oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 117 )

2018 ( 920 )

2017 ( 911 )

2016 ( 878 )

Custom range...

Search Results: 1 - 10 of 74899 matches for " ZHAI Yu-chun "
All listed articles are free for downloading (OA Articles)
Page 1 /74899
Display every page Item
Thermodynamics and kinetics of extracting zinc from zinc oxide ore by the ammonium sulfate roasting method
Yi Sun,Xiao-yi Shen,Yu-chun Zhai
- , 2015, DOI: https://doi.org/10.1007/s12613-015-1095-x
Abstract: Thermodynamic analyses and kinetic studies were performed on zinc oxide ore treatment by (NH4)2SO4 roasting technology. The results show that it is theoretically feasible to realize a roasting reaction between the zinc oxide ore and (NH4)2SO4 in a temperature range of 573–723 K. The effects of reaction temperature and particle size on the extraction rate of zinc were also examined. It is found that a surface chemical reaction is the rate-controlling step in roasting kinetics. The calculated activation energy of this process is about 45.57 kJ/mol, and the kinetic model can be expressed as follows: 1 ? (1 ? α)1/3 = 30.85 exp(?45.57/RT)·t. An extraction ratio of zinc as high as 92% could be achieved under the optimum conditions.
Synthesis of p-Methoxyacetophenone Catalysed with Hβ Zeolite and Competitive Adsorption of the Reactants and Products
Hβ沸石催化合成对甲氧基苯乙酮及其反应物与产物的竞争吸附

