Muffle Furnace Research Articles

Structural, morphological, XPS, dielectric and spectral properties of sol-gel synthesized Ba–Zn–Cr U-type nanocrystalline magnetic oxide materials

Polycrystalline Cr3+ substituted Ba4Zn2Fe36-xCrxO60 (Zn2U) U-type hexaferrite compositions Ba4Zn2Fe36-xCrxO60 (x = 0.0, 0.5, 1.0, 1.5, and 2.0) were fabricated using the sol-gel self-ignition technique. U-type hexaferrite structure was achieved by sintering the powdered samples for 6 h at 1200 °C in a muffle furnace. The phase identification and structural parameters of Zn2U hexaferrites were evaluated by X-ray diffraction peaks of the powdered samples. Lattice parameters (a,c) and unit cell volume decreased upon Cr3+ substitution. The crystallite size was measured between 61 and 57 nm. FTIR spectra revealed the existence of specific absorption (Fe–O) bands at wavenumbers 419 and 539 cm−1. These bands further verify the formation of U-type hexaferrite. SEM micrographs showed the platelet-like morphology of the grains with proper hexagonal structure. X-ray photoelectron spectroscopy (XPS) results confirmed the existence of all metal ions with their corresponding electronic states. The dielectric response of the fabricated Zn2U U-type hexaferrite pellets was investigated at room temperature through a vector network analyzer with a wide frequency band from 1 MHz to 6 GHz. Dielectric constant (εʹ) was increased for the compositions x = 1.0 and 1.5 while dielectric loss (εʺ), tangent loss (tanδ), and ac conductivity (Ϭac) were reduced upon Cr3+ substitution. Single semicircles in the impedance Cole-Cole plots revealed that grain boundaries play a vital role in the conduction process of prepared U-type hexaferrites. Microwave absorption (MW) was improved with Cr3+ substitution. The minimum reflection loss (RL) of −53dB (99.99% MW absorption) at frequency 1.3 GHz was obtained for composition x = 0.5. The dielectric analysis (low losses and high Q-values) of the prepared hexaferrites predicts their appropriate use in high-frequency device applications.

Dielectrically modified Nd3+ doped (Ni–Mn) based spinel ferrite Ni0.5Mn0.5NdxFe2-xO4 nanoparticles for energy storage applications

The neodymium doped Ni–Mn based spinel ferrites nanomaterials Ni0.5Mn0.5NdxFe2-xO4 with doping concentration of 0.00–0.20 were synthesized by sol gel auto-combustion method. All the samples in fine powder were annealed at 600 °C in a muffle furnace for 4 h to remove the impurities and absorbed gases. In XRD patterns, the obtained high intense diffraction peak at (311) is good evidence that the prepared materials are spinel ferrites. With the help of Scherer method, the crystallite size was calculated in nanometer ranging from 13 to 19 nm. Further, the calculated crystallite size was correlated with Williams's Hall, modified Scherrer and size strain plot (SSP) method. The study of surface morphology by scanning electron microscopy (SEM) revealed that some grains are non-uniform at different concentration of neodymium. Fourier transform infrared-spectroscopy (FTIR) analysis was used to study the relationship between transmittance and wavenumber. The pattern obtained from tetrahedral and octahedral site represents two frequency band v1 and v2. The electrical properties like dielectric constant, tangent loss, electric modulus and ac conductivity were studied by impedance analyzer in applied frequency range 1 MHz–3 GHz and result was explained by using Maxwell Wigner method. It was found that there are some relaxation peaks were observed at high frequency due to hopping of electrons. By using Vibrating sample magnetometer (VSM), the magnetic properties were studied in the applied magnetic field ranging from -3kOe to 3 kOe. The hysteresis loop shows the decreasing in retentivity (Mr), magnetization (Ms) and coercive field (Hc). In conclusion, these prepared materials are very useful for energy storage device applications.

