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Samples of alumina – 3 % yttria-stabilized zirconia (YSZ) composites were sintered in rapid processing regimes using 24 GHz microwave heating at rates of up to 200 °C/min and zero hold time. The final relative density was 96–99 % for the samples containing 1.5 and 7.5 wt % YSZ and 98–99 % for the samples containing 13 wt % YSZ. The microwave sintering kinetics were compared for the processes carried out by direct and susceptor-assisted microwave heating. Under direct microwave heating, the effect of an intense microwave electromagnetic field with an estimated absorbed power density of up to 130 W/cm3 resulted in a shift of the shrinkage curves by about 100 °C towards lower temperatures compared to the case of susceptor-assisted heating. The grain size of the samples sintered by direct microwave heating decreased with an increasing heating rate. The mechanical properties were slightly higher for the materials sintered under susceptor-assisted microwave heating. The samples containing 13 wt % YSZ exhibited a microhardness of about 20 GPa and a fracture toughness of about 7 MPa m1/2. [ABSTRACT FROM AUTHOR]

Zirconia has important application prospects in the field of ceramics. However, during a high-temperature heating process, pure zirconia will undergo martensite transformation, which seriously affects its service performance. Metal oxides, such as Y 2 O 3 –CeO 2 doping ZrO 2, effectively improve the toughness and fire resistance of the material. Thus, the drying of Y 2 O 3 –CeO 2 co-doped ZrO 2 powder is an essential step before practical application. The study employs contemporary microwave drying techniques. The results of the experiment show that the average microwave drying rate increases with an increase in mass, water content, and microwave heating power. When the initial mass was 30 g, the initial moisture content was 12 %, microwave power was 720 W, and the drying rate was the fastest. We used four dynamic models: Modified Page, Quadratic, Wang and Singh, and Page to fit the experiment data. The best model was Modified Page, which describes the kinetic process most accurately. Fick's second law describes how, in the drying process, when microwave power is 720 W, initial mass is 15 g and initial water content is 8 %, the effective diffusion coefficient is 5.25 × 10−16 m2/s. Fourier Transforms of the infrared spectrum of the samples before and after drying were analyzed, the intensity of the O–H absorption peak located at 3442.03 cm/s, and O–H–O absorption peak located at 1594.48 cm/s. Both decreased significantly after drying. To discuss the relationship between the microwave power and the diffusion coefficient, the activating energy of microwave heating was 32.01 W/g. The experimental results show high heating efficiency and selective heating of the microwave method. This study provides a theoretical basis and research data for microwave drying of Y 2 O 3 /CeO 2 co-doped ZrO 2 powder in industry. [ABSTRACT FROM AUTHOR]

The study proposes the utilization of microwave-assisted methods for converting neutralization slag (NS) into hydroxyapatite (HAP), offering an alternative to the conventional hydrothermal method. The microwave-assisted approach addresses the challenges encountered in hydrothermal reactions, such as particle agglomeration, reduced specific surface area, prolonged reaction time, high temperature requirements, and inadequate saturation adsorption capacity. By employing the response surface methodology with a Box-Behnken design, the study found that the microwave-assisted method significantly reduced the synthesis time from 90 to 25 min and the temperature from 120 °C to 56 °C. Furthermore, the microwave method consumed only 1/43 of the energy utilized in hydrothermal synthesis. To assess the performance of the synthesized HAP, various detection methods were utilized, including XRD, SEM-EDS, FTIR, Zeta potential, and ICP, which analyzed the crystal structure, crystallinity, morphology, chemical composition, and surface charge of HAP. The BET method was used to measure the specific surface area, further confirming the successful synthesis of HAP. The HAP synthesized through this microwave-assisted method exhibited a saturation adsorption capacity of up to 98.4 mg/g of fluoride ions from vanadium industrial raffinate. This study demonstrates that the microwave-assisted method provides a viable solution for reducing energy consumption and enhancing HAP synthesis efficiency for wastewater treatment in the vanadium industry. [Display omitted] [ABSTRACT FROM AUTHOR]

Samarium oxide (Sm 2 O 3), a quintessential lanthanide oxide, garners significant attention in electrocatalysis and photocatalysis. However, the physicochemical properties of precursors and rare earth oxides are hampered by traditional precipitation reactions, mainly due to the asymmetry of time and space. A new anti-clogging strategy based on pneumatic impingement flow is proposed. Subsequently, nano-sized Sm 2 O 3 powder with an ellipsoidal morphology and a median particle size of 70 nm are prepared using the integration of microchannel reaction and microwave heating. Correlation analysis and morphology evolution mechanism reveal intricate relationships among different variables, emphasizing the importance of achieving balance to effectively control crystal properties. Numerical simulations show that the selective heating of microwave make it significantly superior to conventional. Preliminary economic analysis suggests that producing 1 kg of nano-Sm 2 O 3 can yield $57.56. The combination of microchannels and microwaves offers a pathway for the high-value utilization of rare earths and holds significant industrial application prospects. [ABSTRACT FROM AUTHOR]

Methane pyrolysis is emerging as an attractive clean hydrogen production method. As its commercialization proceeds, the pyrolysis of natural gas (NG) becomes pertinent. In this work, the decomposition of pure methane and a realistic NG mixture are compared experimentally and numerically. Methane and NG pyrolysis are performed between 600 and 1200 °C over a fluidized bed of carbon particles heated by microwaves. Experimentally, no conclusive difference is observed in methane conversion between methane and NG pyrolysis. Numerically, the methane conversion rate is 8.5% higher for NG at 950 °C. The difference diminishes past 950 °C, becoming 0 past 1050 °C. The simulations showed that the enhanced methane decomposition in NG pyrolysis is due to an attack on methane by radicals generated during ethane and propane decomposition. The CO 2 in our NG mixture decomposes into CO. This work validates the longstanding use of methane pyrolysis as a surrogate for NG pyrolysis. • Experimentally, no conclusive difference between NG and pure CH 4 pyrolysis. • Numerically, NG pyrolysis had at most 8.5% higher methane conversion. • Radicals from ethane decomposition attacked methane and increased methane conversion. • Inlet C 2 H 6 > 10 vol% increased the outlet CH 4 rather than aiding its decomposition. • CO 2 in the NG mixture decomposed into CO, implying non-zero GHG emissions. [ABSTRACT FROM AUTHOR]

This study presents a novel microwave-assisted dry reforming of methane (MW-DRM) method, significantly enhancing syngas (H 2 +CO) production at a lower temperature of 400 °C. Compared to conventional heating dry reforming of methane (CH-DRM) processes, MW-DRM achieves higher conversion rates of CH 4 (84.6%) and CO 2 (85.7%) at a lower temperature of 500 °C, significantly reducing energy consumption. The CsRu/CeO 2 catalyst exhibited excellent stability under microwave heating, maintaining high conversion rates and selectivity for 8 h. Detailed characterization using XRD, BET surface analysis, Raman spectroscopy, TEM, and CO chemisorption revealed insights into the structural changes of the catalyst, highlighting the selective impact of microwave heating on the catalyst structure. This study provides a promising approach for sustainable and cost-effective syngas and hydrogen production, aligning with greenhouse gas reduction goals. [Display omitted] • Dry reforming of methane is conducted under microwave conditions. • Microwave-enhanced DRM demonstrated high efficiency. • Compared to CH-DRM, MW-DRM achieves the same activity at 200 °C lower. • CsRu/CeO 2 catalyst demonstrated high stability in DRM. [ABSTRACT FROM AUTHOR]

