Water can be activated by applying plasma to water, for instance, by creating plasma inside (bubbles in) the water, or along a water surface. Plasma-activated water (PAW) typically contains hydrogen peroxide, nitrates, nitrites, and peroxynitrite, and typically has a pH ranging from 2 to 4. The components of PAW and the low pH have proven synergistic antimicrobial effects against bacteria, biofilms, yeasts, and other microorganisms. This paper describes a power modulator and a plasma reactor system for high-yield production of PAW at high production rate. A compact and solid-state dual resonant system has been realized and successfully demonstrated for industrial PAW production. The system generates up to 80-kV (theoretical 120 kV is possible) dual-resonant high-voltage pulses with an oscillation frequency up to 2 MHz, pulse repetition rate > 20 kHz, and an average power of 800-W continuous. In addition to the power modulator, the PAW production system consists of a transient arc plasma reactor and a loop system. Depending on the application, the system is able to activate 10–100 L/h. The disinfecting properties of the PAW production system have been verified by experiments on the reduction of Staphylococcus Epidermidis. Directly after its production, the log reduction of S. Epidermidis can be as high as >8 log. During a period of at least 40 min after its production, the PAW has “mild” disinfecting properties, being able to deactivate S. Epidermidis by 3–4.1 log.

Power modulator for high-yield production of plasma-activated-water

Self-powered triboelectric nanogenerator driven nanowires electrode array system for the urine sterilization

The output power of the pulsed power supply (PPS) pulsates at the pulse repetition frequency (PRF) of pulse load. The pulsating power will result in a large bus voltage ripple. To balance the instantaneous power difference, a single or dual-inductance active storage unit (ASU) is usually connected in parallel with the output terminal of the PPS. Poor compensating current tracking accuracy of ASU will lead to the output current of PPS suffered from serious current spikes, which affects the stability of the bus voltage. A hysteresis current control (HCC) is proposed to achieve an excellent pulse current compensation performance. Compared with the current mode control (CMC), the small-signal modeling of dual-inductance with HCC is established to illustrate good compensation performance. Besides, a valley voltage loop is introduced to regulate the storage capacitor voltage in dual-inductance ASU to reduce the power loss at any pulse duty cycle. An experimental prototype is built to verify the spikes in output current can be eliminated effectively, the bus voltage keeps smooth and stable, and the output capacitor of the per-stage DC/DC converter is reduced significantly.

Stability Improvement of Pulse Power Supply With Dual-Inductance Active Storage Unit Using Hysteresis Current Control

Under air flotation conditions, the effect of an electric field (EF) to the interfacial properties of hydrophobic particles in salt solution was investigated by using molecular dynamics simulation. The varieties of thickness of the hydrophobic layer on the surface of the hydrophobic particles, radial distribution function of Na+, diffusivity of CO2 and H2O, residence time of H2O in the solvent shell of Na+, and the distribution of CO2 near the graphene caused by the applied EF in different NaCl systems were calculated, and all those results were compared with those where there is no EF applied. The results reveal that the thickness of the hydrophobic layer near the hydrophobic particles is decreased under an EF. The coordination number and residence time of H2O in the solvent shell of Na+ are also decreased, which indicates that the restraint of Na+ on surrounding H2O is weakened, and the H2O molecules are more mobile. Under an external EF, the diffusion coefficient of CO2 and H2O is increased, and the quantity of CO2 near the surface of graphene is decreased according to the numerical results of the radial distribution of graphene-CO2. All the results indicate that the EF will decrease the thickness of the hydrophobic layer near hydrophobic particles, which can therefore weaken the adsorption between the hydrophobic particles and the gas molecules. The simulation results in the present study can provide theoretical support for brine mineral flotation under an external EF.

Effect of an Electric Field on Surface Properties of Hydrophobic Particles during a Flotation Process in Salt Water.

FIELD: radio engineering, communication. SUBSTANCE: high-voltage pulse generator has a dc high-voltage source, electrodes lying on both sides of a flat dielectric barrier which is capable of rotating; a flat electrode is tightly placed on the entire surface of one side of the dielectric barrier with possibility of rotating together with the barrier, connected to one terminal of the dc voltage source; a fixed electrode is tightly placed on part of the surface of the opposite side of the dielectric barrier with possibility of sliding on said surface, the fixed electrode being connected to the same terminal of the dc voltage source. Another fixed electrode is placed diametrically opposite on the same side of the barrier with spacing, the fixed electrode being connected the other terminal of the voltage source through a load. EFFECT: obtaining high-voltage pulses of nanosecond duration and high repetition frequency. 2 cl

High-voltage pulse generator

Water treatment is one of the most important issues for all walks of life around the world. Different from the conventional water treatment technology, the advanced power electronic pulse technology has unique features and advantages for the modern water treatment. Unfortunately, there is no literature reported to describe them in a comprehensive and systematic way. To fill this gap, an overview of modern power electronic pulse generators (PPGs) for water treatment is presented. This article, for the first time, classifies the different types of PPGs from the viewpoint of pulse formation. Each of them is discussed, and the advantages and disadvantages are compared and summarized. Aside from that, this article presents the development and trend of the pulse generators suitable for the specified water treatment processes such as electrolysis, sterilization, and discharge degradation. Finally, a list of more than 100 relevant technical papers is also appended for a quick reference.

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Dongpo Zheng

Papers

Power Electronic Pulse Generators for Water Treatment Application: A Review