Study on High-Temperature Oxidation Behavior of Platinum-Clad Nickel Composite Wire

Platinum-clad nickel composite wires with platinum layer thicknesses of 5 μm and 8 μm were prepared by a cladding drawing process. Oxidation experiments were performed using a muffle furnace at temperatures of 500 °C, 600 °C, 700 °C, and 800 °C for 1 h, 2 h, and 3 h. The oxidized samples were examined for high-temperature oxidation behavior using scanning electron microscopy (SEM) with an energy-dispersive X-ray (EDX) spectrometer attached. The results showed that the interface bond between the platinum cladding and the nickel core wire was serrated and that the thickness of the platinum cladding was not uniform. At low temperatures (500 °C and 600 °C), the diffusion rate of the nickel was low. The composite wire could be used for a short time below 600 °C. When the temperature reached 700 °C and above, the nickel diffused to the surface of the composite wire and was selectively oxidized to form a nickel oxide layer. The research results provide a theoretical reference for the selection of a service temperature for platinum-clad nickel composite wires used as the lead material for thin-film platinum resistance temperature sensors.

Preparation Physicochemical Evaluation and Characterization of Tamra Bhasma

Background: Bhasmas is an ancient nanomedicine prepared with herbs and minerals or metals and can be used for curing various diseases and disorders. Bhasma a herbomineral preparation called as Tamra Bhasma prepared from metallic copper which is recommended for various ailments. The Tamra Bhasma was prepared by various processes by sodhana, marana and bhavana. Aim: The aim of the research work was to prepare Tamra Bhasma by subjecting to various methods of preparation such as Sodhana, purification, Marana, incineration and Bhavana, levigation. Tamra Bhasma was prepared by using Electric Muffle Furnace and traditional method varaputa method. Methods: The Bhasma was prepared by Samayana sodhana by incorporation of Tila taila, Takra, Gomutra, Kanji and Kulatha Kwatha. The prepared Bhasma was subjected to quality control and evaluation studies such as ash values, acid insoluble ash value and water-soluble ash value, extractive values, colour, odour, taste, appearance, floating test, finger print analysis, curd test, etc. Results: The prepared Bhasma was subjected to characterizations which include Infrared spectroscopy (FTIR), X-Ray Diffraction (XRD) and (SEM) was performed for the Bhasma and Scanning Electron Microscope was used to determine the size and shape of Bhasma. Conclusion: The ancient methods can be used to prepare these precious formulations and these predominant formulations can be preserved in future.

Optimization of microwave-assisted biodiesel production from watermelon seeds oil using thermally modified kwale anthill mud as base catalyst

A heterogeneous catalyst was developed from raw Kwale red Anthill mud by thermal treatment in a muffle furnace at 900 °C for 4 h. The resulting heterogeneous catalyst was highly porous with a surface area of 42.16m2/g, possessing excellent stability as well as high catalytic activity. Central Composite Design and Machine Learning approach (Python code) were applied to model and optimize biodiesel yield from extracted watermelon oilseed. Highest biodiesel yield of 93.41 wt% was obtained under the experimental conditions of 4min duration, 350 W microwave power, 4 wt% of catalyst, and MeOH/oil ratio of 8:1 based on Central Composite Design rotatable. The optimum value of the biodiesel yield from Machine Learning was 91.7 wt%, showing a marginal performance over the Central Composite Design rotatable value (91.6 wt%) at the optimized conditions of 3 min, 280 W, 3 wt% catalyst loading and MeOH/oil molar ratio of 6:1. The correlation of the coefficient (R2) of the model was 0.9827 for Central Composite Design rotatable while the R2 of the Machine Learning model was 1.0. Thus, python coding in terms of prediction and accuracy of biodiesel yield was superior to Central Composite Design rotatable, even though both models provide a reliable response within the region of data analyzed. The Gas Chromatography-Mass Spectroscopy of the biodiesel produced revealed the presence of both saturated and unsaturated fatty acid methyl esters. Biodiesel properties from watermelon seed oil transesterification fall within the recommended standard for biodiesel fuel. This study concluded that an effective green biowaste catalyst generated from earthen waste could enhance biodiesel production from watermelon seed oil, hence, ensuring sustainability and economic feasibility for biodiesel industries.

