The electrochemical dissolution process of chalcopyrite and bornite in acid bacteria culture medium was investigated by electrochemical measurements and X-ray photoelectron spectroscopy（XPS） analysis. Bornite was mu...The electrochemical dissolution process of chalcopyrite and bornite in acid bacteria culture medium was investigated by electrochemical measurements and X-ray photoelectron spectroscopy（XPS） analysis. Bornite was much easier to be oxidized rather than to be reduced, and chalcopyrite was difficult to be both oxidized and reduced. The relatively higher copper extraction of bornite dissolution can be attributed to its higher oxidation rate. Covellite（CuS） was detected as the intermediate species during the dissolution processes of both bornite and chalcopyrite. Bornite dissolution was preferred to be a direct oxidation pathway, in which bornite was directly oxidized to covellite（CuS） and cupric ions, and the formed covellite（CuS） may inhibit the further dissolution. Chalcopyrite dissolution was preferred to be a continuous reduction-oxidation pathway, in which chalcopyrite was initially reduced to bornite, then oxidized to covellite（CuS）, and the initial reduction reaction was the rate-limiting step.展开更多
破解城市剩余污泥中的微生物细胞,释放细胞内有机成分,是提高污泥厌氧消化效率的关键问题。因此选取城市剩余污泥为试样,分别采用直流、交流电晕放电对其实施处理,采用重铬酸钾法测量污泥试样的溶解性化学需氧量(SCOD),分析电晕引发形...破解城市剩余污泥中的微生物细胞,释放细胞内有机成分,是提高污泥厌氧消化效率的关键问题。因此选取城市剩余污泥为试样,分别采用直流、交流电晕放电对其实施处理,采用重铬酸钾法测量污泥试样的溶解性化学需氧量(SCOD),分析电晕引发形式、电压极性、幅值及频率等参数对剩余污泥微生物细胞破解效果的影响规律。结果显示,采用直流或交流电晕处理污泥均可使其SCOD增大,达到破解污泥中微生物细胞的目的。当采用直流电晕破解污泥时,随着正直流电压从1 k V升高至5 k V,SCOD增长率从15.6%减小至6.8%;随着负直流电压从-1 k V提高至-5 k V,SCOD增长率从0.1%上升至21.4%。当采用交流电晕处理污泥时,其SCOD增长率与交流电压频率和幅值密切相关,交流电晕破解污泥的效果优于直流电晕。分析认为,电晕放电产生的羟基自由基、臭氧等强氧化性物质是导致微生物细胞膜破解,胞内有机成分释放的主要原因。随着电晕放电参数的改变,细胞膜破解的微观物理过程以及细胞外有机成分的降解过程均受到影响,从而导致SCOD增长率的变化。展开更多
In order to evaluate the electrochemical properties of aluminum alloy anode under high current densities in alkaline electrolyte, the galvanostatic discharge, potentiodynamic polarization and hydrogen evolution tests ...In order to evaluate the electrochemical properties of aluminum alloy anode under high current densities in alkaline electrolyte, the galvanostatic discharge, potentiodynamic polarization and hydrogen evolution tests of three experimental Al?Mg?Sn?In?(Ga) alloys were performed. The results show that the alloying element gallium improves the working potentials of experimental Al?Mg?Sn?In alloys under different discharge current densities. The average working potentials of the alloys containing gallium can reach?1.3 V under current density ranging from 650 to 900 mA/cm2, while those of alloy without Ga are only?1.0 V. Such phenomenon is attributed to the solid solution which can form amalgam with aluminum matrix. Such an amalgam can form the hydrolyzed species during the discharge process and lead to the corrosion infiltrating into aluminum matrix.展开更多
Datong coal was extracted with CS2, n-hexane, benzene, methanol, acetone, tetrahydro-furan（THF） and THF/methanol（1：3,v/v） mixed solvent sequentially. The extracts were analyzed with GC/MS. It is presented that gr...Datong coal was extracted with CS2, n-hexane, benzene, methanol, acetone, tetrahydro-furan（THF） and THF/methanol（1：3,v/v） mixed solvent sequentially. The extracts were analyzed with GC/MS. It is presented that group seperation of soluble organic compounds in the coal can be achieved by fractionated extraction using different solvents. The results show that CS2 was effective for extracting arenes from the coal sample, n-Hexane extractable fraction from Datong coal mainly consists of n-alkanes. A great variety of oxygen-containing compounds are dominant in the components of methanol-soluble fraction. Acyclic isoprenoids, pentecyclic triterpanes and a series of cyclohexanes with long-chain alkyl-substitutes are detected in acetone-soluble fraction. Dicyclic aramatic hydrocarbons are identified in benzene-soluble fraction and 4-6 cyclic condensed aramatic hydrocarbons are identified in THF-soluble fraction. The molecular structures detection of 1,2-dichlorobenzene, 2,4-dibromophnol, 2,4,6-tribromophenol and 4-chlorobenzophenone firstly provide information for existence form of bromine and chlorine in coal.展开更多
