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Competitive adsorption of Cd, Cu, Hg and Pb by agricultural soils of the Changjiang and Zhujiang deltas in China

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第11期8卷 1808-1815页

作者： ZHANG Ming-kui ZHENG Shun-an Department of Natural resource sciences School of Natural Resource and Environmental Sciences Zhejiang University Hangzhou 310029 China

Soils can often be contaminated simultaneously by more than one heavy metal. The sorption-desorption behavior of a metal in a soil will be affected by the presence of other metals. Therefore, selective retention and competitive adsorption of the soils to heavy metals can affect their availability and movement through the soils. In this study, the simultaneous competitive adsorption of four heavy metals (Cd, Cu, Hg, and Pb) on ten agricultural soils collected from the Changjiang and Zhujiang deltas, China was assessed. The results showed that the competition affected the behavior of heavy metal cations in such a way that the soils adsorbed less Cd and Hg, and more Pb and Cu with increasing total metal concentrations, regardless of the molar concen- tration applied. As the applied concentrations increased, Pb and Cu adsorption increased, while Cd and Hg adsorption decreased. The adsorption sequence most found was Pb>Cu>Hg>Cd. The maximum adsorption capacity for the heavy metal cations was calculated, and affected markedly by soil properties. The results suggest that Hg and Cd have higher mobility associated to the lower adsorption and that Pb and Cu present the opposite behavior. Significant correlations were found between the maximum adsorption capacity of the metals and pH value and exchangeable acid, suggesting that soil pH and exchangeable acid were key factors controlling the solubility and mobility of the metals in the agricultural soils.

关键词： Competitive adsorption Adsorption sequence Heavy metals Agricultural soils

Electrochemical preparation of the Fe-Ni36 Invar alloy from a mixed oxides precursor in molten carbonates

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International Journal of Minerals,Metallurgy and Materials 2020年第12期27卷 1695-1702页

作者： Yan-peng Dou Di-yong Tang Hua-yi Yin Di-hua Wang school of resource and environmental sciences Wuhan UniversityWuhan 430072China

The Fe-Ni36 alloy was prepared via the one-step electrolysis of a mixed oxides precursor in a molten Na2CO3-K2CO3 eutectic melt at 750℃,where porous Fe_(2)O_(3)-NiO pellets served as the cathode and the Ni10 Cu11 Fe alloy was an inert *** the electrolysis,Ni O was preferentially electro-reduced to Ni,then Fe_(2)O_(3)was reduced and simultaneously alloyed with nickel to form the Fe-Ni36 *** cell voltages were applied to optimize the electrolytic conditions,and a relatively low energy consumption of 2.48 k W·h·kg^(-1) for production of Fe Ni36 alloy was achieved under 1.9 V with a high current efficiency of 94.6%.The particle size of the alloy was found to be much smaller than that of the individual *** process provides a low-carbon technology for preparing the Fe-Ni36 alloy via molten carbonates electrolysis.

关键词： molten carbonates cyclic voltammetry electro-reduction inert anode Invar36 alloy

Effect of doping aluminum and yttrium on high-temperature oxidation behavior of Ni-11Fe-10Cu alloy

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Journal of Rare Earths 2016年第11期34卷 1139-1147页

作者：程新华范磊刘莉杜开发汪的华 school of resource and environmental sciences Wuhan University Institute of Metal Research Chinese Academy of Sciences

Aiming to develop materials for construction of the set-up and electrode of high-temperature molten salt reactors, the effect of Al and Y on the high-temperature oxidation behavior of Ni-11Fe-10Cu at 750 and 950 °C in air were investigated. The oxidation kinetics of Ni-11Fe-10Cu alloy followed parabolic law at 750 °C without spallation and linear law at 950 °C with severe spallation, while that of Ni-11Fe-10Cu-6Al-3Y alloy followed parabolic law at 750 and 950 °C without spallation. The parabolic rate constant （kp） of Ni-11Fe-10Cu was smaller than that of Ni-11Fe-10Cu-6Al-3Y at 750 °C. The oxide scale formed on Ni-11Fe-10Cu at 750 °C was composed of a CuO outer layer, a NiFe2O4 middle layer and a NiO inner layer. The oxide scale formed on Ni-11Fe-10Cu-6Al-3Y at 750 °C was also composed of the similar triplex layers in addition to an internal oxidation zone containing Al, Ni and Cu oxide and the microstructure of the scale changed with increasing temperature. Although the doping Al and Y could improve the adherence of oxide scale, it could aggravate the extent of internal oxidation. Based on the combination of X-ray diffraction （XRD）, scanning electron mi-croscopy/energy dispersive spectroscopy （SEM/EDX） analysis, the microstructure and growth mechanism of the multi-layer oxide scale was studied and the effect of doping Al and Y on the oxidation behavior of Ni-11Fe-10Cu alloy was also discussed.

