples contained 31.2 ± 0.1 wt%, 60.6 ± 0.2 wt% and 91 ± 0.53 wt% of FAMES, respectively. Similarly, the TGA method gave the FAMES contents of the three samples as 33.9 ± 0.4 wt%, 57.8 ± 0.2 wt% and 85.3 ± 0.52 wt%. This study shows that TGA is a fast and simple method for accurately monitoring the triglyceride conversion stages and the purity of the final product during biodiesel production, without the need for extensive sample preparations and expensive standard solutions.

Green synthesis, characterization, and application of metal oxide nanoparticles for mercury removal from aqueous solution

In this work, a novel surface-modified, green-based wheat straw-supported magnetite nanoparticles (Fe3O4-NPs) were synthesized via the green synthesis method, and the adsorption of mercury (Hg(II)) ion from aqueous solutions was methodically investigated. The synthesized wheat straw-supported magnetite (Fe3O4-WSS) NPs were characterized using X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and scanning electron microscopic (SEM) methods. FT-IR and TGA confirmed that the surface of Fe3O4-NPs was functionalized well. The XRD analysis revealed the existence of magnetite in the synthesized wheat straw-supported Fe3O4-NPs of 19.83nm average crystalline size. SEM analysis showed Fe3O4-NPs were almost spherical, with an average particle size of 22.48nm. Adsorption studies were carried out to investigate the adsorption of Hg(II) ions onto Fe3O4-WSS NPs and the effect of various adsorption parameters such as pH, time, adsorbent dosage, and Hg(II) ion concentration. The optimum adsorption conditions were obtained: pH of 6, contact time of 45min, adsorbate of 40mg/L, and adsorbent of 1g. A maximum of 98.04% Hg(II) ion removal efficiency was obtained at these optimum conditions. FT-IR analysis also indicated that surface functional groups such as C = C,-OH, and C-C of the newly produced Fe3O4-NPs led to the more efficient removal of Hg(II) from aqueous solution. The synthesized nano-adsorbent showed an excellent adsorption capability of 101.01mg/g. Hg(II) ions adsorption onto Fe3O4-WSS NPs fitted well with the Langmuir adsorption isotherm model. Therefore, these reasonable findings reveal that Fe3O4-WSS NPs are an efficient and promising adsorbent for Hg(II) removal from aqueous water environments.

Cellulose tosylate as support for α-amylase immobilization

Tremendous potential exists to use cellulose as a support for the immobilization of enzymes. In the current study, cellulose was transformed into cellulose tosylate, and α-Amylase was immobilized using the derivatized polymer. Techniques like Fourier transform infrared, scanning electron microscopy, thermogravimetric analysis, and X-ray diffraction methods were used to characterize the support. The support is a perfect illustration of how both covalent and hydrophobic/ionic types of immobilizations can be experimentally used on support. The support was found to show max degradation at 320.2 °C with 3.2 % residual substance and crystallinity of about 56.6 %. The support presented maximum enzyme loading at the support: enzyme ratio of 1:4. The immobilized enzyme displayed two ideal pH values (about 4.6 and 7) and two ideal temperatures (approximately 60 °C & 40 °C). It was discovered that the immobilized α-amylase could be used easily eight times with 9.9 % residual activity. The findings of this study show that the immobilized cellulose tosylate enzyme has the potential for application in both acidic and neutral pH environments with the best activity for commercial use.

A new method for rapid brucite quantification using thermogravimetric analysis

Brucite [Mg(OH)2] is a trace mineral found in ultramafic deposits that readily reacts to trap atmospheric CO2. Identifying and quantifying brucite content is an essential first step in determining the carbon sequestration capacity of many ultramafic mine tailings. Quantification via X-ray diffraction (XRD) has proven problematic in the past due to peak overlap issues between brucite and chlorite. Quantitative thermogravimetric analysis (TGA) methods have been used previously; however, they typically require multiple long (>10 h) analyses. Here, we demonstrate a method for rapid quantification of brucite content via TGA. Using an exponential model to fit and ignore mass loss from other minerals, brucite can be consistently detected and quantified at abundances of as low as 0.3 wt.%, a detection limit that is superior to XRD. Relative errors are as low as 3.4% for brucite abundances greater than 2 wt.%.

