Efficient reduction of vanadium (V) with biochar and experimental parameters optimized by response surface methodology.

Water pollution deteriorates ecosystems and has a great threaten to the environment. The environmental benefits of wastewater treatment are extremely important to minimize pollutants. Here, the biochar purchased from the related industry was used to treat the wastewater which contained high concentration of vanadium (V). The concentration of vanadium was measured by the IC-OES and the results showed that 96.1% vanadium (V) was reduced at selected reaction conditions: the mass ratio of biochar to vanadium of 5.4, reaction temperature of 90 °C, reaction time at 60 min and concentration of H2SO4 of 10 g/L, respectively. Response surface methodology confirmed that all the experimental parameters had positive effect on the reduction of vanadium (V), which could improve the reduction efficiency of vanadium (V) as increased. The influence of each parameter on the reduction process followed the order: A (Concentration of H2SO4) > C (mass ratio of biochar to vanadium) > B (mass ratio of biochar to vanadium). Especially, the mass ratio of biochar to vanadium and concentration of H2SO4 had the greatest influence on the reduction process. This paper provides a versatile strategy for the treatment of wastewater containing vanadium (V) and shows a bright tomorrow for wastewater treatment.

Recent advances in hierarchical MoS2/graphene-based materials for supercapacitor applications.

Hierarchical MoS2/graphene (MoS2/G) has been widely researched in energy storage via supercapacitors. The combination of MoS2 with graphene not only provides high conductivity but also enhances the structural stability, which are critical factors determining the electrochemical performance for energy storage. In this review, the recent development of various hierarchical MoS2/G nanostructures in supercapacitor applications is summarized by classifying the materials into MoS2/G nanospheres, MoS2/G nanosheets, and MoS2/G-based ternary composite. The description of the structural characteristics and electrochemical performance gives a clear and profound understanding of hierarchical MoS2/G nanostructures as a supercapacitor material. In addition, further research prospects of hierarchical MoS2/G are suggested.

Titanium-Enriched Slag Prepared by Atmospheric Hydrochloric Acid Leaching of Mechanically Activated Vanadium Titanomagnetite Concentrates.

The titanium-enriched slag was obtained via atmospheric hydrochloric acid leaching of mechanically activated vanadium titanomagnetite concentrates (VTMCs). Under the influence of mechanical activation, specific physicochemical changes were observed via X-ray diffractometry, scanning electron microscopy, and granulometric laser diffraction analysis. Experimental findings revealed that the mechanical activation of VTMCs resulted in a decrease in the median volume particle diameter (d50) and an increase in the specific surface area (SA) with an increased milling time. The results of the leaching experiment revealed that the mechanical activation treatment favors the extraction of iron (Fe) and titanium dioxide (TiO2) from the VTMCs. The Fe and TiO2 extractions from the mechanically activated sample after 10 h compared with the unactivated sample were increased by 12.82% and 4.73%, respectively. The presence of the ilmenite phase in the titanium-enriched slag was confirmed by X-ray diffractometry and EDS patterns, and the content of the TiO2 in the enriched slag can get as high as 43.75%.

Hierarchical Brookite TiO2-Bi2MoO6 Nanospheres with Efficient Visible-Light-Driven Photocatalytic Response.

Hierarchical TiO2-Bi2MoO6 nanospheres as efficient visible-light responsive photocatalyst are fabricated by dispersing brookite TiO2 nanorods on the hierarchical Bi2MoO6 nanospheres, which provides visible-light absorption and large surface area. The morphologies, surface area and light absorption features of as-prepared TiO²-Bi²MoO6 can be rational controlled by varying the loading amount of TiO² nanorods on hierarchical Bi²MoO6 nanospheres. As a result, the TiO²-Bi²MoO6-3 yields 380 ppm CO² production for decomposing 2-propanol at 11 h under visible light irradiation, realizing 4.4 times enhancement of photocatalytic property with respect to pure TiO² nanorods. Moreover, the three-dimensional hierarchical architecture enables the hybrid TiO²-Bi²MoO6 excellent cycling stability.

