Microplasma Synthesis of Antibacterial Active Silver Nanoparticles in Sodium Polyacrylate Solutions

The great demand for functional, particularly biologically active, metal nanoparticles has led to the search for technologically effective, green, and controlled methods of synthesizing these metal nanoparticles. Plasma glow discharge is one of the most promising techniques in this direction. The results of studies based on the synthesis of colloidal solutions of stabilized silver nanoparticles (AgNPs) by the microplasma method in solutions of a nontoxic surfactant sodium polyacrylate (NaPA) are presented. It is shown that AgNPs with a size of 2–20 nm are formed in solutions of 0.05–0.2 mmol⋅L−1 AgNO3 + 5 g⋅L−1 NaPA at U = 250 V by tungsten cathode plasma glow discharge. At 20°C, the yellow solutions are formed with λmax ≈ 410 nm, which are stable during long-term storage. It was found that the process of AgNPs formation corresponds to a first-order reaction on the AgNO3 concentration. Its value has little effect on the geometry of nanoparticles, so the Ag(I) concentration in solution is one of the main factors influencing the rate of microplasma synthesis of AgNPs. The antimicrobial activity of synthesized AgNPs solutions against strains of Escherichia coli, Staphylococcus aureus, and Candida albicans was established.

Design of Mazzilli’s Zero Voltage Switching (ZVS) Circuit as Plasma Glow Discharge Generator

Purification water has several methods; one of them is the plasma generation. The circuit used to generate plasma is Zero Voltage Switching (ZVS), where its use uses the resonance circuit concept. The main category to generate plasma glow discharge is the circuit should generate high voltage output with a current range from 10-6 A to 1 A. In this study, when ZVS connected to the flyback converter with an input voltage of 12 V, the output values of 11 kV and 11 μA were obtained. In comparison, if ZVS was not connected to the flyback converter, the circuit is less stable, and the output value is weak because the output values only reach 8.97 kV and 8.97 μA. For maximum output, the ZVS circuit should be connected to the converter circuit due to the flyback converter can repair and strengthen the voltage. The flyback converter circuit is affected by the diode and capacitance effects. The effect of using capacitors in a flyback converter circuit is when the capacitance is too low, the ripple will form. Then when capacitance reaches a specific value, the ripple will decrease, and the voltage graph will approach a straight line. Hence the use of components in the ZVS and the flyback converter need to be considered because it affects how the release of plasma glow discharge will form.