Pyrolysis of hybrid polyurethane inorganic thermal insulation: thermogravimetric analysis and FTIR spectra

Purpose. The purpose of this work is to study the process of thermal decomposition (pyrolysis) of two samples of a hybrid organic-inorganic (OIH) heat-insulating material based on data obtained by thermogravimetric analysis and IR-Fourier spectrometry. The goal set predetermined the following research tasks: to find out the basic chemical structure of the OIH samples (by functional groups), to study the order of processes in materials when heated in nitrogen, to calculate the activation energy, the pre-exponential factor, to determine the pyrolysis mechanism. Methods. The methods of thermogravimetric analysis and IR-Fourier spectrometry were used in the work. Samples for spectrometric analysis were prepared in the process of thermogravimetric tests using the “freezing” experiment method. Results and discussion. The paper studies the structural features of two samples of hybrid polyurethane inorganic (OIH) thermal insulation material and traces the physicochemical processes that occur when they are heated under dynamic conditions in a nitrogen atmosphere up to 750 °C. The multi-stage nature of the pyrolysis of the OIH material is shown. The pyrolysis of the first sample is a threestage process. For the second sample, decomposition proceeds in two stages. All stages are endothermic. This indicates the predominance of energy costs for breaking bonds between the organic and inorganic parts and other conclusions. It has been established that the pyrolysis of OIH samples at all stages is carried out according to the mechanism of nucleation and the growth of nuclei (active centers of destruction). Analysis of the IR spectra of the samples showed that both samples were prepared using Desmodur aliphatic isocyanates. Conclusions. The paper studies the chemical structure and physicochemical changes when heating the new group of materials — hybrid organic-inorganic (OIH) heat-insulating materials. The article is a continuation of a team of authors systematic study of a thermal behavior of modern types of polymer thermal insulation.

Intrinsic combustion kinetics of rapid-pyrolysis Zhundong coal char

Driven by the demand for accurate intrinsic kinetics for the prediction of the combustion rate of purely fired Zhundong coal (ZDC) in a slag tapping boiler, the surface activation function (SAF) and intrinsic kinetic parameters of two types of rapid-pyrolysis ZDC chars were revealed via the isothermal and nonisothermal thermogravimetric analysis methods. The isothermal kinetic results show that the activation energy (E), reaction order and SAF of these two chars were the same, at 146 kJ/mol, 0.78 and X0.44 (1 – X)−0.48, respectively. Therefore, the difference in the intrinsic reaction rate between these two chars was caused only by the different pre-exponential factors, which are mainly influenced by the specific surface area and catalytic elements in char ash. Nonisothermal kinetic parameters were obtained via the isothermal model-fitting method (ISOM), thereby using the isothermal SAF to fit the nonisothermal data at different heating rates (βs). The results indicate that the E values of the two chars were 148.95 ± 3.12 kJ/mol and 146.16 ± 1.66 kJ/mol, indicating that β has little influence on E. These measured values are consistent with the isothermal E values, so the ISOM is suitable for the determination of the nonisothermal kinetics of rapid-pyrolysis char combustion.

Thermogravimetric analysis-based proximate analysis of agro-byproducts and prediction of calorific value

Domestic agro-byproduct potential in Korea is estimated to be approximately 4,018 × 103 tons of oil equivalent per year. Majority of agro-byproducts are unused and discarded. These unused agro-byproducts can potentially be converted into solid fuel for value addition. The energy potentials of solid fuels are generally characterized by proximate analysis and measuring calorific value; however, owing to the use of coal and coke, both the analyses could be expensive and time-consuming. Proximate analysis via thermogravimetric analysis is a relatively low cost and less time-consuming method than proximate analysis by ISO method (ISO 18134-1:2015, ISO 18123:2015, ISO 18122:2015). Thermogravimetric analysis-based proximate analysis of four agro-byproducts (pepper stem, perilla stem, corn stalk, and kenaf) was conducted. Additionally, the calorific values obtained from several equations based on the proximate analysis results were compared to that of the calorific value measured using calorimeter. The maximum difference between proximate analysis using thermogravimetric analysis and ISO method was 4.73%p, which was attributed to change in moisture content. It is recommended to measure the moisture content of biomass for 120–150 min (at 105 °C) and ash content for 80–120 min (at 815 °C). Three of the equations indicated a difference of less than 1.5 MJ kg−1 between the TGA-derived and the measured calorific value. For this study, It was determined that both proximate analysis and prediction calorific value can be conducted by thermogravimetric analysis.