The utilization of hydrogen as an energy carrier faces a challenge due to its limited presence in its pure form in the Earth's atmosphere, necessitating its extraction from various sources. Among hydrogen production methods, microwave-induced plasma molecular cracking shows promise as an alternative. This review explores how different operational parameters of a microwave-induced plasma system with gas-phase discharge impact hydrogen production performance. Performance indicators include hydrogen production rate, energy yield, and final hydrogen concentration. Parameters influencing hydrogen production encompass microwave power, gas flow rate, initial hydrogen concentration, steam addition, gas injection method, and plasma-forming gas type. Other vital system parameters are also discussed. Higher absorbed power leads to increased hydrogen production, albeit less efficiently. Elevated carrier gas flow rate reduces residence time, consequently lowering performance, while higher fuel gas flow rates enhance hydrogen production. Introducing steam can enhance indicators and reduce soot, and injecting fuel gas directly into the plasma torch tip yields optimal hydrogen production. Avoiding excessive power, fuel gas flow, or water vapor is important, as hydrogen saturation can limit further performance enhancement. • Microwave-induced plasma appears as a promising alternative for H 2 production. • Operational parameters' impacts on the system performance were analyzed. • Steam addition and gas injection methods' impacts on H 2 production were discussed. • Optimal practices for enhanced H 2 production were determined. [ABSTRACT FROM AUTHOR]

The challenge for efficient management of post-consumer plastic and biomass waste has grown over the past few decades due to their dramatic increases. In comparison to conventional gasification, microwave-assisted co-gasification of plastics and corn stover offers many benefits, including increased H 2 yield and gas components compared to unfavorable char/tar. Nonetheless, for future commercialization of the process and ease of product separation, further reduction of the undesirable tar is necessary, which can be achieved over the catalytic route. In this work, we studied the catalytic effect of magnetite for microwave-assisted co-gasification of corn stover and plastic to make syngas with higher H 2 and lower tar selectivity over non-catalytic conditions. A 1:1:1 ratio of plastic-corn stover-magnetite was used to evaluate the reaction parameters such as temperature, space velocity, heating media, and catalytic cycles under gasification conditions. In comparison with the microwave non-catalytic route, a 100% increase in the total H 2 yield with 76% higher H 2 production efficiency (mmol/kWh) was achieved in the presence of the magnetite catalyst, while reducing the overall tar formation from 9% to 2%. When magnetite was reduced in situ during the reaction, it coupled with microwave and delivered oxygen radicals that cracked down plastic and corn stover intermediates generated from the synergistic effect under microwave heating. Soon after the oxygen transfer process initiated, magnetite reached its final oxidation state consisting of microwave-active Fe and Fe 3 C phases that continued coupling with microwaves along with the generated graphitic carbon to maintain the heat necessary to further reduce the generated tar and make additional gaseous products, as confirmed by XRD, Raman, and TGA analyses. [Display omitted] • Catalytic co-gasification of waste feedstock was demonstrated using microwave energy for production of clean hydrogen • Catalyst and microwave synergy doubled the H 2 production compared to non-catalytic reaction with 76% higher H 2 production efficiency (mmol/kWh) • Catalytic gasification reduced the tar yields from 9% from non-catalytic reactions to 2% • Magnetite delivered oxygen radicals that cracked down plastic and corn Stover intermediates • Synergy between microwaves and catalyst + feedstock resulted in H 2 -rich syngas with reduced tars [ABSTRACT FROM AUTHOR]

Microwave heating is considered an environmentally friendly and cost-effective method for sintering. Temperature field regulation and local hotspots are gaining widespread attention during microwave sintering. In this study, sol-gel method was employed to synthesize SiC fibers via microwave heating by uniformly combining the raw materials with Cu and Ni catalysts. The thermal effects and growth mechanisms of SiC were investigated using COMSOL Multiphysics software and DFT calculations for samples with Cu and Ni catalysts, respectively. The occurrence of magnetic losses played a significant role at low temperatures in the samples with Ni catalyst, resulting in the formation of local hotspots and the formation of molten Ni–Si alloys.Whereas, a reflection effect was observed in the samples with Cu catalyst, resulting in a more uniform temperature distribution. The V-L-S growth mechanism was identified in the SiC fibers synthesized with Ni catalyst during microwave heating, while the V–S growth mechanism was observed in the SiC particles synthesized with Cu catalyst. [ABSTRACT FROM AUTHOR]

Hierarchical defect-rich UiO-66 membrane showing unprecedented CO 2 /N 2 and n -/ i -C 4 H 10 separation performances was prepared through combining hollow-structured UiO-66 seeds with epitaxial growth under single-mode microwave heating. Ultrathin-oriented selective top layer, hollow-structured bottom layer, and high missing-linker number in the framework were concurrently achieved in the membrane. [Display omitted] [ABSTRACT FROM AUTHOR]

This present work explored the possible use of sandbox seed (Hura crepitans) shell (SSS) waste as a feedstock for synthesizing green solid alkali biocatalyst in the microwave-aided sandbox oil (SBO) transesterification to obtain SBO biodiesel (SBOB). The solid catalyst was produced using a calcination method by burning raw SSS in the open air to obtain ash heated for 3 h in a furnace at 500 °C. The calcined sandbox shell ash (CSSA) produced was characterized using standard techniques to establish its catalytic potency. Also, a model was developed to simulate the process and examine the interactive effect of process input variables on SBOB yield using the Taguchi approach. The CSSA characterization showed it composed of K (44.99 %), Ca (1.54 %), and Mg (1.87 %) with crystalline compounds of K and Mg. The physisorption results gave a mean pore size of 18.142 nm and a surface area of 6.1125 m2/g. The best combination of the input variables determined for the process is a heating power of 450 W, methanol:SBO of 8:1, time of 1.5 min, and CSSA loading of 2 wt% with an optimum SBOB yield of 98.27 wt%. The SBOB produced met standard specifications for biodiesel. Microwave application to the SBO transesterification aided in rapidly completing the reaction. The study concluded that sandbox seeds and their shells are promising feedstock for cheap and sustainable biodiesel production. [Display omitted] • Novel biocatalyst from Sandbox shell wastes was synthesized and characterized. • Sandbox oil biodiesel was produced via transesterification with the biocatalyst. • The transesterification process was modeled and optimized by Taguchi method. • 98.27 wt% biodiesel yield was achieved using the optimum values obtained. • Sandbox oil biodiesel produced satisfied the standard specifications. [ABSTRACT FROM AUTHOR]

The microstructure, reaction mechanism and mechanical properties of (MgCoNiCuZn)O high-entropy ceramics prepared by microwave sintering technology were studied. Single-phase (MgCoNiCuZn)O high-entropy ceramics can be prepared in about 1 h when the preforming pressure is 5 MPa and the temperature is higher than 900 °C. By analyzing the microscopic morphology and density, it can be known that the density gradually increases with the increase of temperature. When the temperature is higher than 1000 °C, the pores in the sample indicate the packing, agglomeration and segregation of Cu2+ atoms at the grain boundaries. When the mass of the raw material is 20 g, it exhibits a good impedance matching effect during microwave heating. The sintered (MgCoNiCuZn)O ceramic with a density of 92.87 %, a flexural strength of 290 ± 20 MPa, an elastic modulus of 187.05 ± 5 GPa, and a microhardness of about 7 GPa. [ABSTRACT FROM AUTHOR]

Chemical looping dry reforming of methane (CLDRM) offers a sustainable pathway to convert methane (CH 4) and carbon dioxide (CO 2) to syngas, i.e., a mixture of hydrogen (H 2) and carbon monoxide (CO). However, carbon deposition caused by high gas temperature remains a crucial challenge for the CLDRM. We proposed microwave (MW) heating-assisted CLDRM to leverage the selective heating feature of MWs to create a thermal gradient between solid and gas phases. This thermal gradient, i.e., a higher solid temperature than the gas temperature, can promote desired reduction and oxidation (redox) reactions, while suppressing undesired gas phase reactions, in particular, CH 4 decomposition. At bulk temperature of 800 °C, the MW heating-assisted CLDRM achieved a maximum CH 4 conversion of 97% and H 2 /CO ratio of around 2. Compared to the conventionally heated CLDRM, the MW heating increased the redox extents of magnetite (the oxygen carrier) by 2.5 and 1.5 times, respectively, and suppressed carbon deposition. [Display omitted] • A new chemical looping dry reforming of methane adopting microwave heating. • Magnetite as a good microwave absorber and oxygen carrier. • Increasing methane conversion, hydrogen selectivity, and reduction extent of magnetite. • Mitigating carbon deposition on the magnetite oxygen carrier. [ABSTRACT FROM AUTHOR]

