An innovative technology,nitric acid pressure leaching of limonitic laterite ores,was proposed by our research team.The HNO3 regeneration is considerable significance for the improvement of the proposed technology and...An innovative technology,nitric acid pressure leaching of limonitic laterite ores,was proposed by our research team.The HNO3 regeneration is considerable significance for the improvement of the proposed technology and its commercial application,but it has not been systematically investigated.Herein,regenerating HNO3 from Ca(NO3)2 solution with low-cost H2SO4,and simultaneous synthesis of fibrous CaSO4·2H2O by-products were studied.As a theoretical basis,the solubility of CaSO4·2H2O in HNO3 medium is studied.It is concluded that the solubility of CaSO4·2H2O increases with increasing temperature or increasing HNO3 concentration,which has considerable guiding significance for the subsequent experimental research and analysis.Then,the effects of various factors on the residual Ca^2+ concentration of filtrate,the regenerated HNO3 concentration and the morphology of synthesized products are investigated using ICP-AES and SEM.And the effect mechanism is also analyzed.The results indicate the regenerated HNO3 concentration reaches 116 g/L with the residual Ca^2+ concentration being 9.7 g/L at the optimum conditions.Moreover,fibrous CaSO4·2H2O by-products with high aspect ratios(length,406.32μm;diameter,14.71μm;aspect ratio,27.62)can be simultaneously synthesized.展开更多
Rice husk ash was used as a new, green, and cheap adsorbent for FeCl3. Characterization of the obtained reagent showed that rice husk ash supported FeCl2·2H2O was formed. This reagent is efficient at catalyzing t...Rice husk ash was used as a new, green, and cheap adsorbent for FeCl3. Characterization of the obtained reagent showed that rice husk ash supported FeCl2·2H2O was formed. This reagent is efficient at catalyzing the synthesis of multisubstituted quinolines by the Friedl鋘der heteroannulation of o‐aminoaryl ketones with ketones or β‐diketones under mild reaction conditions. This methodology allows for the synthesis of a broad range of substituted quinolines in high yields and with excellent regioselectivity in the absence of a solvent.展开更多
To promote the scale-up production and industrial application of magnesium oxide （MgO） whiskers, MgO whiskers were prepared by the calcination method of the precursor. The precursor MgSO4·5Mg（OH）2·2H2O ...To promote the scale-up production and industrial application of magnesium oxide （MgO） whiskers, MgO whiskers were prepared by the calcination method of the precursor. The precursor MgSO4·5Mg（OH）2·2H2O （152 MOS） single component was prepared by hydrothermal synthesis reaction in MgSO4 solution and NaOH solution. MgO whisker was prepared by heating treatment of the precursor at low heating speed to keep the structure of the precursor not be destroyed. The composition, the morphology and the structure of these whiskers were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results indicate that the MgO whisker was about 0.5-1.2 μm in diameter and 20-80 μm in length, with an aspect ratio no less than 100.展开更多
Thermal decomposition processes taking place in solid state complex of Zn1-xMnxC2O4·2H2O have been investigated in air using TG-DTG/DTA, XRD and TEM techniques. TG-DTG/DTA curves showed that the decomposition pro...Thermal decomposition processes taking place in solid state complex of Zn1-xMnxC2O4·2H2O have been investigated in air using TG-DTG/DTA, XRD and TEM techniques. TG-DTG/DTA curves showed that the decomposition proceeded through two well-defined steps with DTA peaks closely to correspond to the weight loss. XRD and TEM showed that the final decomposition product of Zn1-xMnxC2O4·2H2O was Zn1-xMnxO and most of the individual particles were of size 10-13 nm. Kinetics analysis of Zn1-xMnxC2O4·2H2O decomposition steps was performed under nonisothermai conditions, the activation energies were estimated by Friedman and Flynn-Wall-Ozawa （FWO） methods, and the most probable kinetic model has been estimated with multiple linear regression method. The activation energies for the two decomposition steps of Zn1-xMnxC2O4·2H2O were 155.7513 and 215.9397 kJ/mol, respectively.展开更多
