Microwave Heating Research Articles (Page 1)

The 12 principles of green chemistry guide the scientific community toward the development of chemical processes that are more respectful of the environment and safer for human health. In organic synthesis, this mainly involves the use of sustainable alternatives to conventional organic solvents, energy-efficient processes, and waste minimization. In this context, this review focuses on the use of deep eutectic solvents (DES) in microwave-assisted organic synthesis. Indeed, DES, due to their nonvolatility, nonflammability, and low toxicity compared to conventional organic solvents, are considered desirable "green solvents" for the development of environmentally friendly processes. Moreover, their physicochemical properties make them ideal media for microwave heating. Thus, all organic syntheses using DES as solvent and microwave heating documented in the literature are reported, including heterocycle synthesis, nitrogen quaternization reactions, 5-hydroxymethylfurfural production, Knoevenagel reactions, and miscellaneous transformations. The recyclability of DES-based systems and their scalability, where applicable, are reported. Mechanistical considerations when DES are involved are also described. Compared with conventional heating methods, microwave heating of DES media generally results in good yields and a significant reduction in reaction times. This DES-MW combination appears promising for more sustainable organic syntheses.

The emissions from internal combustion engines (ICEs) contribute to climate change, air pollution, and pose risk to human health. This review is the first part of a research study that aims to employ computational fluid dynamics (CFD) to develop a clean and efficient combustion strategy focussing on ammonia as an alternative fuel. This article discusses background related to ammonia economy, safety, and its impact on the environment and human health. Combustion characteristics of ammonia are analysed in this article. The review explores various techniques such as blended and dual fuels that are employed to optimize the ignition, including developments in recent ammonia commercial engines. It discusses challenges for minimizing nitrogen-based emissions and also delves into investigations of hydrogen generation through ammonia decomposition, with a focus on microwave heating as an efficient method. Literatures on CFD models tailored to ICEs are also examined. The methodologies of CFD model and techno-economic approach of ammonia decomposition by microwave heating are described. Key findings referred that nearly 4% of ammonia production currently utilizes sustainable sources. Hydrogen with selective catalytic reduction reduces the temperature of reaction to below 200 °C and produces water vapour as a byproduct. Ammonia decomposition by microwave heating occurs at temperatures 100–200 °C lower than conventional methods. Moreover, the localized ammonia decomposition by microwave heating for hydrogen production proves to be 4.5% more efficient than hydrogen storage for transportation. The preliminary CFD investigation from this study suggests the feasibility of using ammonia as a carbon-free fuel for spark ignition ICEs. Compared to methane (CH 4 ) combustion, ammonia shows a 2.5% increase in thermal efficiency and approximately 40% reduction in NOx emissions. This study lays the groundwork for future exploration of ammonia and hydrogen as potential cornerstone for cleaner and more sustainable ICEs.

Stretchable transparent dielectric heaters are essential for smart thermal management in next-generation wearable electronics. However, existing hydrogel electrode-based devices suffer from rapid degradation under environmental stresses, limiting their real-world applicability. Here, ionogel electrodes leveraging non-volatility and thermal stability, which achieve covalent bonding integration with poly(vinyl chloride) gel to eliminate interfacial delamination in stretchable heaters are introduced. The ionogel electrodes exhibit high ionic conductivity (13mScm-1), stretchability (187%), and transparency (>90%), making them ideally suited for deformable transparent devices. The resulting stretchable transparent dielectric heaters deliver unprecedented performance, reaching 98.6°C at 400V with ultrafast heating rates (1.56°Cs-1), 14 times faster than hydrogel electrode-based dielectric heaters. Remarkably, the heaters achieve the therapeutic temperature of 45°C for wearable applications at 100V, representing an 80% voltage reduction compared with a hydrogel electrode-based dielectric heater. Also, the heater demonstrates environmental resistance across extreme temperatures (4-80°C), low humidity (10-60% relative humidity), and repeated drying-swelling cycles, while sustaining functionality over extended operation (≥12h). Demonstrations in wearable thermoregulation, transparent de-frosting, and smart greenhouse systems validate the practical viability of the system and establish it as a transformative solution for soft electronics in the real world.