Microwave heating (MWH) of lignocellulosic biomass with susceptors has attracted attention for H 2 production. In this study, H 2 is produced from cellulose via MWH at 800 °C in a steam atmosphere with magnetite used as the susceptor. The effects of steam feeding and MWH on the product yields are experimentally investigated in comparison with conventional heating (CH). The H 2 and CO 2 yields are increased by steam feeding for both MWH and CH because the water–gas shift reaction occurs. Without steam feeding, MWH enhances H 2 and CO production, thereby increasing the maximum energy efficiency. With steam feeding, the steam gasification of C is more predominant for CH than for MWH as the reduction in the C content in the char of CH is higher than that of MWH. MWH reduces the formation of secondary char, and it is therefore expected to overcome issues such as the clogging or blockage of gas lines. • H 2 produced from cellulose via MWH in steam atmosphere with magnetite as susceptor. • MWH increases energy efficiency when steam is not fed into reaction vessel. • With steam fed into the reaction vessel, CH has higher energy efficiency than MWH. • MWH is expected to solve problems such as clogging or blockage of gas lines. [ABSTRACT FROM AUTHOR]

This work presents the study of effect of morphology of carbonyl iron, carbonyl iron-based, and e-waste-based mixtures on microwave absorption properties. Firstly, the flake shaped carbonyl iron particles and its mixture are prepared using conventional and efficient ball milling and blending method, respectively. It provides the absorption in lower frequency region. Further, the covered frequency range starts to shifts slowly towards higher frequency ranges due to the morphological changes. On the other hand, effect of complex morphology of e-waste-based mixtures are also studied. These heterogeneous mixtures are developed using the cutting mill and blending methods that can provide the absorption in higher frequency with very narrow bandwidth. In this manner, effect of morphology on single layer microwave absorption performance of developed heterogenous material is proposed. It is also explored that the developed samples cover a wider bandwidth by utilizing the multilayering technique. A three-layer absorber is designed using genetic algorithm and the results are also validated. The structural and morphological study of the developed heterogeneous materials has been done using X-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) analysis. Also, rigorous study has been done on magnetic properties and Cole-Cole plots to understand the magnetic and dielectric losses respectively occurring inside the materials. The results showed wide bandwidth absorption of 11.62 GHz (≤−10 dB bandwidth) in the lower frequency region ranges from 0.5 to 12.12 GHz (i.e., L, C, and X-band). The total thickness achieved is 1.85 mm which is very compact (<2 mm). Thus, a thin and wideband microwave absorber at lower frequency range using heterogeneous morphology of developed materials is also presented. The proposed microwave absorbing materials can be potentially utilized for the shielding applications. [Display omitted] • Study explores the impact of morphology on microwave absorption in heterogeneous mixtures. • Milled Carbonyl iron and its mixture exhibit absorption in lower frequency regions. • E-waste-based mixtures with complex morphology exhibit absorption in higher frequency regions. • Multilayering techniques extend bandwidth, with a three-layer absorber designed using genetic algorithms. • Wideband absorption (11.62 GHz) achieved in the lower frequency range (0.5–12.12 GHz) at a compact (<2 mm) thickness. [ABSTRACT FROM AUTHOR]

Different drying methods were used to prepare catalytic membranes for the simultaneous removal of dust and NO to explore their effect on the distribution of active components, with the structural properties, filtration performance, catalytic performance, and working mechanism of the preferred prepared catalytic membrane systematically investigated. The results indicated that microwave drying, in contrast to traditional electric drying with blasting, effectively inhibited the migration of the precursor solution to achieve uniform loading of active components, thus endowing the catalytic membrane with excellent catalytic activity. Meanwhile, the pore structure of the fibrous ceramic substrate was not almost affected by the loaded catalyst and still exhibited high porosity. These characteristics contributed to the development of a catalytic membrane with good filtration and catalytic performance, as well as superior adaptable NO concentration and filtration velocity properties. Therefore, fibrous ceramic-based catalytic membranes prepared using microwave assistance offer considerable application prospects for integrated purification of high-temperature flue gases. Furthermore, the removal of dust and NO was determined to follow the Eley–Rideal reaction mechanism and surface filtration mechanism of the residual dust cake, respectively. [ABSTRACT FROM AUTHOR]

The production of hydrogen-rich gas used in fuel cell-powered cars from steam reforming and sorption-enhanced steam reforming of ethanol was studied over nickel-impregnated mesoporous carbon catalyst in conventional and microwave heated reactor systems. Two important process intensification methods, sorption-enhanced reforming and microwave heating, were investigated to obtain a sustainable and energy-efficient system. Higher hydrogen yield was observed in the microwave heated system compared to the conventional heated system. With an increase in the reaction temperature, the hydrogen yield and hence the hydrogen concentration were increased in both systems. Sorption-enhanced steam reforming resulted in very high hydrogen purity, higher than 97 %, containing no carbon monoxide and carbon dioxide before the breakthrough point in the microwave system at 500 °C. The outperformance of the microwave system compared to the conventional system was proved in terms of the hydrogen yield and purity. • Nickel impregnated mesoporous carbon catalyst has a high microwave absorption capacity in the microwave system. • Higher hydrogen yield and purity were achieved in the microwave system. • Sorption-enhanced results revealed very high H 2 purity in the MW reactor at 500 °C during the first 25 min of the reaction. • The enhancement in hydrogen yield and purity in the MW system are evidence of its superiority to the conventional system. [ABSTRACT FROM AUTHOR]

Microwave heating has been applied to improve cement-based materials (CBMs) structures deicing efficiency, which reduce the effect of icing on their service life. Moreover, the enhanced thermal properties of CBMs can further improve their deicing efficiency. In this study, silicon carbide (SiC) ceramic particles with favorable thermal properties were used to prepare the SiC cement-based materials (SCBMs). The effect of SiC ceramic on the mechanical strength of CBMs was investigated. Next, the heat transfer and storage ability of CBMs were investigated to analyze the changes in their thermal-physical parameters. Then, the surface thermal responses of the CBMs during microwave heating and off were recorded to characterize their temperature evolution in a low-temperature condition. Furthermore, the deicing efficiency of CBMs was determined using the ice layer shedding time (ILST) as the index. The results show that the filling effect of SiC ceramic on CBMs improved their mechanical strength within a certain content range. However, a large content of SiC ceramic caused an increase in the weak area and porosity within the CBMs, further reducing their mechanical properties. The thermal-physical parameters of CBMs were improved after adding SiC ceramic. The thermal conductivity and thermal effusivity of SCBMs-100 were 13.17 W/(m·K) and 1.44 W/(mm2·K), respectively, 7.90 and 2.35 times higher than the control group. Due to the favorable thermal properties of SCBMs, their heating rate and surface temperature field distribution characteristics were further improved. Furthermore, with the increase of SiC ceramic content, the ILST of SCBMs was further reduced during microwave heating. Therefore, the SiC ceramic was a favorable material, improving the thermal properties and deicing efficiency of CBMs to a certain extent. However, considering its effect on the deterioration of the mechanical properties of CBMs, the optimal content of SiC ceramic might be 75%. [ABSTRACT FROM AUTHOR]

