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Journals
Processes
Special Issues
Microwave Applications in Chemistry and Industry
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Microwave Applications in Chemistry and Industry

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Chemical Processes and Systems".

Deadline for manuscript submissions: 20 December 2024 | Viewed by 7293

Special Issue Editors

Prof. Dr. Junwu Tao

E-Mail Website
Guest Editor
LAPLACE Laboratory, Toulouse INP-ENSEEIHT, University of Toulouse, 31071 Toulouse, France
Interests: microwave device design; microwave power application; computational electromagnetic and multi-physics
Special Issues, Collections and Topics in MDPI journals
Dr. Li Wu

E-Mail Website
Guest Editor
College of Electronics and Information Engineering, Sichuan University, Wangjiang Road 29, Chengdu, China
Interests: microwave plasma device design and its applications; microwave power application
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Kama Huang

E-Mail Website
Guest Editor
College of Electronics and Information Engineering, Sichuan University, Wangjiang Road 29, Chengdu, China
Interests: fundamental microwave theory; novel microwave applications
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Microwave heating exploits the interaction between electromagnetic waves and materials to convert microwave energy into heat. This has resulted in the widespread use of microwave energy in industrial, scientific and medical sectors. The advantages of microwave heating compared to conventional heating are numerous; its efficiency thanks to selective heating leads to a shortened heating time, it has easily controllable temperature rise dynamics, etc. In many applications, the use of microwaves appears environmentally friendly; for example, it leads to a possible reduction in solvents and in the quantity of wastewater in microwave-assisted chemistry. Microwaves are expected to become increasingly popular, with the development of new microwave technologies solving many problems in the future, particularly in energy-intensive industrial sectors, to replace conventional heating.

The industrialization of microwave heating depends heavily on the control of two main weak points of this technology, namely the presence of hot spots, and the risk of thermal runaway. Solving these problems creates the need for (i) a better understanding of the mechanisms of interaction between electromagnetic waves and the media under treatment; (ii) the development and manufacture of dedicated equipment; (iii) the study of the electromagnetic properties of new materials. The popularization of multi-physics simulation tools, progress in the development of microwave and radio frequency equipments, and the appearance of new materials all contribute to innovative solutions for microwave power applications at both the laboratory scale and industry scale.

This Special Issue, titled “Microwave Applications in Chemistry and Industry”, aims to shows the most recent advances in the following areas:

  • Microwave and RF applications in chemistry;
  • Microwave and RF applications in materials processing;
  • Microwave and RF applications in food science and engineering;
  • Microwave and RF applications in biomass and waste processing;
  • Microwave and RF applications in medicine and biology;
  • Microwave-driven plasma and applications;
  • Microwave RF device design and optimization;
  • Dielectric and magnetic properties measurement and modeling;
  • Scaling up for microwave industrial applications.

Prof. Dr. Junwu Tao
Dr. Li Wu
Prof. Dr. Kama Huang
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • microwave power
  • microwave processing of chemical reactions
  • microwave processing of materials
  • microwave-driven plasma
  • biomass and waste processing
  • device design and optimization
  • scaling up for microwave industrial applications

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Further information on MDPI's Special Issue polices can be found here.

Published Papers (6 papers)

