Experimental and simulation studies on the improvement of coal dust pollution by an aqueous solution of sodium α-alkenylsulfonate and amino acid-based surfactants.

The use of surfactants is crucial for the prevention and control of coal dust pollution in coal mining operation areas, yet there still exist many challenges in the control of coal dust pollution. In this paper, the green biomass-based amino acid surfactant sodium myristoyl glutamate (SMG) and the anionic surfactant sodium α-alkenyl sulfonate (AOS) were selected to investigate the improvement of coal dust wettability by single and binary solutions from the macroscopic and microscopic perspectives. Molecular simulations were used to reveal the microscopic mechanism of the wettability of coal dust by the different solutions. Experimental measurements showed that the contact angle of the AOS + SMG aqueous solution was as low as 13.8° on a coal surface. Coating the coal dust with the AOS + SMG solution reduced the surface tension by 12.02% compared to coating the coal with a single component solution. Additionally, the use of the binary AOS + SMG solution increased the hydrophilic group content in the coating by 11.77% compared to a single component solution, and the linkage between hydrophilic groups was enhanced, which pulls the water molecules to wet the coal dust. These research results should provide a new way to promote more environmentally friendly coal dust pollution control technology.

WSe2-loaded co-catalysts Cu3P and CNTs: Improving photocatalytic hydrogen precipitation and photocatalytic memory performance.

Photocatalytic decomposition of water for hydrogen production using semiconductor photocatalysts in visible light is considered one of the most promising environmentally friendly ways to produce hydrogen. In this work, the calcination method was adopted to prepare an efficient Cu3P/WSe2/CNTs composite photocatalysts. Cu3P and carbon nanotubes (CNTs) were used as co-catalysts to reduce the composite rate of the photogenerated supports of the photocatalyst. The unique metallic properties of Cu3P as a transition metal phosphide makes it a cost-effective alternative to noble metal co-catalysts. CNTs can serve both as co-catalysts and as a suitable carrier to accelerate the transfer rate of photogenerated electrons. The experimental results showed that the Cu3P/WSe2/CNTs composite photocatalyst exhibited stronger activities in photocatalytic hydrogen production than pure WSe2. In particular, a higher quantum yield of 30.27% at the range 400-700 nm was achieved with a loading of 4% CNTs, a calcination temperature of 300 °C and a calcination time of 2.0 h. In contrast, the quantum yield of pure WSe2 was only 14.01%. The highest hydrogen production rate was 6.987 mL in 4.0 h, and the average hydrogen production rate was 712.985 µmol·h-1g-1, which was 2.39 times higher than that of pure WSe2.The catalytic memory performance of the composite samples was also examined. The results indicated that the best catalytic memory performance was achieved under the pre-illumination condition of 5.0 h. The amount of hydrogen produced under darkness for 4.0 h was up to 4.934 mL and the average hydrogen production rate was 503.454 µmol·h-1g-1. The average hydrogen production rate was 1.69 times higher than the average hydrogen production rate of pure WSe2 under light conditions.

Does microplastic really represent a threat? A review of the atmospheric contamination sources and potential impacts.

Microplastics (MPs) are regarded as one of the major atmospheric contaminants that have gained wide attention across the globe in the current dispensation. Airborne MPs have been collected in atmospheric fallouts, in indoor and outdoor air as well as along roadways and indoor dust. The most dominating constituent shapes and forms of identified airborne MPs are fibers and synthetic textiles, respectively. With the breathing mechanism as a spontaneous practice for survival, the inhalation of airborne MPs is an inevitable deal. The level of toxicity of MPs to organisms stems from its physiochemical speciation. The smaller size and almost weightless nature make it possible to suspend in the atmosphere and be inhaled and create potential health problems. Nonetheless, the data available concerning the presence of airborne MPs and its environmental and human health impacts is limited. In this review, we extensively discuss the rigorous and suitable methodologies adopted for the analysis of airborne MPs in previous studies. The characteristics and sources of airborne MPs, the potential health impacts on humans, and some mitigating measures have also been discussed thoroughly.