CHEN Ping,ZHAI Yu-chun,
陈平
,翟玉春

过程工程学报 , 2010,
Abstract: 研究了无溶剂条件下,Hβ沸石催化苯甲醚(AN)与乙酸酐(AA)的多相Friedel-Crafts酰化反应选择性生成对甲氧基苯乙酮(P-MOAP),探讨了反应物摩尔比、催化剂用量和反应温度对产品收率的影响.在AN0.1mol,AN/AA摩尔比1:1.5,催化剂用量1.0g,反应温度95℃,反应时间4h的条件下,最终产品收率为73.25%.利用Langmuir-Hinshelwood机理研究了该反应的动力学,结果表明,反应物和产物的竞争吸附是由于吸附平衡常数不同.催化剂对产物P-MOAP的吸附远大于反应物,且提高反应温度,产物的吸附平衡常数降低.
Adsorption Equilibrium and Kinetics of CO2 and H2O on Activated Carbon
XU Dong, ZHANG Jun, LI Gang, XIAO Penny, WEBLEY Paul, ZHAI Yu-Chun
无机材料学报 , 2012, DOI: 10.3724/sp.j.1077.2012.00139
Abstract: Activated carbon is well applied in pressure swing adsorption process for CO2 capture. The real flue gas contains saturated water vapor as well. In this study, single and binary components adsorption equilibrium and kinetics of H2O/CO2 were studied according to their adsorption isotherms and breakthrough curves. Results showed that activated carbon could adsorb high amount of CO2 and low amount of N2, that showed a good CO2/N2 selectivity. As activated carbon contains the functional groups, the activated carbon can adsorb large amount water at high water partial pressure. However, because of different CO2 adsorption mechanism, water adsorption has almost no impact on CO2 adsorption on activated carbon. The kinetics study showed that CO2 adsorption velocity on activated carbon is much faster than that of H2O.
Kinetics of Synthesis Nanophosphor Eu0.12Y1.78Ca0.10O3―δ
SI Wei, WANG Jing, WANG Xiu-Hui, GAO Hong, ZHAI Yu-Chun
无机材料学报 , 2011, DOI: 10.3724/sp.j.1077.2011.00726
Abstract: The nanophosphor Eu0.12Y1.78Ca0.10O3―δ was synthesized by homogeneous precipitation method under ultrasonic condition. The structures, composition and morphology of the nanophosphor Eu0.12Y1.78Ca0.10O3―δ were characterized by X―ray diffraction(XRD), energy dispersive spectrometre(EDS), inductively coupled plasma atomic emission spectrometry(ICP―AES) and transmission electron microscope(TEM). The synthesis kinetics of nanophosphor Eu0.12Y1.78Ca0.10O3―δ was investigated using differential thermal analysis and thermo gravimetric analysis (DTA―TG) at different heating rates in argon. The results show that the Eu0.12Y1.78Ca0.10O3―δ is body―centered― cubic―structured spherical nano―polycrytalline with grain size of 20nm. The precursor of nanophosphor Eu0.12Y1.78Ca0.10O3―δ is Y(OH)3 with hexagonal phase structure. The average apparent activation energy of the three reaction stages of precursor is calculated to be 102.06, 488.00 and 302.74kJ/mol by using the Doyle―Ozawa and Kissinger methods, respectively. The reaction order and frequency factor are determined by Kissinger method. The kinetics equations of each reaction stage is deduced as dα/dt=8.86×108e―12280/T(1―α)1.36; dα/dt=4.05× 1033e―58700/T(1―α)1.32; dα/dt=7.14×1019e―36410/T(1―α)1.27.
Preparation of ultrafine silica from potash feldspar using sodium carbonate roasting technology
Jia-nan Liu,Xiao-yi Shen,Yan Wu,Jun Zhang,Yu-chun Zhai
- , 2016, DOI: https://doi.org/10.1007/s12613-016-1313-1
Abstract: A novel process was developed for the preparation of ultrafine silica from potash feldspar. In the first step, potash feldspar was roasted with Na2CO3 and was followed by leaching using NaOH solution to increase the levels of potassium, sodium, and aluminum in the solid residue. The leaching solution was then carbonated to yield ultrafine silica. The optimized reaction conditions in the roasting process were as follows: an Na2CO3-to-potash feldspar molar ratio of 1.1, a reaction temperature of 875°C, and a reaction time of 1.5 h. Under these conditions, the extraction rate of SiO2 was 98.13%. The optimized carbonation conditions included a final solution pH value of 9.0, a temperature of 40°C, a CO2 flow rate of 6 mL/min, a stirring intensity of 600 r/min, and an ethanol-to-water volume ratio of 1:9. The precipitation rate and granularity of the SiO2 particles were 99.63% and 200 nm, respectively. We confirmed the quality of the obtained ultrafine silica by comparing the recorded indexes with those specified in Chinese National Standard GB 25576―2010.
Reaction condition optimization and kinetic investigation of roasting zinc oxide ore using (NH4)2SO4
Hong-mei Shao,Xiao-yi Shen,Yi Sun,Yan Liu,Yu-chun Zhai
- , 2016, DOI: https://doi.org/10.1007/s12613-016-1332-y
Abstract: An orthogonal test was used to optimize the reaction conditions of roasting zinc oxide ore using (NH4)2SO4. The optimized reaction conditions are defined as an (NH4)2SO4/zinc molar ratio of 1.4:1, a roasting temperature of 440°C, and a thermostatic time of 60 min. The molar ratio of (NH4)2SO4/zinc is the most predominant factor and the roasting temperature is the second significant factor that governs the zinc extraction. Thermogravimetric–differential thermal analysis was used for (NH4)2SO4 and zinc mixed in a molar ratio of 1.4:1 at the heating rates of 5, 10, 15, and 20 K·min?1. Two strong endothermic peaks indicate that the complex chemical reactions occur at approximately 290°C and 400°C. XRD analysis was employed to examine the transformations of mineral phases during roasting process. Kinetic parameters, including reaction apparent activation energy, reaction order, and frequency factor, were calculated by the Doyle–Ozawa and Kissinger methods. Corresponding to the two endothermic peaks, the kinetic equations were obtained.
The Covariance Structure Model Analysis of the Factors affecting the Entrepreneur's Human Capital Pricing in Venture Capital
Yu-chun WEN
Canadian Social Science , 2007,
Abstract: This paper carries on the analysis of the factors affecting entrepreneur's human capital pricing in venture capital, focusing on the much-dimensionality characteristic, then establishes a logical and comprehensive theory frame which can reflect all the factors affecting entrepreneur's human capital pricing. Further by using covariance structure model (CSM), we make an empirical analysis of these factors. The result shows, in venture capital the control rights of entrepreneur is the most important factor affecting the entrepreneur's human capital pricing, the scale of enterprise is the least one, with the enterprise management performance in the middle. Key Words: venture capital, the entrepreneur's human capital pricing, factors, covariance structure model Résumé: L’article présent, sur la base de l’analyse des facteurs affectant la fixation du prix du capital humain de l’entrepreneur dans l’investissement-risque, a établi pour ce problème multi-dimensions un cadre théorique logique et capable de refléter complètement ces facteurs influants. L’auteur adopte d’ailleurs la méthode analytique du modèle de la structure de covariance (CSM) pour effectuer une étude positiviste sur ces facteurs. Le résultat montre que, dans l’investissement-risque, le pouvoir de contr le de l’entrepreneur est le premier facteur en jeu, la perfomance de l’entreprise le deuxième et la dimension de l’entreprise le dernier. Mots-Clés: investissement-risque, fixation du prix du capital humain de l’entrepreneur, facteurs affectants
Performance of Ag and F Doped TiO_2 Photocatalytic Materials
银、氟双元素改性TiO2光催化材料的性能

