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Shu J.,Kunming University of Science and Technology | Shu J.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | Cheng S.,Kunming University of Science and Technology | Cheng S.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | And 10 more authors.
RSC Advances | Year: 2017

Copper loaded activated carbon (Cu-AC) was prepared by impregnating it with cupric nitrate followed by microwave heating and then used for removing dyes in wastewater. The Cu-AC was thoroughly characterized by N2 adsorption and desorption isotherms, SEM, EDS, XRD, XPS, FT-IR, and Raman. It was proven that cupric nitrate was successfully loaded onto activated carbon with the resulting formation of copper, copper oxide, and cuprous oxide. The Cu-AC was used to treat five kinds of dyes in wastewaters (Rhodamine B, MB, Amaranth, Congo red, and Eosin-Y). Comparing the adsorption capacity of these five dye wastewaters, it was proven that copper and copper oxides have photocatalytic degradation ability that can improve dye removal efficiency. Experimental adsorption data of MB were fit using several kinetic and isotherm models. Kinetic studies indicated that a pseudo-second order is the most suitable model for the adsorption process with a correlation coefficient of R2 > 0.999. The equilibrium adsorption data of MB showed that it followed the Langmuir isotherm; the Langmuir maximum adsorption capacity was 373 mg g−1. Compared with ordinary activated carbon, the maximum adsorption capacity of Cu-AC increased by 37.8%. Additionally, through thermodynamic calculations the negative value of ΔG and positive value of ΔH showed that the adsorption was a spontaneous and endothermic process. All the above results reveal that Cu-AC can be an effective absorbent for removing dyes from wastewater. © The Royal Society of Chemistry.


Fu L.,Kunming University of Science and Technology | Fu L.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | Zhang L.,Kunming University of Science and Technology | Zhang L.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | And 6 more authors.
Ultrasonics Sonochemistry | Year: 2017

A synergistic extraction method for gold from the refractory gold ores via ultrasound and chlorination-oxidation was developed. The effects of solid-liquid ratio, extraction time, ultrasound power, NaClO concentration and NaOH concentration on the extraction rate of gold from the refractory gold ore were investigated. The optimum conditions were as follows: NaClO concentration of 1.5 mol/L, NaOH concentration of 1.5 mol/L, solid-liquid ratio of 5, ultrasound power of 200 W and ultrasound time of 2 h. Under the optimal conditions, 68.55% of gold was extracted. However, only 45.8% of gold was extracted after 6 h without the ultrasound-assisted extraction. XRD and SEM were used to analyze the influence of ultrasound on the mineral properties and strengthening mechanism. The results showed that the interface layer was peeled, new surface was exposed, reaction resistance was reduced, the liquid-solid reaction was promoted and reaction speed was greatly improved under ultrasound. According to the results of range and variance analysis, the optimum leaching experiment with orthogonal design was almost identical with the optimum experiment of single factor. Among them, the ultrasound power was the most significant factors affecting leaching rate of gold. Compared with other extraction method, the synergistic extraction process decomposed completely sulfide and improved significantly the extraction rate of gold. © 2017 Elsevier B.V.


Lin G.,Kunming University of Science and Technology | Lin G.,Key Laboratory of Unconventional Metallurgy | Lin G.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | Zhang L.,Kunming University of Science and Technology | And 11 more authors.
Applied Thermal Engineering | Year: 2017

Microwave roasting of siderite at 800 °C with different holding times and the catalytic combustion effects on anthracite are investigated. The heating rate curves indicate that siderite can be heated in microwave field, and the heating rate increases considerably when FeCO3 almost decomposes and oxidizes to Fe3O4 and Fe2O3. The combustion rate increases by 31.74% with 0.5% roasting products of siderite as catalyst at a holding time of 40 min using microwave roasting. The Fe2O3 content in roasting products increases with microwave holding time. The size distribution results indicate that small particles cluster together and the amount of large particles increases with holding time, thereby the decreasing catalytic effect on anthracite at holding time above 40 min. The thermogravimetric-derivative thermogravimetric (TG-DTG) analysis results indicate that ignition temperature, combustion reactivity and burnout index significantly improve with catalyst addition. Differential scanning calorimeter (DSC) analysis results show that heat release of anthracite with catalyst increases by 10.09% compared with that of raw-anthracite. © 2017 Elsevier Ltd


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.


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.


Yin S.,Kunming University of Science and Technology | Yin S.,Key Laboratory of Unconventional Metallurgy | Yin S.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | Yin S.,Yunnan Provincial Key Laboratory of Intensification Metallurgy | And 15 more authors.
Chemical Engineering and Processing: Process Intensification | Year: 2015

A new solvent extraction system of extracting La(III) with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (P507) has been investigated to intensify the extraction process in microreactor, and solve the problems like long mixing time, low processing capacity, large factory area occupation, and high energy consumption in the conventional rare earth solvent extraction equipment. In this work, extraction equilibrium studies show that the initial aqueous pH value 4.00 and saponification rate 40% are the optimal operation condition. The effects of volumetric flow rate on extraction efficiency are analyzed, and the results indicate that increasing flow ratio could improve the extraction efficiency greatly, up to almost 100%, and the two phases keep parallel flow while keeping an aqueous-organic interface in the microchannel. The mass transfer rate is proportional to the initial pH and P507 concentration, and approaches almost a constant value at high pH and extractant concentration, and the transfer process between the two phases accompanied with an interface chemical reaction is confirmed to proceed satisfactorily in a short time (residence time. =. 0.37. s). The features of the microreactors, i.e., large specific surface area and short diffusion distance are effective for the efficient extraction of La(III). © 2015 Elsevier B.V.


Zhang L.,Kunming University of Science and Technology | Zhang L.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | Zhang G.,Kunming University of Science and Technology | Zhang G.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | And 6 more authors.
Journal of Sol-Gel Science and Technology | Year: 2016

Abstract: We prepared the carboxymethyl-dithiocarbamate-functionalized silica nanoparticle for detecting silver ions in aqueous media. The functionalized silica nanoparticles were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy and thermogravimetric analysis. The functionalized silica nanoparticles realize highly sensitive and selective detection for Ag+ in aqueous solution with an apparent color change over a pH range of 4–6 and under interfering ions. The functionalized silica nanoparticles allow fast detection for Ag+ at 90 °C with a low minimum detectable concentration (0.09 mM). And a remarkable color change also occurs in the presence of Ag+ solutions containing EDTA. This developed technique can easy and fast detect silver ions by the naked eye without using any sophisticated instrumentation. Graphical Abstract: [Figure not available: see fulltext.] © 2016 Springer Science+Business Media New York


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.

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