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In order to promote the practical application of the heterogeneous Fenton process in wastewater treatment, Fe3O4 nanoparticles were prepared and used to degrade organic pollutants efficiently over a wide pH range, using phenol as a model. During fabrication, the effects of Fe2+/Fe3+ ratio and thermal treatment temperature were investigated and optimized. Using a transmission electron microscope and X-ray diffraction, the nanoparticles were found in the form of Fe3O4 with an average size of 15 nm. The effects of Fe3O4 nanoparticle concentration H2O2 concentration, and pH on the removal efficiency and chemical oxygen demand (COD) abatement efficiency of phenol were investigated. Under optimized conditions, the nano-Fe3O4 heterogeneous Fenton system could achieve phenol and COD removal efficiencies of 100 and 70% respectively. This nanocatalyst was observed to have a high efficiency at a wider pH range (2-9), and a possible mechanisms for this effect was proposed. [ABSTRACT FROM AUTHOR]

Highly ordered sodium-free titanate nanotube films were one-step prepared on F-doped SnO2-coated (FTO) glass via an electrophoretic deposition method by using sodium titanate nanotubes as the precursor. It was found that the self-assembled formation of highly ordered sodium titanate nanotube films was accompanied with the effective removal of sodium ions in the nanotubes during the electrophoretic deposition process, resulting in the final formation of protonated titanate nanotube film. With increasing calcination temperature, the amorphous TiO2 phase is formed by a dehydration process of the protonated titanate nanotubes at 300°C and further transforms into anatase TiO2 when the calcination temperature is higher than 400°C. Compared with the as-prepared titanate nanotube film, the calcined titanate nanotube film (300-600°C) exhibits attractive photoinduced superhydrophilicity under UV-light irradiation. In particular, 500°C-calcined films show the best photoinduced superhydrophilicity, probably due to synergetic effects of enhanced crystallization, surface roughness, and ordered structures of the films. [ABSTRACT FROM AUTHOR]

Mesoporous Au-TiO2 nanocomposite plasmonic photocatalyst with visible-light photoactivity was prepared by a simple spray hydrolytic method using photoreduction technique at 90°C. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and N2 adsorption-desorption isotherms. The formation of hydroxyl radicals (• OH) on the surface of visible-light illuminated Au-TiO2 nanocomposites was detected by the luminescence technique using terephthalic acid as probe molecules. The photocatalytic activity was evaluated by photocatalytic decolorization of Rhodamine-B (RhB) aqueous solution under visible-light irradiation (λ > 420 nm). The results revealed that the TiO2 could be crystallized via spray hydrolysis method, and the photoreduction technique was facilitated to prepare Au nanoparticles in the mesoporous TiO2 at 90°C. The light absorption, the formation rate of hydroxyl radicals, and photocatalytic decolorization of Rhodamine-B aqueous solution were significantly enhanced by those embedded Au nanoparticles in the Au-TiO2 nanocomposites. The prepared Au-TiO2 nanocomposites exhibit a highly visible-light photocatalytic activity for photocatalytic degradation of RhB in water, and their photocatalytic activity is higher than that of the pristine TiO2 nanoparticles due to the surface plasmon resonance. [ABSTRACT FROM AUTHOR]

Precursor powders of 15 and 22 mol% calcia-stabilized zirconia solid electrolytes were synthesized by a freeze-drying method and calcined at 900°C. Sensor elements were fabricated via uniaxial pressing of the calcined powders and subsequently sintered at 1650°C. X-ray diffraction and scanning electron microscopy techniques were used to analyze the phase composition and microstructure. The electrical response of the gas sensors to oxygen and the complex impedance in air were investigated at various operating temperatures. The correlation between electrical properties and sensor material chemical compositions as well as microstructure is discussed. [ABSTRACT FROM AUTHOR]