The pioneering objective of a permanent outpost on the lunar surface requires the development of technologies for in situ resource utilisation. Consolidation of lunar soil into products is imperative to avoid unaffordable transportation burdens. The paper addresses the feasibility of the Local Microwave Heating effect as a promising technology for sintering lunar regolith based on microwave radiation, with a simple solid-state generator requiring a relatively modest amount of energy. Experiments were conducted using terrestrial simulants with physical and chemical properties similar to those of lunar regolith. Laboratory equipment with a purpose-built microwave actuator was designed and manufactured with "Design for Embarking" in mind. Experiments have demonstrated the feasibility of the proposed technology with a reasonable degree of confidence. Solid artefacts were obtained with proper setting of microwave parameters and appropriate scanning strategy, proving the feasibility of regolith sintering with a localised microwave source A roadmap for future development of the technology has been established. • Preliminary study on Localized Microwave Sintering of Lunar Regolith: Highlights. • Localized Microwave Heating is effective to consolidate lunar regolith simulants. • A solid-state generator with an open-end antenna is a promising lightweight low-energy system for ISRU. • Microwave heating of regolith is feasible regardless of the simulant's ilmenite content. • The technique can be used to produce 3D parts using an additive approach. [ABSTRACT FROM AUTHOR]

Sc 2 O 3 –ZrO 2 ceramic powders has excellent features such as high-temperature resisting, abrasion resisting, and erosion resisting, which makes it rapidly become a new high-performance ceramic material. The appropriate drying method can effectively reduce the agglomeration and coarsening of Sc 2 O 3 –ZrO 2 ceramic powder, which is beneficial for obtaining finer ceramic powders. Microwave heating was used to dry Sc 2 O 3 –ZrO 2 ceramic powders, and the influence laws of kinetic parameters of initial water contents, initial masses, and microwave powers on drying process were discussed by using the single factor experimental method. The experiment results demonstrated that average desiccation rate grew with increase of the three variables. Drying efficiency increases with increasing initial masses and initial water contents, while the opposite is true for microwave powers. The experimental data of Sc 2 O 3 –ZrO 2 ceramic powders drying were fitted and analyzed by Two-term exponential, Page, Quadratic, and Simplified Fick's diffusion models, and it was discovered that the Quadratic model could accurately describe the Sc 2 O 3 –ZrO 2 ceramic powders desiccation progress. To evaluate the variations of the Sc 2 O 3 –ZrO 2 ceramic powders before and after desiccation, they were characterized using FT-IR and FE-SEM, and the outcomes showed that microwaves can dry Sc 2 O 3 –ZrO 2 ceramic powders quickly and efficiently and improve their dispensability. The effective diffusion coefficient was computed by Fick's second law, which increased and then decreased with the growth of the initial masses, initial water contents, and microwave powers of Sc 2 O 3 –ZrO 2. For instance, the effective diffusion coefficients for different initial masses are 8.3917 × 10−5, 9.4614 × 10−5, 1.2515 × 10−4, 1.2267 × 10−4, and 9.9496 × 10−5 m2/s, correspondingly. The drying activation energy was computed using the Arrhenius index model to be −16.095 g/W (R2 reaching 0.99999). In this article, we combine experimental research with theoretical calculations to explore the effects of initial mass, initial moisture content, and microwave heating power on drying rate and microwave energy efficiency, which provides an important theoretical foundation and referential value for the actual desiccation progress of other ceramic powders. [ABSTRACT FROM AUTHOR]

SiC@SiO 2 nanofiber material holds great potential for a wide range of applications in microelectronic devices and electromagnetic wave absorption. However, its development has been hindered by high energy consumption (＞1500 °C) and complex fabrication methods. This work introduces a sample approach to produce the SiC@SiO 2 nanofiber at temperature of ∼1000 °C by using microwave heating. The SiC@SiO 2 nanofiber possess a unique bead-like structure, which are composed of single-crystalline SiC nanowires and amorphous SiO 2 beads. The growth mechanism under the action of microwave was explained. Moreover, the SiC@SiO 2 nanofiber exhibits an Excellent electromagnetic wave absorption performance with a minimum refection loss (RL min) value of −36.54 dB. The successful preparation of SiC@SiO 2 nanofiber provides a new idea for preparing ceramic materials with low cost and high efficiency in the future. [ABSTRACT FROM AUTHOR]

Microwave hyperthermia is an effective non-ionizing heating method for tumor sensitization. Therapy planning is necessary to achieve optimal hyperthermia treatment. This study aims to simulate two microwave antennas with different geometrical aperture's, used in hyperthermia, to choose the one giving better heating performances. The analysis of both the antennas provides a maximum temperature of 44.2°C and 41.9°C for the antenna with parallel plates and the trapezoidal antenna. Additionally, the Bland-Altman analysis shows an agreement between thermal simulations and measured temperatures with an average difference of 0.11°C and - 0.06 °C for parallel and trapezoidal antennas. [ABSTRACT FROM AUTHOR]

Employing electromagnetic(EM)-assisted catalytic heating to produce hydrogen (H 2) directly from petroleum reservoirs is an emerging technology for decarbonizing fossil fuel industry. Transforming hydrocarbons to clean H 2 in situ will enable pure hydrogen extraction to surface while simultaneously sequestering carbon underground with the assistance of downhole hydrogen membrane separation technology. Here, we aim to characterize the role of shale rocks in enhancing EM heating and catalyzing shale oil conversion to hydrogen as natural catalysts under EM irradiation. Flow-through experiments are well designed and conducted in a customized microwave reactor system. We also identified for the first time that shale rocks exhibit a "thermal runaway" (TR) phenomenon which occurs at a temperature of 280 °C. After TR happens, the energy needed for heating shale samples to a high enough temperature is significantly reduced under EM irradiation. Further, we identified that metal-rich minerals in shale rocks play an evident natural catalytic effect on shale oil conversion to hydrogen. As a result, hydrogen with a percentage of 1 mol.% starts to be generated at a measured temperature of 253–421 °C in the presence of shale rocks and is a dominant gas in the generated gas products at high temperatures. The highest production rate and concentration of H 2 gas are 178 sccm and 77 mol.% from the conversion of 0.4 g of shale oil, respectively. Importantly, CO 2 generated during the process is negligible. This work lays a foundation for leveraging the abundant shale rocks and their natural catalytic effect for more efficient, cost-effective, in-situ hydrogen production directly from shale reservoir via the EM-assisted catalytic heating technology we recently proposed. The novel approach is to covert shale oil to low-cost, clean hydrogen via in-situ electromagnetic(EM)-assisted catalytic heating by leveraging the abundant petroleum resources in reservoirs, existing oilfield infrastructure and data sheets, natural catalysts in reservoir rocks, and inexpensive off-peak electricity from renewable energy (i.e., wind and solar), with the assistance of downhole hydrogen membrane separators. [Display omitted] • A natural-catalysis-based in-situ clean hydrogen production from shale oil is investigated and validated. • Thermal runaway (TR) phenomenon is first reported in shale rocks under microwave irradiation. • Pure shale rocks can be re-heated to over 600 °C with a very low input power once TR occurs. • Hydrogen starts to be generated at a measured temperature of 253–421 °C in shale samples. • The highest concentration of hydrogen reaches 77.2 mol.% during shale oil cracking by microwave heating. [ABSTRACT FROM AUTHOR]

SiCnws/SiOC nanowires composites with a 3D network structure, exhibiting enhanced electromagnetic microwave absorption properties, were synthesized using carbothermal reduction. The solid precursor, organosilane waste, was employed, enabling cost-effective and environmentally friendly production. The structure and morphology of SiCnws/SiOC nanowires composites were extensively investigated by XRD, SEM, TEM, XPS spectra, and Raman spectra. Moreover, the composite demonstrated superior electromagnetic wave absorbing properties, including wide effective absorption bandwidth (EAB) of 2.73 GHz, strong minimum reflection loss (RL min) of −52.66 dB, and thin thickness of 2.40 mm. These excellent electromagnetic wave attenuation properties stem from the synergistic strategy of dielectric and conductive losses, resulting from the unique 3D network heterostructural architecture. This work not only offers improved EMW absorption solutions but also contributes to waste recycling and resource recovery. [ABSTRACT FROM AUTHOR]

