Decomposition mechanism of a mixed rare earth concentrate with sodium hydroxide in the microwave heating process

2019 ◽  
Vol 132 ◽  
pp. 220-227 ◽  
Author(s):  
Yukun Huang ◽  
Ting-an Zhang ◽  
Zhihe Dou ◽  
Guihong Han ◽  
Yijun Cao ◽  
...  
2021 ◽  
Author(s):  
Wannaporn Klangpetch ◽  
Alisa Pattarapisitporn ◽  
Suphat Phongthai ◽  
Pannapapol Jaichakan

Abstract This study aimed to produce xylooligosaccharide (XOS) and arabino-xylooligosaccharide (AXOS) from rice husk (RH) using microwave treatment combined with enzymatic hydrolysis and evaluate their prebiotic properties. The RH was pretreated by a microwave heating process at 140, 160 and 180°C for 5, 10, and 15 min to obtain crude arabinoxylan (AX). The results emphasized that increasing microwave pretreatment time increased sugar content. The crude AX was then extracted with 2% (w/v) sodium hydroxide at 25°C for 24 h. The obtained AX was then used as a substrate for XOS production by commercial xylanases. The results showed that the oligosaccharide produced by Pentopan Mono BG and Ultraflo Max provided xylobiose and xylotriose as the main products. Interestingly, AXOS was also present in the oligosaccharide product. Furthermore, the oligosaccharides obtained were able to promote the growth of Lactobacillus spp. and to resist degradation more than 70% after exposure to simulated human digestion.


2013 ◽  
Vol 58 (3) ◽  
pp. 919-922 ◽  
Author(s):  
K. Granat ◽  
B. Opyd ◽  
D. Nowak ◽  
M. Stachowicz ◽  
G. Jaworski

Abstract The paper describes preliminary examinations on establishing usefulness criteria of foundry tooling materials in the microwave heating technology. Presented are measurement results of permittivity and loss tangent that determine behaviour of the materials in electromagnetic field. The measurements were carried-out in a waveguide resonant cavity that permits precise determination the above-mentioned parameters by perturbation technique. Examined were five different materials designed for use in foundry tooling. Determined was the loss factor that permits evaluating usefulness of materials in microwave heating technology. It was demonstrated that the selected plastics meet the basic criterion that is transparency for electromagnetic radiation.


2018 ◽  
Vol 15 (1) ◽  
pp. 47-55
Author(s):  
Xuebing Li ◽  
Haifen Yang ◽  
Ning Wang ◽  
Tijian Sun ◽  
Wei Bian ◽  
...  

Background: Morin has many pharmacological functions including antioxidant, anticancer, anti-inflammatory, and antibacterial effects. It is commonly used in the treatment of antiviral infection, gastropathy, coronary heart disease and hepatitis B in clinic. However, researches have shown that morin is likely to show prooxidative effects on the cells when the amount of treatment is at high dose, leading to the decrease of intracellular ATP levels and the increase of necrosis process. Therefore, it is necessary to determine the concentration of morin in biologic samples. Method: Novel water-soluble and green nitrogen and sulfur co-doped carbon dots (NSCDs) were prepared by a microwave heating process with citric acid and L-cysteine. The fluorescence spectra were collected at an excitation wavelength of 350 nm when solutions of NSCDs were mixed with various concentrations of morin. Results: The as-prepared NSCDs were characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The fluorescence intensity of NSCDs decreased significantly with the increase of morin concentration. The fluorescence intensity of NSCDs displayed a linear response to morin in the concentration 0.10-30 μM with a low detection limit of 56 nM. The proposed fluorescent probe was applied to analysis of morin in human body fluids with recoveries of 98.0-102%. Conclusion: NSCDs were prepared by a microwave heating process. The present analytical method is sensitive to morin. The quenching process between NSCDs and morin is attributed to the static quenching. In addition, the cellular toxicity on HeLa cells indicated that the as-prepared NSCDs fluorescent probe does not show obvious cytotoxicity in cell imaging. Our proposed method possibly opens up a rapid and nontoxic way for preparing heteroatom doped carbon dots with a broad application prospect.


2020 ◽  
Vol 39 (1) ◽  
pp. 54-62
Author(s):  
Hua Chen ◽  
Junjiang Chen ◽  
Weijun Wang ◽  
Huan Lin

AbstractThe multimode resonant cavity is the most common cavity. The material often shows on selective heating performance during the heating process due to the effect of microwave heating having a closely relationship with the electromagnetism parameters. This paper is based on finite difference time domain method (FDTD) to establish the electromagnetic-thermal model. The electromagnetic sensitivity property parameters of sodium chloride including relative dielectric constant, loss angle tangent and water content of sodium chloride is studied during the heating and drying process. The heating rate and the electric field distribution of sodium chloride, at the different water content, were simulated with the electromagnetic characteristic parameters changing. The results show that with the electromagnetic sensitivity property parameters varying, the electric field strength, heating rate and steady-state temperature of the heating material will all have a variety in the cavity. Some measures are proposed to improve the heating efficiency and ensure the stability of the microwave heating system in the industrial application.


2017 ◽  
Vol 42 (2) ◽  
pp. e13468
Author(s):  
Pu Guang Yi ◽  
Pu Cheng Xi ◽  
Jun Wang ◽  
Song Chun Fang

2020 ◽  
Vol 7 (3) ◽  
pp. 196-206
Author(s):  
Shunda Lin ◽  
Mamdouh Omran ◽  
Shenghui Guo

: Microwave heating technology is considered one of the most likely to replace traditional heating methods due to its efficient, quick, and green heating transmission that meets the requirements of sustainable development. Microwave heating can strengthen chemical reactions and change the morphology of minerals, and it can save energy and achieve rapid and efficient heating, clean production, and emission reduction. Therefore, this paper summarizes the research status of microwave heating in the recovery of valuable metals (Cu, Au, V),) from metallurgical waste ore and rare earth elements from rare earth minerals in recent years, expounds the principle of microwave heating, and summarizes the previous experimental phenomena. Finally, the development potential, opportunities, and difficulties of microwave technology in future industrial applications are discussed.


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