Design and synthesis of multistructured three-dimensionally ordered macroporous composite bismuth oxide/zirconia: Photocatalytic degradation and hydrogen production.

Two types of three-dimensionally ordered macroporous (3DOM) Bi2O3/ZrO2 composites were prepared by the sol-gel method combined with the decompression filling method using polystyrene (PS) microspheres and EO20PO70EO20 (P123) as the templates. The crystal structure, morphology, and surface physicochemical properties of Bi2O3/ZrO2 composites were well characterized by X-ray diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and N2 adsorption-desorption measurements. The results show that 3DOM Bi2O3/ZrO2 composites possessed mixed crystal phases including the monoclinic bismuth oxide and mixed zirconia phases, and moreover exhibited a regular arrangement and pure tetragonal (or hexagonal) macroporous structure. Moreover, compared to Bi2O3/ZrO2, the specific surface areas of 3DOM Bi2O3/ZrO2 composites were ca. 2.7-2.8 times. In addition, the properties of 3DOM Bi2O3/ZrO2 composites with the tetragonal "fishing net" and hexagonal "honeycomb" structure were compared, and the relationship between the structure and activity of 3DOM Bi2O3/ZrO2 composites was determined. The results show that in the UV photocatalytic degradation of pollutants and splitting of water into hydrogen using 3DOM Bi2O3/ZrO2 composite, the tetragonal "fishing net" structure exhibited better activity than the hexagonal "honeycomb" structure. This can be attributed to different photocatalytic properties of the composites with different structures (tetragonal "fishing net" and hexagonal "honeycomb" structures).

[Spatial variability and management zone of soil major nutrients in tobacco fields in Qiannan mountainous region].

Spatial variability and management zone of soil major nutrients in tobacco fields in Qian-nan mountainous region were analyzed using geostatistics and fuzzy c-mean algorithm. Results indicated that the level of soil organic matter (OM) was moderate, and alkalytic nitrogen (AN), available phosphorus (AP) and available potassium (AK) were rich according to tobacco soil nutrient classification standards. Coefficients of variation (CV) of OM, AN, AP and AK were moderate. Contents of OM, AN, AP and AK fitted log-normal distributions. Correlation analysis showed moderate correlations between OM and AN, AP and AK. OM and AN were best described by Gaussian semivariogram models, while AP and AK were described by exponential models. The four nutrients displayed moderate spatial autocorrelation. There were significant differences among lag distances of four soil nutrients. OM, AN, AP and AK in the majority of studied regions varied at moderate to very rich levels, and deficiencies of OM, AN, AP and AK only accounted for 0.93%, 0.53%, 0.24% and 7.91% of the total studied region, respectively. Based on the results, the studied region was divided into two management zones (MZ), namely MZ1 and MZ2, accounting for 69. 8% and 30. 2% of the studied region respectively. The soil levels of OM, AN, AP and AK in MZ1 were significantly lower than those in MZ2 (P < 0.01).