Plasmas interacting with organic liquids can lead to novel synthetic processes that are not feasible with conventional vacuum systems due to vapor pressure limitations. Of particular interest are processes that eliminate the generation of waste-streams. Here we show that He+O2 plasma can drive the epoxidation of alkenes in solution, in a process that generates epoxides without oxidant waste-streams, runs at room temperature and atmospheric pressure, and requires no catalyst. The reactions between different reactive oxygen species generated in the plasma and the target alkene, trans-stilbene in this study, have been identified and optimization of the plasma conditions within the constraints of the current experimental setup have led to yields of ~70%, which are of preparative interest.

The emerging field of atmospheric pressure plasmas (APPs) for treatment of various solutions and suspensions has led to a variety of plasma reactors and power sources. This article reports on the design, characterisation and modelling of a novel plasma-microbubble reactor that forms a dielectric barrier discharge (DBD) at the gas-liquid interface to facilitate the transfer of short-lived highly reactive species from the gas plasma into the liquid phase. The use of microbubbles enabled efficient dispersion of long-lived reactive species in the liquid and UVC-induced oxidation reactions are triggered by the plasma radiation at the gas-liquid interface. A numerical model was developed to understand the dynamics of the reactor, and the model was validated using experimental measurements. Fluid velocities in the riser region of the reactor were found to be an order of magnitude higher for smaller bubbles (~500 µm diameter) than for larger bubbles (~2500 µm diameter); hence provided well-mixed conditions for treatment. In addition to other reactive oxygen species (ROS) and reactive nitrogen species (RNS), ���� Interfacial area m-1 Dynamic liquid velocity Pa s Volume m 3 Molecular weight g mol-1 1.0 Introduction Ozone has been established as an excellent oxidising agent and used on industrial scale for water treatment worldwide (Loeb et al., 2012). Its high oxidation potential of 2.07 V is superior to that of chlorine (1.36 V), and

Electrokinetic transport of a charged dye within a free liquid film stabilized by a cationic surfactant, trimethyl-(tetradecyl)ammonium bromide, subjected to an external electric field was investigated. Confocal laser scanning microscopy was used to visualize fluorescein isothiocyanate (FITC) separation within the stabilized liquid film. Numerical simulations were performed using the finite element method to model the dynamics of charged dye separation fronts observed in the experiments. Because of the electrochemical reactions at the electrodes, significant spatial and temporal pH changes were observed within the liquid film. These local pH changes could affect the local zeta potential at the gas−liquid and solid−liquid film boundaries; hence, the flow field was found to be highly dynamic and complex. The charged dye (FITC) used in the experiments is pH-sensitive, and therefore, electrophoresis of the dye also depended on the local pH. The pH and the electroosmotic flow field predicted from the numerical simulations were useful for understanding charged dye separation near both the anode and the cathode.

Understanding the production mechanisms of ozone and other reactive species in atmospheric pressure dielectric barrier discharges (DBDs) has become increasingly important for the optimization and commercial success of these plasma devices in emerging applications, such as plasma medicine, plasma agriculture, and plasma catalysis. In many of these applications, input power modulation is exploited as a means to maintain a low gas temperature. Although the chemical pathways leading to ozone production/destruction and their strong temperature dependence are relatively well understood, the effect of the on-time duration on the performance of these modulated DBDs remains largely unexplored. In this study, we use electrical and optical diagnostics, as well as computational methods, to assess the performance of a modulated DBD device. The well-established Lissajous method for measuring the power delivered to the discharge is not suitable for modulated DBDs because the transients generated at the beginning of each pulse become increasingly important in short on-time modulated plasmas. It is shown that for the same input power and modulation duty-cycle, shorter on-time pulses result in significantly enhanced ozone production, despite their operation at slightly higher temperatures. The key underpinning mechanism that causes this counter-intuitive observation is the more efficient net generation rate of ozone during the plasma on-time due to the lower accumulation of NO2 in the discharge volume.

Utilizing CO 2 in an electro-chemical process and synthesizing value-added chemicals are amongst the few viable and scalable pathways in carbon capture and utilization technologies. CO 2 electro-reduction is also counted as one of the main options entailing less fossil fuel consumption and as a future electrical energy storage strategy. The current study aims at developing a new electrochemical platform to produce low-carbon e-biofuel through multifunctional electrosynthesis and integrated covalorisation of biomass feedstocks with captured CO 2. In this approach, CO 2 is reduced at the cathode to produce drop-in fuels (e.g., methanol) while value-added chemicals (e.g., selective oxidation of alcohols, aldehydes, carboxylic acids and amines/amides) are produced at the anode. In this work, a numerical model of a continuous-flow design considering various anodic and cathodic reactions was built to determine the most techno-economically feasible configurations from the aspects of energy efficiency, environment impact and economical values. The reactor design was then optimized via parametric analysis.

Procedures used in Electrokinetic investigations of surfactant-laden interfaces, liquid films and foam system. Cocis (2018),

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