A chemical model,based on Pitzer activity coefficient model,is developed with a speciation approach to describe the solubility and chemistry of nesquehonite in concentrated chloride solutions.The chemical equilibrium ...A chemical model,based on Pitzer activity coefficient model,is developed with a speciation approach to describe the solubility and chemistry of nesquehonite in concentrated chloride solutions.The chemical equilibrium constants for nesquehonite and aqueous species,i.e.0 3 MgCO,3 MgHCO,and MgOH +,are precisely calculated as a function of temperature according to the Van't Hoff equation by use of standard Gibbs free energy,standard formation enthalpy and heat capacity.The most recent solubility data are regressed to obtain new Pitzer parameters with good agreement.The predictive ability of the new model is improved significantly in comparison with previous models.The behavior of speciation chemistry for nesquehonite in various chloride media is explained through this modeling work on the basis of the 2 3 Mg /CO bearing species distribution,activity coefficient and pH changes.展开更多
Many scientific and engineering problems need to use numerical methods and algorithms to obtain computational simulation results because analytical solutions are seldom available for them.The chemical dissolution-fron...Many scientific and engineering problems need to use numerical methods and algorithms to obtain computational simulation results because analytical solutions are seldom available for them.The chemical dissolution-front instability problem in fluid-saturated porous rocks is no exception.Since this kind of instability problem has both the conventional(i.e.trivial)and the unconventional(i.e.nontrivial)solutions,it is necessary to examine the effects of different numerical algorithms,which are used to solve chemical dissolution-front instability problems in fluid-saturated porous rocks.Toward this goal,two different numerical algorithms associated with the commonly-used finite element method are considered in this paper.In the first numerical algorithm,the porosity,pore-fluid pressure and acid/solute concentration are selected as basic variables,while in the second numerical algorithm,the porosity,velocity of pore-fluid flow and acid/solute concentration are selected as basic variables.The particular attention is paid to the effects of these two numerical algorithms on the computational simulation results of unstable chemical dissolution-front propagation in fluid-saturated porous rocks.The related computational simulation results have demonstrated that:1)the first numerical algorithm associated with the porosity-pressure-concentration approach can realistically simulate the evolution processes of unstable chemical dissolution-front propagation in chemical dissolution systems.2)The second numerical algorithm associated with the porosity-velocity-concentration approach fails to simulate the evolution processes of unstable chemical dissolution-front propagation.3)The extra differential operation is the main source to result in the failure of the second numerical algorithm.展开更多
基金Projects(51374248,51320105006)supported by the National Natural Science Foundation of ChinaProject(NCET-13-0595)supported by the Program for New Century Excellent Talents in University,ChinaProject(CX2014B091)supported by the Hunan Provincial Innovation Foundation for Postgraduate,China
文摘The electrochemical dissolution process of chalcopyrite and bornite in acid bacteria culture medium was investigated by electrochemical measurements and X-ray photoelectron spectroscopy（XPS） analysis. Bornite was much easier to be oxidized rather than to be reduced, and chalcopyrite was difficult to be both oxidized and reduced. The relatively higher copper extraction of bornite dissolution can be attributed to its higher oxidation rate. Covellite（CuS） was detected as the intermediate species during the dissolution processes of both bornite and chalcopyrite. Bornite dissolution was preferred to be a direct oxidation pathway, in which bornite was directly oxidized to covellite（CuS） and cupric ions, and the formed covellite（CuS） may inhibit the further dissolution. Chalcopyrite dissolution was preferred to be a continuous reduction-oxidation pathway, in which chalcopyrite was initially reduced to bornite, then oxidized to covellite（CuS）, and the initial reduction reaction was the rate-limiting step.
