In situfabrication of S-type BiOIxBryheterojunction with metallic Bi for boosting photocatalytic activity for CO2reduction.

Heterojunction construction and morphology control have always been considered effective ways to promote the capability of photocatalysts. In this work, BiOIxBry, S-type heterojunction photocatalysts with metallic Bi nanoparticles, were synthesizedin situusing a solvothermal method, and the influence of reaction temperature (180 °C-220 °C) and dopant doping amount on the catalysts' microscopic morphology, structure, and catalytic properties were researched. Study results revealed the 1:1 BiOIxBrysynthesized at 200 °C exhibited the optimum behavior in CO2reduction. Its catalytic CO2reduction to CH3OH was 932.88µmol gcat-1and C2H5OH was 324.46µmol gcat-1under the analog light source for 8 h, which was approximately 1.92 and 1.49 times higher than that of BiOI-200 °C, respectively. The reinforced catalytic properties are probably attributed to the synergistic effect between metallic Bi nanoparticles and BiOIxBryheterojunction. Thanks to the SPR effect ofin situmetallic Bi, the catalysts' photocarrier separation efficiency is facilitated. Additionally, the heterojunction formation contributes to that trend and more importantly, preserves the charge carriers with strong redox capacity in BiOIxBry, proving product selectivity. We also present a potential electron transfer mechanism involved in the BiOIxBryphotocatalytic CO2reduction based on the characterization analysis and experimental results.

Effects of salvianolic acid A on intestinal microbiota and lipid metabolism disorders in Zucker diabetic fatty rats.

Salvianolic acid A (SalA) is the main water-soluble component isolated from Salvia miltiorrhiza. This study explored the influences of SalA on intestinal microbiota composition and lipid metabolism in Zucker diabetic fatty (ZDF) rats. The 6-week-old male ZDF rats were treated with distilled water (N = 10) and low dose (SalA 0.5 mg/kg/d, N = 10), medium dose (SalA 1 mg/kg/d, N = 10), and high dose (SalA 2 mg/kg/d, N = 10) of SalA, with the male Zucker lean normoglycemic rats of the same week age as controls (given distilled water, N = 10). The blood glucose, body weight, and food intake of rats were examined. After 7 and 8 weeks of continuous administration, oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were performed, respectively. Serum fasting insulin (FINS), total cholesterol (TC), triglyceride (TG), and free fatty acid (FFA) were determined. Liver tissues were stained using hematoxylin-eosin (HE) and oil red O staining. Fecal samples were analyzed by 16S rRNA gene sequencing. Small intestinal tissues were stained using HE and immunohistochemistry. The tight junction proteins (ZO-1/Occludin/Claudin-1) and serum levels of LPS/TNF-α/IL-6 were evaluated. SalA reduced insulin resistance, liver injury, serum FFA, liver TC and TG levels in ZDF rats, and improved lipid metabolism. After SalA treatment, intestinal microbiota richness and diversity of ZDF rats were promoted. SalA retained the homeostasis of intestinal core microbiota. SalA reduced intestinal epithelial barrier damage, LPS, and inflammatory cytokines in ZDF rats. Overall, SalA can sustain intestinal microbiota balance and improve the lipid metabolism of ZDF rats.

Treatment on thiodicarb in pesticide wastewater with walnut shells-derived carbon and its improved modification: adsorption behavior.

