Nano-Y2O3 and nano-CeO2 of different weight ratio mixed with deionizing water were doped into MoO2 powder by liquid-solid doping method. The diameter 1.80 and 0.18 mm alloy wires of Mo-0.3Y, Mo-0.3Ce, and Mo-0.15Y-0.1...Nano-Y2O3 and nano-CeO2 of different weight ratio mixed with deionizing water were doped into MoO2 powder by liquid-solid doping method. The diameter 1.80 and 0.18 mm alloy wires of Mo-0.3Y, Mo-0.3Ce, and Mo-0.15Y-0.15Ce were prepared through reduction, iso- static pressing, sintering, and drawing. Tensile properties, second phase microstructure and fracture surface appear- ance of wires were analyzed. The better refining effect for Mo alloy powder can be gotten after two kinds of nano- particle oxide doped into MoO2 than only one doped. Nano-Y2O3 and nano-CeO2 have different influences on sintering process. For nano-CeO2, the constraining effect of grain growth focuses on the initial sintering stage, nano- Y2O3 plays refining grains roles in the later densification stage. Nano-Y2O3 is undistorted and keeps intact in the process of drawing; and nano-CeO2 is elongated and bro- ken into parts in the drawing direction. The strengthening effect of nano-Y2O3 and nano-CeO2 keeps the finer grains and superior tensile properties for Mo-0.15Y-0.15Ce wire.展开更多
Aggregates of cerium dioxide nanoparticles(nano-CeO_2) were successfully prepared via a facile solvothermal process in this study. The crystallographic information and morphological information of nano-CeO_2 were syst...Aggregates of cerium dioxide nanoparticles(nano-CeO_2) were successfully prepared via a facile solvothermal process in this study. The crystallographic information and morphological information of nano-CeO_2 were systematically studied by X-ray diffraction(XRD),transmission electron microscopy(TEM), laser particle size analyzer(LA) and specific surface area and pore size analyzer during the solvothermal process. Among all the obtained samples, the 18-h solvothermal-prepared nano-CeO_2 aggregates show the best crystallinity and the largest specific surface area of 110.92 m^2·g^(-1). Owing to the high activity derived from the high specific surface area of the aggregates, the application as arsenic(As) adsorption was also studied. The adsorption efficiency of arsenic by nano-CeO_2 aggregates was established as the function of adsorbent dose, then pH value and at last adsorption time.The results indicate that the nano-CeO_2 aggregates show a high efficiency in removing arsenic from low As concentration solution, from which the nano-CeO_2 adsorbent could be easily separated. In addition, the adsorption kinetics is best fitted to pseudo-second-order model(R^2 = 0.99999).展开更多
γ-A12O3-supported CeO2 catalysts were pre- pared by microemulsion and impregnation methods and characterized by X-ray diffraction （XRD） and scanning electron microscope （SEM） techniques. At the same time, the des...γ-A12O3-supported CeO2 catalysts were pre- pared by microemulsion and impregnation methods and characterized by X-ray diffraction （XRD） and scanning electron microscope （SEM） techniques. At the same time, the desulfurization activity of catalysts was investigated. The results show that nanoscale active substances and a high desulfurization effect are achieved by microemulsion, exhibiting a significant dominance compared with traditional impregnation method. The optimal preparation condition is temperature of 30 ℃ and ratio of [H20]/[surface active agent] of 7 with slow demulsification. The activated catalysts still keep high and stable desulfurization activity during a wide temperature range of 450-600 ℃. Among a series of prepared catalysts, the desulfurization rate of 6CeOz/γ-A1203 is the highest, reaching up to 80 % when temperature is higher than 550℃. The catalytic reduction mechanism of SO2 over nano-CeOz/γ-A1203 follows redox mechanism.展开更多
