Pulsed Discharge Plasma in High-Pressure Environment for Water Pollutant Degradation and Nanoparticle Synthesis

Abstract

The application of high-voltage discharge plasma for water pollutant decomposition and the synthesis of nanoparticles under a high-pressure argon gas environment (~4 MPa) was demonstrated. The experiments were carried out in a batch-type system at room temperature with a pulsed DC power supply (15.4 to 18.6 kV) as a discharge plasma source. The results showed that the electrode materials, the pulsed repetition rates, the applied number of pulses, and the applied voltages had a significant effect on the degradation reactions of organic compounds. Furthermore, carbon solid materials from glycine decomposition were generated during the high-voltage discharge plasma treatment under high-pressure conditions, while Raman spectra and the HRTEM images indicated that titanium dioxide with a brookite structure and titanium carbide nanoparticles were also formed under these conditions. It was concluded that this process is applicable in practice and may lead to advanced organic compound decomposition and metal-based nanoparticle synthesis technologies.

Gas/Liquid Pulsed Discharge Plasma in a Slug Flow Reactor under Pressurized Argon for Dye Decomposition

“…Excitation or ionization of molecules or atoms caused by inelastic collisions is promoted and more reactive species are generated, leading to increased collisional energy loss . In addition, when high-voltage discharge plasma was introduced into the gas/liquid environment, physical effects, including shock wave generation, UV radiation, and strong electrical field, were also observed. ,, Under high-pressure conditions, the emission intensity of the pulsed discharge plasma was high, which may have also increased the energy loss. Meanwhile, because water demonstrates high absorption in the vacuum UV region, direct photooxidation of a dye in water was very limited .…”

“… 3 Furthermore, lower energy and operating cost are required to produce plasma in a gas/liquid environment than as a direct discharge in a liquid. 4 In addition, the gas–liquid interface surface area is large, making it highly effective for gaseous species to diffuse inside the liquid. 5 When high-voltage electrons are introduced into a gas/liquid environment, gas molecules or atoms are ionized first to form initial radicals.…”

“…Cold plasma technology has gained immense attention because of its environmentally friendly advantages, simplicity, effectiveness, and cost-effectiveness. , Discharge plasma is usually easier to generate in a gas medium than in a liquid medium . Furthermore, lower energy and operating cost are required to produce plasma in a gas/liquid environment than as a direct discharge in a liquid . In addition, the gas–liquid interface surface area is large, making it highly effective for gaseous species to diffuse inside the liquid .…”

The 2022 Plasma Roadmap: low temperature plasma science and technology

“…The development of novel approaches to excite and generate plasma discharges has been motivated by the unique needs of the increasingly large amount of application areas being tackled by plasma technology. New plasma generation approaches are often required to generate plasmas in dense media including high pressure gases or liquids and pulsed generation of plasmas by ultra-high electric fields with durations as small as hundreds of picoseconds [3,4].…”