The health problems caused by water pollution cannot be ignored, and the contribution of pesticides to water pollution has also become increasingly unignorable. The modified semi-coke as an adsorbent for reducing pesticide pollution to water was obtained from activated semi-coke which was modified by nitric acid (HNO3). The semi-coke was obtained by carbonization using 60 mesh walnut shell powder. After acid-base deashing, the semi-coke is dipped into zinc chloride (ZnCl2) solution to obtain activated semi-coke. Through BET analysis, the specific surface areas of semi-coke, activated semi-coke and modified semi-coke were 26.8 m2/g, 243.9 m2/g, and 339.6 m2/g respectively. An extremely high adsorption capacity of the adsorbents which is used to treat wastewater was achieved. The optimum adsorption conditions for modified semi-coke on thiodicarb solution were 30 mg/L of thiodicarb solution, adsorbent dosage of 0.01 g, adsorption temperature of 25 °C and adsorption time of 90 min. The optimum adsorption amount of 29.54 mg/gsor was achieved (sor is the abbreviation for sorbent). Moreover, through kinetics study, the result manifests that the modified semi-coke adsorption process is more fitted to the second-order kinetic model. This study provided a research implication theoretically for the treatment of pesticides in water.

Distribution and sources of PM2.5-bound free silica in the atmosphere of hyper-arid regions in Hotan, North-West China.

The composition of atmospheric fine particulate matter (PM2.5) is complex and exhibits strong regional differences. Free silica (α-SiO2) in atmospheric particulate matter is carcinogenic and is an important component of respirable particulate matter in urban areas. Measurements determined that the concentration of silicon dioxide (α-SiO2) in PM2.5 in the urban area of Hotan City, China, was 8.02 µg·m-3 during the dust period and exceeded 1.77 µg·m-3 during the non-dust period. The proportion of α-SiO2 in PM2.5 was 8.07% during the dust period and 2.25% during the non-dust period. Atmospheric visibility during the dust period was mainly influenced by the content of atmospheric floating dust. Analysis of α-SiO2 pollution sources during the dust period showed that the air masses containing sand and dust originated from the desert hinterland. Following passage through oasis areas, the air mass was effectively reduced in the concentration of α-SiO2 in PM2.5. During the dusty period, α-SiO2 and PM2.5 originated from the same source in Hotan City. Moreover, wind speed was the main influencing factor for the α-SiO2 concentration. During the non-dust period, α-SiO2 and PM2.5 were not from the same source of pollution.

Humidity and PM2.5 composition determine atmospheric light extinction in the arid region of northwest China.

Atmospheric visibility can directly reflect the air quality. In this study, we measured water-soluble ions (WSIs), organic and element carbon (OC and EC) in PM2.5 from September 2017 to August 2018 in Urumqi, NW China. The results show that SO42-, NO3- and NH4+ were the major WSIs, together accounting for 7.32%-84.12% of PM2.5 mass. Total carbon (TC=OC+EC) accounted for 12.12% of PM2.5 mass on average. And OC/EC > 2 indicated the formation of secondary organic carbon (SOC). The levels of SO42-, NO3- and NH4+ in low visibility days were much higher than those in high visibility days. Relative humidity (RH) played a key role in affecting visibility. The extinction coefficient (bext) that estimated via Koschmieder formula with visibility was the highest in winter (1441.05 ± 739.95 Mm-1), and the lowest in summer (128.58 ± 58.00 Mm-1). The bext that estimated via IMPROVE formula with PM2.5 chemical component was mainly contributed by (NH4)2SO4 and NH4NO3. The bext values calculated by both approaches presented a good correlation with each other (R2 = 0.87). Multiple linear regression (MLR) method was further employed to reconstruct the empirical regression model of visibility as a function of PM2.5 chemical components, NO2 and RH. The results of source apportionment by Positive Matrix Factorization (PMF) model showed that residential coal combustion and vehicle emissions were the major sources of bext.

In situ ultrasound-assisted ion exchange synthesis of sphere-like AgClxBr1-x composites with enhanced photocatalytic activity and stability.

