Highly efficient and selectivity removal of heavy metal ions using single-layer NaxKyMnO2 nanosheet: A combination of experimental and theoretical study.

Manganese oxides (MnO2) are widely applied in heavy metal ions removal due to their low-cost, environmental-friendly and biocompatibility. However, the adsorption capacity of MnO2 need to be further improved to satisfy the demand of practical application. Herein, a highly dispersed single layer NaxKyMnO2 nanosheet was synthesized by a facile wet-chemical method with sodium dodecyl sulfonate as surfactant. The high surface specific area, excellent dispersibility and abundant oxygen vacancies endowed NaxKyMnO2 nanosheets with potential in heavy metal ions adsorption. The adsorption experiments results showed that NaxKyMnO2 nanosheets possessed high efficiency and selectivity towards lead ion (Pb2+) with a high adsorption capacity of 2091.8 µmol g-1. The NaxKyMnO2 also showed an excellent reusability with the removal rate of 95.4% for Pb2+ even after five cycles. Moreover, both the theoretical calculation and experimental data illustrated that the single layer NaxKyMnO2 nanosheets possess high selectivity to Pb2+ adsorption.

Facile synthesis of 2Dα-MnO2nanosheets for the removal of heavy metal ions.

Removal of heavy metal ions (HMIs) has attracted great attentions due to the fact that they have serious effect on environment and human beings. Manganese oxide (MnO2) was widely used as absorbent for the HMIs removal on account of its low-cost, eco-friendly and biocompatibility. The modification of morphological and structure is recognized as the effective route to improve the adsorption capacity. In this work, 2Dα-MnO2nanosheets were synthesized by hydrothermal method with Al3+additive. With the merits of high specific surface area, high dispersity in aqueous solution and abundant surface defects, 2Dα-MnO2nanosheets exhibited excellent HMIs adsorption performance. The maximum adsorption capacity of 2Dα-MnO2nanosheets reached 1.604 mmol g-1(Pb2+) and 0.813 mmol g-1(Cd2+), respectively and can maintain stable after five cycles. Besides, the established adsorption kinetics fitted well with pseudo-second-order adsorption kinetics model. Based on the above results, 2Dα-MnO2is efficient for the removal of HMIs and possesses remarkable practical application potential.

Synthesis and dielectric properties of the eco-friendly insulating gas thiazyl trifluoride.

Sulfur hexafluoride (SF6), which is known as a superior electrically insulating and arc-quenching medium, plays a decisive role in the modern transmission and distribution network of electric energy, especially in high-voltage power networks. However, the ever-increasing usage of SF6 also leads to the continuous escalation of atmospheric SF6 levels, which is considered to be the main cause of the greenhouse effect. To decrease this environmental impact, eco-friendly alternatives to SF6 have been researched for decades. To date, no significant success has been made regarding replacement gases for transmission networks. Some potential alternatives have comparatively lower global warming potential (GWP) but involve technical trade-offs. Thiazyl trifluoride, which has some excellent chemical and electric properties, is a novel substitution candidate for SF6. In this article, an efficient synthetic route starting from sulfur monochloride and followed by ammonization and fluorination was proposed. The structures of the intermediates and the target products were determined by X-ray diffraction (XRD), infrared spectroscopy (IR), and gas chromatography-mass spectrometry (GC-MS). The effects of some determining factors on the yield and purity, including the molar ratio of the reactants, recrystallization conditions and condensation temperature, were also investigated. The results showed that the overall yield of thiazyl trifluoride was approximately 25%, while the purity could be up to 90.6% under optimal conditions.

Electrochemical degradation of dye on TiO2 nanotube array constructed anode.

A high oxygen evolution potential (2.6V) and conductivity of Ti/TiO2 NTs/Ta2O5-PbO2 anode was fabricated by mixed metal oxide. A well-aligned TiO2 nanotubes was successfully prepared by using 1-butyl-3-methylimidazolium tetrafluoroborate as the electrolyte. The surface structure of anodes were characterized by scanning electron microscope, X-ray diffraction and energy dispersive X-ray spectroscopy. During the electrochemical degradation experiments, the effects of different anodes, current density, initial pH value and concentration were discussed. The results showed that co-doped Ta2O5 coating is an effective method to improve the surface morphology and the electrochemical characterization of Ti/TiO2 NTs/PbO2. At the initial pH value of 3 and current density of 12 mA cm-2, the removal rates of Acid Orange 7 and total organic carbon with Ti/TiO2 NTs/Ta2O5-PbO2 anode were almost 100% and 98.3%. Comparing with Ti/PbO2 anode at the same charge consumption (3 A h L-1), the instantaneous current efficiency of the Ti/TiO2 NTs/Ta2O5-PbO2 anode and Ti/TiO2 NTs/PbO2 anode increased by 40.0% and 27.1%, respectively. The highest rate of k.OH on Ti/TiO2 NTs/Ta2O5-PbO2 anode was 12.4 µmol (L min)-1. The organic dyes are oxidized into CO2 and H2O by .OH radical. The reaction process and mechanism during the electrochemical degradation were discussed.

Novel and efficient synthesis of insulating gas- heptafluoroisobutyronitrile from hexafluoropropylene.

A novel and efficient preparation route of insulating gas-heptafluoroisobutyronitrile was developed. The synthetic route involved halogen-exchange fluorination, decomposition of bis-(perfluoroisopropyl) ketone and dehydration reaction. Overall, the desired compound was produced without the use of extremely toxic and expensive substances. Structures of the as-obtained products were determined by 19F NMR, 13C NMR, IR and GC-MS. The effects of several variables on reaction yield including nature of potassium fluoride, the catalyst dosage, temperature, solvent and molar ratio of raw materials were all investigated. The results indicated that the total yield of heptafluoroisobutyronitrile could reach 42% from original materials under optimal conditions and the mechanism of the reaction was proposed.

A novel and efficient synthetic route to perfluoroisobutyronitrile from perfluoroisobutyryl acid.

A novel synthetic route to perfluoroisobutyronitrile from perfluoroisobutyryl acid which has mild conditions and low toxicity is described. This study introduces detailed synthetic protocols and characterization including GC-MS, 13C NMR and 19F NMR spectroscopy of perfluoroisobutyryl acid, perfluoroisobutyryl chloride, perfluoroisobutyl amide and perfluoroisobutyronitrile. Besides, this route is superior to the established patent and shows potential application in high voltage electrical equipment.

Large-Scale Synthesis of Metal-Ion-Doped Manganese Dioxide for Enhanced Electrochemical Performance.

One-dimensional (1D) MnO2 was widely applied in areas of enzyme biosensors, industrial sieves, and energy storage materials owing to its excellent thermal, optical, magnetic, and chemical features. However, its practical application into energy storage devices is often hindered by the bad electronic conductivity (from 10(-5) to 10(-6) S cm(-1)). As is widely known, doping with hetero elements is an efficient way to enhance the electronic conductivity of metal oxides. Herein, a novel and simple molten-salt method is developed to achieve a large-scale preparation of 1D MnO2 nanowires. Such an approach also realizes the easy tuning of electrical properties through doping with different transition metal ions. On the basis of first-principle calculation as well as four-probe measurement, we determined that the conductivity of the doped MnO2 nanowires can be promoted efficiently by utilizing such protocol. Meanwhile, a possible doping route is discussed in detail. As a result, a superior electrochemical performance can be observed in such metal ions (M(+))-doped nanowires. Such high-quality M(+)-doped MnO2 nanowires can satisfy a broad range of application needs beyond the electrochemical capacitors.