Plasma cutting arc characteristics are investigated for different turbulence models, i.e. the Reynolds stress model (RSM), the k–ϵ model and its variants, the renormalization group (RNG) k–ϵ model, the RNG k–ϵ model taking into account the low Reynolds number effect and the realizable k–ϵ model. The results of the RSM and the RNG k–ϵ model taking into account the low Reynolds number effect are in reasonable agreement with experiment. They both predict very close voltage, shock wave location and temperature variation along the axis to experiment. On the other hand, the other three models overestimate the turbulence effects and predict much lower velocity and temperature, especially the standard k–ϵ model, which predicts that the temperature is about 10 000 K lower than the experiment in certain plasma jet regions.
Surface amino group
regulation and structural engineering of graphitic
carbon nitride (g-CN) for better catalytic activity have increasingly
become a focus of academia and industry. In this work, the ammonia
plasma produced by a microwave surface wave plasma generator was developed
as a facile source to achieve fast, controllable surface modification,
and structural engineering of g-CN by ultrafast plasma treatment in
minutes, thus enhancing photocatalytic performance of g-CN. The morphology,
surface hydrophilicity, optical absorption properties, and states
of C–N bonds were investigated to determine the effect of plasma
immersion modification on the g-CN catalyst. The structure and photoelectric
features of the plasma-modified samples were characterized by X-ray
diffractometry, Fourier transform infrared spectroscopy, X-ray photoelectron
spectroscopy, and electrochemical impedance spectroscopy. The results
indicate that the ammonia plasma-treated g-CN–NH3 exhibits an ultrathin nanosheet structure, enriched amino groups,
and an ideal molecular structure, a narrower band gap (2.35 eV), extended
light-harvesting edges (560 nm), and enhanced electron transport ability.
The remarkably enhanced photocatalytic activity demonstrated in the
photoreduction and detoxification of hexavalent chromium (Cr(VI))
can be ascribed to the optimization of the structural and photoelectric
properties induced by the unique ammonia plasma treatment. The effective
and ultrafast approach developed in this work is promising in the
surface amino group regulation and structural engineering of various
functional materials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.