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Shang X.,Kunming University of Science and Technology | Shang X.,Key Laboratory of Unconventional Metallurgy | Shang X.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | Chen J.,Kunming University of Science and Technology | And 2 more authors.
High Temperature Materials and Processes | Year: 2016

This paper proposes an analytical approach to optimize the thickness of refractories for achieving maximum microwave power transmission in microwave heating based on the analysis of power transmission coefficient (PTC). The microwave PTCs of alumina (Al2O3) ceramics over the temperature range of 22-1,379°C at 2,450 MHz, mullite ceramics in the temperature range of 27-1,027°C at 2.45 GHz and 400-1,300°C at 915 MHz are studied. The results show that there are several transmission peaks in the PTC patterns. The transmission peak amplitude depends sensitively on the thickness of the refractory and the peak shifting towards a smaller thickness as the temperature of the refractory increases. We also show that high microwave transmission can only be achieved in a refractory with a small thickness corresponding to a slight transmission peak shift in the entire microwave heating (less than one eighth wavelength in the refractory). © 2016 by De Gruyter. Source


Xia H.,Kunming University of Science and Technology | Xia H.,Yunnan Provincial Key Laboratory of Intensification Metallurgy | Xia H.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | Peng J.,Kunming University of Science and Technology | And 5 more authors.
Green Processing and Synthesis | Year: 2015

The present study attempts to utilize Eupatorium adenophorum to prepare high surface area activated carbon (HSAAC) with K2CO3 activation using microwave heating. The operational variables including microwave power, K2CO3/C mass ratio and heating time on the adsorption capability and yield were identified. Additionally, the surface characteristics of HSAAC were characterized by nitrogen adsorption isotherms, X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The optimum conditions resulted in HSAAC with an iodine number of 1696 mg/g and a yield of 32.88%. The Brunauer-Emmett-Teller (BET) surface area and total volume were 2768 m2/g and 1.149 ml/g, respectively. The findings strongly support the feasibility for preparation of HSAAC from E. adenophorum by microwave heating. © 2015 by De Gruyter. Source


Liu C.-H.,Yunnan Provincial Key Laboratory of Intensification Metallurgy | Liu C.-H.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | Liu C.-H.,Kunming University of Science and Technology | Zhang L.-B.,Yunnan Provincial Key Laboratory of Intensification Metallurgy | And 13 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2013

The permittivity of low grade Panzhuhua ilmenite ore at 2.45 GHz in the temperatures from 20 °C up to 100 °C was measured using the technology of open-ended coaxial sensor combined with theoretical computation. The results show that both the real (ε′ and imaginary (ε″) part of complex permittivity (ε′jε″ of the ilmenite significantly increase with temperature. The loss tangent (tan δ) is a quadratic function of temperature, and the penetration depth of ilmenite decreases with temperature increase from 20 °C to 100 °C. The increase of the sample temperature under microwave radiation displays a nonlinear relationship between the temperature (T) and microwave heating time (t). The positive feedback interaction between complex permittivity and sample temperature amplifies the interaction between ilmenite and the microwave radiation. The optimum dimensions for uniform heat deposition vary from 10 cm to 5 cm (about two power penetration depths) in a sample being irradiated from both sides in a 2.45 GHz microwave field when temperature increases from room temperature to 100 °C. © 2013 The Nonferrous Metals Society of China. Source


Zhang L.-H.,Yunnan Provincial Key Laboratory of Intensification Metallurgy | Zhang L.-H.,Key Laboratory of Unconventional Metallurgy | Zhang L.-H.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | Zhang L.-H.,Kunming University of Science and Technology | And 20 more authors.
RSC Advances | Year: 2014

The extraction and separation of cobalt from sulphate solution containing Ni2+ and Co2+ by the process of microfluidic extraction was investigated on a counter-current flow interdigital micromixer with channels of 40 μm width, which has two opposite inlets and an upwards outlet. Meanwhile, the comparative batch extraction experiments were conducted in separatory funnels. The effects of pH and flow rates or contact time on the microfluidic and batch experiments were studied using an aqueous solution containing 73.09 g L-1 of nickel and 2.44 g L-1 of cobalt and 20 vol% PC88A diluted with 260# solvent naphtha. In addition, cobalt extraction isotherms (Mc-Cabe Thiele) were constructed to determine the number of stages. The results of percentage extraction and separation factor of microfluidic extraction was better than that of batch extraction. The features of the microreactors, i.e. large specific surface area and short diffusion distance were effective for the efficient extraction and separation of cobalt from nickel. This journal is © the Partner Organisations 2014. Source


Bao J.,Kunming University of Science and Technology | Bao J.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | Guo S.,Kunming University of Science and Technology | Guo S.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | And 11 more authors.
RSC Advances | Year: 2015

Hierarchical Bi2WO6 nanoarchitectures with a size of 2-3 μm were prepared via a facile microwave-assisted solution-phase reaction process. Monodisperse spherical Ag2CO3 nanoparticles with an average size of about 10 nm were deposited onto the surface of the Bi2WO6 nanoarchitectures to form a novel Ag2CO3/Bi2WO6 heterojunction structure through a facile in situ precipitation-deposition method. The obtained samples were characterized using XRD, XPS, SEM, TEM (HRTEM), UV-vis DRS and nitrogen adsorption-desorption techniques. The photocatalytic evaluation demonstrates that the decoration with Ag2CO3 nanoparticles significantly enhances the photocatalytic activity of Bi2WO6 and the photocatalytic performance is greatly influenced by the content of deposited Ag2CO3. The 30 wt% Ag2CO3-loaded Bi2WO6 sample exhibited the highest photocatalytic activity for the degradation of rhodamine B (RhB) under visible light irradiation. Meanwhile, it also possesses excellent cycling stability and superior photocatalytic performance toward other pollutants. The dramatically enhanced photocatalytic activity and stability can be mainly ascribed to well-matched energy bands and heterojunctions between Ag2CO3 and Bi2WO6, which can effectively improve the separation of photo-induced electron-hole pairs at the heterojunction interfaces. © The Royal Society of Chemistry 2015. Source

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