Efficient removal of tetracycline antibiotic by nonthermal plasma-catalysis combination process

Abstract

This study presents an innovative approach to plasma catalysis by employing nonthermal plasma type gliding arc with various iron oxides -Fe(II), Fe(III) and Ferrate Fe(VI)- for the removal of tetracycline antibiotic (TC). The experimental results demonstrated significant improvements in degradation rates, with plasma-Fe(VI) achieving complete degradation after 15 min of treatment and the plasma-Fe(II) achieving 97.28% removal after 30 min. The effect of TC initial concentration and catalyst dose was investigated, revealing that lower TC concentration favored the degradation and shortened treatment times with even a minimum amount of catalyst doses enhancing degradation results. Higher total organic carbon (TOC) removal was achieved in the combination systems (83.01%; 82.07%; and 42.82% for plasma/Fe(VI); plasma/Fe(II); and plasma /Fe(III) respectively) compared to plasma alone barely achieved 25.67% of mineralization. Additionally, the study examined the role of various radical scavengers-targeting <sup>•</sup>OH, superoxide, and free electrons- in the degradation process. TC intermediates were also identified, degradation pathways were proposed, and the intermediates toxicity was assessed. This research contributes to a deeper understanding of organic compounds treatment using nonthermal plasma, combination with the ferrate process or other catalysts.