关键词： Ni-Fe-Cu alloy doping rare earths high-temperature oxidation behavior multi-layer oxide scale

Rare metals preparation by electro-reduction of solid compounds in high-temperature molten salts

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Rare Metals 2016年第8期35卷 581-590页

作者： Wei Xiao Di-Hua Wang school of resource and environmental sciences Hubei International Scientific and Technological Cooperation Base of Sustainable Resource and Energy Wuhan University

Direct electro-reduction of solid compounds in molten salts is a simple and straightforward electrolytic metallurgical method, which outperforms traditional pyrometallurgical methods such as carbothermic and met- allothermic reductions in terms of economic viability, energy efficiency and carbon footprint. To better highlight the features of the direct electro-reduction of solid com- pounds in molten salts in extraction of rare metals, the scope of this paper is focused on the know-how of the cathodic process of the direct electro-reduction of solid compounds in molten salts in extraction of rare refractory metals including Ti, Zr, Hf, V, Nb, Ta, Mo and W, and rare disperse metals including Ga and Ge. In line with an introduction of the basic concept of the method, the char- acteristics of reaction paths in different systems are sum- marized and the corresponding strategy on tailoring energy efficiency and microstructure of electrolytic products are rationalized. The economic competence of the method might be enhanced by extending the method to controllable production of rare metals with high added values, well- defined microstructure and intriguing functionality.

关键词： Rare metals Molten salt electrolysis Solidcompounds Electrochemical metallurgy

Capture and electro-splitting of CO_2 in molten salts

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Journal of Energy Chemistry 2019年第1期28卷 128-143页

作者： Wei Weng Lizi Tang Wei Xiao school of resource and environmental sciences Hubei International Scientific and Technological Cooperation Base of Sustainable Resource and EnergyWuhan University

Due to the serious greenhouse gas effects caused by the increasing concentration of atmospheric CO_2,carbon capture and storage(CCS) has been an important area of research and many technologies are developed within this field. Molten salt CO_2 capture and electrochemical transformation(MSCC-ET) process is a desirable method due to a high CO_2 solubility, a wide potential window of molten salts and easily-controlled electrode reactions. Generally, electro-splitting CO_2 in molten salts begins with CO_2 absorption reactions to form CO_3^(2-), which is then followed by the carbon deposition at the cathode and O_2 evolution at the anode. As a result, CO_2 is electro-converted to O_2 and carbon with different morphologies, compositions, microstructures and functional properties. This report introduces the MSCC-ET process, summarizes the reactions occurring in the molten salts and at the electrode surfaces, as well as the morphological variations of the cathodic products. The inert anode materials, cost estimation and scale-up evaluation of the process are then discussed. It is presumed that with a comprehensive understanding of the electrode reactions during electrolysis and the functional properties of carbon materials obtained during CO_2 electro-splitting can provide a foundation for further developing this environmentally friendly process.

关键词： CO2 electro-splitting Molten salt electrolysis Inert anodes Cost evaluation

Spatial and Temporal Variability of PM_(2.5) Concentration in China

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Wuhan University Journal of Natural sciences 2016年第4期21卷 358-368页

作者： XU Gang JIAO Limin ZHAO Suli CHENG Jiaqi school of resource and environmental sciences Wuhan University

PM_（2.5） has become an increasing public concern recently because of its visibility reduction and severe health risks. For the whole year of 2013, hourly PM_（2.5） data of 496 monitoring sites scattered in 74 cities of China are collected to analyze temporal and spatial variability of PM_（2.5） concentration. Different temporal scales（seasonal variation, monthly variation and daily variation） and spatial scales（urban versus rural, typical areas and national scale） are discussed. Results show that PM_（2.5） concentration changes significantly in both long-term and short-term scales. An apparent bimodal pattern exists in daily variation of PM_（2.5） concentration and the daytime peak appears around 10：00 am while the lowest concentration appears around 16：00 pm. Spatial autocorrelation analysis and Ordinary Kriging are used to characterize spatial variability. Moran＇s I of PM_（2.5） concentration in three typical regions, the Beijing-Tianjin-Hebei region, the Yangtze River Delta region and the Pearl River Delta region, is 0.906, 0.693, 0.746, respectively, which indicates that PM_（2.5） is strong spatial correlated. Spatial distribution of annual PM_（2.5） concentration simulated by Ordinary Kriging shows that 7.94 million km2（83%） areas fail in meeting the requirement of China＇s National Ambient Air Quality Standards Level-2（35 mg/m3） and there are at least three concentrated highly polluted areas across the country.