AgClxBr1-x composites with different halogen molar ratios (Cl/Br) were prepared by a facile ultrasound-assisted ion-exchange method. The formation of close contact between AgCl and AgBr facilitated the transportation of photoexcited charge carriers and contributed to the enhanced visible-light-driven photocatalytic degradation of different kinds of antibiotics. The AgClxBr1-x composites had a sphere-like morphology and tunable band gaps from 2.95 to 2.57 eV depending on Cl/Br mole ratios. Besides, the AgClxBr1-x composite was optimized by varying halogen mole ratios (Cl/Br) to achieve the highest photocatalytic activity. Results indicated that AgCl0.75Br0.25 showed the best photocatalytic degradation performance, which was about 2.36 and 2.78 times that of the single AgCl towards ciprofloxacin (CIP) and metronidazole (MNZ) degradation, respectively. Meanwhile, a possible photocatalytic degradation mechanism was discussed, and results indicated that the holes (h+) and •OH were the dominant active species in the AgCl0.75Br0.25 system.

[Effect of Liquid Water Content of Particles and Acidity of Particulate Matter on the Formation of Secondary Inorganic Components in Xinjiang Petrochemical Industrial Area].

Secondary species are dominant components of PM2.5 in Dushanzi, Xinjiang. It is crucial to investigate the conversion process of secondary components in the atmosphere for regional air pollution control. The water-soluble components were analyzed for samples collected from Dushanzi District of Xinjiang from September 2015 to July 2016. The results showed that the total water-soluble ions (TWSIs) showed a seasonal variation consistent with PM2.5, and the seasonal variation of the ions was in the order-winter (67.86 µg·m-3) > autumn (13.77 µg·m-3) > spring (10.09 µg·m-3) > summer (4.85 µg·m-3); secondary ions (NH4+, SO42-, and NO3-)-accounting for 98% of TWSIs in winter. The results of the aerosol thermodynamic model (E-AIM) that explores the particle liquid water and acidity in Dushanzi District showed that the particles in Dushanzi are acidic with an annual in-situ pH of 0.81, and the pH value of the winter samples was the highest (2.93). The seasonal variation of particles in water was of the order: winter (331.32 µg·m-3) > autumn (5.91 µg·m-3) > spring (5.46 µg·m-3) > summer (1.62 µg·m-3). The annual average nitrogen oxidation rate and sulfur oxidation rate were 0.13 and 0.47, respectively, indicating a secondary conversion of regional pollutants. Further analysis showed that the concentration of sulfate in the particle phase was significantly affected by liquid water content of particles and in-situ pH. The formation of nitrate was mainly caused by heterogeneous reactions under high water content of particle.

Distribution, sources, risks, and vitro DNA oxidative damage of PM2.5-bound atmospheric polycyclic aromatic hydrocarbons in Urumqi, NW China.

Research has focused on the impacts of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere due to their potential carcinogenicity. In this study, we investigated the seasonal variation, sources, incremental lifetime cancer risks (ILCRS), and vitro DNA oxidative damage of PAHs in Urumqi in NW China. A total of 72 atmospheric samples from Urumqi were collected over a year (September 2017-September 2018) and were analyzed for 16 PAHs that are specifically prioritized by the U.S Environmental Protection Agency (U·S EPA). The highest PAHs concentrations were in winter (1032.66 ng m-3) and lowest in spring (146.00 ng m-3). Middle molecular weight PAHs with four rings were the most abundant species (45.28-61.19% of the total). The results of the diagnostic ratio and positive matrix factorization inferred that the major sources of atmospheric PAHs in Urumqi were biomass burning, coking, and petrogenic sources (52.9%), traffic (30.1%), coal combustion (8.9%), and the plastics recycling industry (8.1%). ILCRS assessment and Monte Carlo simulations suggested that for all age groups PAHs cancer risks were mainly associated with ingestion and dermal contact and inhalation was negligible. The plasmid scission assay results showed a positive dose-response relationship between PAHs concentrations and DNA damage rates, demonstrating that toxic PAHs was the primary cause for PM2.5-induced DNA damage in the air of Urumqi.

Facile photo-ultrasonic assisted synthesis of flower-like Pt/N-MoS2 microsphere as an efficient sonophotocatalyst for nitrogen fixation.