Analysis of structural and optical properties in co doped Mn,Gd in bismuth ferrite (BiFeO3) thin films prepared by sol-gel technique

In this paper, we reported the structural and optical properties of co-doped bismuth ferrite (Bi0.99Gd0.01Fe0.99Mn0.01 O3) thin films that were fabricated on corning glass substrates by sol-gel spin coating technique. The thin films were deposited in different layers on the glass substrates(3,4,5-layers) and annealed at 550 °C in a muffle furnace for 2 hrs in air. The effect of co-doping and thickness on structural and optical properties of bismuth ferrite perovskite thin film was systematically studied and analyzed. The X-ray diffraction pattern of the sample films fabricated confirms the existence of a Rhombohedral structure with space group (RE). Transmittance spectra and absorption spectra were determined by Ultraviolet–visible (UV–Vis) spectrophotometer. The optical band gap of films with different coating layers was estimated from Tauc’s plot of the optical data.

Effects of graphene content on the wear properties of aluminum matrix composites prepared by powder metallurgy route

In this experimental work, the effect of graphene addition (GPNS) on the sliding wear properties of aluminum (Al) metal powder composite was investigated. A ball milling mixture was used to combine four different amounts of graphene (0, 0.5, 1, and 1.5 wt%) with aluminum metal powder. The powder was compacted using a UTM machine and sintered using an electric muffle furnace. Electron microscopy (SEM), elemental electron dispersion (EDS), and X-ray diffraction (XRD) were used to characterize the microstructure, elements, and phases of sintered Al-GPNs specimens. Mechanical properties were investigated using hardness and density. Sliding wear test against EN-32 Counter disc was conducted using pin and disc wear test. The morphology of sintered composite shows that the addition of graphene makes the microstructure homogeneous. Al-1GPNs sintered composite showed maximum hardness (55Hv) and density (2.56 g/ cm3). The addition of graphene also improved the wear and friction properties, and Al-1GPNs sintered composite exhibited minimum weight loss.

Thermoluminescence mechanism of microwave combustion synthesized γ-irradiated Al2O3:Tm3+ phosphor

The thermoluminescence (TL) mechanism of γ-irradiated Al2O3:Tm3+ phosphor is presented in this paper. Al2O3:Tm3+ phosphors are synthesized by muffle furnace combustion (MFC) and microwave combustion (MWC). XRD results exhibit the stable alpha phase of Al2O3 and crystallite size is found to be ∼99 and ∼147 nm for MFC and MWC synthesized samples respectively. The optical band gap (Eg) of MFC and MWC synthesized Tm3+-doped materials is found to be 4.27 and 4.31 eV, respectively using DRS. TL glow curves of γ -irradiated Al2O3:Tm3+ phosphor are recorded for the dose ranging from 0.1 to 20 Gy. TL glow curves of γ - irradiated phosphor show a prominent peak at ∼453 K along with a shoulder at ∼500 K. The prominent TL glow peak (455 K) intensity of MWC synthesized Al2O3:Tm3+ is ∼2.56 times higher than MFC synthesized phosphor. The TL emission spectra of 455 K glow peak show emission at 298, 355, 394, 466, 526, and 658 nm corresponding to the 1I6→3H6, 1D2→3H6, 3P2→3H4, 1G4→3H6, 1D2→3H5 and 1D2→3H4 characteristic transitions of Tm3+. TL emission spectrum exhibits Cr3+ (R-lines) and Mn4+ characteristic emission peaks at 453 K along with Tm3+ emission. TL intensity of the MWC synthesized sample's prominent peak at 453 K increases linearly with a dose from 0.1 to 15 Gy and then it increases super-linearly with a dose up to 20 Gy. The kinetic parameters were calculated and the process of ionization of electrons from Tm3+, electron trap in host lattice, and its recombination mechanism is proposed.