Thermal Analysis of Parylene Thin Films for Barrier Layer Applications.

Biocompatible polymer films demonstrating excellent thermal stability are highly desirable for high-temperature (>250 °C) applications, especially in the bioelectronic encapsulation domain. Parylene, as an organic thin film, is a well-established polymer material exhibiting excellent barrier properties and is often the material of choice for biomedical applications. This work investigated the thermal impact on the bulk properties of four types of parylene films: parylene N, C, VT4, and AF4. The films, deposited using the standard Gorham process, were analyzed at varying annealing temperatures from room temperature up to 450 °C. Thermal properties were identified by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) methods, while X-ray diffraction (XRD) analysis showed the effect of high-temperature exposure on the structural properties. In addition to thermal and structural analysis, the barrier properties were measured through the helium transmission rate (HTR) and the water vapor transmission rate (WVTR). Fluorinated parylene films were confirmed to be exceptional materials for high-temperature applications. Parylene AF4 film, 25um thick, demonstrated excellent barrier performance after 300 °C exposure, with an HTR and a WVTR of 12.18 × 103 cm3 (STP) m−2 day−1 atm−1 and 6.6 g m−2 day−1, respectively.

5-Hydroxyisophthalic acid and neocuproine containing copper(II) complex as a promising cytotoxic agent: Structure elucidation, topology, Hirshfeld surface, DFT calculations, and molecular docking analysis

We aimed to synthesize a new copper(II) complex, namely [Cu(H2IPA)(NC)(Cl)]⋅H2O (1) (where, H3IPA = 5-hydroxy isophthalic acid and NC = 2,9-dimethyl-1,10-phenanthroline or Neocuproine) as a promising chemotherapeutic agent. Complex 1 was structurally characterized by single-crystal X-ray diffraction (SCXRD), UV-Visible, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and powder X-ray diffraction (PXRD) methods. Single crystal diffraction analysis reveals that Cu(II) ion exists in a distorted square pyramidal geometry, with the ligation of a chloride ion, two oxygen atoms, and two nitrogen atoms. Topological structural simplification of complex 1 shows ins as an underlying net. The prominent intermolecular interactions and their quantitative contributions in complex 1 were investigated using Hirshfeld Surface (HS) analysis. The DFT calculations were also performed to validate the experimental results (XRD, FTIR, and UV-Visible). In vitro cytotoxicity of complex 1 was performed against acute myeloid leukemia (THP-1), colorectal (SW480), and prostate cancer (PC-3) cell lines by utilizing MTT assay. The result shows that complex 1 has the ability to inhibit the growth of cancer cells at a lower concentration. The morphological changes that occur during apoptosis were carried out with acridine orange/ethidium bromide (AO/EB) staining methods on THP-1 and SW480 cancer cell lines. Additionally, comprehensive molecular docking studies were performed to understand the potential binding interactions of complex 1 with target protein and DNA double helix.

Synthesis and characterization of antibacterial polyurethane rigid foam nanocomposites by incorporation of tea tree oil as a natural biocide