文摘破解城市剩余污泥中的微生物细胞,释放细胞内有机成分,是提高污泥厌氧消化效率的关键问题。因此选取城市剩余污泥为试样,分别采用直流、交流电晕放电对其实施处理,采用重铬酸钾法测量污泥试样的溶解性化学需氧量(SCOD),分析电晕引发形式、电压极性、幅值及频率等参数对剩余污泥微生物细胞破解效果的影响规律。结果显示,采用直流或交流电晕处理污泥均可使其SCOD增大,达到破解污泥中微生物细胞的目的。当采用直流电晕破解污泥时,随着正直流电压从1 k V升高至5 k V,SCOD增长率从15.6%减小至6.8%;随着负直流电压从-1 k V提高至-5 k V,SCOD增长率从0.1%上升至21.4%。当采用交流电晕处理污泥时,其SCOD增长率与交流电压频率和幅值密切相关,交流电晕破解污泥的效果优于直流电晕。分析认为,电晕放电产生的羟基自由基、臭氧等强氧化性物质是导致微生物细胞膜破解,胞内有机成分释放的主要原因。随着电晕放电参数的改变,细胞膜破解的微观物理过程以及细胞外有机成分的降解过程均受到影响,从而导致SCOD增长率的变化。
基金Project supported by the Open Fund of the State Key Laboratory of Powder Metallurgy,China
文摘In order to evaluate the electrochemical properties of aluminum alloy anode under high current densities in alkaline electrolyte, the galvanostatic discharge, potentiodynamic polarization and hydrogen evolution tests of three experimental Al?Mg?Sn?In?(Ga) alloys were performed. The results show that the alloying element gallium improves the working potentials of experimental Al?Mg?Sn?In alloys under different discharge current densities. The average working potentials of the alloys containing gallium can reach?1.3 V under current density ranging from 650 to 900 mA/cm2, while those of alloy without Ga are only?1.0 V. Such phenomenon is attributed to the solid solution which can form amalgam with aluminum matrix. Such an amalgam can form the hydrolyzed species during the discharge process and lead to the corrosion infiltrating into aluminum matrix.
基金Projects 20076051, G1999022101, and 98029016 supported by National Natural Science Foundation of China, the Special Found for Major State BasicResearch Project, and Research Found for the Doctoral Program of Higher Education
文摘Datong coal was extracted with CS2, n-hexane, benzene, methanol, acetone, tetrahydro-furan（THF） and THF/methanol（1：3,v/v） mixed solvent sequentially. The extracts were analyzed with GC/MS. It is presented that group seperation of soluble organic compounds in the coal can be achieved by fractionated extraction using different solvents. The results show that CS2 was effective for extracting arenes from the coal sample, n-Hexane extractable fraction from Datong coal mainly consists of n-alkanes. A great variety of oxygen-containing compounds are dominant in the components of methanol-soluble fraction. Acyclic isoprenoids, pentecyclic triterpanes and a series of cyclohexanes with long-chain alkyl-substitutes are detected in acetone-soluble fraction. Dicyclic aramatic hydrocarbons are identified in benzene-soluble fraction and 4-6 cyclic condensed aramatic hydrocarbons are identified in THF-soluble fraction. The molecular structures detection of 1,2-dichlorobenzene, 2,4-dibromophnol, 2,4,6-tribromophenol and 4-chlorobenzophenone firstly provide information for existence form of bromine and chlorine in coal.
基金Supported by the National Natural Science Foundation of China (21076212,21076213,21146006)the National Basic Research Program of China (2009CB219904)Key Program in Science and Technology of Qinghai Province (2010-G-A4)
文摘A chemical model,based on Pitzer activity coefficient model,is developed with a speciation approach to describe the solubility and chemistry of nesquehonite in concentrated chloride solutions.The chemical equilibrium constants for nesquehonite and aqueous species,i.e.0 3 MgCO,3 MgHCO,and MgOH +,are precisely calculated as a function of temperature according to the Van't Hoff equation by use of standard Gibbs free energy,standard formation enthalpy and heat capacity.The most recent solubility data are regressed to obtain new Pitzer parameters with good agreement.The predictive ability of the new model is improved significantly in comparison with previous models.The behavior of speciation chemistry for nesquehonite in various chloride media is explained through this modeling work on the basis of the 2 3 Mg /CO bearing species distribution,activity coefficient and pH changes.
基金Project(11272359)supported by the National Natural Science Foundation of China
文摘Many scientific and engineering problems need to use numerical methods and algorithms to obtain computational simulation results because analytical solutions are seldom available for them.The chemical dissolution-front instability problem in fluid-saturated porous rocks is no exception.Since this kind of instability problem has both the conventional(i.e.trivial)and the unconventional(i.e.nontrivial)solutions,it is necessary to examine the effects of different numerical algorithms,which are used to solve chemical dissolution-front instability problems in fluid-saturated porous rocks.Toward this goal,two different numerical algorithms associated with the commonly-used finite element method are considered in this paper.In the first numerical algorithm,the porosity,pore-fluid pressure and acid/solute concentration are selected as basic variables,while in the second numerical algorithm,the porosity,velocity of pore-fluid flow and acid/solute concentration are selected as basic variables.The particular attention is paid to the effects of these two numerical algorithms on the computational simulation results of unstable chemical dissolution-front propagation in fluid-saturated porous rocks.The related computational simulation results have demonstrated that:1)the first numerical algorithm associated with the porosity-pressure-concentration approach can realistically simulate the evolution processes of unstable chemical dissolution-front propagation in chemical dissolution systems.2)The second numerical algorithm associated with the porosity-velocity-concentration approach fails to simulate the evolution processes of unstable chemical dissolution-front propagation.3)The extra differential operation is the main source to result in the failure of the second numerical algorithm.