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Research

15 pages, 3125 KiB  
Article
A High-Performance Microwave Heating Device Based on a Coaxial Structure
by Jintao Duan, Wei Xiao, Guilan Liu, Fengming Yang, Huacheng Zhu and Yang Yang
Processes 2024, 12(9), 1942; https://doi.org/10.3390/pr12091942 - 10 Sep 2024
Viewed by 724
Abstract
Continuous-flow microwave heating stands out for its ability to rapidly and uniformly heat substances, making it widely applicable in chemical production. However, in practical applications, the permittivity of the heated liquid changes dramatically as the reaction progresses, affecting the efficiency and uniformity of [...] Read more.
Continuous-flow microwave heating stands out for its ability to rapidly and uniformly heat substances, making it widely applicable in chemical production. However, in practical applications, the permittivity of the heated liquid changes dramatically as the reaction progresses, affecting the efficiency and uniformity of continuous-flow heating. Herein, this work presents a novel microwave heating device based on a coaxial structure for high-performance heating. Our approach commenced with the development of a multiphysical field model, incorporating spiraled polytetrafluoroethylene (PTFE) as a water channel and the coaxial waveguide as a container. The analysis shows that the uniform distribution of the sectional electric field of electromagnetic waves in the TEM mode within the coaxial structure can enhance heating uniformity. Then, a continuous-flow microwave heating system for different liquid loads was established, and experimental measurements were conducted. The heating efficiency for all loads exceeded 90%, which basely matched the simulation results, validating the accuracy of the model. Finally, the heating efficiency and uniformity under different permittivity loads were analyzed, as well as the impact of channel radius on heating efficiency. The device exhibits high heating efficiency under different loads, with uniform radial electric field distribution and stable heating uniformity. This continuous-flow microwave device is suitable for chemical research and production because of its high adaptability to the large dynamic range of permittivity, contributing to the promotion of microwave energy applications in the chemical industry. Full article
(This article belongs to the Special Issue Microwave Applications in Chemistry and Industry)
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19 pages, 14284 KiB  
Article
The Research on Microwave Drying Characteristics of Polyethylene Terephthalate Materials Based on Frequency and Power Tuning Technology
by Chongwei Liao, Zhongqi He, Rong Tang, Weixin Zhang, Changjun Liu and Chuanlong Wang
Processes 2024, 12(7), 1488; https://doi.org/10.3390/pr12071488 - 16 Jul 2024
Cited by 1 | Viewed by 775
Abstract
Polyethylene Terephthalate (PET), renowned for its exceptional physical and chemical properties, finds widespread use in our daily lives. However, conventional PET drying methods are time consuming and energy intensive. Leveraging microwave heating effects, we investigated drying characteristics concerning both microwave parameters and PET [...] Read more.
Polyethylene Terephthalate (PET), renowned for its exceptional physical and chemical properties, finds widespread use in our daily lives. However, conventional PET drying methods are time consuming and energy intensive. Leveraging microwave heating effects, we investigated drying characteristics concerning both microwave parameters and PET permittivity. The PET permittivity variation during heating is related to the microwave reflection at the incident port. Our innovative approach involves frequency and power tuning based on reflection. This method not only significantly improved heating uniformity and reduced temperature covariance (COVT) but also led to a more uniformly distributed temperature profile and a drastic reduction in energy consumption. Integrating precise and rapid frequency tuning, we compared our method’s efficiency with traditional approaches, revealing an impressive time savings of 2 h and an energy consumption limited to approximately less than 3 kWh/kg. Notably, our laboratory system’s logistic models of the Moisture Ratio (MR) related to rotary rates, masses, and powers whose averages of R-square are 0.9972, 0.9982, and 0.9977, respectively, which provide intriguing insights for industrial production forecasts during variable frequency PET drying. Full article
(This article belongs to the Special Issue Microwave Applications in Chemistry and Industry)
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11 pages, 2805 KiB  
Article
Analysis of Microwave Effects on the MnO2-Catalyzed Toluene Oxidation Pathway
by Fengming Yang, Yi Ye, Lili Ding, Huacheng Zhu, Jianhong Luo, Long Gao, Yunfei Song and Shumeng Yin
Processes 2024, 12(6), 1074; https://doi.org/10.3390/pr12061074 - 24 May 2024
Viewed by 827
Abstract
Microwave radiation has become an effective catalytic combustion method, especially in the degradation of volatile organic compounds (VOCs) such as toluene using catalysts like MnO2. In this study, a spine waveguide microwave reactor was designed to investigate the influence of different [...] Read more.
Microwave radiation has become an effective catalytic combustion method, especially in the degradation of volatile organic compounds (VOCs) such as toluene using catalysts like MnO2. In this study, a spine waveguide microwave reactor was designed to investigate the influence of different microwave processing conditions on the degradation of toluene catalyzed by MnO2. An experimental system for microwave-assisted catalytic degradation of toluene was established to explore the relationship between microwave power, catalyst conductivity, and toluene degradation rate. The results showed that the efficiency of MnO2 catalyzing toluene degradation had a nonlinear relationship with microwave power, first increasing to a peak and then decreasing. Additionally, the experiment found that the degradation rate of toluene was positively correlated with the conductivity of MnO2. Subsequent characterization analyses using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) further verified the changes in the microstructure and properties of MnO2 under microwave heating. The characterization results showed that with the increase in microwave power, the relative content of Mn3+ on the surface of MnO2 increased, and the relative content of adsorbed oxygen also increased accordingly. At a microwave power of 100 W, the treated MnO2 displayed the optimal ratio of manganese oxidation state and oxide, both close to 1:1, which was more conducive to the degradation of toluene. Based on these findings, this study hypothesized that the microwave-enhanced catalytic degradation of toluene by MnO2 may be attributed to changes in the surface electron transfer kinetics of MnO2, providing new insights into the field of microwave-enhanced catalysis. Full article
