Research on the wetting mechanism of coal dust by different surfactants: combination of experimental characterization and molecular dynamics simulation.

Surfactants can reduce the surface tension of water and improve the efficiency of spray dust reduction, but the synergistic mechanism of composite surfactant solutions wetting coal dust remains unclear. In this study, sodium dodecyl sulfonate (SDDS)/sodium dodecylbenzene sulfonate (SDBS) solution and SDDS/primary alcohol ethoxylate (AEO-9) solution were prepared to wet three types of coal with different deterioration degrees. The surface tension, contact angle, and functional group composition were measured. The results show that SDDS/AEO-9 solution had lower surface tension and critical micelle concentration than SDDS/SDBS solution at the same mixing ratio. When the ratio of SDDS: SDBS was 2:1, it had the best wetting effect on coal dust. It is found that for SDDS/SDBS solutions, aliphatic hydrocarbons and surface tension have a positive correlation with the contact angle, and hydroxyl groups have a negative correlation with the contact angle. For SDDS/AEO-9 solution, only the surface tension and contact angle show a significant linear relationship. The main factors that affect the wetting change with the combination of surfactants. AEO-9 has an electrostatic shielding effect on SDDS, while SDBS increases the electrostatic repulsion between SDDS solution and electronegative functional groups of coal. The synergism among these surfactants plays an important role in the process of wetting coal.

Preparation and characterization of magnetic modified bone charcoal for removing Cu2+ ions from industrial and mining wastewater.

Heavy metal water pollution is an urgent global problem to be addressed. Copper ions are common toxic heavy metal pollutants in wastewater. In order to remove the excessive copper ions in wastewater, in this study, chicken bone charcoal was modified by sodium dodecyl sulfonate and combined with magnetic nanoparticles prepared with ferric chloride hexahydrate and ferrous sulfate heptahydrate to produce a high efficiency adsorbent. The characterization of the magnetically modified bone charcoal was analyzed by scanning electron microscopy, surface and porosity analyses, FTIR and thermogravimetric analysis. The optimal adsorption conditions of magnetically modified bone charcoal for Cu2+ were obtained through batch experiments. The highest removal rate and adsorption capacity of Cu2+ was 99.98% and 15.057 mg/g, respectively, when the pH was 3.0, adsorbent dosage was 0.2 g, initial concentration of the Cu2+ solution was 50 mg/L, and temperature was 25 °C. The adsorption process fitted well with the Langmuir isotherm and the pseudo-second-order kinetic model. The regeneration experiment indicated that M-SDS-BC-500 maintained a high removal rate after five repetitions. The results suggest that the adsorbent has wide application prospects.

Synthesis and Performance of a Novel High-Efficiency Coal Dust Suppressant Based on Self-Healing Gel.

During transportation and storage, coal produces a lot of dust, which pollutes the environment and threatens the occupational health of workers. Although many dust suppressants have been developed for dust prevention at work, the implementation of current dust suppressants does not meet the requirements due to various factors such as the hydrophobic nature of coal dust and a harsh external environment. In this study, hydroxyethyl cellulose, acrylamide, and stearyl methyl acrylate were used for micelle polymerization to prepare an environmental protection dust suppressant for preventing dust during coal storage and transportation. The microstructure of the reactants and the products was analyzed by Fourier transform infrared as well as scanning electron microscopy. The strength and self-healing tensile properties of binder coal were taken as indicators to determine the best synthesis dosage and conditions. The dust suppressant particles are applied to the dust accumulation area, contact each other after water absorption, and swell to complete the healing, to achieve the purpose of dust control. The evaluation of the relevant properties of the dust suppressant reveals that the dust suppressant has a good covering effect, an excellent dust suppressant performance, and a significant dust suppression action.

Hydrogenation of Functionalized Nitroarenes Catalyzed by Single-Phase Pyrite FeS2 Nanoparticles on N,S-Codoped Porous Carbon.

Catalytic hydrogenation of nitroarenes is an industrially very important and environmentally friendly process for the production of anilines; however, highly chemoselective reduction of nitroarenes decorated with one or more reducible groups in a nitroarene molecule remains a challenge. Herein, a novel hybrid non-noble iron-based nanocatalyst (named as FeS2 /NSC) was developed, which was prepared from biomass as C and N source together with inexpensive Fe(NO3 )3 as Fe source through high-temperature pyrolysis in a straightforward and cost-effective procedure. Comprehensive characterization revealed that single-phase pyrite FeS2 nanoparticles with precisely defined composition and uniform size were homogeneously dispersed on N,S-codoped porous carbon with large specific surface area, hierarchical porous channels, and high pore volume. The resultant catalyst FeS2 /NSC demonstrated good catalytic activity for hydrogenation of functionalized nitroarenes with good tolerance of various functional groups in water as a sustainable and green solvent. Compared with bulk pyrite FeS2 and other non-noble metal-based heterogeneous catalysts reported in the literature, a remarkably enhanced activity was observed under mild reaction conditions. More importantly, FeS2 /NSC displayed exclusive chemoselectivity for the reduction of nitro groups for nitroarenes bearing varying readily reducible groups.

One-pot selective N-formylation of nitroarenes to formamides catalyzed by core-shell structured cobalt nanoparticles.

One-pot direct N-formylation of readily available nitroarenes with ammonium formate catalyzed by core-shell structured cobalt nanoparticles has been developed. A broad set of nitroarenes was successfully converted to their corresponding formamides in good to high yields with various functional group tolerance. This heterogeneous catalyst can be easily removed from the reaction medium and can be reused several times without a significant loss of reaction efficiency.