Recent studies have shown that the lack of ideal anodes with both good activity and stability is still one of the critical problems in electrochemical oxidation for organic wastewater treatment The electrochemical properties, the activity and stability for anodic oxidation of various phenolic compounds, and the degradation mechanism on a novel β-PbO2 electrode modified with fluorine resin were investigated. The anode life after modification was greatly improved to be more than 10 yr in common electrochemical current conditions. Such an anode was effective for partial degradation of phenolic compounds, but selective because reactive activities were varied with different substituents. Characterized by SEM and XRD, the crystal form of the anode was verified to be mainly β-PbO2, and it hardly changed when used for p-nitrophenol degradation for around 320 h although there existed slow electrode corrosion. The active species generated during anodic oxidation were determined to be mainly hydroxyl radical and little ozone. The reactions between hydroxyl radical and phenolic compounds were proved to be electrophilic reactions, based on which a general electrochemical degradation mechanism for aromatic compounds was proposed. In general, such a novel anode has a good performance for organics degradation with perfect electrode life, showing potential for environmental application. [ABSTRACT FROM AUTHOR]

Examines the partial degradation of phenol by advanced electrochemical oxidation process. Use of electrolytic reactor with beta-PbO[sub2] anode containing fluorine resin; Impact of operating parameters on the degradation rate of phenol; Recommendation of partial reduction for economical wastewater treatment.

In mullite–alumina composite precursors, interaction between the silica matrix and the fine γ-alumina texture strongly influences the precursor phase transformation, the nucleation and the crystal geometry both of the mullite and of the α-alumina. The mullite–alumina composite precursor calcined at 1000 °C has a layered structure probably derived from the layered texture of the γ-alumina. The phase transition of this layered texture is retarded by the presence of the silica matrix and a metastable mullite phase is formed before nucleation of α-alumina. By leaching away the silica matrix, the remaining layered texture is readily transformed into very fine, thin α-alumina platelets by calcination at 1000 °C. This seems to be one reason for the appearance of elongated mullite grains in a pure mullite matrix and the platelet shaped α-alumina grains in the mullite–alumina composite prepared from diphasic precursors. © 1998 Chapman & Hall [ABSTRACT FROM AUTHOR]

The introduction of oxygen in electrochemical oxidation at relatively high temperature and pressure as a promoter resulting in synergetic effects, greatly improves the mineralization of high-concentrated organic pollutants. [ABSTRACT FROM AUTHOR]

Peroxymonosulfate-based electrochemical advanced oxidation processes (PMS-EAOPs) have great potential for sustainable water purification, so an in-depth understanding of its catalytic mechanism is imperative to facilitate its practical application. Herein, the performance enhancement and mechanism of electroenhanced PMS activation by single-atom Fe catalyst modified carbon felt was investigated. Compared with the anode, the cathode exhibited faster bisphenol A degradation (kcathode = 0.073 vs. kanode = 0.015 min-1), increased PMS consumption (98.8 vs. 10.3%), and an order of magnitude reduction of Fe dissolution (0.068 vs. 0.787 mg L-1). Mass transfer is a key factor limiting PMS activation, while the electrostriction of water in the hydrophobic region caused by cathode electric field (CEF) significantly increased mass transfer coefficient (km, cathode = 1.49 x 10-4 vs. km, anode = 2.68 x 10-5 m s-1). The enhanced activation of PMS is a synergistic result between electroactivation and catalyst-activation, which is controlled by the applied current density. ¹O2 and direct electron transfer are the main active species and activation pathway, which achieve high degradation efficiency over pH 3 to 10. Density functional theory calculations prove CEF increases the adsorption energy, lengthens the O-O bond in PMS, and promotes charge transfer. A flow-through convection unit achieves sustainable operation with high removal efficiency (99.5% to 97.5%), low electrical energy consumption (0.15 kWh log-1 m-3), and low Fe leaching (0.81% of the total single atom Fe). This work reveals the critical role of electric fields in modulating Fenton-like catalytic activity, which may advance the development of advanced oxidation processes and other electrocatalytic applications. [ABSTRACT FROM AUTHOR]

This study conducted a questionnaire survey to examine the influence mechanism of perceived management commitment on the safety compliance and participation of graduate students and to verify the mediating role of psychological capital. The questionnaire was distributed to graduate students through the MyCOS network platform. SPSS was used to conduct reliability and validity tests, test, correlation analysis, and bootstrapping mediation effect test. The results demonstrated that the perceived management commitment has a positive effect on both safety compliance and safety participation, with psychological capital as the mediating role. This study explains how graduate students' perceived management commitment from their supervisors influences their safety behaviors. [ABSTRACT FROM AUTHOR]