The goal of this study was to test the effect of metal-impregnated carbon-based catalysts on the conversion of methane to hydrogen gas and solid carbon using microwave reactor technology. Monometallic and bimetallic catalysts on activated carbon supports (Ni/AC, Fe/AC, NiFe/AC) are compared during methane pyrolysis testing. Catalytic methane pyrolysis was carried out in a microwave reactor at reaction temperatures of 600 °C and 800 °C. For comparison, one of the catalysts (NiFe/AC) was tested in a conventionally heated reactor at 800 °C. The prepared catalysts were characterized by X-ray diffraction (XRD), while post-reaction catalysts were characterized by XRD and SEM. During reaction testing, the monometallic Ni/AC catalyst exhibited the best catalytic activity (CH 4 conversion: 46.0 and H 2 yield: 46.9 %) when reacted in the microwave reactor, however, it suffered from rapid deactivation from carbon deposition (carbon yield: 0.39 g C/g catalyst). The bimetallic NiFe/AC catalyst was slightly less active (CH 4 conversion: 36.9 and H 2 yield: 40.5 %) but it was more resistant to carbon formation (carbon yield: 0.27 g C/g catalyst) suggesting it may have greater long-term stability. The NiFe/AC catalyst was also the most energy efficient as it required the least microwave power to maintain the 800 °C reaction temperature compared to the other catalysts tested. Methane conversion of the bimetallic NiFe/AC at 800 °C under microwave irradiation was three times the conversion under conventional heating at the same reaction temperature. This work demonstrates the use of microwave-specific catalysts for catalytic methane pyrolysis in a microwave reactor, and can be used as a foundation for further methane pyrolysis process and catalyst optimization for CO x -free H 2 production. • Ni and Fe-based catalysts supported on activated carbon produced high yields of hydrogen under microwave reaction conditions. • Combined Ni–Fe catalysts had slightly lower activity but demonstrated better resistance to carbon-related deactivation. • The formation of nanotubes in the spent Ni-based catalyst was observed by SEM of the spent catalyst. [ABSTRACT FROM AUTHOR]

To our knowledge, this is the first study to successfully synthesise high-temperature-phase copper selenide (β -Cu 2 Se) at room temperature using rapid microwave hybrid heating (MHH). Controlling the starting Cu/Se ratio is the critical parameter for adjusting the content of α - and β -phases in the as-synthesised sample. The relatively low Cu composition causes impurities to form in the Cu 3 Se 2 phase, deteriorating the thermoelectric (TE) properties of the Cu 2 Se material. The β phase formation at room temperature promotes electrical conductivity. The thermal conductivities of the Cu 2.0 Se samples were 0.5–0.8 Wm−1K−1 at 303–673 K. A strong electronic-phonon interaction may potentially couple electronic thermal conductivity (κ e) and lattice thermal conductivity (κ L), resulting in incomplete separability of κ L and κ e in the β -Cu 2.0 Se sample. The Cu 2.0 Se exhibited a ZT value of 0.65 at 523 K because of its considerably lowered thermal conductivity. [ABSTRACT FROM AUTHOR]

In this work, Vulcan XC-72 supported platinum electrocatalysts (Pt/C) are synthesized by using a two-step, microwave-assisted polyol method. The effect of synthesis conditions on the properties of Pt/C electrocatalysts is investigated at various temperatures (140–200 °C) and corresponding autogenous-pressures (1.0–7.5 bar) at a constant synthesis duration of 35 min. A completely sealed reaction vessel is used to heat the polyol mixture above its boiling point of 140 °C. Catalysts are characterized by XRD, TGA, FTIR, BET, SEM, TEM, Cyclic voltammetry (CV), and the results are compared with the properties of commercial Pt/C. Pt/C catalyst synthesized at 160 °C exhibits the highest ECSA of 69.2 m2/g Pt, highest Pt loading efficiency of 92%, narrowest Pt particle size distribution with an average of 3.6 nm, and Pt crystallite size of 2.3 nm. SEM and TEM confirm the formation of micron-sized Pt agglomerations for the catalysts synthesized at 180 and 200 °C. Characterization studies show that the polyol method presented in this study is suitable for synthesizing Pt/C catalysts which have comparable properties to commercial Pt/C. • An alternative microwave-assisted polyol method to synthesize Pt/C catalysts was presented. • Polyol synthesis of Pt/C catalysts at high temperature/autogenous-pressures is possible. • Catalysts show comparable properties to the commercial ones. • Synthesis temperature can effectively control the size of Pt nanoparticles. [ABSTRACT FROM AUTHOR]

Hydrogen is the potential future resource to cater the energy and chemical requirements. Microwave-assisted pyrolysis (MAP) could be the potential technology to obtain green hydrogen from lignocellulosic biomass waste. The proximate and elemental composition varies with the type of lignocellulosic biomass, which influences the yield of hydrogen. In MAP, the operating parameters including microwave power, heating rate, temperature, and susceptor play an important role in hydrogen production. Cellulose, hemicellulose, and lignin present in the lignocellulosic biomass undergo decomposition when they are subjected to MAP. Most importantly, the susceptor material added to the feedstock induces the plasma, which would help the cleavage of the bonds to form hydrogen gas. When the microwave power intensity is high, then the generation of hydrogen would be high. During the MAP, the formed char from the biomass would act as susceptor cum catalyst, hence it further speeds up the hydrogen generation pathways. The energy and time required for the MAP are very less compared to conventional pyrolysis. The present review manuscript would help the research community to understand the possible applications of MAP for hydrogen production. [Display omitted] • Hydrogen production is dramatically influenced by the type of biomass. • High volatile matter with high hydrogen content in the biomass favors green hydrogen. • Microwave-assisted pyrolysis parameters play a key role in hydrogen yield. • High microwave power, heating rate, and temperature favor a high yield of hydrogen. • Biomass cracking reaction mechanism to hydrogen is explained. [ABSTRACT FROM AUTHOR]

The environmental performance of nonthermal plasma assisted dry reforming of methane (NTP-DRM) for hydrogen production from methane rich natural gas is investigated and compared with the current state of the art steam reforming technology through a cradle-to-gate life cycle assessment (LCA). The NTP-DRM technologies studied in this analysis include dielectric barrier, microwave, and pulsed plasma discharges. Due to the level of technology the study is considered as the prospective LCA of selected types of NTP-DRMs for hydrogen production. Of these, the NTP-DRM using microwave and pulsed plasma presented better environmental performance. The impact categories include midpoints levels applying TRACI 2.1 and AWARE for the water scarcity, using ecoinvent 3.8 and US NETL databases. The scenario analysis regarding carbon dioxide, electricity, and natural gas sources, revealed the highly dependency of NTP-DRMs technologies environmental performance to the energy efficiency of the processes. In terms of steam reforming of methane (SRM) despite the main contribution of steam use in the technology environmental performance, the uncertainty analysis showed higher sensitivity to natural gas input. Investigation showed that using renewable energy sources can have significant improvement regarding NTP-DRMs environmental performance and specifically global warming potential. Accordingly, at their current reactant conversion and product selectivity reaching the energy use of eV per molecule of reactant equal or less than 2, can be a proper target for the studied best case NTP-DRM to make their environmental behavior competitive with the state-of-the-art SRM technologies. • Prospective cradle-to-gate life cycle assessment (LCA) of selected nonthermal plasmas (NTP) for dry reforming of methane (DRM). • Comparative LCA between the NTP-DRM and the current state-of-the-art steam reforming of methane (SRM). • Uncertainty and scenario analysis, with a particular emphasis on critical hotspots. • Assessing NTP-DRM's energy efficiency requirement to make it environmentally acceptable compared to current SRM technologies. [ABSTRACT FROM AUTHOR]

