Microwave Unit Research Articles

Effect of the microwave treatment on anti-nutrients of soybeans

BACKGROUND: Soybeans contain anti-nutrients that have to be inactivated before being used as feed for livestock and poultry. AIM: Obtaining the new data on the effect of the heat treatment on soybeans. MATERIALS AND METHODS: Soybeans of the Dongsheng 22 and SK Alta varieties were processed with micronization, autoclaving and microwaves in the developed microwave unit. RESULTS: After micronization, the decrease in total starch was 10–16%, after autoclaving and microwave treatment — 15–17%. The three kinds of treatment did not have a significant effect on total phenolic content. The content of flavonoids increased by 7–9% after autoclaving and micronization and by 16% after microwave treatment. When micronizing and autoclaving soybeans, no changes in antioxidant activity were observed, but with microwave treatment, it increased by 3–5%. The decrease in trypsin inhibitor activity was 80% after microwave treatment and 73–79% after micronization and autoclaving. The tannin content was reduced by 10% with microwave treatment and by 7–9% after micronization and autoclaving. The decrease in phytic acid content was 43–45% and repeated for all kinds of treatment. CONCLUSION: The reduction of antinutrients after micronization, autoclaving and microwave processing ensures the use of soybeans for feed. Milder temperature conditions and cyclic processes of heating and cooling during microwave processing increase the safety of soybeans. The higher heating rate and low energy costs of microwave processing ensure economic feasibility.

From Waste to New Ways: Feasibility of Microwave-Assisted Extraction of Chitin from Green Mussels (Perna Viridis) for Development of TEA-Functionalized CO2 Capture Adsorbent

As the world progresses, environmental problems emerge, such as the rise in global greenhouse gas emissions, specifically carbon dioxide (CO2) and improper waste management. To address these issues, this study aims to extract a natural polymer, chitin, from waste green mussel shells using a novel microwave-assisted extraction method. The extracted chitin was used as a support material for the functionalization of the adsorbent for potential CO2 capture. The process involves demineralization and deproteinization for mussel shells under the influence of a microwave unit. Results show that microwave power level 2 has produced the highest chitin yield (6.40%) among all the power levels. To enhance its CO₂ adsorption capacity, the extracted chitin underwent a sol-gel pre-treatment followed by functionalization with triethanolamine (TEA). Scanning electron microscopy (SEM) revealed a "brick wall-like" or flaky crystal structure with an increased surface roughness, suggesting successful TEA incorporation. Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) confirmed the presence of amine groups and enhanced thermal stability of the functionalized chitin. These characteristics are essential for CO₂ capture applications. This research demonstrates that waste green mussel shells coupled with microwave-assisted extraction can be a promising route in extracting chitin and its potential application to CO2 capture. Future work will focus on improving the pre-treatment process to produce a more suitable chitin support and optimizing the adsorbent's CO₂ capture capacity.

Preparation of uranium-plutonium oxide solid solution powder from ammonium uranyl-plutonyl carbonate in a laboratory microwave unit

The method of obtaining a solid solution powder of uranium-plutonium oxides (with 38% plutonium content) from the AUPuC pulp of the process (ammonium uranyl-plutonyl carbonate) using microwave radiation in reducing and atmospheric environments was proposed and tested at the laboratory level. For research purposes, the pulp obtained by coprecipitation of uranium and plutonium from nitrate solution (stripping product simulator) was prepared in advance. The process consists of three main stages: oxidation of Pu(IV) to Pu(VI), precipitation, and conversion in a laboratory microwave unit. According to the X-ray phase analysis, the powder obtained in a reducing atmosphere is a solid cubic solution (UxPu1–x)O2. The powder obtained in an atmospheric environment is a mixture of two oxides, PuO2 and U3O8. Scanning electron microscopy and electron probe microanalysis of the powder obtained in an atmospheric environment showed a fairly uniform distribution of U, Pu, and O in the solid phase.

