A new heterogeneous wet oxidation catalyst, Cu–Ni bimetallic oxides supported on γ-Al2O3/TiO2, was synthesized using a wet impregnation method. The physicochemical characteristics of the as-synthesized catalyst were assessed using various modern methods such as scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), N2 adsorption–desorption, and X-ray photoelectron spectroscopy (XPS). Compared with monometallic Cu or Ni oxide catalysts, this new supported Cu–Ni bimetallic oxide catalyst presented a higher activity and stability in quinoline mineralization. The impact of the microwave (MW) power, temperature, pH and H2O2 dosage was studied on the basis of the TOC mineralization. At a MW power of 500 W, pH 7, 333 K and a 22.75 mmol L−1 H2O2 dosage, an 81% abatement of the TOC was reached. Based on the results of metal leaching and XPS analysis, the stability of the Cu–Ni bimetallic supported catalyst, along with the role of the copper and nickel, is discussed.

•Perchlorate can be reduced using Ag nanoparticles loaded TiO2 nanotube arrays.•The photoelectrocatalytic properties of Ag-TNTs were studied upon UV irradiation.•Influencing factors and reaction mechanisms of perchlorate reduction were discussed.Photoelectrocatalytic reduction of aqueous perchlorate using Ag nanoparticles loaded TiO2 nanotube arrays (Ag-TNTs) in the presence of a hole scavenger (citric acid, Cit) under UV light irradiation was investigated in this study. TiO2 nanotube arrays (TNTs) were prepared by anodic oxidation and Ag nanoparticles were loaded on TNTs by photodeposition. Ag-TNTs were characterized by X-ray diffraction, scanning electron microscope and X-ray photoelectron spectroscopy. The influences of Ag doping content, photogenerated electron, photogenerated hole, hydroxyl radical, initial pH and applied voltages on photoelectrocatalytic perchlorate reduction were studied and the optimum reaction conditions were determined. Results indicated that Ag-TNTs have the best photoelectrocatalytic activity when the nominal mass ratio of Ag to TiO2 is 0.84%. With an initial perchlorate concentration of 0.001 mM, the perchlorate reduction efficiency can reach 62% in the presence of Cit (0.15 mM) after 6 h reaction (368 ± 0.5 K) at applied voltage of 1.5 V.

The spatial and temporal distributions of polycyclic aromatic hydrocarbons (PAHs) in the Songhua River, Harbin, China, were investigated. Seventy-seven samples, 42 water and 35 sediment samples, were collected in April and October of 2007 and January of 2008. The concentrations of total PAHs in water ranged from 163.54 to 2,746.25 ng/L with the average value of 934.62 ng/L, which were predominated by 2- and 3-ring PAHs. The concentrations of total 16 PAHs in sediment ranged from 68.25 to 654.15 ng/g dw with the average value of 234.15 ng/g dw, which were predominated by 4-, 5- and 6-ring PAHs. Statistical analysis of the PAH concentrations shown that the highest concentrations of the total PAHs were found during rainy season (October of 2007) and the lowest during snowy season (January of 2008). Ratios of specific PAH compounds, including fluoranthene/(fluoranthene + pyrene) (Flu/(Flu + Pyr)) and phenanthrene/(phenanthrene + anthracene) (An/(Ant + PhA)), were calculated to evaluate the possible sources of PAH contaminations. These ratios reflected pyrolytic inputs of PAHs in Songhua River water and a mixed pattern of pyrolytic and petrogenic inputs of PAHs in the Songhua River sediments. Ecotoxicological risk levels calculated for PAHs suggested that there were individual PAHs, which can less frequently cause biological impairment in some samples, but no samples had constituents that may frequently cause biological impairment. Total toxic benzo[a]pyrene equivalent of ΣcPAHs varied from 10.03 to 29.7 ng/g dw and from 0.36 to 1.92 ng/g dw for total toxic tetrachlorodibenzo-p-dioxin equivalent. The level of PAHs indicated a low toxicological risk to this area.