Microwave (MW)-assisted process intensification technology has the potential to improve catalytic conversion under mild reaction conditions. In this study, a series of MW-sensitive CNTs-Co 3 O 4 composites were designed and synthesized as catalysts for the conversion of NaBH 4 to H 2. It was found that MW irradiation leads to a 19.6 (35 °C) to 49.5% (55 °C) increase in the hydrogen generation rate (HGR) of NaBH 4 hydrolysis catalyzed by the CC14, which is attributed to the combined contribution of thermal and non-thermal effects of microwave irradiation. Moreover, the NaBH 4 hydrolysis catalyzed by CC14 catalyst at different heating modes followed the zero-order kinetic model, and the pre-exponential factor of NaBH 4 hydrolysis catalyzed by CC14 catalyst under MW irradiation was approximately 157 times higher than under conventional heating, indicating that microwave irradiation increased the effective collision frequency at the reaction interface of CC14 catalyst. In addition, the selective and instantaneous heating of microwave irradiation was demonstrated by using a specially designed pseudo-homogeneous low temperature reaction system. Moreover, DFT calculations show that the rate-determining step of NaBH 4 hydrolysis is H 2 O dissociation. [Display omitted] • Hydrogen generation rate increased from 19.6 to 49.5% under microwave irradiation. • Microwave intensification results in a high HGR of 5685 mL min−1 g−1 at 40 °C. • MW micro-domain heating is proved in pseudo-homogeneous low temperature reaction. • Both MW thermal and non-thermal effects enhance the rate of NaBH 4 hydrolysis. • DFT confirms H 2 O dissociation is the rate-determining step of NaBH 4 hydrolysis. [ABSTRACT FROM AUTHOR]

Carbon micro/nanocoils with excellent electromagnetic cross-polarization capability have promising applications in the microwave absorption field. However, carbon micro/nanocoils with hierarchical porous structures remain challenging. Herein, a novel catalyst-free strategy and a one-step carbonization process were provided to fabricate biomass-driven carbon microcoils with hierarchical porous structures from waste biomass. Due to the synergistic effects of interfacial polarization, multiscale relaxation, and negative imaginary permeability formed by the helical/chiral open-loop pore structure, the porous carbon microcoils (PCMC) exhibits optimized impedance matching, improved dielectric loss, and enhanced electromagnetic wave attenuation and absorption efficiency. The minimum reflection loss (RL min) of PCMC reaches −63.65 dB at 4.68 GHz, and the RL min of PCMC reaches −27.6 dB even at 1.59 mm thickness. The maximum effective absorption bandwidth (EAB) can reach 5.78 GHz at 1.86 mm matching thickness. These results can serve as a basis for reusing other green wastes and for manufacturing advanced PCMC-based microwave absorbers at low cost. [ABSTRACT FROM AUTHOR]

• Permittivity and permeability of lunar simulants important to NASA were measured at 2.45 GHz. • A temperature range of −185 °C to 250 °C was investigated. • The simulants JSC-1A, NU-LHT-4 M, NUW-LHT-5 M, CSM-LHT-1G were studied. • Pyroxenite and anorthosite from the Stillwater mine, Montana, and synthetic glass were measured. • For a single simulant a linear relationship between sample density and permittivity is suggested. Lunar simulants are used to approximate the behavior of the lunar regolith. This work focuses on materials responses relevant for microwave heating to inform in-situ resource utilization of lunar regolith for landing pads and building infrastructure. Microwave dielectric permittivity and magnetic permeability measurements have been made for the first time on several new highland lunar simulants (NU-LHT-4M, NUW-LHT-5M and CSM-LHT-1G). One mare lunar simulant (JSC-1A) is included in this work. We present these measurements in the low temperature range −185 °C to 250 °C and in the frequency range 50 MHz to 3 GHz. The dominant minerals in the simulants are the minerals bytownite, ortho- and clino-pyroxenes, olivine, and glass. Less complex rock feedstocks for highland simulants, anorthosite and pyroxenite, were also measured separately. The dielectric measurements were performed on samples having different densities. Differences in the dielectric responses were noted, however all simulants were weak microwave absorbers at the low temperatures. This data assists with planning for a hybrid approach to microwave sintering at the lunar south pole. [ABSTRACT FROM AUTHOR]

High entropy oxide powders (ZrTiCoNiNb)O x were successfully synthesised using microwave heating with a TE666 resonant mode at temperatures ranging from 700 °C to 900 °C. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) techniques were carried out to characterize the samples, and the behavior of the samples when they undergo microwave heating was investigated. The mechanism of thermal field modulation (TFM) was explored to reduce the temperature gradients and improve heating efficiency. The temperature field distribution was simulated using COMSOL software. The process of synthesising (ZrTiCoNiNb)O x using microwave heating was found to comprise four stages: thermal accumulation, local solid-phase reaction, synchronous reaction and grain growth. A phase transition from multi-phase mixing to a fixed high entropy phase was observed. The effectiveness of the mechanism of thermal field modulation was confirmed via analogue computation and experimentation. [ABSTRACT FROM AUTHOR]

This research aimed to purify the environment of undesired substances by converting oily sludge (OS) micro-char fuel generation by microwave. The North Refineries Company (NRC) Baiji was the source of the OS sample utilized in this study. Micro-char manufacture, which has improved solid carbon characteristics, uses various microwave power and irradiation times. The parameters conditions at a range of power: feed of 5 g, 10 min of irradiation time, and microwave power ranges of 200, 400, and 600 W, respectively, under a nitrogen pressure of 3 L/min. While at the range of irradiation time: the feed was 5 g, microwave power was fixed at 600 W (the best microwave power discovered), and the range of irradiation duration was 5, 10, and 15 min. The ideal circumstances were (5 g, 600 W, and 15 min, under N2 pressure). The fuel ratio was increased from 0.70 to 0.97 OS with a 38.57% rise in the percentage of micro-char at 600 W and 15 min of irradiation time, while the HHV was increased from 9.40 to 17.22 MJ/kg at a rate of 83.20% as finding micro-char had improved as a solid carbon fuel. In general, micro-char has a fuel ratio and a higher HHV, making it suitable for solid carbon fuel in the oil industry. [ABSTRACT FROM AUTHOR]

Due to the unintentional spilling or dumping of dirty wastewater into rivers, which has a significant impact on the quality of water resources, the textile sector poses a global pollution concern. In this study, thulium vanadate (TmVO 4) was prepared by multiple fabrication techniques, including Pechini, sonochemical, microwave, and co-precipitation. The effect of these fabrication methods on the purity, morphology, shape, and size of as-prepared TmVO 4 was investigated. Characterization tests revealed that when the Pechini method was used at pH = 10, better morphology and uniform nanorods were formed. The effect of the preparation methods on photocatalytic activity was also discovered, with higher efficiency (71.7%) achieved over TmVO 4 prepared by the Pechini process at pH = 10 under visible light after 90 min. • Preparation of TmVO 4 by Pechini, sonochemical, microwave, and co-precipitation approaches. • Preparation methods affect the purity, morphology, and size of TmVO 4. • Investigation of fabrication methods on the photocatalytic activity. • Formation of TmVO 4 nanorods using Pechini method at pH = 10. • High ability of TmVO 4 for degradation of methyl orange dye (71.7%) in the visible region. [ABSTRACT FROM AUTHOR]

