Alkali metal(Li, Na, K) doped ZnO powders were synthesized by solid-state reaction at different calcination temperatures and holding time. Effects of holding time and K sources on the infrared emissivity of ZnO were i...Alkali metal(Li, Na, K) doped ZnO powders were synthesized by solid-state reaction at different calcination temperatures and holding time. Effects of holding time and K sources on the infrared emissivity of ZnO were investigated. The structure and surface morphologies of samples were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The UV-Vis absorption and infrared emissivities were investigated by a UV-Vis spectrophotometer and an infrared emissometer, respectively. XRD patterns confirm the wurtzite structure of the as prepared samples with single phase. Smooth grain surfaces are detected in all doped ZnO samples, while ZnO:Li and ZnO:Na present the aggregation of grains. The redshifts in the optical band-gap are observed in K-, Na-, and Li-doped ZnO with the values 3.150, 3.144, and 3.142 eV. Due to better crystalline quality, ZnO:K shows a lower emissivity than others. The emissivity of K-doped ZnO decreases to the minimum value(0.804), at 1200 °C and holding 2 h. Compared with KNO3 as K source, K2CO3 doped ZnO has lower emissivities.展开更多
The compound materials （shorted by Ti/13X） of doping of TiO2 into 13X molecular sieves has-been achieved by methods namely impregnation. Technical parameters of preparation for Ti/13X were determined by removal effi...The compound materials （shorted by Ti/13X） of doping of TiO2 into 13X molecular sieves has-been achieved by methods namely impregnation. Technical parameters of preparation for Ti/13X were determined by removal efficiency of simulation dyeing wastewater containing reactive bright-red X-3B （shorted by X-3B）. In various preparation parameters, the influence of Ti loaded on 13X molecular sieves on X-3B removal efficiency is most important. The optimum condition for volume of TiCI4 loaded on 13X molecular sieves is 8 ml at 95.9%, produced sample referred as M8. M8 was characterized using X-Ray Diffraction （XRD）, Scanning Electron Microscope （SEM）. XRD patterns of M8 revealed the incorporation of titanium into framework of 13X molecular sieves, due to the presence ofTiO2 anatase phase. SEM image showed that M8 has a large number of wormhole-like channels, in comparison with that of 13X molecular sieves. The photocatalytic tests were carried out for degradation of X-3B. The results showed that the dosage of Ti/13X, reaction time, pH, and concentration of X-3B influence the X-3B removal efficiency. The optimum conditions of photodegradation as the following： MS/X-3B ratio, Conc. is 0.3 g/l, reaction time is 120 rain, pH is 2-6. The photodegradation reaction of Ti/13X with X-3B followed first order kinetics. The rate constants and t1/2 for M8 sample at 0.3 g/l M8/ X-3B solution ratio were 430 min^-1 and 16 min, respectively.展开更多
The utility of GIS （geographic information system） methods and spatial statistical analysis on spectral maps of sediment samples were examined. Detailed elemental maps are often constructed using energy dispersive X...The utility of GIS （geographic information system） methods and spatial statistical analysis on spectral maps of sediment samples were examined. Detailed elemental maps are often constructed using energy dispersive X-ray techniques and SEM （scanning electron microscopy）. The elemental neighborhood associations of a single element, P （phosphorus）, were quantified at a magnification of 3,000 ×. For each of the 170,000 pixels on the images which displayed a strong P concentration, neighborhoods from 0.1μm^2 to 12 μm^2 were examined for associated elemental concentrations. PCA （principal component analysis） revealed two significant neighborhood types associated with P in samples of pH 4, and three neighborhood types at pH 8. These neighborhoods corresponded to Mg-P associations commonly found to be chemically prevalent in river sediments impacted by agricultural operations. Discriminant analysis showed that the greatest accuracy in predicting sample pH could be achieved by using a neighborhood size of 12 ~m2. Potassium at relatively large neighborhood sizes was the element most significant in predicting pH. While many of the chemical associations in close proximity to P could be predicted and explained through mineral solubility, spatial analysis provided some interesting insights into the structure of the samples. Results also indicted differences in the spatial scale associated with different processes.展开更多