Justification of the Microwave Unit Parameters for Removing Fat from the Bones

Justification of the Microwave Unit Parameters for Removing Fat from the Bones

Experimental microwave assisted CO2 desorption of a solid sorbent in a fluidized bed reactor

In this study, a novel method has been applied to regenerate CO2 from a solid sorbent (Zeolite 13X) using a mono-mode microwave unit under fluidization conditions. Several parameters have been varied to investigate their effect on the desorption characteristics as well as on the energy consumption. While flow rate varied between 200 Nml/min to 1,000 Nml/min, regeneration temperature changed from 40 °C to 100 °C. Microwave initial forward power also varied from 15 W to 30 W.Volumetric heating of microwave led to desorption of CO2 from the sorbent effectively while fluidization enhanced the heat transfer within the sorbent by providing homogeneous heat transfer with lower desorption time and absorbed energy. The most dominant parameters on the desorption time and energy consumptions were found to be flow rate and regeneration temperature, respectively. Under different conditions, the energy consumptions to regenerate a kg CO2 varied between 2.84 MJ and 27.17 MJ. Even though the lowest energy consumption was obtained when the flow rate was 200 Nml/min at 40 °C; the time for a complete desorption found to be quite high with this flow rate. Therefore, a minimum energy consumption of 3.87 MJ/kg CO2 within a short period of regeneration time can be achieved under the fluidization regime with the flow rate of 1,000 Nml/min at 40 °C. While an increase in the flow rate also caused a slight increase in the energy consumption for low regeneration temperatures, it resulted in a significant decrease under higher regeneration temperatures. Furthermore, the main drawback of low flow rate conditions is that most of the energy was consumed to remove the last 10 % of CO2 from the sorbent. Therefore, fluidization plays a significant role on the removal of CO2, especially between the 90 % and 100 % regeneration percentages.This work is the first study in the literature that has investigated the effects of fluidization on the desorption characteristics of CO2 under mono-mode microwave conditions. It was proved that fluidization reduced the energy consumption of CO2 desorption with higher microwave efficiency.

Preparation of Uranium/Plutonium Oxide Solid Solution Powder from Ammonium Uranyl–Plutonyl Carbonate in a Laboratory Microwave Unit

Preparation of Uranium/Plutonium Oxide Solid Solution Powder from Ammonium Uranyl–Plutonyl Carbonate in a Laboratory Microwave Unit

Enhancing Graphitic Carbon Precursors from Coal Pyrolysis: A Comparative Analysis of Microwave Plasma and Conventional Thermal Upgradation Methods.

This study investigates and compares the efficacy of conventional thermal pyrolysis and microwave (MW) plasma pyrolysis in upgrading coal-derived precursors. Coal samples presenting a range of ranks were pyrolyzed under various reactive and nonreactive atmospheres using a pyroprobe, with the pyrolyzates analyzed by gas chromatography-mass spectrometry (GC-MS). Comparative MW plasma tests were conducted using a modified countertop MW unit, with condensed products similarly analyzed by GC-MS. A predominant coal devolatilization product-benzene was selected for analyzing the reactive MW plasma upgradation. Results demonstrate that conventional thermal pyrolysis lacks effectiveness in upgrading the precursors. To gain insight into the underlying reasons, chemical kinetic simulations were conducted. Oppositely, reactive MW plasma pyrolysis demonstrated remarkable precursor upgradation. These condensed MW plasma pyrolysis products were then subjected to a carbonization and graphitization heat-treatment with a comprehensive graphitic quality assessment conducted using X-ray diffraction and transmission electron microscopy. After graphitization, the MW plasma-upgraded precursor produced a carbon with a crystallite size several times greater than that of the initial benzene. By MW plasma processing, the poorly graphitizable benzene precursor was transformed into a highly graphitizable precursor comparable to coal tar pitch. The underlying reasons for this significant improvement were investigated by analyzing the compositional changes in the precursor under various reactive environments.

Возможности исследования процесса горения металлизированных энергетических конденсированных систем методом сверхвысокочастотного излучения

The paper considers processes of the electromagnetic radiation propagation at the frequency of 9.027 GHz (corresponding to the wavelength in vacuum of 33.2 mm) in the round-section waveguides of an experimental unit to determine the burning rate of the mixed energy-condensed systems under the high pressure conditions. Qualitative theoretical analysis of the electromagnetic radiation interaction with single metal and contrast dielectric particles in the carrier dielectric medium of a condensed system and arrays of metal and contrast dielectric particles distributed in space was carried out. The paper evaluates the influence of electromagnetic radiation, base material and filler particles on parameters of the resulting standing wave in the microwave unit waveguide for measuring the burning rate of an energy-condensed system, and assesses theoretically the qualitative effect of the filler content on the error in the microwave measurement system. Results of the experimental study of combustion of two model energy-condensed systems, as well as the exemplary model dielectric material (transformer oil) by the microwave method, were analyzed. Study results are the practical justification for introducing the microwave method in diagnosing combustion characteristics of the energy-condensed systems containing particles of the metallized filler

Microwave‐Assisted Fabrication of Superamphiphobic Surfaces on Aluminum Substrates