Semiconductor photocatalytic technology is a sustainable and less energy consuming one for nitrogen (N2) reduction to produce ammonia (NH3). In this study, flower-like hierarchical N doped MoS2 (N-MoS2) microsphere was synthesized as a photocatalyst by one-step solvothermal method, which was assembled by numerous interleaving nanosheets petals with thin thickness. Besides, Pt nanoparticles were loaded on the surface of N-MoS2 via photo-ultrasonic reduction method. The as-prepared Pt/N-MoS2 photocatalyst exhibited higher N2 fixation ability than that over pure MoS2 and N-MoS2, which can be attributed to that the N doping narrows the band gap, and the Schottky barrier due to the existence of Pt nanoparticles improves the charge transfer and carrier separation. The reduction of N2 with ultrasonic irradiation was also investigated under visible light irradiation to evaluate the sonophotocatalytic activity of the Pt/N-MoS2 microsphere. The results showed that the N2 reduction rate of sonophotocatalysis (133.8 µmol/g(cat)h) was higher than that of sonocatalysis and photocatalysis, which can be ascribed to the synergistic effect of ultrasound and visible light irradiation. The effects of catalyst dosage, ultrasonic power and ultrasonic pulse on the photocatalytic efficiency were also studied. Meanwhile, a possible mechanism for improved sonophotocatalytic performance was also proposed.

One-pot sonochemical synthesis of 3D flower-like hierarchical AgCl microsphere with enhanced photocatalytic activity.

A highly uniform 3D flower-like hierarchical AgCl microsphere was prepared by sonochemical method with the existence of ß-dextrin. The 3D flower-like hierarchical structure can be ascribed to the existence of ß-dextrin, which provides nucleation sites for the growth of nanosheets because of the strong interaction between ß-dextrin and Ag+. The 3D flower-like hierarchical AgCl microspheres were assembled by numerous interleaving nanosheet petals with small thickness. Benefiting from the unique structural features, the as-prepared 3D flower-like hierarchical AgCl microsphere exhibited higher degradation efficiency with degrading 98.17% of methylene blue (MB) and 88.50% of tetracycline (TC) within 40 min, which were both remarkably higher than those of irregular AgCl under visible light irradiation. Besides, the photocatalytic degradation rate constant of 3D flower-like hierarchical AgCl microsphere (0.063 min-1) for MB was 3.94 times higher than that of irregular AgCl (0.016 min-1). Moreover, a possible mechanism for the formation and excellent photocatalytic performance of 3D flower-like hierarchical AgCl microsphere was also proposed.

Facile One-Step Sonochemical Synthesis and Photocatalytic Properties of Graphene/Ag3PO4 Quantum Dots Composites.

In this study, a novel graphene/Ag3PO4 quantum dot (rGO/Ag3PO4 QD) composite was successfully synthesized via a facile one-step photo-ultrasonic-assisted reduction method for the first time. The composites were analyzed by various techniques. According to the obtained results, Ag3PO4 QDs with a size of 1-4 nm were uniformly dispersed on rGO nanosheets to form rGO/Ag3PO4 QD composites. The photocatalytic activity of rGO/Ag3PO4 QD composites was evaluated by the decomposition of methylene blue (MB). Meanwhile, effects of the surfactant dosage and the amount of rGO on the photocatalytic activity were also investigated. It was found that rGO/Ag3PO4 QDs (WrGO:Wcomposite = 2.3%) composite exhibited better photocatalytic activity and stability with degrading 97.5% of MB within 5 min. The improved photocatalytic activities and stabilities were majorly related to the synergistic effect between Ag3PO4 QDs and rGO with high specific surface area, which gave rise to efficient interfacial transfer of photogenerated electrons and holes on both materials. Moreover, possible formation and photocatalytic mechanisms of rGO/Ag3PO4 QDs were proposed. The obtained rGO/Ag3PO4 QDs photocatalysts would have great potentials in sewage treatment and water splitting.

