Mostafa Hassan

PhD. level: 2018 - 2022
Supervisor: Zdenko Machala
Consultant: Mário Janda
Title (en):
Investigation of plasma-liquid interactions in aerosols and bulk liquids by advanced optical/electrical diagnostics and related properties of the plasma activated water
Title (sk):
Vyšetrovanie interakcie plazmy s kvapalinami v aerosóloch a na rozhraní pokročilými optickými/elektrickými diagnostikami a vlastnosti plazmou aktivovanej vody
Abstract (en):  hide
My PhD research (motivation) focuses on studying the transport mechanism of various gaseous reactive oxygen and nitrogen species (RONS) created by atmospheric air plasma type streamer corona discharge and other several external sources separately in contact with water. The transport mechanism of these long–lived RONS (H2O2, HNO2, NO2, NO, and O3) having different Henry’s law solubility coefficients, is investigated in hybrid plasma/gas–bulk/aerosol interaction with deionized water in two different configuration systems. Bulk reactor through a fixed surface area with different volumes and Aerosol reactor through droplets in the sub-micrometer dimension with a larger integrated surface-area-to-volume ratio produced in two ways. First: an aerosol of non-charged microdroplets of the same sizes using the compressor nebulizer. Second: electrospray of charged microdroplets with polydisperse sizes produced by the positive dc high voltage applied on the hollow needle electrode where the water flows through. In the gas phase, the concentration of gaseous RONS is measured using electrochemical gas sensors and UV-Vis absorption spectroscopic technique. In the aqueous phase, UV-Vis spectroscopy colorimetric methods are used to measure the concentration of the solvated RONS in water (H2O2, NO2¯, NO3¯, and O3) which were added to the chemical reagents. The optical diagnostic techniques were employed to analyze the sizes and surface area of the electrosprayed microdroplets during plasma/gas–water interaction/transport. Several variants of this versatile technique have been developed with different planar laser system setups, in parallel with, Fast/High-speed camera imaging technique method. This study provides a better understanding of plasma RONS transport into the water as a function of different key parameters, such as interaction time, gas–water interface surface area, and (non) charged microdroplets. It will lead to design optimization of the plasma–liquid interaction systems which underline many air plasma applications in biomedicine, environmental sciences, and agriculture.