Recovery of high purity Si from kerf-loss Si slurry waste by flotation method using PEA collector.

Separation and recovery of high-purity Si powder from kerf-loss Si slurry waste is a critical challenge for the photovoltaic industry. A green surfactant poly (propylene glycol) bis (2-aminopropyl ether) (PEA) was employed as a collector to facilitate the separation of Si and SiC from kerf-loss Si waste during flotation process. Single flotation tests of Si and SiC were conducted using 5 × 10-6 mol/L PEA, respectively. The separation efficiencies of Si and SiC in conjunction with PEA adsorption mechanism were investigated. It was found that the maximum recoveries rate of SiC and Si were 90.59% (pH 9.00) and 80.93% (pH 1.96), respectively. Furthermore, the maximum Si grade was determined as 92.31% at pH 8.95 for the sinking part of the mixture generating excellent floatability and selectivity. Zeta potential measurements, FT-IR spectra, and XPS analyses demonstrated that PEA was present on the surface of Si and SiC through electrostatic and hydrogen-bond interactions. The adsorption mechanism was explained based on the results. This research provides an efficient and environmentally friendly route for the separation and recovery of high purity silicon from kerf-loss Si waste.

New Insights into the Stability of Anhydrous 2H-Imidazolium Fluoride and its High Dissolution Capability toward a Strongly Hydrogen-Bonded Compound.

Fluorides have been widely applied in pharmaceutical, medicinal, and materials science as well as in fine chemical manufacturing. The performance of fluorides, however, can be markedly affected by the water content. One previous study (Maiti, A.; et al. Phys. Chem. Chem. Phys. 2008, 10, 5050) suggested that anhydrous 1,3-dimethylimidazolium fluoride ([DMIm]F) was unstable since the fluoride undergoes a self-decomposition reaction. Herein we first show quantum-chemical calculation evidence that although gas-phase [DMIm]F is unstable, the bulk phase of anhydrous [DMIm]F is quite stable. We then demonstrate the successful synthesis of the anhydrous [DMIm]F compound via the reaction between 1,3-dimethylimidazolium iodide and silver fluoride. Importantly, we find that anhydrous [DMIm]F possesses a high dissolution capability toward 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), although it is known that TATB is hardly dissolved in many common organic solvents. Our Born-Oppenheimer molecular dynamics (BOMD) simulations further show that the high dissolving ability of anhydrous [DMIm]F toward TATB can be attributed to the chemical reaction between the F- anion and the TATB molecules, which disrupts the strong hydrogen-bonding interaction among the TATB molecules. Alternatively, water molecules in hydrous [DMIm]F tend to form a hydration layer around the F- anion, thereby preventing F- from reacting with the TATB molecule. This result explains why TATB is barely dissolved in hydrous [DMIm]F.

Separation and Recovery of Refined Si from Al-Si Melt by Modified Czochralski Method.

Separation of refined silicon from Al-Si melt is still a puzzle for the solvent refining process, resulting in considerable waste of acid and silicon powder. A novel modified Czochralski method within the Al-Si alloy is proposed. After the modified Czochralski process, a large amount of refined Si particles was enriched around the seed crystalline Si and separated from the Al-Si melt. As for the Al-28%Si with the pulling rate of 0.001 mm/min, the recovery of refined Si in the pulled-up alloy (PUA) sample is 21.5%, an improvement of 22% compared with the theoretical value, which is much larger 1.99 times than that in the remained alloy (RA) sample. The content of impurities in the PUA is much less than that in the RA sample, which indicates that the modified Czochralski method is effective to improve the removal fraction of impurities. The apparent segregation coefficients of boron (B) and phosphorus (P) in the PUA and RA samples were evaluated. These results demonstrate that the modified Czochralski method for the alloy system is an effective way to enrich and separate refined silicon from the Al-Si melt, which provide a potential and clean production of solar grade silicon (SoG-Si) for the future industrial application.

Study on ultrasound-assisted oxidative desulfurization for crude oil.