[Display omitted] • Wood waste collected at mechanical treatment plant in various periods of the year. • Organosolv treatment to produce a cellulose pulp for manufacturing containerboard. • Results show good reproducibility of the organosolv process applied to wood waste. • Obtained a pulp with an average cellulose content of about 76%. Wood waste is a valuable material that could constitute an abundant and inexpensive source for the production of new materials the recovery of energy. In Europe, about 46% of wood waste is recycled to particleboard and fiberboard, while the other fraction is incinerated. However, a considerable quantity of wood waste shows potential for its transformation into value-added products due to its compositional quality. In this work, wood waste collected at a mechanical treatment plant underwent organosolv treatment to produce a cellulose pulp suitable for manufacturing containerboard. Three variables (temperature, acid concentration, and ethanol concentration) were investigated to find an optimal solution to produce wood pulp by means of Design of Experiment. Wood waste was microwave-heated at 160 °C for 15 min using an acidified ethanol–water solution (2% w/w H 2 SO 4 and 0.8 w/w ethanol concentration), producing pulp with an average cellulose content of 76% where 93% of initial cellulose was retained. Thanks to a one-pot approach, ethanol was totally recovered, 62% of initial lignin was precipitated, and 20 g/l of hemicellulose-derived sugars solution was obtained. Finally, three wood waste samples collected in different periods of the year yielded comparable outcomes, suggesting a good reproducibility of the organosolv process. ANOVA test with a significance level of 0.01 showed a p-value of 0.029 and 0.235 for cellulose content and cellulose recovery, respectively. This study paves the way for an industrial symbiosis between recycling centers and paper mills located in the same territory. [ABSTRACT FROM AUTHOR]

The perovskite structure oxide, CaMnO 3 , has been extensively investigated and applied as a potential microwave absorption material due to its versatile dielectric and spontaneous polarization. However, the low conductivity of pure CaMnO 3 material limits its further application. Herein, to increase dielectric loss and achieve better microwave absorption properties, lanthanum (La)-doped CaMnO 3 (Ca 1-x La x MnO 3) ceramics were fabricated by a high temperature solid state reaction. The results of XRD and XPS show that the La atom was efficiently doped at the Ca site in CaMnO 3 , which carries excess positive charges and affects the valence state of Mn ions and the concentration of oxygen vacancies. Therefore, the conductivity and imaginary permittivity of Ca 1-x La x MnO 3 ceramics increased dramatically with La-doped content. Benefiting from the tunable dielectric and impedance properties, Ca 1-x La x MnO 3 ceramics can be utilized in a highly efficient way to absorb microwave radiation with a thin thickness. The sample with x = 0.04 shows the best microwave absorption property, with an RL min value of -52.63 dB (d = 1.41 mm) and effective absorption bandwidth coves full X band in the thickness range from 1.315 mm to 1.395 mm. [ABSTRACT FROM AUTHOR]

A TEMPO-oxidized cellulose (TOC)/nanofiber cellulose (NFC) biomass aerogel was prepared through freeze-drying (FD) for cationic dye adsorption. The stir freezing method was utilized to build cellular pores so as to improve the mechanical property of aerogel. The dielectric-assisted microwave (MW) heating was adopted to increase the FD rate. The results showed that the proposed method could simultaneously intensify the mass and heat transfer of FD, reducing more than 36% of drying time. The TOC/NFC aerogel exhibited a high mechanical property with 91.36 kPa of compressive stress at 80% strain. The maximum adsorption capabilities of aerogel prepared by stir freezing for methylene blue (MB) and malachite green (MG) dyes were 248.27 and 227.30 mg·g–1, respectively. The prepared aerogel showed high selective adsorption of cationic dyes in binary dye solutions. Moreover, the prepared aerogel exhibited a satisfactory recycling performance in 20 cycles of adsorption/desorption experiments. This work provides a new freezing and FD strategy to prepare TOC/NFC aerogels with promising applications in industrial printing and dyeing wastewater treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

The susceptor and susceptor thickness significantly influence the microwave heating process. This work theoretically investigates the effects of two different susceptors with various thicknesses on microwave heating of raw meat. A susceptor with low dielectric loss (alumina) and a susceptor with high dielectric loss (SiC) are used for present study to investigate the effect of dielectric loss during microwave heating. The addition of the alumina susceptor either enhances or diminishes the heating rate of resonating samples depending on thickness, while the addition of the SiC susceptor improves the heating uniformity of resonating samples. The addition of susceptors on thick samples shows different characteristics from resonating samples. High heating rate and heating uniformity are the two major criteria for several microwave heating applications. Hence, the optimum susceptor thicknesses for specific sample dimensions are determined based on either high heating rate or heating uniformity. [ABSTRACT FROM AUTHOR]

Atenolol (ATN) belongs to a class of drugs known as β-blockers. This medicine works on the heart and blood vessels by blocking the action of some natural chemicals in the body. ATNs are present in surface water and sediments from hospitals and wastewater treatment plants. In the current study ATN degradation using hybrid processes of peroxymonosulfate (PMS)/ultraviolet (UV)/microwave (MW) were investigated. The reaction kinetics and scavengers' effects were also evaluated. Experiments were carried out in a 1.5-L reactor with UV lamp and MW and then analyzed by high-performance liquid chromatography. Artificial neural networks was implemented for modelling and particle swarm optimization technique was used to specify the optimal status for ATN degradation. According to the result, only MW power and PMS parameters had a linear relationship with efficiency, and other parameters had non-linear relationship. Moreover, increasing PMS dosage and MW power in neutral pH has a significant effect on ATN degradation. As per our result, optimum conditions in the experiments were pH 6.2 and 28.8 mg/L ATN initial concentration, 3.05 mg/L PMS concentration, 14.30 min UV time, 19.90 min MW time and 630 W MW power. In this situation the ATN degradation rate was about 97% which according to the sensitivity analysis by Pearson correlation method, pH had the greatest effect on the degradation efficiency in the range of 3-7. Nitrate (NO3-), chloride (Cl-) and humic acid (HA) were used as scavengers. The findings showed that increasing the concentration in HA and NO3- decreased the efficiency, but Cl- did not have much effect on the results. According to the results, this method can be efficient for the degradation of ATN. [ABSTRACT FROM AUTHOR]

One-dimensional layer structure a-MoO 3 nanobelts with abundant oxygen defects were effectively synthesized through a hydrothermal route and decorated by ZnO nanoparticles via a liquid-phase chemical process. ZnO nanoparticles (NPs) with a size of approximately 50 nm were uniformly dispersed on the a-MoO 3 nanobelt surface, forming an n-n heterostructure at the two-phase interface. The crystalline structure, microtopography, element composition, valence state, surface-to-volume ratios, optical properties, and work function of the ZnONP-decorated a-MoO 3 samples were analyzed. ZnONP-decorated a-MoO 3 nanobelts with different proportions of ZnO were synthesized and subjected to ethanol sensing. The 25% loaded ZnONP-decorated a-MoO 3 nanobelts were found to offer the best response (R a /R g = 19.2 at 100 ppm), which was 3.6 times higher than that of pristine α-MoO 3 (5.37) with a low detection limit (108 ppb). The response time was significantly lower (14–27 s) than that of pristine a-MoO 3 (5–8 s). Furthermore, the sensor has ultrahigh selectivity and reliable stability for ethanol. Layered MoO 3 nanobelts have a unique sensing mechanism, which is the catalytic oxidation of lattice oxygen on the MoO 3 surface to form oxygen vacancies and free electrons. The excellent sensing performance was ascribed to the unique 1-D nanobelt morphology of the a-MoO 3 carrier, the abundance of oxygen defects, and the formation of heterojunction barriers at the two-phase interface. [ABSTRACT FROM AUTHOR]