Synthesis and characterization of novel Tea Tree Oil (TTO) loaded antibacterial polyurethane rigid foams using two distinct methods is reported. In the first method, 3-aminopropyltriethoxysilane (APTS) functionalized mesoporous silica was used as the carrier of TTO for preparing amino-functionalized mesoporous silica (TTO-NH2-MCM-41). In the second one, TTO is encapsulated by silica via the sol-gel method, then using APTS, silica nanocontainers functionalized with amino groups (TTO@NH2-SiO2NCs), which is known to display antibacterial properties. Field Emission Scanning Electron Microscopic (FE-SEM), High-Resolution Transmission Electron Microscopic (HRTEM), Fourier transform infrared (FTIR), Brunauer-Emmett-Teller (BET), and Thermogravimetric Analysis (TGA) analyses were used to characterize morphological, structural, and thermal properties of the prepared nanoparticles, respectively. The prepared antibacterial polyurethane rigid foams, which had 2.5, 5, and 7 percent of the two synthesized nanoparticles, characterized by FE-SEM, ATR-FTIR, TGA, and antibacterial performance assay methods, respectively. The obtained results from the viable cell count (direct contact) antibacterial performance method exhibited that antibacterial polyurethane rigid foam containing 7 % of TTO-NH2-MCM-41 has a robust antibacterial activity with > 99.9 % reduction of viable bacteria (>4 Logarithmic reduction) for Staphylococcus aureus bacteria.

Polymerization of D,L-lactide in the presence of Boltorn™ polyester polyol

Objects. To synthesize monodisperse biodegradable hyperbranched polymers based on D,L-lactide in the presence of Boltorn™ H30 polyester polyol as a macroinitiator.Methods. 1H and 13C nuclear magnetic resonance (NMR) spectroscopy was used to study the chemical structure of the Boltorn™ H30 polyester polyol and (Boltorn™ H30)-PDLA hyperbranched copolymers. The molecular weight distribution of the polymers was studied by gel permeation chromatography (GPC). In order to study the thermal stability of Boltorn™ H30 polyester polyol, thermogravimetric analysis (TGA) was used. Polymerization of D,L-lactide was carried out in a block in the presence of Boltorn™ H30 polyester polyol.Results. The degree of branching of Boltorn™ H30 polyester polyol was calculated from NMR data, while the TGA method was used to determine the upper operational temperature range. The polymerization of D,L-lactide in the presence of Boltorn™ H30 polyester polyol used as a macroinitiator was studied. The molecular weight characteristics of the obtained copolymers were studied by NMR and GPC.Conclusions. Optimum conditions were determined for the polymerization of D,L-lactide when using Boltorn™ H30 polyester polyol as a macroinitiator. The possibility of synthesizing narrowly dispersed hyperbranched polymers (Boltorn™ H30)-PDLA under the described conditions was demonstrated.

Characterization of activated carbons for water treatment using TGA-FTIR for analysis of oxygen-containing functional groups

Water treatment with activated carbon (AC) is an established method for the removal of organic micropollutants and natural organic matter. However, it is not yet possible to predict the removal of individual pollutants. An appropriate material characterization, matching adsorption processes in water, might be the missing piece in the puzzle. To this end, this study examined 25 different commercially available ACs to evaluate their material properties. Frequently reported analyses, including N_2 adsorption/desorption, CHNS(O), point of zero charge (PZC) analysis, and X-ray photoelectron spectroscopy, were conducted on a selected subset of powdered ACs. Inorganic elements examined using X-ray fluorescence and X-ray diffraction spectroscopy revealed that relative elemental contents were distinctive to the individual AC’s raw material and activation procedure. This study also is the first to use thermogravimetric analysis (TGA) coupled to Fourier-transform infrared spectroscopy (FTIR) to conduct quantitative analyses of functional surface oxygen groups (SOGs: carboxylic acid, anhydride, lactone, phenol, carbonyl, and pyrone groups) on such a large number of ACs. The comparably economical TGA method was found to provide good surrogates for the PZC by pyrolytic mass loss up to 600 ^{circ }C (ML_{600}), for the oxygen content by ML_{1000} and for the carbon content by oxidation. Mass loss profiles depict the AC’s chemistry like fingerprints. Furthermore, we found that SOG contents determined by TGA-FTIR covered a wide individual range and depended on the raw material and production process of the AC. TGA and TGA-FTIR might therefore be used to identify the suitability of a particular AC for a variety of target substances in different target waters. This can help practitioners to control AC use in waterworks or wastewater treatment plants.