The inactivation of Escherichia coli (E. coli) in water was investigated systematically with Ag-coated TiO2 thin film under UV-C irradiation. Compared with UV-C irradiation alone, the inactivation of E. coli by the UV/Ag-TiO2 process was enhanced and the photoreactivation of the bacteria was much repressed. Moreover, atomic force microscopy (AFM) measurements of E. coli showed that the presence of Ag-TiO2 thin film during UV exposure could expedite the destruction of cell wall and cell membrane, which was further confirmed by the formation of malondialdehyde (MDA) and leakage of intracellular potassium ion (K+) and protein. The results suggest that the cell structure destruction might be the major reason for the enhancement of inactivation efficiency, and the prepared Ag-TiO2 thin films show potential as a new improvement tool for UV-C disinfection.

Perfluorooctane sulfonate (PFOS) and ZnO nanoparticles (nano-ZnO) are widely distributed in the environment. However, the potential toxicity of co-exposure to PFOS and nano-ZnO remains to be fully elucidated. The test investigated the effects of co-exposure to PFOS and nano-ZnO on the hypothalamic–pituitary–thyroid (HPT) axis in zebrafish. Zebrafish embryos were exposed to a combination of PFOS (0.2, 0.4, 0.8 mg/L) and nano-ZnO (50 mg/L) from their early stages of life (0–14 days). The whole-body content of TH and the expression of genes and proteins related to the HPT axis were analyzed. The co-exposure decreased the body length and increased the malformation rates compared with exposure to PFOS alone. Co-exposure also increased the triiodothyronine (T3) levels, whereas the thyroxine (T4) content remained unchanged. Compared with the exposure to PFOS alone, exposure to both PFOS (0.8 mg/L) and nano-ZnO (50 mg/L) significantly up-regulated the expression of corticotropin-releasing factor, sodium/iodidesymporter, iodothyronine deiodinases and thyroid receptors and significantly down-regulated the expression of thyroid-stimulating hormone, thyroglobulin (TG), transthyretin (TTR) and thyroid receptors. The protein expression levels of TG and TTR were also significantly down-regulated in the co-exposure groups. In addition, the expression of the thyroid peroxidase gene was unchanged in all groups. The results demonstrated that PFOS and nano-ZnO co-exposure could cause more serious thyroid-disrupting effects in zebrafish than exposure to PFOS alone. Our results also provide insight into the mechanism of disruption of the thyroid status by PFOS and nano-ZnO.Download high-res image (82KB)Download full-size image

•First time to investigate the developmental toxicity of PFOS to zebrafish in early life stage in the presence of MWCNTs.•The adverse effects induced by PFOS on zebrafish larvae were reduced in the presence of MWCNTs.•The activities of SOD, CAT and GSH-Px and the level of ROS and MDA were all decreased.Both carbon nanotubes (CNTs) and perfluorooctane sulfonate (PFOS) are used widely. There is considerable concern regarding their ecotoxicity. CNTs might interact with PFOS in water and result in different impacts compared with those after single exposures. To our knowledge, the developmental toxicity of PFOS in the presence of multi-walled carbon nanotubes (MWCNTs) in the early life stage of zebrafish (from 3 h post fertilization (hpf) to 96 hpf) was investigated for the first time in this study. The embryos and larvae were exposed to PFOS (0.2, 0.4, 0.8, and 1.6 mg/L), MWCNTs (50 mg/L), and a mixture of both. Compared with PFOS exposure, the adverse effects induced by PFOS on the hatching rate of zebrafish embryos and the heart rate and body length of zebrafish larvae were reduced in the presence of MWCNTs, and mortality and malformation were also alleviated. In addition, zebrafish larvae exposed to PFOS showed decreased activities of superoxide dismutase, catalase, and glutathione peroxidase, as well as decreased levels of reactive oxygen species and malondialdehyde, in the presence of MWCNTs, indicating that oxidative stress and lipid peroxidation was relieved. Thus, the presence of MWCNTs reduces the developmental toxicity of PFOS in the early life stage of zebrafish.Download high-res image (163KB)Download full-size image