Identifying the best technique for extracting water ice deposits in permanently shadowed regions at the lunar poles will be crucial in determining how successful a long-term or permanent settlement at these locations will be for future scientific and technology missions. This study uses a low-power microwave heating method to extract water from icy lunar simulants. Samples of lunar highland and mare simulants at different water contents (3–15 wt %) were heated using 250 W, 2.45 GHz microwaves. A maximum of 67 ± 5% [2SD] of the water was extracted during heating runs of 25 min. Water was extracted more efficiently from the highland simulant than from the mare simulant. A significant reason for the different efficiency of water extraction in icy lunar simulants was the differing porosity of the samples made from different simulants. Pore space filled with ice leads to a reduced contact area between grains and an increased area of free ice, which causes poor heating performance. The results indicated that differences in chemical composition between the simulants had a negligible effect on water extraction, as the contact area between grains seems to dominate water extraction. This study found that low-power microwave heating is an effective technique for extracting water from cryogenic Icy simulants. It was also found that using a simple input energy principle (Input Energy = Absorbed Power x Heating Time) to estimate the additional heating time was sufficient to overcome inefficient heating due to differing absorbed powers. For undersaturated samples, microwave heating was an efficient heating mechanism, but is less efficient for saturated samples where alternative heating methods may be more efficient at melting free ice before employing microwave heating. • Microwave heating can be used to extract water from cryogenic icy lunar simulants. • Compositional differences in simulants have negligible effects on water extraction. • Water-saturated samples show low extraction compared to low-water-content samples. • The low extraction is due to low grain contact area and increased ice surface area. • The saturated sample's low water extraction can be mitigated by additional heating. [ABSTRACT FROM AUTHOR]

The process of dry reforming of methane (DRM) can allow the conversion of methane and carbon dioxide, the two main greenhouse gases (GHG), into syngas which can be either used as feedstock for chemicals production or it can undergo through separation step for H 2 recovery. However, the heat required for the reaction is obtained by combustion of fossil fuels, so CO 2 footprint of the process is significant. Another problematic aspect of the process concerns the heat transfer to the catalytic volume: for allowing the catalytic bed to reach and maintain the reaction temperature, the heating medium outside the tubes containing the catalyst must have a temperature higher than 1000 °C. A process intensification could be performed by combining two innovative technologies: (i) the use of electrification for the energy supply (microwave heating and direct electrification) and (ii) the adoption of structured catalysts with high thermal conductivity. This work proposed the study of electrified DRM process using two Ni-based structured catalysts prepared starting by different carriers, a Silicon carbide (SiC) honeycomb monolith and a Si–SiC open-cell foam. The electrification of the DRM process has been realized by using either microwave heating or electrification through Joule (or ohmic) heating, and the experimental tests have been performed at different space velocity values. The configuration of the carriers has been carefully chosen in order to enhance the heat and mass transport phenomena, allowing to assure a flat temperature profile along the entire catalytic bed. The results have shown that the SiC monolith is more suitable than the Si–SiC foam for a microwave-assisted catalytic test. In fact, the higher fraction of void in the foam determines a lower heat absorption, and a consequently higher energy consumption (8.29 kWh/Nm3 H 2 and 4.2 kWh/Nm3 H 2 , for the foam and the monolith respectively). Moreover, the monolith-based catalyst approached the thermodynamic equilibrium values in terms of CH 4 conversion in all the investigated temperature range, while in the same tests the foam-based catalyst reached these values only at the higher temperatures. Conversely, the foam-based catalyst has shown the best performance in the electrification tests through Joule heating: the CH 4 conversion approached the equilibrium values in the investigated temperature range and, more important, the energy consumption value was of 2.6 kWh/Nm3 H 2 , very close to the theoretical one (1.90 kWh/Nm3 H 2) and equal to about ¼ of that obtained with microwaves. [ABSTRACT FROM AUTHOR]

Rapid microwave sintering processes with heating rates of up to 300 °C/min and zero isothermal hold have been implemented using a 5 kW 24 GHz gyrotron system for high-temperature microwave processing of materials. ZnO-based varistor ceramics, BaTiO 3 /SrTiO 3 dielectric ceramics and Gd:CeO 2 ceramics for solid electrolyte applications have been sintered to densities of up to 96% of the theoretical value. Using in situ optical dilatometry, correlation between the development of thermal instability under intense volumetric microwave heating and the early onset of densification has been revealed. The influence of the absorbed microwave power on densification and grain growth has been studied by comparing direct and susceptor-assisted microwave heating processes. The possibility of tailoring the microstructure and functional properties of the obtained materials by choosing optimal regimes of rapid microwave sintering is discussed. [ABSTRACT FROM AUTHOR]

The ZnSe/ZnO heterostructures were synthesized with the microwave-assisted hydrothermal method, using zinc acetate and zinc nitrate as a source of Zn2+ ions. Materials were characterized by X-ray diffraction (XRD), X-ray photoemitted electron spectroscopy (XPS), Raman spectroscopy, and scanning electron microscopy (SEM). The incorporation of ZnSe into the ZnO matrix produced changes both in the size of the ZnO crystallites and in the lattice parameters. Optical and texture analyses revealed that ZnSe particles cause a decrease in gap energy and a greater than 90% increase in the specific surface area of ZnSe/ZnO heterostructures compared to bare ZnO particles. ZnSe/ZnO heterostructures synthesized using zinc acetate as a Zn ion source exhibited better photocatalytic performance in visible light compared to pure ZnO. [ABSTRACT FROM AUTHOR]

Combining mullite with SiC ceramics is considered to be an effective method to reduce the sintering temperature of ceramics while maintaining excellent performance of the resultant materials. However, traditional heating methods used in this process are still more energy intensive. This work presents a fabrication method for producing mullite-bonded SiC ceramics via microwave heating and an in situ mullite reaction bonding. Via the proposed method, the preparation of samples with a bending strength of 125 ± 6 MPa and a porosity of 36.2% can be achieved at 1200 °C for 15 min. The microwave coupling effect and the impedance matching effect of SiC particles provide the heat source for the rapid sintering of the mullite-bonded SiC ceramics at low temperature. Bridging configuration of mullite between SiC particles occurred due to the unique coupling effects during microwave heating. Moreover, the low sintering temperature and short holding time inhibit the formation of the detrimental cristobalite phase. This work indicates that this rapid and low-temperature preparation method of mullite-bonded SiC ceramics has potential uses in the industrial production of high-performance SiC ceramics. [Display omitted] [ABSTRACT FROM AUTHOR]

Equiatomic Ni–Ti alloy reinforced with 0, 2.5, 5, and 10 vol % SiC nanoparticles was synthesized through mechanical alloying and microwave sintering process. In this method, a mixture of Ti and Ni powders and SiC nanoparticles (0–10 vol%) were mechanically milled for 30 h, compressed under 1 GPa pressure, and then sintered at 900–1100 °C by microwave heating. Microstructural analysis of the synthesized samples was performed using X-ray diffraction and scanning/transmission electron microscopy, and their hardness was determined using a Vickers microhardness tester. Structural studies revealed the formation of a complex phase structure consisting of the austenite (B2–NiTi), the martensite (B19′-NiTi), and the nickel-rich (Ni 3 Ti) and titanium-rich (NiTi 2) phases. HR-TEM investigations confirmed an increased Ni 3 Ti phase in the austenitic NiTi matrix nearby the martensitic NiTi phase. It was found that adding SiC nanoparticles to Ni–Ti increased the amount of hard Ni 3 Ti phase, promoted the stability of the martensite phase at room temperature, and retarded the matrix grain growth during the sintering process. Microhardness tests showed that when the content of SiC nanoparticles increased up to 5 vol %, the microhardness increased considerably to 9 GPa and then declined. The high microhardness of synthesized nanocomposites is due to the formation of Ni 3 Ti and NiTi martensitic phases and their nanocrystalline structure. [ABSTRACT FROM AUTHOR]