Investigation of Pyrolysis and Mild Oxidation Characteristics of Tar-Rich Coal via Thermogravimetric Experiments

Tar-rich coal has the potential to substitute the supply of oil-gas resources, which is abundant in China. The effective conversion of tar-rich coal into oil-gas products can promote coal utilization, reduce resource wastage, alleviate environmental pollution, and benefit carbon neutrality. Nevertheless, less work, if any, has been performed on the pyrolysis and mild oxidation behaviors of tar-rich coal in Northwestern China. The influences of limited oxygen addition and an extremely low heating rate on the micromorphology of the residual semi-coke are yet to be fully understood. Here, an experimental study on the pyrolysis and mild oxidation characteristics of tar-rich coal was conducted by the thermogravimetric analysis method, with further elucidation of the physical–chemical properties of the residual semi-coke. Experimental results show that an increase in the ultimate temperature of pyrolysis leads to a decline in the residue mass, while the mass loss from 500 to 550 °C presents the maximum elevation. Volatile matter is inclined to discharge from a certain direction, and the pores formed in various directions hold different possibilities. The organic components undergo both pyrolysis and slow oxidation with limited oxygen in the heating medium. Compared with an inert atmosphere, the mass loss under conditions of a small amount of O2 is brought forward but prolonged. Compared with a N2 atmosphere, the oxidation reactions of tar-rich coal are weakened in the presence of CO2. A large decrease in the heating rate exerts an unfavorable effect on the production of total volatiles. An extremely low heating rate possibly brings about a change in the mechanism of chemical bond cracking during pyrolysis. More pores can be yielded in tar-rich coal with an increase in the heating rate, and the morphology of the residual semi-coke after pyrolysis is susceptible to the heating rate. The present study offers an improved understanding of the pyrolysis characteristics of tar-rich coal as well as insights into the efficient utilization of tar-rich coal.

Access to Green Pyrotechnic Compositions via Constructing Coordination Polymers: A New Approach to the Application of 3,4-Dinitropyrazole.

Alkali and alkaline-earth metal salts with 3,4-dinitropyrazole (DNP) were synthesized by the reaction of DNP with stoichiometric amounts of the corresponding metal hydroxide-, oxide-, or carbonate-based highly pure salts, and products were fully characterized. Determination of single-crystal structures of all new complexes except for the lithium and strontium salts was performed by X-ray diffraction techniques. The cesium salt crystallized no water among them. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) manifested that these salts have satisfactory thermal stabilities with decomposition temperatures above 210 °C. They also showed that there exists strong bonding of crystallized water among lattices, which disappeared at temperatures equal to or above 115 °C except for salts MES-3, MES-4, and MES-9. In addition, the percentage of water contents was confirmed by using DSC and TGA methods. The constant-volume combustion heats of these metal salts containing DNP anions were measured using an oxygen bomb calorimeter due to their expectant interest in energetic materials, and their standard molar formation enthalpies were obtained. The investigated salts were found to be insensitive toward friction and impact. Findings of burning tests performed with experimental formulations using MES-1, MES-7, MES-8, and MES-9 certify that these four salts might be more promising candidates for application in green pyrotechnics.

Synthesis, characterization, and evaluation of antimicrobial performance of N‐[3‐(dimethylamino)propyl]methacrylamide based copolymer on pathogens

