Plasma Co-Polymerization of HMDSO and Limonene with an Atmospheric Pressure Plasma Jet

Plasma co-polymers (co-p) were deposited with an atmospheric pressure plasma jet (APPJ) using a precursor mixture containing hexamethyldisiloxane (HMDSO) and limonene. A coating with fragments from both precursors and with siloxane, carbonyl and nitrogen functional groups was deposited. The flow rate of limonene was found to be an important parameter for plasma co-polymerization to tune the formation and structure of the functional groups. The FTIR and XPS analysis indicates that with increasing flow rate of limonene a higher proportion of carbon is bound to silicon. This is related to a stronger incorporation of fragments from limonene into the siloxane network and a weaker fragmentation of HMDSO. The formation mechanism of the nitroxide and carboxyl groups can be mainly differentiated into in-plasma and post-plasma reactions, respectively.

Hydrodynamics and mass transfer investigations in a biphasic plasma reactor

This work aims to investigate the radical mechanism responsible for the degradation of a highly soluble pollutant in water. The AG25 dye was chosen as substrate and the GAD-Spray as biphasic reactor to treat it remotely. The study is conducted through experiments and simulations using Comsol Multiphysics-chemical engineering module. The Hydrodynamics coupled with the plasma-reaction has demonstrated that a low mass transfer in the droplet favorites the removal of the pollutant. It indicates that the plasma-reactions take place at the stagnant liquid film are far from the bulk of the droplet. Numerical modeling fitted by the conversion rate of the reagent has shown that the peroxynitrous acid HOONO (PON) is responsible for the degradation of AG25 in water. Consequently, and according different kinetic mechanisms, a radical mechanism has been predicted based on this deduction. The removal and the degradation rates were of 88 and 83% respectively during 90 min after the plasma exposure. The results of simulations showed a significant agreement between the calculated and the real removal rate of AG25. Through this study, it can be confirmed that GAD-spray-tower plasma reactor is efficient to eliminate and degrade remotely a very soluble pollutant through the HOONO (PON) plasma long-lived species.

Effects of plasma kinetic modeling on performance characterization of plasma actuators for active flow control

This work focuses on the development of a multiscale computational fluid dynamics (CFD) simulation framework for the investigation of the effects of plasma kinetics on the performance of a microscale dielectric barrier discharge plasma actuator (DBD-PA). To this purpose, DBD-PA multi-scale dual-step modelling approach has been implemented, by considering plasma chemistry and flow dynamic. At first, a microscopic plasma model based on the air plasma kinetics has been defined and plasma reactions have been simulated in zero-dimensional computations in order to evaluate the charge density. At this aim computations have been performed using the toolbox ZDPlasKin, which solves plasma reactions by means of Bolsig+ solver. An alternate current (AC) electrical feeding has been assumed: in particular, the sinusoidal voltage amplitude and the frequency have been fixed at 5 kV and 1 kHz at atmospheric pressure and 300 K temperature in quiescent environment. The predictal charge density has been in a macroscopic plasma-fluid model based on Suzen Dual Potential Model (DPM), which has implemented in the computation fluid dynamic CFD code OpenFoam. Hence, as second step, 2D-CFD simulations of the electro-hydrodynamic body forces induced by the microscale DBDPA have been performed, based on the previously predicted charge densities at the operating conditions. Quiescent flow over a dielectric barrier discharge actuator has been simulated using the plasma-fluid model. The novel modelling framework has been validated with experimental data.

Solvent-free synthesis of morphology-controllable nickel sulfides via one-pot plasma reactions for high-performance lithium-ion batteries

Morphology-controllable nickel sulfides are synthesized via a solvent-free one-pot plasma reaction as Li-ion battery cathodes.