Chinese shale reservoirs are typically deep, clay-rich, and highly water-sensitive, which severely limits the effectiveness of conventional hydraulic fracturing. To address this challenge, we propose a microwave-assisted waterless fracturing method and investigate its feasibility through laboratory experiments on core samples from the Gulong shale and tight sandstone formations in the Daqing Oilfield. A coupled model integrating microwave power dissipation, pore water heating, and thermal stress evolution is developed to interpret the underlying mechanisms. Experimental results show that, under microwave irradiation (200 W, 40 s) and initial pore water content of 2.1–6%, fracturing is successfully induced without external fluid injection. The tensile failure of the rock coincides with the peak internal pore pressure generated by rapid vaporization and thermal expansion of pore water, as confirmed by a modified tensile strength measurement method. Fracture patterns observed in SEM and post-treatment imaging align with model predictions, demonstrating that microwave energy absorption by pore water is the primary driver of rock failure. The technique eliminates water-related formation damage and is inherently suitable for deep, water-sensitive reservoirs. This study provides experimental evidence and mechanistic insight supporting microwave-based waterless fracturing as a viable approach for challenging shale formations.

In this work, a sustainable method for the hydration of both terminal and internal alkynes is presented, affording the corresponding ketones with complete Markovnikov regioselectivity. The key advantage of this approach lies in the use of recently developed three-component, double-acidic deep eutectic solvents (DESs), designed by our research team, which act as triple-active media-simultaneously serving as solvents, reagents, and catalysts. The reaction setup is straightforward and can be carried out under conventional or dielectric heating, typically providing the desired products in good to excellent yields. For terminal alkynes, microwave heating further enhances the sustainability of the process by a significant reduction of reaction times. The reusability of the reaction medium is demonstrated through recycling experiments, while the calculation of two green metrics (sE-factor and EcoScale) highlights the environmental benefits of this strategy.

Despite the benefits of pharmaceuticals in medicine, concerns about their presence in wastewater sludge highlight the need for sustainable strategies that focus on reducing and managing their environmental release. Introducing pharmaceutical residues into the environment through the land application of biosolids poses substantial risks to the public and the ecosystem. As a way to reduce pharmaceutical contamination in biosolids, a study was conducted using biochemical methane potential (BMP) assays to evaluate the effectiveness of electromagnetic heating methods for advancedanaerobic digestion (AD). Thermal sludgepretreatment was evaluated using radio frequency (RF) heating at 13.56MHz and microwave (MW) heating at 2450MHz. Both methods are compared in terms of reducing ubiquitous pharmaceuticals, specifically ibuprofen (IBP), diclofenac (DCF), and carbamazepine (CBZ). Both pretreatments enhanced the removal of pharmaceuticals by facilitating their transformation into more accessible and biodegradable forms in both the aqueous and total phases of the sludge. In particular, RF heating yielded a DCF removal efficiency of 92% in the aqueous phase of sludge. Even IBP and DCF accumulated in control BMPs incubated under both thermophilic and mesophilic conditions, thermal pretreatment facilitated the co-metabolic degradation of target pharmaceuticals through an accelerated hydrolysis stage, resulting in their improved removal during advanced digestion. Compared to the control, RF pretreatment combined with AD improved DCF removal by 17% in the total phase and increased persistent CBZ removal by 5%. Thermal pretreatment also reduced the release of pharmaceuticals into the aqueous phase during advanced digestion compared to the control. Considering the feasibility of RF and MW heatings at full scale, the integration of energy-efficient RF heating technology into digestion is preferred to reduce pharmaceutical levels building up in the ultimate disposal route, including both the centrate side streams and agricultural land.

Comparative study on the degradation mechanism of C-phycocyanin under different heat treatments: Insights from spectroscopy and molecular dynamics simulations.

