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Xing B.,CAS Institute of Automation | Yang Y.,Kunming University of Science and Technology | Yang Y.,Yunnan Metallurgy Group Corporation | Qian L.,Yunnan Environmental Monitoring Center
Asian Journal of Chemistry | Year: 2016

A vortex-assisted liquid-phase microextraction was applied for the extraction of trace amounts of platinum(II) prior to flame atomic absorption spectrometry detection in the water sample. Ammonium pyrolysine dithiocarbamate was used as the chelating agent and noctanol as an extractant. The fine droplets of n-octanol were made and dispersed as a cloud in the aqueous sample with the help of vortex mixing. Different parameters such as the pH, the amount of ammonium pyrolysine dithiocarbamate, the composition and volume of the extraction agent and vortex time were studied to get the optimum results. Under optimal conditions, the low limit of detection is 2.0 μg mL-1. Recoveries of platinum spiked into tap water samples were in the range of 85.0∼91.5 %. The relative standard deviations is 2.12 % (n = 6). The correlation coefficient of the calibration curve is 0.9977. The proposed method was successfully applied for the determination of platinum in the real tap water samples. Source


Li Y.,Kunming Institute of Precious Metals | Li Y.,Sino Platinum Metals Co. | Wang J.-k.,Yunnan Metallurgy Group Corporation | Wei C.,Kunming University of Science and Technology | And 3 more authors.
Minerals Engineering | Year: 2010

Low-grade complex Pb-Zn oxide ore is an important source, and the reserve is very great in the world. It is very difficult to obtain Pb and Zn from the source by traditional technology. In this work, a new technology characterized by sulfidation of low grade Pb-Zn oxide ore with elemental sulfur was developed. The effects of temperature, time, particle size and sulfur amount on the sulfidation extent of Pb-Zn oxide ore was studied at a laboratory-scale. The experimental results show that the sulfidation extent of Pb and Zn oxide reaches 98% and 95% under the optimum conditions, respectively. A flotation concentrate was obtained with 38.9% Zn and 10.2% Pb from the materials which was treated by sulfidation, and the recovery of Zn and Pb is 88.2% and 79.5%, respectively. Crown Copyright © 2010. Source


Hou Y.-Q.,Kunming University of Science and Technology | Xie G.,Kunming University of Science and Technology | Xie G.,Yunnan Metallurgy Group Corporation | Tao D.-P.,Kunming University of Science and Technology | And 4 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2011

Based on the thermodynamic data for the related pure substances, fifteen possible chemical reactions in the SiCl 4 hydrogenation system of Siemens process that is one of the main process for the polysilicon production were studied. The ΔG m Θ curves of the fifteen chemical reactions in the system versus temperature were fitted by the assistant of computer. The values of ΔG m Θ for most reactions are greater than zero at the range of 973K to 1773 K. That is to say that the value of equilibrium constant is small. Therefore, the small degree of the reactions was carried on. Five independent reactions in the process were decided and the relation between K p Θ and temperature was fitted by the assistance of computer based on the thermodynamic data for the related pure substances. The value of K p Θ for main reaction (1) increases a little at high temperature, but the value of K p Θ for side-reactions (2) and (5) increase quickly. Besides, the value of K p Θ for main reaction (1) is low at low temperature, for example only 0.1571 at 1373 K. Therefore, the transformation ratio of SiCl 4 to SiHCl 3 being low is a objective fact which can not be changed. Furthermore, the influencing factors, such as the temperature, pressure and feeding mole ratio, on the transformation ratio from SiCl 4 to SiHCl 3 were studied. The diagrams of η-transformation ratio are presented as function of temperature, pressure and feeding mole ration, respectively. The transformation ratio of SiCl 4 to SiHCl 3 decreases with increasing the temperature, and the pressure have a positive effect on the transformation ratio. Furthermore, the excess of H 2 is necessary in SiCl 4 hydrogenation system of the modified Siemens process. Form the thermodynamic above, The results show that the optimum operation parameters are at 1050°C, 0.3 MPa and feeding mole ratio n H2/n SiCl4 of 4. Under this condition, the transformation ratio from SiCl 4 to SiHCl 3 is 25.78%. Source


Li Z.,Kunming University of Science and Technology | Li Z.,Kunming Gui Yan Pharmaceutical Co. | Chen J.,Yunnan Metallurgy Group Corporation | Liu M.,Kunming University of Science and Technology | Yang Y.,Kunming University of Science and Technology
Analytical Methods | Year: 2014

A supramolecular solvent made up of reverse micelles of nonanoic acid, dispersed in a continuous phase of tetrahydrofuran (THF) and water, is proposed for the simple, rapid and efficient microextraction of copper (Cu) and lead (Pb) in water samples prior to flame atomic absorption spectrometry determination. A new Schiff base was synthesized and used as the chelating agent in this study. Some important extraction parameters such as the pH, Schiff base concentration, the composition and volume of the supramolecular solvent and vortex time are evaluated, obtaining the most favorable results. Under the optimized conditions, the calibration curves were linear in the range of 10-800 μg L-1 for Cu and 10-500 μg L-1 for Pb, respectively. The limits of detection (LOD) were 0.29 μg L-1 and 0.45 μg L-1, with the enrichment factors of 27 and 22 for Cu and Pb, respectively. Recoveries of Cu and Pb spiked in water samples were in the range of 91.2-102.1%. The results show that the proposed method is suitable for the determination of Cu and Pb in water samples. This journal is © the Partner Organisations 2014. Source


Li Z.,Kunming University of Science and Technology | Li Z.,Kunming Gui Yan Pharmaceutical Co. | Chen J.,Yunnan Metallurgy Group Corporation | Liu M.,Kunming University of Science and Technology | Yang Y.,Kunming University of Science and Technology
Analytical Methods | Year: 2014

A new method based on ultrasound-assisted cloud point extraction (UA-CPE) using the mixture of non-ionic surfactant alkylphenol ethoxylate NP-7 and alkylphenol ethoxylate NP-9 for the preconcentration of trace amounts of lead (Pb) and cadmium (Cd) in water samples prior to determination by FAAS has been developed. In this method, Pb and Cd react with ammonium pyrrolidinedithiocarbamate (APDC), yielding hydrophobic complexes, which then are extracted into the surfactant-rich phase. Compared with the traditional CPE, faster phase separation and higher recovery were obtained using the ultrasound-assisted process and a series of non-ionic nonyl phenol ethoxylate surfactants in the present UA-CPE. Variable parameters affecting the CPE procedure were evaluated and optimized. Under the optimized conditions, the calibration graph was linear in the range of 10-500 μg L-1 for Pb and Cd. The detection limits were 0.5 μg L-1 and 0.28 μg L -1 with relative standard deviations of 2.6% and 3.4% for Pb and Cd, respectively. The enrichment factors were 57 and 63 for Pb and Cd, respectively, for 10 mL of preconcentrated solution. The method was successfully applied to the determination of Pb and Cd in water samples. © the Partner Organisations 2014. Source

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