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The construction of semiconductor heterojunction photocatalysts that improve the separation and transfer of photoinduced charge carriers is an effective and widely employed strategy to boost photocatalytic performance. Herein, we have successfully constructed a CdS/Ag/Bi2WO6 Z-scheme heterojunction with an Ag-bridge as an effective charge transfer channel by a facile process. The heterostructure consists of both CdS and Ag nanoparticles anchored on the surface of Bi2WO6 nanosheets. The photocatalytic efficiency of the CdS/Ag/Bi2WO6 system was studied by the decontamination of tetracycline (TC) and Rhodamine B (RhB) under visible light irradiation (λ ≥ 420). The results exhibited that CdS/Ag/Bi2WO6 shows markedly higher photocatalytic performance than that of CdS, Bi2WO6, Ag/Bi2WO6, and CdS/Bi2WO6. The trapping experiment results verified that the •O2− and h+ radicals are the key active species. The results of photoluminescence spectral analysis and photocurrent responses indicated that the CdS/Ag/Bi2WO6 heterojunctions exhibit exceptional efficiency in separating and transferring photoinduced electron−hole pairs. Based on a series of characterization results, the boosted photocatalytic activity of the CdS/Ag/Bi2WO6 system is mostly due to the successful formation of the Ag-bridged Z-scheme heterojunction; these can not only inhibit the recombination rate of photoinduced charge carriers but also possess a splendid redox capacity. The work provides a way for designing a Z-scheme photocatalytic system based on Ag-bridged for boosting photocatalytic performance. [ABSTRACT FROM AUTHOR]

In order to clarify the reaction process of Si phase, Differential Scanning Calorimeter (DSC), as the main measurement, was used to prepare Si samples and monitor the sintering reaction process. Combined with X-ray diffraction analysis, the formation process of Si phase was summarized. The reaction between K2SiF6 and Al powders occurred at 580°C, but not completed until 660°C. The whole formation process of Si includes two different stages: One is the solid–solid reaction stage, the other is the solid–liquid reaction stage.

Based on field data of polycyclic aromatic hydrocarbons (PAHs) in water and sediment in Nansi Lake. The concentrations and the partitioning characteristic of PAHs in the water and sediment were studied. The lgKd of high molecular weight PAHs were higher than the low molecular weight PAHs. The most of PAHs Kd values were negligible correlated with TOC, soluble salt, clay and pH of the sediment in Nansi Lake.

The work investigated the concentration of perfluorinated compounds (PFCs) in surface water, sediments and aquatic plants of Nansi Lake, China. The total concentration of 12 PFCs was in the range of 34.07–153.39 ng/L in surface water. The short-chain PFCs were dominant PFC homologs, and the concentration of PFOA was higher than that of PFOS in water samples. The total concentration of 12 PFCs was in the range of 0.63–1.62 ng/g (dry weight, DW) in the sediments. There were more long-chain PFCs (PFOA and PFOS) than short-chain PFCs in sediments, with no apparent connection according to the concentration of PFCs in water and sediments. Moreover, the bioaccumulation factors (BAF) indicated the aquatic plants had significant absorption for long-chain PFCs (PFOA and PFOS), especially PFOS. The log BAF value of Ceratophyllum demersum Linn for PFOS was the highest in all aquatic plants. Risk assessment indicated that the water environment of Nansi Lake was at a safe level. [ABSTRACT FROM AUTHOR]

The work investigated the distribution of twelve perfluorinated compounds (PFCs) in surface water and soil in the partial areas of Shandong Province, China. The total concentration of PFCs was in the range of 36.1–1,236.21 ng/L in surface water and 4.23–48.72 ng/g dw (dry weight) in the soil. The concentration of PFOA is higher than that of PFOS in all the surface water and soil. There was a positive correlation between PFOS and PFOA. The ratio method and principal component analysis (PCA) were used to identify the potential source of PFCs in surface water. The results showed that atmospheric precipitation, industrial emissions and domestic sewage were the main reasons for PFCs pollution in the surface water of partial areas of Shandong Province, China. [ABSTRACT FROM AUTHOR]

The concentrations of heavy metals (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were investigated in water, sediment and biota (aquatic plant, fish and shrimp) of Nansi Lake by an inductively coupled plasma-atomic emission spectrometry. The lower concentrations of heavy metals in lake water and the higher concentrations of heavy metals in sediment implied that there were low-level, persistent inputs of heavy metals in the Nansi Lake. The concentrations of Cr and Fe in aquatic plants exceeded their corresponding toxic concentrations. The correlations among the concentrations of heavy metals in water, sediment, aquatic plants and animals were lower. The factor analysis and the correlation analysis of different heavy metals in water, sediment and aquatic biota samples showed that most heavy metals had the same source except As. This finding implied that As was of different source compared to the other heavy metals in Nansi Lake. The comparison of heavy metals in different samples from upper lake and lower lake showed that the contamination of heavy metals in upper lake was more serious than that in lower lake. The intensive coal mining and more coal thermal plants were an important reason leading to contamination of heavy metals in Nansi Lake. The heavy metals in aquatic organisms were not accumulated along food web except As and Zn. There was a positive correlation between the accumulation of As and Zn and food web based on bioaccumulation factors value in Nansi Lake. Risk assessment of heavy metals in water, sediment and animals indicated that the water environment of Nansi Lake is safe at present. However, people should pay more attention to the intake of As and Zn. [ABSTRACT FROM AUTHOR]

Novel Bi2W2O9 and Bi2Mo2O9 with irregular polyhedron structure were successfully synthesized by a hydrothermal method. Compared to ordinary Bi2WO6 and Bi2MoO6, the modified structure of Bi2W2O9 and Bi2Mo2O9 were observed, which led to an enhancement of photocatalytic performance. To investigate the possible mechanism of enhancing photocatalytic efficiency, the crystal structure, morphology, elemental composition, and optical properties of Bi2WO6, Bi2MO6, Bi2W2O9, and Bi2Mo2O9 were examined. UV-Vis diffuse reflectance spectroscopy revealed the visible-light absorption ability of Bi2WO6, Bi2MO6, Bi2W2O9, and Bi2Mo2O9. Photoluminescence (PL) and photocurrent indicated that Bi2W2O9 and Bi2Mo2O9 pose an enhanced ability of photogenerated electron–hole pairs separation. Radical trapping experiments revealed that photogenerated holes and superoxide radicals were the main active species. It can be conjectured that the promoted photocatalytic performance related to the modified structure, and a possible mechanism was discussed in detail. [ABSTRACT FROM AUTHOR]