Highly dispersed negative carboxyl groups can be formed on carbon black （CB） surface modified with strong nitric acid. Therefore positive cations can be uniformly absorbed by carboxyl groups and precipitated within ...Highly dispersed negative carboxyl groups can be formed on carbon black （CB） surface modified with strong nitric acid. Therefore positive cations can be uniformly absorbed by carboxyl groups and precipitated within a confinement space on modified CB surface to prepare highly dispersed nanomaterials. In this paper, the formation and dispersion status of surface negative carboxyl groups, adsorption status of Ce^3＋, surface confinement nucleation, crystallization and calcination process were studied by EDS, SEM, and laser particle size analysis. The results show that the carboxyl groups formed on modified CB surface are highly dispersed, and Ce^3＋ cations can be uniformly anchored by carboxyl groups. Therefore, highly dispersed Ce^3＋ can react with OH^- within a confinement surface region to form positive nano-Ce（OH）4 nuclei which also can be adsorbed by electrostatic attraction. After independent growth of Ce（OH）4 without agglomeration, highly dispersed CeO2 nanoparticles without agglomeration can be prepared together with the help of effectively isolates by CO2 released in the combustion of CB.展开更多
In this study,aquatic toxic effect of atrazine,and nano-CeO2,the accumulation,reproduction and adsorp-tion of atrazine onto nano-CeO2 and the facilitated transport of atrazine into D.magna by nano-CeO2 were exam-ined....In this study,aquatic toxic effect of atrazine,and nano-CeO2,the accumulation,reproduction and adsorp-tion of atrazine onto nano-CeO2 and the facilitated transport of atrazine into D.magna by nano-CeO2 were exam-ined.The results showed that atrazine concentrations of 3.0,4.0,and 10.0 mg/L exhibited 43%,56%,68% mortali-ties,respectively,which indicated the mortality was 56% while the concentration of nano-CeO2 was 4.0 mg/L.D.magna accumulated considerably more atrazine when exposed to atrazine-contaminated water in the presence of nano-CeO2.At the same time,atrazine and nano-CeO2 yielded a significant reduction of the reproduction rate at all concentrations tested.What is more,the co-exposure of nano-CeO2 and atrazine was observed to significantly de-crease the reproduction rate of D.magna,and atrazine adsorbed on nano-CeO2 quickly.Therefore,attention should be paid to their associations with other contaminants for the risk assessment of nano-CeO2 and it is worthy of notice that the sorption of atrazine on nano-CeO2 would enhance the toxicity of atrazine to D.magna.展开更多
基金financially supported by the National Tungsten and Molybdenum Value-added Utilization Tech-nology Industry Development(No.2012BAE06B02)Shanxi Province Science and Technology Innovation Plan(No.2012KTCQ01-08)
文摘Nano-Y2O3 and nano-CeO2 of different weight ratio mixed with deionizing water were doped into MoO2 powder by liquid-solid doping method. The diameter 1.80 and 0.18 mm alloy wires of Mo-0.3Y, Mo-0.3Ce, and Mo-0.15Y-0.15Ce were prepared through reduction, iso- static pressing, sintering, and drawing. Tensile properties, second phase microstructure and fracture surface appear- ance of wires were analyzed. The better refining effect for Mo alloy powder can be gotten after two kinds of nano- particle oxide doped into MoO2 than only one doped. Nano-Y2O3 and nano-CeO2 have different influences on sintering process. For nano-CeO2, the constraining effect of grain growth focuses on the initial sintering stage, nano- Y2O3 plays refining grains roles in the later densification stage. Nano-Y2O3 is undistorted and keeps intact in the process of drawing; and nano-CeO2 is elongated and bro- ken into parts in the drawing direction. The strengthening effect of nano-Y2O3 and nano-CeO2 keeps the finer grains and superior tensile properties for Mo-0.15Y-0.15Ce wire.
基金financially supported by the Sichuan Province Science and Technology Support Program (No. 2014GZ0090)
文摘Aggregates of cerium dioxide nanoparticles(nano-CeO_2) were successfully prepared via a facile solvothermal process in this study. The crystallographic information and morphological information of nano-CeO_2 were systematically studied by X-ray diffraction(XRD),transmission electron microscopy(TEM), laser particle size analyzer(LA) and specific surface area and pore size analyzer during the solvothermal process. Among all the obtained samples, the 18-h solvothermal-prepared nano-CeO_2 aggregates show the best crystallinity and the largest specific surface area of 110.92 m^2·g^(-1). Owing to the high activity derived from the high specific surface area of the aggregates, the application as arsenic(As) adsorption was also studied. The adsorption efficiency of arsenic by nano-CeO_2 aggregates was established as the function of adsorbent dose, then pH value and at last adsorption time.The results indicate that the nano-CeO_2 aggregates show a high efficiency in removing arsenic from low As concentration solution, from which the nano-CeO_2 adsorbent could be easily separated. In addition, the adsorption kinetics is best fitted to pseudo-second-order model(R^2 = 0.99999).