● Soil N mineralization (Nmin) rates varied spatially among cropland fields.● Soil Nmin rates increased with a decreasing elevation.● Soil Nmin was mainly affected by SOC, TN, and available C and N.● Nmin in cropland soil should be considered when evaluating regional water pollution. Soil nitrogen mineralization (Nmin) is a key process that converts organic N into mineral N that controls soil N availability to plants. However, regional assessments of soil Nmin in cropland and its affecting factors are lacking, especially in relation to variation in elevation. In this study, a 4-week incubation experiment was implemented to measure net soil Nmin rate, gross nitrification (Nit) rate and corresponding soil abiotic properties in five field soils (A–C, maize; D, flue-cured tobacco; and E, vegetables; with elevation decreasing from A to E) from different altitudes in a typical intensive agricultural area in Dali City, Yunnan Province, China. The results showed that soil Nmin rate ranged from 0.10 to 0.17 mg·kg−1·d−1 N, with the highest value observed in field E, followed by fields D, C, B, and A, which indicated that soil Nmin and Nit rates varied between fields, decreasing with elevation. The soil Nit rate ranged from 434.2 to 827.1 µg·kg−1·h−1 N, with the highest value determined in field D, followed by those in fields E, C, B, and A. The rates of soil Nmin and Nit were positively correlated with several key soil parameters, including total soil N, dissolved organic carbon and dissolved inorganic N across all fields, which indicated that soil variables regulated soil Nmin and Nit in cropland fields. In addition, a strong positive relationship was observed between soil Nmin and Nit. These findings provide a greater understanding of the response of soil Nmin among cropland fields related to spatial variation. It is suggested that the soil Nmin from cropland should be considered in the evaluation of the N transformations at the regional scale.

Titanate nanotube films are fabricated on F-doped SnO2-coated glass substrates via an electrophoretic deposition method using hydrothermally prepared titanate nanotubes as precursors. The effects of calcination temperature on the microstructures and photoactivity of as-prepared titanate nanotube films are investigated and discussed. The results indicate that the intercalated sodium ions (Na+) in the as-prepared titanate nanotubes are easily removed during the electrophoretic deposition. The phase transformation of titanate to anatase and diffusion of Na+ ions from glass substrates into films occur at 400 °C. With increasing calcination temperature, the crystallization of anatase enhances and sodium content in the films increases. At 500 °C, the tubular structure still holds and the films show the highest photocatalytic activity probably due to their good crystallization, large specific surface areas and tubular structures. [ABSTRACT FROM AUTHOR]

Whilst ongoing increases in the deposition of atmospheric nitrogen (N) in China have attracted a lot of attention, to date there has been little research on phosphorus (P) deposition. In this study, we quantified inorganic P (PO 4 3−), dissolved organic P (DOP) and total P (TP) in bulk deposition at four sites in the Sichuan Basin, Southwest China. Chengdu (CD), Shifang (SF), Yanting (YT), and Gongga (GG). They represent the land use categories urban, suburban, agricultural and forest, respectively, during 2008–2018 at CD and YT, 2015–2018 at SF, and 2007–2014 at GG. Annual average TP concentrations (deposition rates) were 0.07 (0.61), 0.49 (3.22), 0.17 (1.07) and 0.01 (0.20) mg L−1 (kg ha−1 yr−1), at CD, SF, YT and GG, respectively. The TP concentrations at YT and GG showed significant increasing trends over the years, with very little change at CD and a decline at SF because of the implementation of environmental control measures. Average PO 4 3− to DOP ratios were 0.65, 0.95, 0.82 and 0.81 at CD, SF, YT and GG, respectively, indicating that DOP accounts for a higher proportion at the urban site, and dominated by combustion sources. Bulk P deposition showed higher deposition rates in summer and lower in winter. These results highlight the importance of long term monitoring in detecting spatial and temporal changing trends of the chemical composition, so as to implement effective policies to eliminate air pollution, especially for Southwest China, where there is limited research on atmospheric P deposition. [Display omitted] • Bulk P deposition showed increasing trends at the agricultural and forest sites. • Dissolved organic P dominates P bulk deposition over inorganic P. • The Southwest region is becoming a P deposition hotspot in China. [ABSTRACT FROM AUTHOR]