Mg-La alloys were prepared by constant voltage electrolysis in the molten salt system of MgC12-LaC13-KC1 at 750℃, with a graphite crucible as the anode and a tungsten rod as the cathode. The effect of oxide and fluor...Mg-La alloys were prepared by constant voltage electrolysis in the molten salt system of MgC12-LaC13-KC1 at 750℃, with a graphite crucible as the anode and a tungsten rod as the cathode. The effect of oxide and fluoride addition on the electrolysis was investigated comprehensively. X-ray diffraction （XRD） was used to characterize some of the Mg-La alloy products and the sludges. As the content of MgO or La203 in the electrolyte increased, both the current efficiency and the mass of alloy product decreased, indicating that both MgO and La203 may take part in the reactions in the electrolyte. When the same mass of the oxide was added, compared with La203, MgO had a more pronounced effect on both the current efficiency and the mass of alloy product. XRD studies confirmed the formation of LaOC1 when MgO or LazO3 was added into the electrolyte. The formation of LaOCl sludge would be the main reason for the negative effect of the oxide addition on both the current efficiency and the mass of alloy. In the electrolytic system, the addition of CaF2 was not helpful to suppress the negative effect of MgO on the electrolysis, probably due to the complex reactions of the La compounds in the electrolyte.展开更多
Microwave was applied to roasting the zinc oxide fume obtained from fuming furnace for the removal of F and Cl. The effects of important parameters, such as roasting temperature, holding time and stirring speed, were ...Microwave was applied to roasting the zinc oxide fume obtained from fuming furnace for the removal of F and Cl. The effects of important parameters, such as roasting temperature, holding time and stirring speed, were investigated and the process conditions were optimized using response surface methodology (RSM). The results show that the effects of roasting temperature and holding time on the removal rate of F and Cl are the most significant, and the effect of stirring speed is the second. The defluorination rate reaches 92.6% while the dechlorination rate reaches 90.2%, under the process conditions of roasting temperature of 700 °C, holding time of 80 min and stirring speed of 120 r/min. The results indicate that the removal of F and Cl from fuming furnace production of zinc oxide fumes using microwave roasting process is feasible and reliable.展开更多
In order to extract gallium from a high-silica-content flue dust generated in corundum production,a mixed acid solution of H2SO4 and HF was used for leaching,and test parameters of the leaching process were optimized....In order to extract gallium from a high-silica-content flue dust generated in corundum production,a mixed acid solution of H2SO4 and HF was used for leaching,and test parameters of the leaching process were optimized.Experimental results show that the leaching rate of gallium was only 38%when H2SO4 was used as leaching agent.Composition analysis results of micro areas in this corundum flue dust indicate that the content of gallium in silica-enriched phases was high;this portion of gallium was insoluble in H2SO4 solution.The leaching rate of gallium increased significantly with addition of HF due to corrosion of silica.Effects of reaction time,temperature,and concentrations of HF and H2SO4 on leaching rates of gallium were investigated.The leaching rate of gallium reached 91%when this corundum flue dust was leached in a mixed acid solution of H2SO4 and HF for 4 h,at a temperature of 80°C,with a liquid-to-solid ratio of 5:1(mL/g).The optimal concentrations of H2SO4 and HF in the mixed acid solution were 1.5 and 6.4 mol/L,respectively.展开更多
Tailoring the microstructure of pristine TiO2 is essential to narrow its band gap and prolong the charge lifetime. In particular, strategies involving fluorine have been used successfully to tune the surface chemistry...Tailoring the microstructure of pristine TiO2 is essential to narrow its band gap and prolong the charge lifetime. In particular, strategies involving fluorine have been used successfully to tune the surface chemistry, electronic structure, and morphology of TiO2 photocatalysts to improve their photocatalytic activity based on the strong complexation between fluoride ions and TiO2 and the high electronegativity of fluorine. In this review, we summarize the strategies involving fluorine to establish highly efficient TiO2 photocatalytic systems or fabricate highly efficient TiO2 photocatalysts. The main fluorine effects(i.e. the effects of fluorine on photocatalysis) include the following four aspects:(1) Surface effects of fluoride on TiO2 photocatalysis,(2) effects of fluorine doping on TiO2 photocatalysis,(3) fluoride-mediated tailoring of the morphology of TiO2 photocatalysts, and(4) the effects of fluorine on non-TiO2 photocatalysis. Additionally, the unique applications of these fluorine effects in photocatalysis, including selective degradation of pollutants, selective oxidation of chemicals, water-splitting to produce H2, reduction of CO2 to produce solar fuels, and improvement of the thermostability of TiO2 photocatalysts, are reviewed.展开更多
基金Projects(2012BAE01B04)supported by the National Key and Technology R&D Program of ChinaProject(KZCX2-XB3-06)supported by Western Action Program,Chinese Academy of Sciences
文摘Mg-La alloys were prepared by constant voltage electrolysis in the molten salt system of MgC12-LaC13-KC1 at 750℃, with a graphite crucible as the anode and a tungsten rod as the cathode. The effect of oxide and fluoride addition on the electrolysis was investigated comprehensively. X-ray diffraction （XRD） was used to characterize some of the Mg-La alloy products and the sludges. As the content of MgO or La203 in the electrolyte increased, both the current efficiency and the mass of alloy product decreased, indicating that both MgO and La203 may take part in the reactions in the electrolyte. When the same mass of the oxide was added, compared with La203, MgO had a more pronounced effect on both the current efficiency and the mass of alloy product. XRD studies confirmed the formation of LaOC1 when MgO or LazO3 was added into the electrolyte. The formation of LaOCl sludge would be the main reason for the negative effect of the oxide addition on both the current efficiency and the mass of alloy. In the electrolytic system, the addition of CaF2 was not helpful to suppress the negative effect of MgO on the electrolysis, probably due to the complex reactions of the La compounds in the electrolyte.
