RESUMEN

For dry reforming of methane, the active metal particle size of the catalyst has a significant effect on both the reaction activity and the resistance to carbon deposition. In this study, nickel particles of different sizes (Ni13, Ni25, and Ni37) supported on the MgO(100) slab are used to study the mechanism of CH4 activation and carbon growth based on DFT theoretical calculations. According to the results, the energy of adsorption for reaction intermediates changes depending on the size of the active metal. The adsorption process of CH3, CH2, CH and C on Ni25/MgO has a maximum exothermic value. Furthermore, the energy barriers of CH4 four-step dehydrogenation are lowest on Ni25/MgO during the CH4 activation process. The growth process of carbon deposition on the catalysts is also investigated in this work. The results indicate that the growth of carbon from C5 to C6 is difficult to proceed on Ni13/MgO due to size and active site limitation. Additionally, with an increase in particle size of the active metal, the absolute value of growth energy and average carbon binding energy of Cn increase on both Ni25/MgO and Ni37/MgO. It is proved that smaller particle size presents better resistance to carbon deposition. In the studied size range, Ni25/MgO is demonstrated to have greater catalytic activity and better resistance to carbon deposition.

RESUMEN

This work is a premier demonstrating the technical feasibility of remediation of PAHs-contaminated soil by g-C3N4/Fe3O4. g-C3N4/Fe3O4 has been synthesized by typical two steps involved the synthesis of g-C3N4 and the subsequent in situ co-precipitation of Fe3O4 nanoparticles. g-C3N4/Fe3O4 exhibits excellent visible-light-driven photocatalytic activity for the degradation of phenanthrene in soil at circumneutral pH. The enhanced photocatalytic activity of g-C3N4/Fe3O4 should be attributed to the hybrid of Fe3O4 and g-C3N4 and appropriate Fe3O4 loading amount can improve not only the visible light absorption ability but also the separation of the photo-induced electron-hole pairs. The phytotoxicity evaluation, a preliminary ecological risk assess, was conducted on lettuce cultivation experiments. Base on the data of growth indexes including seeds germination percentage, root length, leaf length, and fresh weight of lettuce, it can be conclude that photocatalytic oxidation based on g-C3N4/Fe3O4 provide a mild oxidation process to degrade the phenanthrene from contaminated soil and there is no negative impact on the growth of lettuce. This work definitely demonstrates that this soil remediation method based on g-C3N4/Fe3O4 is technologically feasible and has immense potential in the application of remediation of organic pollutant contaminated soils.

Asunto(s)

RESUMEN

Multiple state-of-the-art techniques, such as multi-dimensional micro-imaging, fast multi-channel micro-spetrophotometry, and dynamic micro-imaging analysis, were used to dynamically investigate various effects of cell under the 900 MHz electromagnetic radiation. Cell changes in shape, size, and parameters of Hb absorption spectrum under different power density electromagnetic waves radiation were presented in this article. Experimental results indicated that the isolated human red blood cells (RBCs) do not have obviously real-time responses to the ultra-low density (15 µW/cm(2), 31 µW/cm(2)) electromagnetic wave radiation when the radiation time is not more than 30 min; however, the cells do have significant reactions in shape, size, and the like, to the electromagnetic waves radiation with power densities of 1 mW/cm(2) and 5 mW/cm(2). The data also reveal the possible influences and statistical relationships among living human cell functions, radiation amount, and exposure time with high-frequency electromagnetic waves. The results of this study may be significant on protection of human being and other living organisms against possible radiation affections of the high-frequency electromagnetic waves.

Asunto(s)