Degradation of pesticides in aqueous solutions using plasma bubbles
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Date
2025-07-08
Authors
Μπαστάνη, Αλεξάνδρα
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Abstract
For the purpose of the present thesis, the degradation of the pesticide atrazine in aqueous solutions using cold plasma bubbles was investigated, employing two different plasma bubbles reactors. Specifically, atrazine solutions were prepared using both tap water and ultrapure water as a water matrix.
For each water matrix, the physicochemical parameters, like the pH and electrical conductivity values, were determined at different plasma treatment times. What is more, the different plasma generated reactive species present in both water matrices were identified and quantified both in the liquid phase of the solution, using a variety of different analytical techniques, and in the gaseous phase in the bubbles reactor, above the liquid solution, using optical emission spectroscopy (OES).
After the water characterization, atrazine solutions with varying concentrations and the presence or absence of different scavengers were prepared, in order to evaluate the degradation efficiency of the atrazine solutions under controlled plasma treatment in various experimental environments. The degradation of the pollutant was examined in two different plasma bubbles reactors, the DBD Bubbles reactor and the Corona Bubbles reactor, which was designed by modifying the DBD Bubbles reactor.
In order to compare the atrazine degradation in the two pollutants, experiments were conducted under the same treatment conditions (voltage, frequency, plasma gas and plasma gas flow rate) in both bubbles reactors. Moreover, experiments were conducted employing different plasma gases, to evaluate their impact on atrazine degradation. Furthermore, kinetic parameters of the degradation reactions of atrazine, such as their reaction rates and reaction constants were determined under different experimental conditions. In addition, the removal efficiency of total organic carbon (TOC) of the initial atrazine solutions was determined. Last but not least, the electrical characteristics of the discharges, which include the voltage, current and power values, as well as the production yield of the major plasma-generated reactive species participating in the degradation of atrazine were calculated.
The main purpose of this experimental series was to compare the performance of the two plasma bubbles reactors in terms of atrazine degradation efficiency, while also investigating the influence of the water matrix quality on the process, aiming to define the optimal operational conditions for an energy-efficient, cost effective and environmentally sustainable plasma treatment process.
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Keywords
Atrazine, Cold atmospheric plasma, plasma bubbles, Dielectric barrier discharge, Reactive oxygen and nitrogen species, Energy efficiency, Wastewater, Corona discharge