ABSTRACT In this study, carrot slices were dehydrated using microwave (MW) pretreatment compared to conventional convective drying (CCD) alone at two air temperatures (60°C and 80°C). The treatments included CCD60, CCD80, MW + CCD60, MW + CCD80, with freeze‐drying (FD) as the control. The research aimed to analyze the kinetics of water removal to evaluate the efficiency of the different drying methodologies. Additionally, the physicochemical properties of the dehydrated carrot slices were examined, including rehydration ratio (RR), texture, antioxidant capacity, shrinkage. Besides the ultrastructure via transmission electron microscopy (TEM) was measured. The results indicated that the processing time during MW + CCD led to significant time savings of 66% and 57% for temperatures of 60°C and 80°C, respectively. The fitting of the drying curves to the Page model revealed a diffusion mechanism for CCD ( n > 1) and a sub‐diffusion mechanism for MW + CCD ( n < 1). Notably, MW pretreatment improved the rehydration ratio and resulted in less shrinkage compared to CCD. The crispest samples were found to be FD, followed by MW + CCD60 and MW + CCD80. Furthermore, the use of MW pretreatment significantly enhanced antioxidant capacity, comparable to that of CCD samples. Ultrastructural analysis showed that MW treatment disrupted cell membranes and altered cell wall structure, which was associated with the lack of appreciable diffusive processes in MW + CCD drying. These findings highlight the potential advantages of incorporating MW technology as a pretreatment in the dehydration process of carrot slices. This approach aligns with the goal of producing high‐quality, convenient, and nutritionally valuable vegetable‐based snacks. This work led to a significant improvement in the final product quality parameters like texture, shrinkage, rehydration and antioxidant compounds compared to CCD.

Effect of pH and proportion on structural properties of Hylon VII starch - gellan gum blends processed in a microwave hermetic system.

Collaborative mechanisms of impeller stirring and microwave heating in hydrofluoric acid dissociation of beryllium ore: Multiphysics-field numerical simulation

Multiphysics simulation and optimization of microwave-assisted regeneration of spent activated carbon for enhanced energy efficiency.

Intracavity directional microwave heating based on a single-source multifrequency phased array

Promoting effect of microwave heating and thermal storage balls on drying and triboelectrostatic separation of wet CGFS particles

Microwave assisted rapid synthesis of TiO2 NFs@COF S-scheme heterojunction photocatalyst for highly efficient photocatalytic hydrogen evolution.

Methane pyrolysis into hydrogen and solid carbon: A comparative analysis of conventional and microwave heating approaches

Concept for a Cesium-Free negative ion source based on microwave heating of a low work function granular material

The rapid growth of electric vehicles and portable electronics has led to a surge in lithium-ion battery (LIB) consumption, creating an urgent need for efficient and sustainable recycling solutions. Among the established recycling methods, including pyrometallurgical, hydrometallurgical, and direct recycling, thermal treatment plays a critical role. However, conventional heating techniques are often energy-intensive and time-consuming due to their low heating rates. This highlights the importance of exploring advanced rapid heating technologies for recycling spent LIBs. This review examines the role of heating in various LIB recycling processes and systematically introduces emerging rapid heating technologies, such as microwave heating, joule heating, and short contact time heating. In addition, advanced approaches, including induction heating, plasma heating, and CSR heating processes, are discussed in terms of their principles, process flows, unique effects, and applications in LIB recycling. Finally, current challenges and future perspectives are outlined to support the efficient and scalable use of rapid heating technologies in spent LIB recycling, and the rapid heating process is also proposed for the efficient recycling of spent LIBs.

This study discusses the problem of environmental law violations caused by illegal exploitation of fossil energy resources, which is still a major challenge in Indonesia. One potential alternative approach is the development of new renewable energy from the nyamplung plant (Calophyllum inophyllum), which naturally grows on marginal and coastal lands. This study aims to answer three main problem formulations: (1) Why is nyamplung fruit worthy of being used as a substitute for fossil fuels? (2) How is nyamplung relevant in reducing environmental law violations? (3) How to examine and facilitate the phenomenon of nyamplung growth as an innovative solution in the context of environmental law? The objectives of this study are to evaluate the efficiency of biodiesel production from nyamplung, examine its contribution to the environmental law system, and propose community-based intervention policies. The method used is library research and descriptive-qualitative analysis with an ecological legal approach. Data were obtained from international journals, national policies such as Law No. 32 of 2009 and Presidential Regulation No. 22 of 2017, and reports on research results on transesterification-based biodiesel technology using heterogeneous catalysts. The results show that nyamplung oil has a high oil content (65–75%) and can be processed into high-quality biodiesel that meets ASTM D6751 and EN 14214 standards. The production process that utilizes modern technology, such as microwave heating, can produce conversion efficiency of up to 98–99%. The use of nyamplung in the community has also been proven to be able to suppress environmental law violations by providing legal and sustainable energy pathways. The conclusion of this study is that nyamplung is a strategic alternative to replace fossil fuels that is not only superior in terms of technical and environmental aspects, but also has a strong driving force in enforcing environmental law based on ecological justice. Therefore, synergy is needed between the state, local communities, and the private sector in strengthening local plant-based energy policies such as nyamplung.