The field of superamphiphobic surface fabrication has evolved rapidly in the last decade; however, research on important issues such as sustainability and green chemistry procedures is still scarce. Herein, a simple method of microwave irradiation (MW) to minimize energy consumption during the preparation of superamphiphobic aluminum (Al) surfaces is reported. Al substrates are first etched in diluted HCl solutions to generate a microstructure and then irradiated in a commercial microwave unit for several time intervals, temperatures, and pressures. The surfaces are then coated with different compounds, and the wettability is tested with high and very‐low surface tension liquids. Optical profilometry and scanning electron microscopy images show that the density of hierarchical micro‐nanostructures increases with MW time, temperature, and pressure. At 170 °C and 7.9 bar, the surfaces present a high density of structures and re‐entrant topographies. The obtained coatings display excellent repellence to liquids with surface tensions as low as 27.5 mN m−1. X‐ray photoelectron spectroscopy data show the importance of efficient surface functionalization for the production of superamphiphobicity in Al substrates. The results show that MW irradiation of Al substrates can be a green and efficient method for fabricating superamphiphobic surfaces.

Разработка эффективных устройств обеззараживания зерна на основе анализа биоэлектромагнитных взаимодействий

The use of commonly used grain disinfection methods based on electromagnetic radiation is accompanied by high energy costs and insuffi ciently high-quality sterilization. The best characteristics have been demonstrated by a method of resonance-low-frequency disinfection, which needs to be eff ectively implemented taking into account the purpose of research. The analysis of bioelectromagnetic interactions showed the ineffi ciency of the solenoid due to the lack of Lorentz strength from the magnetic component and a weak and uneven electrical component. To avoid these shortcomings, the authors proposed improved solutions for the solenoid, evaluated the possibility of using multipolar electromagnets, and developed a new decontamination device with a uniform electrical component (E-fi eld). They also provided theoretically described the advantages of a new device based on the E-fi eld. An experiment was conducted on the disinfection of wheat grain at a plant with a capacity of 400 kg/h with a working fi eld frequency of 600 Hz. For a correct comparative assessment, the experiment was also conducted on an improved solenoid and a microwave installation Sigma-1. The results were subject to phytoevaluation conducted according to the standard methodology. Based on the experimental data, the authors determined the disinfection effi ciency coeffi cient, which was 280 for a new device, 16.6 for an advanced solenoid, and 2.3 for the Sigma-1 microwave unit. At the same time, the device based on the E-fi eld provided a reduction in the total contamination of the material with fungi and bacteria in 3.1 times, the improved solenoid - in 1.8 times. Power consumption was 30 and 410 watts, respectively. The experiment results confi rm the eff ectiveness of the new device based on the E-fi eld, which is characterized by low energy consumption, low metal consumption, simple design, and safe operation.

An Ultra-wide Bandwidth Low-frequency Radio Astronomical Cryogenic Receiver for FAST Telescope

This paper presents an ultra-wide bandwidth (UWB) low-frequency radio astronomical cryogenic receiver for the Five-hundred-meter Aperture Spherical radio Telescope (FAST). It covers 6.6:1 bandwidth from 0.5 to 3.3 GHz. The receiver consists of a Quad-Ridged Flared Horn (QRFH), a cryogenic microwave unit, an optical transceiver and a warm microwave and frequency mixing unit. A QRFH with a concentric-loaded dielectric spear is developed: the average return losses are larger than 20 dB; the average ports polarization isolation is 43.87 dB; the average dish efficiency is higher than 65%. Many UWB cryogenic low loss components are developed for the fabrication of a cryogenic microwave unit. The average noise temperature lower than 14.2 K and 22.5 K are achieved as referred to the input ports of cryogenic Dewar and the output of horn, respectively. Compared to other similar advanced UWB receivers, such as Parkes 0.7–4.2 GHz (6:1 bandwidth) receiver and FAST 0.27–1.62 GHz (6:1 bandwidth) receiver, wider relative bandwidth of the proposed receiver is achieved and it is a new attempt to expand the bandwidth of UWB low-frequency receiver.

Modular microwave unit for heat treatment of raw materials at factory-farm enterprises

The objective of the work is to develop a microwave unit with removable modules for continuous heat treatment and disinfection of animal-derived raw materials of different structures with resonators, providing electromagnetic safety without shielding and high electric field intensity with reduced operating costs while preserving the feeding value of the product. The study includes 3D modeling of resonators for each module using CST Microwave Studio software and multi-criteria evaluation of regression models of process parameters, allowing one to estimate the feeding value of the product. The first module is designed for heat treatment of secondary animal-derived raw materials, including frozen blocks of meat waste. There are modules can be installed simultaneously or separately in the microwave unit, depending on demand and available raw materials. All modules are removable and easy to clean after completion of heat treatment, and the source block is closed and is subject only to maintenance inspection. Studies of electromagnetic safety for the perforated cylindrical resonator were performed. The operating modes of the second module were found, the duration of defrosting and heating of the animal colostrum was 10–15 min with the generator power of 4.8 kW and energy costs of 0.18–0.20 kW·h/kg.