Experimental research on muffle furnace dynamic properties

Purpose. To develop the method and software for building empirical models of muffle furnaces with two heating elements. Methodology. The method for processing experimental data according to the improved algorithm, which is based on the areas method, is used for constructing empirical models of the muffle furnace. Experimental research of the muffle furnace dynamic is conducted using the following methodology. The muffle furnace is cooled to the room temperature and then the lower heater is turned on and temperatures at the furnace output are fixed using the experimental two-channel temperature controller MIC-344. The second cycle of the experimental research began by cooling the furnace to the room temperature with turning on the upper heater. Observations based on the results of the experiment are conducted until the temperature is stabilized at the two outputs of the muffle furnace. Archiving of temperature trends is carried out using the RS485/Ethernet interface and the SmartReview software (a product of private limited company “Microl”). Findings. The developed software can be used for iteratively selection of the optimal empirical model based on the criterion of the root mean square deviation of the calculated and experimental data. The calculating method for the acceleration curve based on the transfer functions coefficients with a variable discreteness step is improved in order to compare the experimental data with the empirical modeling results. Twelve empirical models were tested for four signal transmission channels in the process of experimental research. It has been established that only four of them are stable (have left-hand roots of the characteristic equation). Among the selected sustainable models, the model with the numerator polynomial equaled to two and denominator polynomial equaled to three has been established as the best model (according to the established criterion). A structural diagram is created based on the synthesized empirical model of the muffle furnace, which includes four transfer functions and cross connections. Originality. For the first time, the empirical model of a muffle furnace with two electrical energy sources has been developed, which describes its dynamic properties as the object of automatic control with high accuracy, which enables to reveal the presence of internal cross-connections, that significantly complicate the controlling process of the object. Practical value. The created empirical models with two electric sources (tens) can be used for the synthesis of the high-precision automatic temperature control system of the muffle furnace.

Preparation of Porous Carbon Materials as Adsorbent Materials from Phosphorus-Doped Watermelon Rind

In this study, phosphorus-doped watermelon rind carbon material (WC-M) was prepared by a muffle furnace, and the adsorption performance of WC-M material to dyes was investigated. At the same time, the effects of dye concentration, pH, adsorption time, adsorption temperature, and other factors on the adsorption effect were investigated. In the experiment, a muffle furnace was used to carbonize the watermelon rind doped with phosphoric acid, which simplified the experimental operation. Regarding the results of SEM analysis, the surface structure of WC-M materials is diverse. Isothermal maps of nitrogen adsorption and desorption show that the material contains more microporous structures and exhibits more active sites. The experimental results show that WC-M materials show good adsorption properties against cationic dyes (malachite green, MG) and anionic dyes (active black, AB). The neutral condition is conducive to the adsorption of MG, and the alkaline condition is conducive to the adsorption of AB. The adsorption rate reaches a maximum in the initial stage of adsorption, the adsorption capacity reaches 50% of the total adsorption capacity within 10 minutes before the reaction, and then the adsorption capacity gradually decreases until the adsorption equilibrium. The adsorption mechanism was explored by the pseudo-first-order kinetic model, second-order kinetic model, and intraparticle diffusion model. At the same time, through the analysis of multiple isotherm models, the overall adsorption process followed the Langmuir isotherm model, the adsorption of MG was more inclined to monolayer electron adsorption, and the adsorption capacity reached 182.68 mg⋅g−1. The reusability of WC-M materials in MG and AB adsorption was discussed. At this time, the concentrations of AB and MG were 120 mg⋅L−1 and 150 mg⋅L−1, and after 10 h of desorption, the desorption rates of MG and AB reached 67.7% and 83.3%, respectively; after five adsorption–desorption cycles, the adsorption rate of MG was still 78.5%, indicating that WC-M materials have good recovery effect. At the same time, the use of watermelon rind as an adsorption material belongs to the high-value application of watermelon rind, which belongs to “turning waste into treasure” and will not pose a certain threat to the environment. This experiment is also suitable for durian rind, pineapple rind, and other “waste” biomass materials, and the experiment has certain generalizations.

Experimental and Simulation Analysis to Predict the Optimum Biodiesel Yield from Two Different Feedstock Using Heterogenous Base Catalyst

Abstract: Biodiesel can be easily used an alternative fuel. Using the Soxhlet apparatus, the oil waas extracted, and centrifuged to separate the oil. The physical characteristics of oil was determined. A number of >3 indicates an acid, while a value < 3 indicates a base. If the FFA content is >0.5, the substance is an acid, and if it’s less than 0.5, a base. Suitable solvent based on its physicochemical characteristics was selected. In this study two types of seeds were used. A mixed heterogeneous base catalyst containing CaO prepared from waste egg shells andcockle shells. The egg shells and cockle shells were dried in microwave oven for 24 hours at 120◦C and placed in Muffle furnace at 900 ◦C and mixed in 1:1 ratio. SEM, EDAX and FTIR were used to characterize the catalyst. The two feedstock used in this study was Solanum Torvum and Murraya Koenigii. Double Step Esterification was preferred. The oil was treatedwith the strong acid H2SO4 . Then oil along with methanol was treated with both acid and basecatalyst separately to give Fatty Acid Methyl Ester. Finally optimum condition was found for maximum yield of FAME, was obtained using RSM.