The existence of sulfur compounds in crude oil will bring many problems such as corrosion, catalyst poisoning and pollution to the petroleum processing process. Therefore, how to reduce the sulfur content as much as possible in the process of crude oil processing has become an important research topic in the petroleum processing industry. In this paper, ultrasonic-oxidative desulfurization is studied. The effects of reaction temperature, reaction time, amount of oxidant and demulsifier on desulfurization rate are investigated. And the effect of oxidative desulfurization and single oxidative desulfurization under ultrasonic treatment are compared. It is found that the addition of ultrasonic treatment can enhance the desulfurization effect of desulfurizer, the desulfurization efficiency can be increased by about 10% under ultrasonic treatment (100 W, 70 kHz); ultrasonic wave plays an auxiliary role in the system, it can promote heterogeneous reactions, improve the activity of oxidants, and promote the degradation of macromolecular compounds. Finally, physical desulfurization, chemical desulfurization and biological desulfurization technologies are compared.

Direct access to multi-functionalized benzenes via [4 + 2] annulation of α-cyano-ß-methylenones and α,ß-unsaturated aldehydes.

An efficient [4 + 2] benzannulation of α-cyano-ß-methylenones and α,ß-unsaturated aldehydes was achieved under metal-free reaction conditions selectively delivering a wide range of polyfunctional benzenes in high yields respectively (up to 94% yield).

Hierarchical Ag/Bi2MoO6 hollow nanoboxes with high photocatalytic performance.

Well-ordered hierarchical Ag/Bi2MoO6 hollow nanoboxes are obtained through an artful hydrothermal method. Ag3PO4 nanocubes serve as growth templates and precursor sources of Ag. Ag3PO4 is reduced to Ag nanoparticles, which are dispersed on the nanosheet-built hierarchical Bi2MoO6 nanoboxes. With the investigation of intermediate products, the growth process of Ag/Bi2MoO6 is studied. Due to the hierarchical hollow structure and the introduction of Ag, the Ag/Bi2MoO6 nanoboxes exhibit enhanced visible-light absorption and photocatalytic performance compared to the pristine Bi2MoO6 microboxes.

Awakening Solar Hydrogen Evolution of MoS2 in Alkalescent Electrolyte through Doping with Co.

Transition metal dichalcogenides, especially MoS2 , have been regarded as promising cocatalysts for the hydrogen evolution reaction (HER) because of a near-zero Gibbs free energy for H+ absorption. However, the HER activity of MoS2 is profoundly restricted by acidic media. Co-doped MoS2 (Co-MoS2 ) nanosheets are found to enable the highly efficient solar H2 evolution of CdS nanowires (NWs) in alkalescent electrolyte. The content of Co in MoS2 is optimized to 2.8 % and the Co-MoS2 content in Co-MoS2 /CdS NWs hybrids is 2.5 wt %; the optimized Co-MoS2 /CdS NWs shows a high H2 evolution rate of 14.22 mmol g-1 h-1 and 71 % apparent quantum efficiency in the Na2 SO3 electrolyte. Moreover, the H2 generation enabled by the Co-MoS2 cocatalyst can exhibit universality in alkalescent electrolytes, such as triethanolamine (TEA) and disodium ethylenediaminetetraacetic acid (EDTA), exhibiting greater photocatalytic H2 generation than Pt/CdS. The design of Co-MoS2 /CdS sheds light on the development of highly efficient low-cost photocatalysts for solar H2 generation from water reduction.

Fabrication of Bi2MoO6/ZnO Heterojunction Nanosheet Array with High Photoelectrochemical Property.

Herein, we demonstrate the synthesis of Bi2MoO6 nanosheet array followed with in-situ electrodepositing ZnO layer, resulting in Bi2MoO6/ZnO heterojunction nanosheet array. The thickness of nanoparticle-based ZnO layer on the surface of Bi2MoO6 nanosheets can be rational controlled by regulating the electrodepositing time. The combination of oriented Bi2MoO6 nanosheet array and ZnO layer could not only enhance the conductivity and surface area but also facilitate the charge separation. As expected, the heterojunction electrode yields a photocurrent density of 430 µA/cm² at 0.8 VSCE, which is much higher than that of pristine Bi2MoO6 and ZnO nanosheet array.