SUN Tong,ZHAI Yu-chun,MA Pei-hua,
孙彤
,翟玉春,马培华

过程工程学报 , 2009,
Abstract: 以多孔泡沫镍为载体,采用水热合成法制备了Ag修饰和Ag-F共改性多孔TiO2光催化材料,用多种方法对其进行了表征,并评价了其对水中罗丹明B的降解性能.罗丹明B的光催化降解反应符合零级动力学规律,TiO2中主要成分为锐钛矿型纳米TiO2晶体,经500℃煅烧0.5 h后光催化性能提高.Ag修饰TiO2的光催化性能随Ag修饰量的增加先升高后下降,Ag修饰量大于0.6%时,其光催化性能又提高,最佳Ag修饰量为1.2%.煅烧处理使样品的光催化性能提高,当Ag修饰量为0.8%时,其光催化性能最优.1.2%Ag和2.0%F共改性的多孔光催化材料的光催化性能远优于单一Ag修饰材料.
Preparation of Porous Photocatalytic Materials by Electroless Composite Plating Method and Their Photodegradation Performance
化学复合镀法制备多孔光催化材料及其光催化性能

SUN Tong,ZHAI Yu-chun,MA Pei-hua,
孙彤
,翟玉春,马培华

过程工程学报 , 2006,
Abstract: 以多孔泡沫镍为载体,采用化学复合镀法制备了性能优良的多孔光催化材料,以产品对水中罗丹明B的降解性能为评价指标,对产品的光催化性能进行评价.产品对水中罗丹明B的光催化降解反应严格符合零级动力学规律.化学复合镀制备多孔光催化材料的最佳工艺条件为:镀液中硫酸镍浓度20 g/L,次亚磷酸钠浓度20 g/L,施镀过程中纳米TiO2投加量0.28g/L,镀液温度90℃,镀液pH值4.6.各因素影响产品性能的顺序为硫酸镍浓度>次亚磷酸钠浓度>镀液温度>镀液pH值>纳米TiO2投加量.纳米Bi2O3复合使产品的光催化性能下降,随着纳米Bi2O3复合量增加,产品的光催化性能提高.ZnO复合使产品的光催化性能有明显改善,随着纳米ZnO复合量的增加,产品的光催化性能提高.Ag修饰导致Bi2O3复合光催化材料的光催化性能下降、ZnO复合光催化材料的光催化性能提高.
Leaching of lead from zinc leach residue in acidic calcium chloride aqueous solution
Le Wang,Wen-ning Mu,Hong-tao Shen,Shao-ming Liu,Yu-chun Zhai
- , 2015, DOI: https://doi.org/10.1007/s12613-015-1094-y
Abstract: A process with potentially reduced environmental impacts and occupational hazards of lead-bearing zinc plant residue was studied to achieve a higher recovery of lead via a cost-effective and environmentally friendly process. This paper describes an optimization study on the leaching of lead from zinc leach residue using acidic calcium chloride aqueous solution. Six main process conditions, i.e., the solution pH value, stirring rate, concentration of CaCl2 aqueous solution, liquid-to-solid (L/S) ratio, leaching temperature, and leaching time, were investigated. The microstructure and components of the residue and tailing were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). On the basis of experimental results, the optimum reaction conditions were determined to be a solution pH value of 1, a stirring rate of 500 r·min?1, a CaCl2 aqueous solution concentration of 400 g·L?1, a liquid-to-solid mass ratio of 7:1, a leaching temperature of 80°C, and a leaching time of 45 min. The leaching rate of lead under these conditions reached 93.79%, with an iron dissolution rate of 19.28%. Silica did not take part in the chemical reaction during the leaching process and was accumulated in the residue.
Page 1 /74899
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.