Semiconductor photocatalysis is promising for the remediation of organic pollutants in environmental wastewater. At present, the main bottlenecks of relative research lie in how to more effectively improve the sunlight activity of photocatalysts and realize their reutilization. Herein, we assembled AgBr-AgCl/Ag on the skeletons of melamine sponge (MS) by immobilizing Ag nanowires (NWs) on MS skeletons, transferring Ag into AgBr-AgCl, and further reducing part Ag+ into metallic Ag. The microstructures of MS@AgBr-AgCl/Ag were characterized by the means of scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). It was found that AgBr-AgCl/Ag NWs were successfully loaded on the skeletons of MS to form a 3D structure, and there existed a composite structure between AgBr and AgCl. The transient photocurrents and electrochemical impedance analyses revealed that the AgBr-AgCl composite structure effectively decreased the impedance of charge carrier transfer, and consequently MS@AgBr-AgCl/Ag NWs displayed much higher photocurrent than MS@AgBr/Ag NWs and MS@AgCl/Ag NWs. The photocatalytic activities of the samples were evaluated by degrading antibiotic sulfadiazine (SD) and five organic dyes (fuchsin basic, methyl orange, acid orange 7, malachite green, and rhodamine B). Beneficial from the excellent visible-light response and charge carrier separation properties, MS@AgBr-AgCl/Ag NWs displayed the optimal photocatalytic activity among these samples. Radical trapping experiments demonstrated that •O2 – and h+ are the main reactive species responsible for organic contaminant degradation. Based on the results of high performance liquid chromatography–mass spectra (HPLC-MS), the possible structures of the main intermediates toward SD degradation were proposed. By filling MS@AgBr-AgCl/Ag NWs into glass tubes and connecting them together, we fabricated a tubular fixed-bed photoreactor for continuous wastewater purification. Overall, this work provides a reference for constructing visible light driven photocatalysts and fixed-bed photoreactors used for the environmental wastewater purification under sunlight irradiation.
Study on the microscopic structure of saline–alkali soil can reveal the change of its permeability more deeply. In this paper, the relationship between permeability and microstructure of saline–alkali soil with different dry densities and water content in the floodplain of southwestern Shandong Province was studied through freeze–thaw cycles. A comprehensive analysis of soil samples was conducted using particle-size distribution, X-ray diffraction, freeze–thaw cycles test, saturated hydraulic conductivity test and mercury intrusion porosimetry. The poor microstructure of soil is the main factor that leads to the category of micro-permeable soil. The porosity of the local soil was only 6.19–11.51%, and ultra-micropores (< 0.05 μm) and micropores (0.05–2 μm) dominated the pore size distribution. Soil saturated water conductivity was closely related to its microscopic pore size distribution. As the F–T cycles progressed, soil permeability became stronger, with the reason the pore size distribution curve began to shift to the small pores (2–10 μm) and mesopores (10–20 μm), and this effect was the most severe when the freeze–thaw cycle was 15 times. High water content could promote the effects of freeze–thaw cycles on soil permeability and pore size distribution, while the increase of dry density could inhibit these effects. The results of this study provide a theoretical basis for the remediation of saline–alkali soil in the flooded area of Southwest Shandong.
In view of the void fraction measurement problem of oil-gas-water three phase flow in oil production logging, in this thesis, optical fiber probe sensor is used to measure the cross-sectional local void fraction. In order to analysis post-treatment raw probe signal preferably and more reasonable, firstly, the characteristic of optical fiber probe pierced bubble is analyzed and simulated by the simulation modeling with ZEMAX, and adopting nonsequential ray tracing method to simulate the track characteristic of the light energy variation in the sensing system, which both from the different horizontal radial positions of probe pierced bubble and different axial positions of the probe; Then, in order to get the accurate local void fraction information, gas-phase distribution features in fluid pipeline and flow regime identification of multiphase flow, the transformation of binary value signal in probe signal post-processing is analyzed and compared by different threshold methods. Finally, the experimental platform of void fraction measurement is built to obtain the probe raw signal of oil-gas-water three-phase which total flow is 30m 3 /d, and the effects of different threshold method are confirmed.
Study on the microscopic structure of saline-alkali soil can reveal the change of its permeability more deeply. In this paper, the relationship between permeability and microstructure of saline-alkali soil with different dry densities and water content in the floodplain of southwestern Shandong Province was studied through freeze-thaw cycles. A comprehensive analysis of soil samples was conducted using particle-size distribution, X-Ray diffraction, Freeze-Thaw cycle test, saturated hydraulic conductivity test and mercury intrusion porosimetry. The poor microstructure of soil is the main factor that leads to the category of micro-permeable soil. The porosity of the local soil was only 6.19–11.51%, and ultra-micropores (< 0.05 µm) and micropores (0.05-2 µm) dominated the pore size distribution. Soil saturated water conductivity was closely related to its microscopic pore size distribution. As the F-T cycles progressed, soil permeability became stronger, with the reason the pore size distribution curve began to shift to the small pores (2–10 µm) and mesopores (10–20 µm), and this effect was the most severe when the freeze-thaw cycle was 15 times. High water content could promote the effects of freeze-thaw cycles on soil permeability and pore size distribution, while the increase of dry density could inhibit these effects. The results of this study provide a theoretical basis for the remediation of saline-alkali soil in the flooded area of Southwest Shandong.
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