Microwave processing of sunflower achenes and its influence on their quality and enzymes activities.

Stricter requirements to environmental compatibility and smaller energy-output ratio highlight the importance of implementing the super high-frequency drying of the crop seeds. The study is aimed at the development of drying optimal parameters and modes of sunflower (Helianthus annuus L.) seeds in a settled small-size conveyor microwave unit. In-gel activity of 6 functionally key enzymes (formate dehydrogenase, glutamate dehydrogenase, malate dehydrogenase, diaphorase, leucine aminopeptidase and non-specific esterases) in polyacrylamide gels after disk electrophoresis was analyzed in order to count on an additional assessment of the temperature influence caused by electromagnetic radiation of the tested drying unit on the sunflower achenes metabolism. The correlation analysis showed the existence of the statistically significant (р < 0.05) negative dependence between the seed materials heating temperature with germination energy (correlation coefficient -0.783) and achenes germination (-0.797). These two parameters (without processing 88 and 96%, respectively) began to reduce sharply when reaching the heating temperatures of 55℃ and more. Enzymes de-activation also started within this range. Considering the collected data about drying of the seed material, the optimal heating conditions were within 26-27 minutes at 800 W and heating temperature 38-40° С. With these parameters the quality of the processed seeds was preserved, and the costs for drying were relatively low (2.61 MJ per 1 kg of the water removed).

Experimental investigation on the effects of microwave irradiation on kimberlite and granite rocks

Abstract This study is a part of an overall research project on the effects of microwave (MW) irradiation on rocks for assisted rock breaking systems as well as mineral processing at McGill University. For the first time, this paper highlights a comprehensive investigation on the effects of microwave irradiation on Canadian kimberlites. Potential contribution to the continuous rock excavation and rock weakening effect prior to implementation of mechanical techniques was explored. Two different kimberlite rocks, i.e. volcaniclastic kimberlite (VK) and hypabyssal kimberlite (HK), and granite samples were studied. Some important physical properties of the rock samples were measured including rock quality designation (RQD), specific gravity, porosity, and specific heat capacity. Rock samples were treated for various exposure times using a multi-mode MW unit at different power levels ranging from 2 kW to 15 kW. The effect of MW irradiation on rock samples was investigated. The results indicate that the mechanical properties including unconfined compressive strength (UCS) and Brazilian tensile strength (BTS) were significantly dropped as a result of MW irradiation. Finally, the effect on rock abrasivity using the Cerchar abrasivity index (CAI) has also been discussed.

Polarization-dependent resonant phenomena in all-dielectric scatterers: inversion of magnetic inductance and electric displacement

The theoretical description and experimental verification of resonant phenomena in electromagnetic fields generated in the near zone of all-dielectric rectangular thin sub-wavelength frames, subjected to an incident microwave, are considered. The geometry of considered problems is presented by means of arrangements of these frames in three orthogonal planes, normal, respectively, to electric component, magnetic component and wave vector of the incident wave. Such trio paves the way to design of 3D all-dielectric multiresonant microwave unit cell. Displacement currents, generated by linearly polarized electromagnetic waves in the system, lead to the formation of magnetic and electric dipoles, each of which possesses own resonant frequency. Resonant inversion of magnetic inductance and electric displacement is observed. The sliding incidence of plane wave on the frame is shown to provide the sharp and deep resonance in the components of generated field. The phase shift equal to π between the magnetic components of incident and generated waves indicates the formation of negative magnetic response. There observes the angular anisotropy of arising dipoles, manifested in values of resonance frequencies and in the dependence of depths of resonant spectral dips upon the orientation of dipoles, with respect to the direction of propagation of incident wave.