AbstractIn this study, poly{N‐[3‐(dimethylamino) propylmethacrylamide‐co‐acrylonitrile}; [P(DMAPMA‐co‐AcN)] copolymer was polymerized by free radical polymerization (FRP) in the presence of azobisisobutyronitrile (AIBN) initiator at 60°C. The structure of the synthesized polymer was characterized by the Fourier transform infrared (FT‐IR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) methods. The bactericidal and fungicidal effects of the solutions prepared by adding methanol to this copolymer to prevent the growth of pathogenic bacteria, yeast, and fungi were evaluated by disk diffusion and broth microdilution method. Since the resistance of bacteria, yeast and fungi, which adversely affect human health, to antibiotics is an important issue, and there has not been any study on the antimicrobial properties of this copolymer, it has directed us to investigate its antimicrobial properties. According to antimicrobial susceptibility tests: The polymer solution showed a broad spectrum of antimicrobial action with 12.3–14.3 mm/inhibition zone diameter on Pseudomonas aeruginosa, Klepsiella pneumoniae, Enterococcus faecalis bacteria, Candida tropicalis, Epidermophyton floccosum yeast and fungi and showed a narrow spectrum of effect on inhibition of the growth of Candida albicans with 10.3 mm/inhibition zone diameter. No antimicrobial effects were observed on Staphylococcus aureus. The minimum inhibition concentration (MIC) value on the test microorganisms was determined as 125–31.25 μl. The data obtained prove that the polymer is in the same group as the interaction of bactericidal and fungicidal drugs. It is also important as a polymer with antimicrobial properties. This study aimed to produce a new polymer with antimicrobial properties. This polymer can be a new and yielding antimicrobial representative in different areas.

Utilization of flue gas desulfurization gypsum to produce green binder for dredged soil solidification: Strength, durability, and planting performance

The massive deposition of sediment in the Yellow River leads to the waste of land resources and is also prone to environmental disasters. In this study, the industrial by-product, flue gas desulfurization gypsum (FGDG), was incorporated with Portland cement (PC) and fly ash (FA) to treat the dredged soil (DS) from the Yellow River. The effects of initial water content of DS (w0), binder content (Aw), and the FGDG content in binder on the strength development and durability of solidified dredged soil (SDS) were analyzed via a series of UCS, pH value, and dry-wet cycles tests. Additionally, the planting performance of SDS was evaluated by planting wheat grass, and the microstructure characteristics were conducted by X-ray diffraction (XRD) analysis, thermogravimetric (TG) analysis, and scanning electron microscope (SEM) method. The results indicate that, when the binder containing 50% FGDG, the SDS sample has good strength and resistance to dry-wet cycles, and decreasing w0, increasing Aw, or reducing the FGDG content in binder can obviously improve the strength and durability of SDS. Furthermore, increasing the FGDG content in binder is more beneficial to germination and growth of plants. The micro-analysis shows that, during the dry-wet cycles test, the amount of hydration products (i.e., C–S–H and AFt) in SDS increased significantly, and the structure became denser, resulting in the increase of strength. During planting, the pH of SDS decreased rapidly to about 8.5, mainly because the root respiration accelerated the carbonization of Ca(OH)2 crystals in sample.

Thermal Decomposition Behavior of Polyimide Containing Flame Retardant SiO2 and Mg(OH)2.

The effects of flame retardant silica (SiO2) and magnesium hydroxide (Mg(OH)2) on the thermal decomposition process of polyimide (PI) are discussed in this paper. Firstly, the decomposition process of PI in a nitrogen and oxygen atmosphere was studied by thermogravimetric analysis and differential scanning calorimetry methods, and the kinetic parameters were calculated by the nonlinear fitting method. In an inert atmosphere, PI decomposition consists of a three-step endothermic reaction, whereas in an oxygen atmosphere, PI decomposition consists of two steps, in which the first step does not change, and the second step changes to a violent exothermic peak. The effects of 3 wt % SiO2 (SPI) and 3 wt % Mg(OH)2 (MPI) on the degradation kinetics of PI are discussed. The results show that under an oxygen atmosphere, SiO2 and Mg(OH)2 hydroxide mainly delayed the second-step oxidation exothermic peak temperature of PI by 5 °C. In summary, the first step of the PI degradation is not affected by oxygen, and the flame retardant mainly acts in the second step, which can delay the oxidation heat release. In addition, the addition of SiO2 could prevent PI from aging whereas Mg(OH)2 has barely effect on the aging of PI.

