Water quality is threatened by numerous pollutants, among which antibiotics are of great concern due to their widespread use and unaltered excretion, leading to water contamination and fostering antibiotic resistance. To comprehensively address sustainable water remediation, herein, the susceptibility to non-thermal plasma degradation of two veterinary antibiotics (Oxytetracycline (OTC) and Lincomycin (LNC)) are compared in an integral approach, including computational analyses, plasma irradiation assays, and a byproduct toxicity assessment. The computational assessment was performed by evaluating the ionization potential (IP) obtained from Density Functional Theory calculations and determining the antibiotics’ susceptible sites for radical attack. Plasma irradiation achieved nearly complete degradation (~100%) of both compounds with the initial concentration of 1 mg L⁻¹, while 60% degradation was observed when the starting concentration was 10 mg L⁻¹. The mineralization rates were 21% and 31% for OTC and LNC, respectively. The degradation profiles followed similar trends, as expected from their comparable IP values. After treatment, the solution exhibited lower biotoxicity compared to the original antibiotics. Therefore, this work represents a step forward in addressing one of the key environmental challenges of our time and encourages further extending the analysis towards the remediation of water polluted with many other organic compounds.

In this work, the reactive species generated by two different plasma jet devices operated with ambient air as working gas are studied experimentally and theoretically. One jet device is based in a non-thermal arc, while the other consists of a dielectric barrier discharge (DBD) with two axial electrodes and a double dielectric barrier. The reactive oxygen and nitrogen species present in the jet effluents were measured by Fourier transform infrared absorption spectroscopy (FT-IR). A very different composition of reactive species was found for the two devices. The arc plasma jet has a chemistry dominated by nitrogen reactive species, while the DBD produces mainly ozone. The gas temperature in the discharge region of the two jets was determined by fitting the emission spectrum of the second positive N2 system. It was found that the neutral gas temperature in the arc jet is significantly higher than in the DBD jet. The chemical composition in the discharge region was studied with a theoretical model that considers multiple chemical reactions, taking into account the gas temperature dependence of the reaction rates. It was observed that most of the species identified by FT-IR are predicted by the theoretical model as the most abundant in the discharge region. This result indicates that the chemical composition of the jet effluents is determined by the gas temperature in the discharge region.

Water pollution due to emerging organic pollutants, such as agrochemicals, has become a topic of growing interest worldwide. The increase of pollutants in aquatic systems stimulated the development of new strategies for water remediation. Plasma technology is an advanced oxidation process which has proved to be an efficient method for organic matter degradation. In this work, a novel design of a trielectrode plasma reactor based on a dielectric barrier discharge extended to a third electrode operated in ambient air is presented. The water to be treated flows through a gutter with low impedance and far from the electrodes connected to the voltage sources. The reactor operates in ambient air, and it does not rely on the use of expensive inert gases. The design of the reactor is easily scalable. The performance of the reactor, in terms of the removal efficiency and the energy yield, was tested in an aqueous solution of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), one of the most widely used around the world. The reactor presents a good efficiency in the removal of the herbicide 2,4-D and values of energy yield of about 240 mg/kW h.