基金Project(51104073)supported by the National Natural Science Foundation of ChinaProject(2013AA064003)supported by the High-tech Research and Development Program of China+1 种基金Project(2014CB643404)supported by the National Basic Research Program of ChinaProject(2012HB008)supported by Yunnan Province Young Academic Technology Leader Reserve Talents,China
文摘Microwave was applied to roasting the zinc oxide fume obtained from fuming furnace for the removal of F and Cl. The effects of important parameters, such as roasting temperature, holding time and stirring speed, were investigated and the process conditions were optimized using response surface methodology (RSM). The results show that the effects of roasting temperature and holding time on the removal rate of F and Cl are the most significant, and the effect of stirring speed is the second. The defluorination rate reaches 92.6% while the dechlorination rate reaches 90.2%, under the process conditions of roasting temperature of 700 °C, holding time of 80 min and stirring speed of 120 r/min. The results indicate that the removal of F and Cl from fuming furnace production of zinc oxide fumes using microwave roasting process is feasible and reliable.
基金Projects(51274240,51204209)supported by the National Natural Science Foundation of China
文摘In order to extract gallium from a high-silica-content flue dust generated in corundum production,a mixed acid solution of H2SO4 and HF was used for leaching,and test parameters of the leaching process were optimized.Experimental results show that the leaching rate of gallium was only 38%when H2SO4 was used as leaching agent.Composition analysis results of micro areas in this corundum flue dust indicate that the content of gallium in silica-enriched phases was high;this portion of gallium was insoluble in H2SO4 solution.The leaching rate of gallium increased significantly with addition of HF due to corrosion of silica.Effects of reaction time,temperature,and concentrations of HF and H2SO4 on leaching rates of gallium were investigated.The leaching rate of gallium reached 91%when this corundum flue dust was leached in a mixed acid solution of H2SO4 and HF for 4 h,at a temperature of 80°C,with a liquid-to-solid ratio of 5:1(mL/g).The optimal concentrations of H2SO4 and HF in the mixed acid solution were 1.5 and 6.4 mol/L,respectively.
文摘Tailoring the microstructure of pristine TiO2 is essential to narrow its band gap and prolong the charge lifetime. In particular, strategies involving fluorine have been used successfully to tune the surface chemistry, electronic structure, and morphology of TiO2 photocatalysts to improve their photocatalytic activity based on the strong complexation between fluoride ions and TiO2 and the high electronegativity of fluorine. In this review, we summarize the strategies involving fluorine to establish highly efficient TiO2 photocatalytic systems or fabricate highly efficient TiO2 photocatalysts. The main fluorine effects(i.e. the effects of fluorine on photocatalysis) include the following four aspects:(1) Surface effects of fluoride on TiO2 photocatalysis,(2) effects of fluorine doping on TiO2 photocatalysis,(3) fluoride-mediated tailoring of the morphology of TiO2 photocatalysts, and(4) the effects of fluorine on non-TiO2 photocatalysis. Additionally, the unique applications of these fluorine effects in photocatalysis, including selective degradation of pollutants, selective oxidation of chemicals, water-splitting to produce H2, reduction of CO2 to produce solar fuels, and improvement of the thermostability of TiO2 photocatalysts, are reviewed.