Aqueous Zinc-ion batteries(ZIBs),using zinc negative electrode and aqueous electrolyte,have attracted great attention in energy storage field due to the reliable safety and low-cost.A composite material comprised of V...Aqueous Zinc-ion batteries(ZIBs),using zinc negative electrode and aqueous electrolyte,have attracted great attention in energy storage field due to the reliable safety and low-cost.A composite material comprised of VO2·0.2H2O nanocuboids anchored on graphene sheets(VOG)is synthesized through a facile and efficient microwave-assisted solvothermal strategy and is used as aqueous ZIBs cathode material.Owing to the synergistic effects between the high conductivity of graphene sheets and the desirable structural features of VO2·0.2H2O nanocuboids,the VOG electrode has excellent electronic and ionic transport ability,resulting in superior Zn ions storage performance.The Zn/VOG system delivers ultrahigh specific capacity of 423 mAh·g^−1 at 0.25 A·g^−1 and exhibits good cycling stability of up to 1,000 cycles at 8 A·g^−1 with 87%capacity retention.Systematical structural and elemental characterizations confirm that the interlayer space of VO2·0.2H2O nanocuboids can adapt to the reversible Zn ions insertion/extraction.The as-prepared VOG composite is a promising cathode material with remarkable electrochemical performance for low-cost and safe aqueous rechargeable ZIBs.展开更多
Low-temperature heat capacities of the compound Ni（C4H7O5）2·2H2O（S） have been measured with an auto- mated adiabatic calorimeter. A thermal decomposition or dehydration occurred in 350--369 K. The temperature...Low-temperature heat capacities of the compound Ni（C4H7O5）2·2H2O（S） have been measured with an auto- mated adiabatic calorimeter. A thermal decomposition or dehydration occurred in 350--369 K. The temperature, the enthalpy and entropy of the dehydration were determined to be （368.141 ±0.095） K, （18.809±0.088） kJ·mol ^-1 and （51.093±0.239） J·K^-1·mol^-1 respertively. The experimental values of the molar heat capacities in the temperature regions of 78-350 and 368-390 K were fitted to two polynomial equations of heat capacities （Cp,m） with the reduced temperatures （X）, [X=f（T）], by a least squares method, respectively. The smoothed molar heat capacities and thermodynamic functions of the compound were calculated on the basis of the fitted polynomials. The smoothed values of the molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were tabulated with an interval of 5 K.展开更多
基金Project(2182040)supported by the Beijing Natural Science Foundation,ChinaProjects(51674026,51974025,U1802253)supported by the National Natural Science Foundation of ChinaProject(FRF-TT-19-001)supported by the Fundamental Research Funds for the Central Universities,China。
文摘An innovative technology,nitric acid pressure leaching of limonitic laterite ores,was proposed by our research team.The HNO3 regeneration is considerable significance for the improvement of the proposed technology and its commercial application,but it has not been systematically investigated.Herein,regenerating HNO3 from Ca(NO3)2 solution with low-cost H2SO4,and simultaneous synthesis of fibrous CaSO4·2H2O by-products were studied.As a theoretical basis,the solubility of CaSO4·2H2O in HNO3 medium is studied.It is concluded that the solubility of CaSO4·2H2O increases with increasing temperature or increasing HNO3 concentration,which has considerable guiding significance for the subsequent experimental research and analysis.Then,the effects of various factors on the residual Ca^2+ concentration of filtrate,the regenerated HNO3 concentration and the morphology of synthesized products are investigated using ICP-AES and SEM.And the effect mechanism is also analyzed.The results indicate the regenerated HNO3 concentration reaches 116 g/L with the residual Ca^2+ concentration being 9.7 g/L at the optimum conditions.Moreover,fibrous CaSO4·2H2O by-products with high aspect ratios(length,406.32μm;diameter,14.71μm;aspect ratio,27.62)can be simultaneously synthesized.
文摘Rice husk ash was used as a new, green, and cheap adsorbent for FeCl3. Characterization of the obtained reagent showed that rice husk ash supported FeCl2·2H2O was formed. This reagent is efficient at catalyzing the synthesis of multisubstituted quinolines by the Friedl鋘der heteroannulation of o‐aminoaryl ketones with ketones or β‐diketones under mild reaction conditions. This methodology allows for the synthesis of a broad range of substituted quinolines in high yields and with excellent regioselectivity in the absence of a solvent.