Synthesis of MnO2 nanoparticles from sonochemical reduction of MnO4(-) in water under different pH conditions.

MnO2 was synthesized by sonochemical reduction of MnO4(-) in water under Ar atmosphere at 20°C, where the effects of solution pH on the reduction of MnO4(-) were investigated. The obtained XRD results showed that poor crystallinity δ-MnO2 was formed at pH 2.2, 6.0 and 9.3. When solution pH was increased from 2.2 to 9.3, the morphologies of δ-MnO2 changed from aggregated sheet-like or needle-like structures to spherical nanoparticles and finally to cubic or polyhedron nanoparticles. After further irradiation, MnO2 was readily reduced to Mn(2+). It was confirmed that H2O2 and H atoms formed in the sonolysis of water acted as reductants for both reduction for MnO4(-) to MnO2 and MnO2 to Mn(2+). The optimum irradiation time for the effective synthesis of MnO2 was 13 min at pH 2.2, 9 min at pH 6.0, 8 min at pH 9.3, respectively.

Sonochemical fabrication of gold nanoparticles-boron nitride sheets nanocomposites for enzymeless hydrogen peroxide detection.

A simple sonochemical route was developed for the preparation of gold nanoparticles/boron nitride sheets (AuNPs/BNS) nanocomposites without using reducing or stabilizing agents. Transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and UV-vis absorption spectra were used to characterize the structure and morphology of the nanocomposites. The experimental results showed that AuNPs with approximately 20nm were uniformly attached onto the BNS surface. It was found that the AuNPs/BNS nanocomposites exhibited good catalytic activity for the reduction of H2O2. The modified electrochemical sensor showed a linear range from 0.04 to 50mM with a detection limit of 8.3µM at a signal-to-noise ratio of 3. The findings provide a low-cost approach to the production of stable aqueous dispersions of nanoparticles/BNS nanocomposites.

One-step simple sonochemical fabrication and photocatalytic properties of Cu2O-rGO composites.

An easy, one-step synthesis of Cu2O-reduced graphene composites (Cu2O-rGO) was developed using a simple sonochemical route without any surfactants or templates. The morphology and structure of the Cu2O-rGO composites were characterised using techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The results indicated that the Cu2O sphere is approximately 200 nm in diameter and composed of small Cu2O particles approximately 20 nm in diameter. The morphology and composition of the Cu2O-rGO composites could be well controlled by simply changing the mole ratio of the reactants under ultrasonic irradiation. The Cu2O-rGO composites displayed better photocatalytic performance for the degradation of methyl orange (MO) than pure Cu2O spheres, which may have potential applications in water treatment, sensors, and energy storage.

Ultrasound assisted reduction of graphene oxide to graphene in L-ascorbic acid aqueous solutions: kinetics and effects of various factors on the rate of graphene formation.

The reduction of graphene oxide (GO) to graphene (rGO) was achieved by using 20 kHz ultrasound in L-ascorbic acid (L-AA, reducing agent) aqueous solutions under various experimental conditions. The effects of ultrasound power, ultrasound pulse mode, reaction temperature, pH value and L-AA amount on the rates of rGO formation from GO reduction were investigated. The rates of rGO formation were found to be enhanced under the following conditions: high ultrasound power, long pulse mode, high temperature, high pH value and large amount of L-AA. It was also found that the rGO formation under ultrasound treatment was accelerated in comparison with a conventional mechanical mixing treatment. The pseudo rate and pseudo activation energy (Ea) of rGO formation were determined to discuss the reaction kinetics under both treatment. The Ea value of rGO formation under ultrasound treatment was clearly lower than that obtained under mechanical mixing treatment at the same condition. We proposed that physical effects such as shear forces, microjets and shock waves during acoustic cavitation enhanced the mass transfer and reaction of L-AA with GO to form rGO as well as the change in the surface morphology of GO. In addition, the rates of rGO formation were suggested to be affected by local high temperatures of cavitation bubbles.