(This article belongs to the Special Issue Microwave Applications in Chemistry and Industry)
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13 pages, 1770 KiB  
Article
Assessment of Fungal Resistance and Preservative Retention in Microwave-Pretreated Norway Spruce Wood
by Sauradipta Ganguly, Marko Petrič, Sadhna Tripathi and Davor Kržišnik
Processes 2024, 12(4), 750; https://doi.org/10.3390/pr12040750 - 8 Apr 2024
Viewed by 1278
Abstract
This study investigates the effectiveness of microwave treatment (MW) on the antifungal properties of Norway spruce wood and the leaching of preservatives. Given the environmental and health concerns about conventional wood preservatives, this study evaluates microwave treatment as a sustainable pretreatment to limit [...] Read more.
This study investigates the effectiveness of microwave treatment (MW) on the antifungal properties of Norway spruce wood and the leaching of preservatives. Given the environmental and health concerns about conventional wood preservatives, this study evaluates microwave treatment as a sustainable pretreatment to limit the leaching of preservatives from wood. In the experiment, wood samples were treated with microwaves at five different energy levels before being impregnated with copper–ethanolamine- and boron-based preservatives. We assessed preservative retention by leaching tests and assessed the resistance of the wood to fungal attack. The results show that MW treatment improves the uptake and fixation of preservatives, reduces leachability, and significantly improves the durability of an otherwise perishable wood against fungal attack. This study emphasises the potential of microwave treatment for wood preservation. It offers an environmentally friendly approach to extending the life of wood products while maintaining their protective properties against decay. Full article
(This article belongs to the Special Issue Microwave Applications in Chemistry and Industry)
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14 pages, 5169 KiB  
Article
Study on the Fixation of Mulberry Leaf Tea in a Multiport Microwave System
by Tao He, Fengxiu Li, Desheng Hou, Lin Wang, Dezhi Gou, Tao Hong and Zhengming Tang
Processes 2024, 12(4), 701; https://doi.org/10.3390/pr12040701 - 29 Mar 2024
Viewed by 942
Abstract
Microwaves have the advantages of faster heating speed, shorter fixation time, and less pollution in tea fixation. However, there are few studies on the microwave fixation of mulberry leaf tea, which is not conducive to the promotion of mulberry leaf tea production. In [...] Read more.
Microwaves have the advantages of faster heating speed, shorter fixation time, and less pollution in tea fixation. However, there are few studies on the microwave fixation of mulberry leaf tea, which is not conducive to the promotion of mulberry leaf tea production. In order to study the fixation of mulberry leaf tea, the coaxial probe method is used to measure the dielectric constant of mulberry leaves, and the relationship connecting the real and imaginary parts of the dielectric constant and the moisture content is obtained through fitting. Based on this, a multiphysics model for mulberry leaf fixation in a six-port microwave cavity is established, which combines the characteristics of mulberry leaves, multiport heating, and mobile heating techniques. The impact of some important parameters, such as the layout and position of input ports and the thickness of mulberry leaves on the fixation process, are studied. The results show that the mutual energy coupling between ports can be reduced by using the noncoherent polarization of electromagnetic waves when the position of the ports in their working planes and the thickness of the mulberry leaves are set to (−0. 14 m, −0.15 m), (0.25 m, −0.15 m), (0.25 m, 0.15 m), (0.14 m, 0.15 m), (0.11 m, 0.0 m), (0.25 m, 0.15 m), (−0.14 m, 0.15 m), (0.11 m, 0.0 m), (0.11 m, 0.0 m), and 0.015 m when good fixation of mulberry leaves can be obtained. The study established a continuous microwave fixation experimental system for mulberry leaf tea. The experimental results indicate that the thickness of the tea affects its temperature uniformity in the microwave fixation system, which in turn affects the final quality of the tea. This study provides a reference for the industrialization of the microwave fixation of mulberry leaf tea. Full article
(This article belongs to the Special Issue Microwave Applications in Chemistry and Industry)
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20 pages, 3763 KiB  
Article
Microwave Drying of Sewage Sludge: Process Performance and Energy Consumption
by Guangyu Wang, Kai Zhang, Bocheng Huang, Kaihua Zhang and Cong Chao
Processes 2024, 12(3), 432; https://doi.org/10.3390/pr12030432 - 20 Feb 2024
Cited by 1 | Viewed by 1678
Abstract
The microwave drying of sewage sludge is characterized by its speed and safety. A novel method for identifying free and bound water is proposed in this study. Experiments were performed to investigate the process performance and energy consumption in a microwave drying unit. [...] Read more.
The microwave drying of sewage sludge is characterized by its speed and safety. A novel method for identifying free and bound water is proposed in this study. Experiments were performed to investigate the process performance and energy consumption in a microwave drying unit. The results indicate that the microwave drying process can be described in three stages, i.e., the preheating stage, constant-rate stage, and decreasing-rate stage. The preheating and constant-rate stages mainly remove free water, while the decreasing-rate stage mainly removes bound water. The Linear model effectively describes the kinetic processes in the constant-rate stage, and the modified Page I model is suitable for describing the decreasing-rate stage. The energy conversion process in microwave drying is explored, revealing that heat efficiency and energy consumption are consistent with microwave power changes. The heat efficiency in the constant-rate drying stage ranges from 60.33% to 71.01%, lower than that in the preheating stage but higher than that in the decreasing-rate stage. Energy consumption in the constant-rate stage ranges from 3.84 kJ/g to 8.20 kJ/g, significantly lower than in the other two stages. These results provide fundamental data for the industrial application of microwave drying of sludge and contribute to the advancement of microwave drying technology. Full article
(This article belongs to the Special Issue Microwave Applications in Chemistry and Industry)
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