基金Project(JB141405)supported by the Fundamental Research Funds for the Central Universities of China
文摘Alkali metal(Li, Na, K) doped ZnO powders were synthesized by solid-state reaction at different calcination temperatures and holding time. Effects of holding time and K sources on the infrared emissivity of ZnO were investigated. The structure and surface morphologies of samples were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The UV-Vis absorption and infrared emissivities were investigated by a UV-Vis spectrophotometer and an infrared emissometer, respectively. XRD patterns confirm the wurtzite structure of the as prepared samples with single phase. Smooth grain surfaces are detected in all doped ZnO samples, while ZnO:Li and ZnO:Na present the aggregation of grains. The redshifts in the optical band-gap are observed in K-, Na-, and Li-doped ZnO with the values 3.150, 3.144, and 3.142 eV. Due to better crystalline quality, ZnO:K shows a lower emissivity than others. The emissivity of K-doped ZnO decreases to the minimum value(0.804), at 1200 °C and holding 2 h. Compared with KNO3 as K source, K2CO3 doped ZnO has lower emissivities.
文摘The compound materials （shorted by Ti/13X） of doping of TiO2 into 13X molecular sieves has-been achieved by methods namely impregnation. Technical parameters of preparation for Ti/13X were determined by removal efficiency of simulation dyeing wastewater containing reactive bright-red X-3B （shorted by X-3B）. In various preparation parameters, the influence of Ti loaded on 13X molecular sieves on X-3B removal efficiency is most important. The optimum condition for volume of TiCI4 loaded on 13X molecular sieves is 8 ml at 95.9%, produced sample referred as M8. M8 was characterized using X-Ray Diffraction （XRD）, Scanning Electron Microscope （SEM）. XRD patterns of M8 revealed the incorporation of titanium into framework of 13X molecular sieves, due to the presence ofTiO2 anatase phase. SEM image showed that M8 has a large number of wormhole-like channels, in comparison with that of 13X molecular sieves. The photocatalytic tests were carried out for degradation of X-3B. The results showed that the dosage of Ti/13X, reaction time, pH, and concentration of X-3B influence the X-3B removal efficiency. The optimum conditions of photodegradation as the following： MS/X-3B ratio, Conc. is 0.3 g/l, reaction time is 120 rain, pH is 2-6. The photodegradation reaction of Ti/13X with X-3B followed first order kinetics. The rate constants and t1/2 for M8 sample at 0.3 g/l M8/ X-3B solution ratio were 430 min^-1 and 16 min, respectively.
文摘The utility of GIS （geographic information system） methods and spatial statistical analysis on spectral maps of sediment samples were examined. Detailed elemental maps are often constructed using energy dispersive X-ray techniques and SEM （scanning electron microscopy）. The elemental neighborhood associations of a single element, P （phosphorus）, were quantified at a magnification of 3,000 ×. For each of the 170,000 pixels on the images which displayed a strong P concentration, neighborhoods from 0.1μm^2 to 12 μm^2 were examined for associated elemental concentrations. PCA （principal component analysis） revealed two significant neighborhood types associated with P in samples of pH 4, and three neighborhood types at pH 8. These neighborhoods corresponded to Mg-P associations commonly found to be chemically prevalent in river sediments impacted by agricultural operations. Discriminant analysis showed that the greatest accuracy in predicting sample pH could be achieved by using a neighborhood size of 12 ~m2. Potassium at relatively large neighborhood sizes was the element most significant in predicting pH. While many of the chemical associations in close proximity to P could be predicted and explained through mineral solubility, spatial analysis provided some interesting insights into the structure of the samples. Results also indicted differences in the spatial scale associated with different processes.