Microwave heating is a method with a uniform heating effect and environmental friendliness in in-place hot recycling, but the microwave absorption capacity of traditional asphalt mixtures is still insufficient. As an excellent microwave-absorbing material, magnetite powder has the characteristics of high temperature resistance, corrosion resistance, and good thermodynamic stability. This study selects it as the microwave-absorbing material, prepares AC (Asphalt Concrete) type and SMA (Stone Mastic Asphalt) type microwave asphalt mixtures by adjusting its content, and investigates its influence on the microwave-heating characteristics and pavement performance of the mixtures. Simulations of the microwave-heating process of AC-type mixtures using COMSOL software (COMSOL Multiphysics 6.2) show that magnetite powder achieves optimal performance in terms of heating effect and economic efficiency when its content is 0.5%. Subsequently, laboratory tests are conducted to study the wave absorption and temperature rise performance of AC and SMA microwave asphalt mixtures; combined with economic factors, the optimal contents of magnetite powder for the two types of mixtures are determined to be 0.5% and 1%, respectively, and at the same time, these results are explained based on multiple physical theories. Furthermore, pavement performance is investigated through laboratory tests, including high-temperature rutting tests, low-temperature bending tests, immersed Marshall tests, and freeze–thaw cycle durability tests, and the results indicate that the high-temperature performance, low-temperature performance, and water stability of the microwave asphalt mixtures all meet the specification requirements for pavement performance. Subsequently, after 15 freeze–thaw cycles, the splitting tensile strength retention rate and stiffness modulus of the two types of mixtures show minimal differences from those of ordinary mixtures, and there is no durability degradation caused by the incorporation of magnetite powder. Finally, outdoor environment verification is carried out, and the results show that under complex conditions such as environmental factors, the wave absorption and temperature rise rates of AC and SMA mixtures at optimal contents are 52.2% and 14.6% higher than those of ordinary AC and SMA asphalt mixtures, respectively. In addition, these microwave asphalt mixtures have the advantages of both sustainability and reduced carbon emissions. By combining simulation methods and experimental verification, this study finally prepared two types of microwave asphalt mixtures with excellent performance, not only improving the microwave absorption and heating performance of asphalt mixtures, but also reducing environmental pollution and energy consumption, which conforms to the development of green transportation.

ABSTRACT Cyanate ester resins are widely applied in electronic information industries and aerospace fields due to their excellent dielectric properties, heat resistance, mechanical performance, and flame retardancy. With the rapid advancement of microelectronic technology, there is an urgent need to further enhance the comprehensive properties of cyanate ester resins. In this work, a novel fluoride‐containing tetrafunctional cyanate ester (FTFCy) monomer was synthesized and copolymerized with bisphenol A dicyanate ester (BADCy). The molecular structure and performance of the resulting copolymer resins were systematically investigated. The results demonstrate that the incorporation of FTFCy significantly improves the heat resistance, dimensional stability and dielectric properties of cyanate ester resins. Specifically, the 5% weight loss temperature of the BADCy/FTFCy resin containing 10 wt% FTFCy reaches 435.4°C, which is obviously higher than that of pure BADCy resin (419.5°C). The glass transition temperature ( T g ) of the BADCy/FTFCy resin with 30 wt% FTFCy increases from 288.5°C for the pure BADCy resin to 315.3°C. For the BADCy/FTFCy resin with 30 wt% FTFCy, the dielectric permittivity ( ε ) and dielectric loss tangent (tanδ) at a frequency of 1 MHz reach 2.78 and 0.0047, respectively, which are significantly lower than those of pure BADCy resin (3.07 and 0.0116). At 10 GHz, the ε and tanδ of this BADCy/FTFCy resin reach 2.70 and 0.0109, corresponding to reductions of 7.5% and 27.8% compared to pure BADCy resin (2.92 and 0.0151). Additionally, when the mass fraction of FTFCy is 30 wt%, the coefficient of thermal expansion (CTE)of the BADCy/FTFCy resin decreases to 58.3 ppm/°C, which is markedly lower than that of pure BADCy resin (65.6 ppm/°C). The BADCy/FTFCy copolymer resins exhibit outstanding comprehensive performances, making them promising candidates for advancing the development of printed circuit boards, electronic packaging materials, and radomes.