基金financially supported by the Natural Science Foundation of Hubei Province, China(No. 2009CDB246)the Applied Basic Research Project of Wuhan City (No. 2015060101010068)
文摘γ-A12O3-supported CeO2 catalysts were pre- pared by microemulsion and impregnation methods and characterized by X-ray diffraction （XRD） and scanning electron microscope （SEM） techniques. At the same time, the desulfurization activity of catalysts was investigated. The results show that nanoscale active substances and a high desulfurization effect are achieved by microemulsion, exhibiting a significant dominance compared with traditional impregnation method. The optimal preparation condition is temperature of 30 ℃ and ratio of [H20]/[surface active agent] of 7 with slow demulsification. The activated catalysts still keep high and stable desulfurization activity during a wide temperature range of 450-600 ℃. Among a series of prepared catalysts, the desulfurization rate of 6CeOz/γ-A1203 is the highest, reaching up to 80 % when temperature is higher than 550℃. The catalytic reduction mechanism of SO2 over nano-CeOz/γ-A1203 follows redox mechanism.
基金This work was supported by the National Key R＆D Program of China （2016YFB0301602） and the National Natural Science Foundation of China （Grant Nos. 21776018 and 21627813）.
文摘Highly dispersed negative carboxyl groups can be formed on carbon black （CB） surface modified with strong nitric acid. Therefore positive cations can be uniformly absorbed by carboxyl groups and precipitated within a confinement space on modified CB surface to prepare highly dispersed nanomaterials. In this paper, the formation and dispersion status of surface negative carboxyl groups, adsorption status of Ce^3＋, surface confinement nucleation, crystallization and calcination process were studied by EDS, SEM, and laser particle size analysis. The results show that the carboxyl groups formed on modified CB surface are highly dispersed, and Ce^3＋ cations can be uniformly anchored by carboxyl groups. Therefore, highly dispersed Ce^3＋ can react with OH^- within a confinement surface region to form positive nano-Ce（OH）4 nuclei which also can be adsorbed by electrostatic attraction. After independent growth of Ce（OH）4 without agglomeration, highly dispersed CeO2 nanoparticles without agglomeration can be prepared together with the help of effectively isolates by CO2 released in the combustion of CB.
基金supported by Chongqing Key Laboratory of Micro/Nano Materials Engineering and Technology (No. KFJJ1106)Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection (No.JLCBE11004)Jiangsu Marine Resources Development Research Institute (No. JSIMR10E04)
文摘In this study,aquatic toxic effect of atrazine,and nano-CeO2,the accumulation,reproduction and adsorp-tion of atrazine onto nano-CeO2 and the facilitated transport of atrazine into D.magna by nano-CeO2 were exam-ined.The results showed that atrazine concentrations of 3.0,4.0,and 10.0 mg/L exhibited 43%,56%,68% mortali-ties,respectively,which indicated the mortality was 56% while the concentration of nano-CeO2 was 4.0 mg/L.D.magna accumulated considerably more atrazine when exposed to atrazine-contaminated water in the presence of nano-CeO2.At the same time,atrazine and nano-CeO2 yielded a significant reduction of the reproduction rate at all concentrations tested.What is more,the co-exposure of nano-CeO2 and atrazine was observed to significantly de-crease the reproduction rate of D.magna,and atrazine adsorbed on nano-CeO2 quickly.Therefore,attention should be paid to their associations with other contaminants for the risk assessment of nano-CeO2 and it is worthy of notice that the sorption of atrazine on nano-CeO2 would enhance the toxicity of atrazine to D.magna.