Experimental Analysis and Remediation Rate of Copper and Nickel Contaminated Industrial Site Soil Using Biochar

Abstract: The most crucial element for construction purposes is healthy and good soil. Through the incorrect disposal of carcinogenic compounds, which seeps into the earth and degrades soil quality, heavy metals and metalloids can contaminate soil. The goal of this project is to turn biomass into biochar and re-apply it to the soil in order to disrupt the source-receptor pathway, which will lead to heavy metal-free soil and an improvement in soil characteristics. Biochar is a material made of waste biomass that is highly porous, carbon-rich, and fine-grained. Pyrolysis is a process in which biomass is subjected to thermochemical conversion without oxygen. Rice husk biomass was pyrolyzed in a muffle furnace at temperatures between 500 and 700 °C to create the biochar that was employed in this experiment. Through physical adsorption or an ion exchange mechanism, biochar has the ability to remove heavy metal ions like copper and nickel. The soil used in this study was gathered from the Kurumbapalayam, Coimbatore, electroplating factory. AAS was used to evaluate soil samples in order to measure the amount of heavy metals present. A method that is useful for calculating the amounts of trace elements contained in the soil sample is the use of an atomic absorption spectrometer (AAS). In order to determine the presence of metal oxide X-Ray Diffraction was done and to know the connection between the biochar and the soil, scanning electron microscopy (SEM) was done. Using a direct shear test, the shear strength of soil treated with various amounts of biochar was evaluated. Additionally evaluated were the soil's compaction characteristics and pH fluctuation in response to the addition of various biochar percentages. The outcome shown that adding biochar to the soil neutralises heavy metals and enhances the characteristics of the soil.

Processing of ore from the Nud II deposit by the method of low-temperature roasting with ammonium sulfate

The Murmansk region has a significant amount of sulfide copper-nickel raw materials. Deposits of the Nud massif associated with Monchepluton are promising for processing. The Nud II deposit cut-off grade ore with an initial Ni content of 0.45 % and Cu of 0.39 % has been chosen as the research object. During the research, the ore was mixed with ammonium sulfate, grinded, and the mixture was roasted in a muffle furnace with static air atmosphere. The roasted mixture was leached in heated distilled water with constant stirring. The maximum metals recovery was achieved when crushing to a fraction of –40 µm, the ratio of ore : ammonium sulfate is equal to 1 : 7, roasting temperature 400 °C, roasting duration 300 min. In the mixture roasted at these parameters, reflexes of copper and nickel sulfates were recorded by the x-ray phase analysis (XRD) method. At the stage of water leaching, the maximum recovery was: Ni – 79.1 %, Cu – 75.8 %.

Experimental Analysis of Heavy Metal Contaminated Electroplating Industrial Site Soil Using Tamarind Seed Biochar

Abstract: Biochar application is a promising strategy for the rehabilitation of contaminated soil while ensuring suitable waste management. Biochar is a highly porous organic material derived from wood, manure, or plant-based biomass through pyrolysis in a low-oxygen environment. Pyrolysis is a technique that produces biochar by means of the thermal decomposition of the feedstock in an oxygen-free environment. In this work, tamarind seed was pyrolyzed in a muffle furnace 500 – 700oC to prepare biochar. The soil is contaminated with the electroplating industrial effluent, which is rich in nickel (Ni), copper (Cu), and chromium (Cr) concentrations. In this study, the atomic absorption spectrophotometer (AAS) technique has been used to find the removal efficiency of heavy metals for a curing time of 7, 14 and 28 days soil samples The result obtained from the physicochemical analysis indicated that the contaminated soils recorded an acidic pH. Adding biochar to contaminated soil in different percentages (2%, 4%, 6%, 8%, and 10%) to increase the pH value and using direct shear test, the shear strength of the soil determined different percentage of biochar. The result obtained adding 8% of Biochar to get optimum Shear strength. The functional groups present in the raw biomass and pyrolyzed biochar are determined using fourier transform infrared spectroscopy (FTIR)

