Lingjun Meng

Evaluation of single and joint toxicity of perfluorooctane sulfonate, perfluorooctanoic acid, and copper to Carassius auratus using oxidative stress biomarkers

Perfluorooctane sulfonate, perfluorooctanoic acid, and copper have been recently regarded as ubiquitous environmental contaminants in aquatic ecosystems worldwide. However, data on their possible combined toxic effects on aquatic organisms are still lacking. In this study, a systematic experimental approach was used to assess the impacts of these chemicals and their mixtures on hepatic antioxidant status of Carassius auratus after 4 days. Oxidative stress was apparently observed for joint exposure by determining biochemical parameters (superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, and malondialdehyde). The integrated biomarker response index was calculated to rank the toxicity order, from which the synergistic effect was tentatively proposed for joint-toxicity action. In addition, these treatments significantly altered trace element homeostasis in different fish tissues, and the concentration distribution of these test chemicals was also measured. Taken together, these results provided some valuable toxicological data on the joint effects of perfluorinated compounds and heavy metals on aquatic species, which can facilitate further understanding on the potential risks of other coexisting pollutants in the natural aquatic environment.

Controlled synthesis of BiVO4/SrTiO3 composite with enhanced sunlight-driven photofunctions for sulfamethoxazole removal

The presence of antibiotics in surface waters is paid more and more attention, which is difficult to be removed by conventional treatment technology, and photocatalytic technology is considered to be a promising method for antibiotics pollutant removal. In the present work, a novel heterojunction photocatalyst was successfully synthesized by self-template method under hydrothermal condition. The photocatalytic activity of as-prepared samples was investigated by degradation of sulfamethoxazole in aqueous solution. The BiVO4/SrTiO3 composites showed superior photocatalytic efficiency under xenon lamp irradiation. The recycling tests proved that BiVO4/SrTiO3 composite was high stability and easily separated. The degradation efficiency of BiVO4/SrTiO3 composite was also greatly influenced by active species. It indicated that approximately 50% TOC reduction was achieved after 1h photocatalytic reaction. The intermediates were investigated by LC-MS analyses, which revealed that the bonds of CO, CS, CC, CN, isoxazole ring and benzene ring were broken by attacking of active species.

A novel method for photo-oxidative degradation of diatrizoate in water via electromagnetic induction electrodeless lamp

In this study, an electromagnetic induction electrodeless lamp (EIEL) was first introduced into UV advanced oxidation processes (AOPs) for photodegradation of Diatrizoate (DTZ), which was the most persistent iodinated X-ray contrast medium (ICM), and traditional Hg lamps were taken as references. Direct photolysis rate of DTZ under EIEL irradiation was 1.34 times as that under Hg irradiation, but the electric energy consumption was 0.87 times. In this sense, the combination of EIEL and oxidants (O2, H2O2 and S2O82-(PS)) was further investigated. The remarkably increased photodegradation rates were observed in UV/PS system due to primary contribution rate of SO4- (62.5%) based on the results of radical concentrations and second-order rate constants of DTZ with SO4- and OH. Inorganic ions influencing the photodegradation process were investigated. The effect of natural organic materials (NOMs) in UV/PS system was studied based on contribution ratios of light screening effect and quenching. Transformation mechanisms of DTZ in UV/PS system included deiodination, intramolecular cyclization, decarboxylation, deacetylation and deamination, which were further confirmed by frontier electron density calculations. The study indicated that UV/PS with EIEL irradiation has the potential to remove pharmaceuticals in contaminated aquatic environments.

Biological Decolorization and Degradation of Malachite Green by Pseudomonas sp. YB2: Process Optimization and Biodegradation Pathway

A novel strain Pseudomonas sp. YB2, which was isolated from activated sludge, was studied for biological decolorization and degradation of malachite green (MG). The results show that this aerobic strain is an aerobic bacterium, which has relatively high salt tolerance and high antibiotic resistance. The optimal performance condition for both bacterial growth and decolorization of MG was at 25–35xa0°C and pH 5.0–7.0. It could efficiently decolorize 90.40% MG at a high concentration up to 1500xa0mg/L in 24xa0h, and concentrations of MG lower than 1000xa0mg/L could be completely decolorized in 12xa0h. The intermediate products of MG were detected using gas chromatography–mass spectrometer, including leucomalachite green, 4,4′-bis(dimethylamino) benzophenone, 4-(dimethylamino) benzophenone, phenol, dimethylaniline. The possible degradation pathways of MG by strain YB2 were proposed. This strain might be potentially useful for biodegradation of MG in real environments.