文摘To promote the scale-up production and industrial application of magnesium oxide （MgO） whiskers, MgO whiskers were prepared by the calcination method of the precursor. The precursor MgSO4·5Mg（OH）2·2H2O （152 MOS） single component was prepared by hydrothermal synthesis reaction in MgSO4 solution and NaOH solution. MgO whisker was prepared by heating treatment of the precursor at low heating speed to keep the structure of the precursor not be destroyed. The composition, the morphology and the structure of these whiskers were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results indicate that the MgO whisker was about 0.5-1.2 μm in diameter and 20-80 μm in length, with an aspect ratio no less than 100.
基金Project supported by the National Natural Science Foundation of China （No. 20071026）.
文摘Thermal decomposition processes taking place in solid state complex of Zn1-xMnxC2O4·2H2O have been investigated in air using TG-DTG/DTA, XRD and TEM techniques. TG-DTG/DTA curves showed that the decomposition proceeded through two well-defined steps with DTA peaks closely to correspond to the weight loss. XRD and TEM showed that the final decomposition product of Zn1-xMnxC2O4·2H2O was Zn1-xMnxO and most of the individual particles were of size 10-13 nm. Kinetics analysis of Zn1-xMnxC2O4·2H2O decomposition steps was performed under nonisothermai conditions, the activation energies were estimated by Friedman and Flynn-Wall-Ozawa （FWO） methods, and the most probable kinetic model has been estimated with multiple linear regression method. The activation energies for the two decomposition steps of Zn1-xMnxC2O4·2H2O were 155.7513 and 215.9397 kJ/mol, respectively.
基金The authors are thankful to funds from the China Postdoctoral Science Foundation(No.RZ1900011127)Qingdao Innovation Leading Talent Program and Taishan Scholars Program and Natural Science Foundation of Shandong(No.ZR2017BEM028)+4 种基金M.S.is thankful to funds from the Science Foundation of Jiangsu Province(No.BK20171169)C.W.L.thanks the support from National Natural Science Foundation of China(No.51802168)China Postdoctoral Science Foundation(No.2018M630753)Natural Science Foundation of Shandong Province(No.ZR2018BEM006)Qingdao Postdoctoral Application Research Project.
文摘Aqueous Zinc-ion batteries(ZIBs),using zinc negative electrode and aqueous electrolyte,have attracted great attention in energy storage field due to the reliable safety and low-cost.A composite material comprised of VO2·0.2H2O nanocuboids anchored on graphene sheets(VOG)is synthesized through a facile and efficient microwave-assisted solvothermal strategy and is used as aqueous ZIBs cathode material.Owing to the synergistic effects between the high conductivity of graphene sheets and the desirable structural features of VO2·0.2H2O nanocuboids,the VOG electrode has excellent electronic and ionic transport ability,resulting in superior Zn ions storage performance.The Zn/VOG system delivers ultrahigh specific capacity of 423 mAh·g^−1 at 0.25 A·g^−1 and exhibits good cycling stability of up to 1,000 cycles at 8 A·g^−1 with 87%capacity retention.Systematical structural and elemental characterizations confirm that the interlayer space of VO2·0.2H2O nanocuboids can adapt to the reversible Zn ions insertion/extraction.The as-prepared VOG composite is a promising cathode material with remarkable electrochemical performance for low-cost and safe aqueous rechargeable ZIBs.
基金Project supported by the National Natural Science Foundation of China （No. 20673050）, the Poat-doctor Start-up Foundation of Liaocheng Univer sity （No. 31805）.
文摘Low-temperature heat capacities of the compound Ni（C4H7O5）2·2H2O（S） have been measured with an auto- mated adiabatic calorimeter. A thermal decomposition or dehydration occurred in 350--369 K. The temperature, the enthalpy and entropy of the dehydration were determined to be （368.141 ±0.095） K, （18.809±0.088） kJ·mol ^-1 and （51.093±0.239） J·K^-1·mol^-1 respertively. The experimental values of the molar heat capacities in the temperature regions of 78-350 and 368-390 K were fitted to two polynomial equations of heat capacities （Cp,m） with the reduced temperatures （X）, [X=f（T）], by a least squares method, respectively. The smoothed molar heat capacities and thermodynamic functions of the compound were calculated on the basis of the fitted polynomials. The smoothed values of the molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were tabulated with an interval of 5 K.