Residual mechanical properties of recycled aggregate concrete at elevated temperatures

AbstractThis research examines the residual mechanical properties of normal and recycled aggregate concrete when subjected to elevated temperatures. The concrete specimens containing recycled aggregate (0%, 50%, 75%, and 100%) were exposed to different temperatures (25, 200, 400, and 600°C) in a muffle furnace at a heating rate of 10°C/min. The variations in flexural strength, compressive strength, and density were then tested according to ASTM standards. Findings from this investigation indicate that the degradation in the mechanical strength of concrete does not seem to be significantly affected by the increase in the percentage of recycled aggregates. However, a significant and linear decrease in the density was observed at 400°C with an increase in the percentage of recycled aggregates. The degradation of the compressive and flexural strengths of recycled aggregate concrete with increasing temperatures obtained from the experimental analysis was compared with the analytical predictions provided by Eurocode 2. Moreover, simplified equations have been proposed to estimate the degradation of the mechanical properties of recycled aggregate concrete at higher temperatures. The incorporation of recycled aggregates into concrete resulted in satisfactory residual performance.

Synthesis of porous g-C3N4 nanosheets with carbon vacancies for photodegradation of direct red 227 and direct black 166 dyes in aqueous solutions

Porous graphitic carbon nitride (g-C3N4) nanosheets with carbon vacancies were synthesized by recalcination of bulk g-C3N4 in a muffle furnace in static air for 2 h at 550 °C. The synthesized product (RCN) was characterized using XRD, FESEM, FTIR, DRS, PL, EDX, and BET-EJH. The photoactivity efficiency of RCN was evaluated by its ability to degrade two heavy anionic textile dyes, direct Red 227 and direct Black 166, under visible light. The results showed RCN in the presence of OH− anions can degrade the mentioned dyes under visible light in a relatively short time. The free radical trapping tests showed that ·O2− is the active species and mainly responsible for color degradation, while the OH− ions from KOH (as a co-catalyst) increased the degradation rate by trapping the photogenerated holes (h+). Combination of photocatalyst and OH− as co-catalyst was used for the first time to degrade anionic textile dyes, direct Red 227 and direct Black 166.

Gas-Sensing Performance of Gadolinium Ferrates with Rod and Butterfly Morphologies

There is an urgent need to develop a low-cost and high-performance gas sensor for industrial production and daily life. Perovskite-type oxides are appropriate materials for resistive gas sensors. In this paper, two gas-sensing materials of gadolinium orthoferrite (GdFeO3) with rod and butterfly morphologies were obtained by annealing the corresponding precursors at 800 °C in a muffle furnace for 3 h. The precursors of GdFe(CN)6·4H2O with novel morphologies were prepared by a co-precipitation method at room temperature. The materials were evaluated in terms of their structure, morphology, and gas-sensing performance. The gas sensor based on GdFeO3 rods showed a better sensing performance than the sensor based on GdFeO3 butterflies. It exhibited the largest response value of 58.113 to 100 ppm n-propanol at a relatively low operating temperature of 140 °C, and the detection limit was 1 ppm. The results show that the GdFeO3 rods-based sensor performed well in detecting low concentration n-propanol. The satisfactory gas-sensing performance of the GdFeO3 rods-based sensor may be due to the porous structure and the large percentages of defect oxygen and adsorbed oxygen (37.5% and 14.6%) on the surface. This study broadens the application of GdFeO3 in the gas sensor area.