Comparison of Microwave and Conventional Indigenous Carbothermal Reduction for Recycling of Discarded Lithium-Ion Batteries

Waste lithium-ion batteries are massively piling up because of ever-increasing consumption. Environmental considerations, limited life cycle, and the presence of lithium, cobalt, manganese, and nickel are the driving forces for recycling. In this study, an active cathode material (LiCoO2, LiNi0.5Mn1.5O4, LiMn2O4) was reduced in a muffle furnace and microwave unit with varying graphite dosages and times, and the Box–Behnken statistical design was pursued for the optimization of reduction parameters. The composition of the magnetic fraction of a muffle furnace reduction at an optimum condition is cobalt 68%, manganese ~ 21%, and nickel ~ 2.5% with a saturation magnetization of ~ 106 emu/g and lithium extraction of ~ 83%. The composition of the magnetic fraction of microwave reduction at optimum condition is cobalt 72%, manganese ~ 9% and nickel ~ 6% with a saturation magnetization value of ~ 90.7 emu/g and lithium extraction of ~ 82%. The muffle furnace route offers a higher magnetic yield and saturation magnetization compared to the microwave route.

Microwave unit for heat treatment of building materials

Building materials microwave processing demonstrates a great number of perspective advantages as compared to traditional heating methods. In order to upgrade the technology of microwave heating there has been developed a mathematical model of the technological process of microwave energy heat treatment of loose building materials. As a result we have won some calculation correlations, developed a numerical model and calculation algorithms for the analysis and synthesis of the microwave dryer of a loose dielectric with losses while it moves along the working camera. The results of the practical calculations have been carried out with the regard for water load and without it, also with the regard for the changes of the electro- and thermal-physic parameters during the heat treatment as well as disregarding them.

Justification of parameters of microwave installation for separation of down from skins of rabbits in the continuous mode

Discusses the problem of reducing the operating costs of decontamination and the separation of fluff from the skins of rabbits in rabbit farms. Rabbit meat production amounted to 4.2 thousand tons, of which 70% of the total volume of Russian production falls on farms. In the Nizhny Novgorod region effectively bred rabbits breed "White Giant", which at the age of 560 days reach up to 6.8 kg, but the processing of skins is quite time-consuming. Rabbit down is widely used in the processing industry as a raw material with unsurpassed qualities for the production of knitwear, felt, cloth. The article describes the developed microwave unit with a disk conveyor with a power consumption of 6 kW, a capacity of 16 kg / h. The results of experimental studies to substantiate the complex of structural and technological parameters and modes of operation of microwave installations based on regression models, taking into account the multicriteria assessment of the technological process of separating the disinfected down raw materials from the skin with the sponge-soaked Mezdra. The annual economic effect of the use of microwave installation for collecting hair from the skins of rabbits in rabbit farms is 187 thousand rubles.

Life-Cycle Assessment of Microwave-Assisted Pectin Extraction at Pilot Scale

The first Life-Cycle Assessment (LCA) of an acid-free, microwave-assisted process for pectin production at pilot scale is reported. The properties of the resulting pectin were measured and compared against the criteria for commercial pectin, while the energy consumption of the microwave process was measured to compare its life cycle impacts with that of the current commercial process. Overall, the pectin met all the criteria for food-grade commercial pectin. The microwave unit was estimated to have <25% of the environmental impact of traditional acid-assisted thermal process in all categories measured and provided an improved yield of 5% (wet weight basis) compared to 3% by thermal heating under normalized conditions. The readouts were comparable with each other over three runs indicating a robust and reproducible process, crucial for scale-up purposes. With the product meeting the relevant criteria and the process being robust and more environmentally friendly, this work demonstrates the practical and co...

Toxicological analysis of Pb and Cd by ET AAS in local anaesthetics for teething (teething gels) based on herbs available in Polish pharmacies

Studies related to the toxicological analyses of metallic impurities in pharmaceuticals (drugs) is an important issue but there is a lack of refereed literature around the safety of teething remedies from herbal origin related to toxic metals impurities. In this article, the levels of Pb and Cd were measured in samples of local anaesthetics for teething (gels) based on herbs. This article was motivated by the fact that Pb and Cd are relevant toxic metals that may cause an adverse effect in babies even at low levels. Additional justifications were (1) the insufficient control of metal impurities in teething gels, (2) the lack of sufficient validation steps and (3) the inadequate sensitivity of applied analytical techniques. The aim of this article was a qualitative and quantitative analysis of Pb and Cd in the most popular and available local anaesthetic for teething (teething gels) based on herbs (n = 5) available in Poland. Metals were determined by ET AAS (electrothermal atomization atomic absorption spectrometry), after digestion in a microwave unit using concentrated nitric acid. It was observed that all samples contained Pb and Cd. The levels of Pb and Cd as impurities (independently of the producer and declared composition) are similar. The concentrations of Pb and Cd, at ng/day levels, to which the user is exposed at daily doses meet the standards of the directive ICH Q3D.