关键词： air pollution PM2 5 spatial-temporal variability spatial autocorrelation

Magnetic properties and heavy metal contents of automobile emission particulates

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2005年第8期6卷 731-735页

作者：卢升高白世强蔡景波徐昶 school of environmental and resource sciences Zhejiang UniversityHangzhou 310029 China

Measurements of the magnetic properties and total contents of Cu, Cd, Pb and Fe in 30 automobile emission particulate samples indicated the presence of magnetic particles in them. The values of frequency dependent susceptibility （Xfd） showed the absence of superparamagnetic （SP） grains in the samples. The IRM20mT （isothermal remanent magnetization at 20 mT） being linearly proportional to SIRM （saturation isothermal remanent magnetization）（R^2=0.901）, suggested that ferrimagnetic minerals were responsible for the magnetic properties of automobile emission particulates. The average contents of Cu, Cd, Pb and Fe in automobile emission particulates were 95.83, 22.14, 30.58 and 34727.31 mg/kg, respectively. Significant positive correlations exist between the magnetic parameters and the contents ofPb, Cu and Fe. The magnetic parameters of automobile emission particulates reflecting concentration of magnetic particles increased linearly with increase of Pb and Cu content, showed that the magnetic measurement could be used as a preliminary index for detection of Pb and Cu pollution.

关键词： Automobile emission particulates Magnetic properties Heavy metal environmental magnetism

Preparation and electrocatalytic properties of Ti/IrO_2-Ta_2O_5 anodes for oxygen evolution

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中国有色金属学会会刊：英文版 2006年第5期16卷 1193-1199页

作者：李保松林安甘复兴 school of resource and environmental Science Wuhan University

The preparation and electrocatalytic activity for oxygen evolution of the thermally prepared Ti anodes coated with IrO2-Ta2O5 were studied. The structure and morphologies of the oxide films with different contents of IrO2 were determined by XRD and SEM respectively. Their electrochemical properties were studied by Linear Sweep Voltammetry, Tafel Plot and Cyclic Voltammetry. The results show that iridium and tantalum can form solid solution and the mutual solubility is affected by the ratio of Ir to Ta in coating solution. With increasing IrO2 content in the coatings, the amount of fine crystallites of IrO2 is increased and the electrocatalytic capability of oxygen evolution is strengthened. The coating adhesion and rigidity decrease, which affects electrochemical activity of the anode when the content of IrO2 is too high. The electrochemically active surface area is determined not only by the content of IrO2but also the structure and morphology of the anode coatings. It is probably due to the existence of proper quantities of inert Ta2O5 which results in a typical morphology of cracks and solid solution structure.

关键词： IrO2-Ta2O5 电催化活性氧排出涂氧化层电极

A robust three-stage approach to large-scale urban scene recognition

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Science China(Information sciences) 2017年第10期60卷 239-251页

作者： Jinglu WANG Yonghua LU Jingbo LIU Long QUAN Department of Computer Science and Engineering The Hong Kong University of Science and Technology school of resource and environmental sciences Wuhan University

To obtain the ultimate high-level description of urban scenes, we propose a three-stage approach to recognizing the 3D reconstructed scene with efficient representations. First, we develop a joint semantic labeling method to obtain a semantic labeling of the triangular mesh-based representation by exploiting both image features and geometric features. The labeling is formulated over a conditional random field(CRF) that incorporates local spacial smoothness and multi-view consistency. Then, based on the labeled reconstructed meshes, we refine the man-made object segmentation in the recomposed global orthographic map with a graph partition algorithm, and propagate the coherent segmentation to the entire 3D meshes. Finally, we propose to generate a compact, abstracted geometric representation for each man-made object which is more visually appealing than the original cluttered models. This abstraction algorithm also leverages CRF formation to partition building footprints into minimal sets of structural linear features which are then used to construct profiles for large-scale scenes. The proposed recognition approach is able to robustly handle reconstructions with poor geometry and connectivity, thanks to the higher order CRF formulations which impose the ubiquitous regularity priors in urban scenes. Each stage performs an individual and uncoupling task. The intensive experiments have demonstrated the superior performance of our approach in robustness, accuracy and applicability.

关键词： 3D reconstruction urban scene recongition semantic segmentation CRF