Catalytic graphitization of biomass-derived ethanosolv lignin using Fe, Co, Ni, and Zn: Microstructural and chemical characterization

Bamboo has just recently emerged as a sustainable source of lignin extraction, paving the way for the development of sophisticated nano- and biomaterials based on lignin. Catalytic pyrolysis effectively synthesized graphitic carbon from biomass resources. This article investigates the influence of various metals (Fe, Co, Ni, and Zn) as catalysts in the catalytic graphitization of bamboo biomass-derived lignin. The graphitization process was carried out through thermal treatments conducted in a tightly closed muffle furnace at 1100 ℃ for a duration of 4 hrs. The metals-catalyzed graphitic carbons appeared flake-like microstructures under SEM with > 80 wt% graphitized carbon composition detected by XPS. Enhancement in the degree of graphitization, crystallite size, interlayer distance, and structural order was achieved within the order of Fe>Co>Ni>Zn. These are corroborated by XRD, indicating Fe-catalyst resulted in lignin graphite with a degree of graphitization of 92.07%, crystallite size (Lc) of 230.2 nm, and interlayer distances of 0.336 nm that are closer to commercial graphite. Raman revealed the Fe-catalysed lignin graphite has a lower defective ratio (ID/IG) of 0.55, while all graphitized lignin showed IG/I2D of > 1.0, indicating multiple layers of graphitic carbon. These findings might pave the way for future high-value graphite-based materials made from low-cost biomass, making it an intriguing prospect.

Characterization of the physicochemical and thermal properties of different forest residues

The assessment of the variability of the fuel properties is essential information to understand combustion behavior and to develop mathematical models. This work comprehensively investigates the physicochemical and thermal properties of four different forest residues (eucalyptus, pine, acacia, and olive). Each fuel is fully characterized in terms of chemical composition by proximate and ultimate analysis and its calorific value. Furthermore, this study examines the variation in terms of the thermal properties and the ash elements to evaluate the tendency for slagging and fouling. Selected samples of the solid biomasses were tested using the Hot Disk Thermal Constants Analyzer TPS 2500S to measure the thermal conductivity, which was found in the range of 0.239–0.404 W/mK. In addition, the heat capacity was evaluated within 0.855–2.442 MJ/m3K, and the thermal diffusivity was between 0.187 and 0.258 mm2/s. The ultimate and proximity analyses were carried out on the fuel samples using LECO TruSpec CHN Macro and LECO CS-200 equipment and a muffle furnace, respectively. The results revealed a higher reactivity of eucalyptus, which was around 2 times higher than the other fuels, and the propensity of acacia to produce pollutant emissions (mostly Nitrogen based) and ash deposition problems due to their chemical composition.

Monitoring of the content of heavy metals and selenium in com-pound feeds for productive animals and poultry

Currently, the issue of regulating the safety indicators of feed for productive animals and poultry in terms of technical regulation is in a regulatory vacuum, since the Technical Regulation "On the safety of feed and feed additives" has not been approved. This situation also applies to indicators of the content of toxic elements, which include selenium and heavy metals such as zinc, copper, iron, capable of accumulation in the body and migration through food chains. In connection with the above, the purpose of the research was to monitor and analyze the content of heavy metals and selenium in compound feeds for productive animals and poultry sold on the territory of St. Petersburg and the Leningrad region as an indicator of toxicological safety.As part of the work, 40 samples of mixed feeds of domestic production were examined. The share of the studied compound feeds for pigs and piglets accounted for 50.0%, for broilers and cattle - 25.0% each. At the first stage, sample preparation and mineralization of samples were carried out in a muffle furnace. At the second stage, using the atomic absorption spectrometer Thermo Scientific Solaar S4, the amount of copper, zinc, iron, selenium in the mineralized sample was determined in accordance with the current regulatory documents. At the third stage, the results were analyzed in comparison with the temporary maximum permissible level according to MDU No. 123-4/281- 8-87 "Temporary maximum permissible level (MDU) of the content of certain chemical elements and gossypol in animal feed and feed additives".The detected concentrations of copper, iron and selenium in the studied samples met the requirements of the current regulatory documentation and did not exceed the established MDU. When determining zinc, it was revealed that 38 samples out of 40 met the requirements of regulatory documentation, in the remaining 2 samples, an excess of MDU was found to be 1.1 and almost 1.5 times, respectively. The obtained results of the monitoring studies allow us to draw a conclusion about the safety of compound feeds in terms of the content of heavy metals and selenium sold on the territory of St. Petersburg and the Leningrad region