Thermogravimetric analysis of the combustion of Tuva coals before and after their carbonization

The process of combusting Tuva coals before and after their carbonization was studied using the methods of thermogravimetric analysis and electron microscopy. Coal samples were subjected to thermomechanical and elemental analysis, which revealed a higher content of volatile substances in Kaa-Khem coal (47.5 %) compared to Chadan coal (10 %). Following carbonization, a decrease in volatile substances to 11.5 % and 9.3 %, respectively, was observed. The conducted thermogravimetric analysis showed the ignition temperature of the coke residue of the Kaa-Khem and Chadan coal samples to increase by 76 °C and 90 °C, respectively, after carbonization. The burnup temperature of the coke residue after carbonizing (723 °C) Kaa-Khem coal samples remained effectively the same, while the Chadan coal showed an increase from 704 °C to 727 °C. The carbonization of coals was established to decrease the maximum reaction rate from 19 % per min to 10% per min for Kaa-Khem coal and from 26 % per min to 11 % per min for Chadan coal. The process of combusting the coke residue after coal carbonization was found to shift into the region of higher temperatures: from 448–723°C to 524–724°C for Kaa-Khem coal and from 436–704 °C to 526–727 °C for Chadan coal. A morphological analysis of the surface of coal particles after carbonization showed the appearance of larger-size pores and cracks on the surface of carbonates compared to coal before carbonization. The conclusion is made that the content of volatile substances, rather than the developed pore structure, comprises the main factor in improving the combustion characteristics of Tuva coals under the conditions of non-isothermal heating before and after their carbonization.

Construction of a 3D Metal-Organic Framework and Its Composite for Water Remediation via Selective Adsorption and Photocatalytic Degradation of Hazardous Dye.

In this work, a new bimetallic Na(I)–Zn(II) metal–organic framework (MOF), formulated as [Na2Zn3(btc)2(μ-HCOO)2(μ-H2O)8]n (1) (H3btc = benzene tricarboxylic acid), and its composite (ZnO@1) have been successfully synthesized using solvothermal and mechanochemical solid grinding methods. 1 and ZnO@1 were characterized by diffraction [single-crystal X-ray diffraction (XRD) and powder XRD], spectroscopic (ultraviolet–visible diffuse reflectance spectroscopy and Fourier transform infrared spectroscopy), microscopic (transmission electron microscopy), and thermal (thermogravimetric analysis) methods. The surface area and porosity of 1 were determined using a Brunauer–Emmett–Teller analyzer. Single-crystal diffraction of 1 confirms that Na1 and Zn2 have octahedral coordination environments, whereas Zn1 has a tetrahedral coordination geometry. Topological simplification of 1 shows a 3,6-connected kgd net. Na(I)–Zn(II) MOF (1) is crystallized with slight porosity and exhibits good tendency toward the encapsulation of zinc oxide nanoparticles (ZnO NPs). The photocatalytic behaviors of 1 and its composite (ZnO@1) were investigated over MB dye under sunlight illumination with promising degradation efficiencies of 93.69% for 1 and 97.53% for ZnO@1 in 80 min.

Obtaining additional product from sugar beet

The possibility of intermediate products - yellow sugars - processing for obtaining additional products manufactured by the sugar industry is studied in this work. Their main disadvantage is the presence of a non-sugars film on the crystal surface. This film contains high molecular weight colouring agents and other compounds that have not been removed during the juice purification process. The objectives of this study were to select the optimal conditions for the affination purification of yellow sugar crystals, to determine its quality characteristics, and to assess the possibility of its application in food production. The use of yellow sugar melting as an affining solution was justified in the work. The affination process optimal parameters were selected with the mathematical modeling methods. The efficiency of mineral compounds and toxic elements removal in the process of affination was studied, the microbiological parameters of sugars were determined. It was found out that the affination process caused a decrease in the total microbial contamination and the amount of mucus-forming microflora, while thermophilic microorganisms, yeasts and moulds completely disappeared. Affinated yellow sugar contained less sucrose than white sugar did. It partially retained mineral and organic components of sugar beet, and this increased its demand. A product from affinated yellow sugar with the rosehip powder added was produced; rational conditions for its obtaining were selected within the framework of the study. The characteristics of this product were investigated by sensory, spectral and thermogravimetric analysis methods. It was found out that the rosehip powder added into the composition of the product based on affinated yellow sugar had a beneficial effect on its characteristics. The studies carried out allow us to conclude that affinated yellow sugar is possible to use as a raw material for obtaining new products.