Dibutyl phthalate degradation and toxicity assessment based on hydroxyl radicals generated by plasma jet.

[Display omitted] • An atmospheric-pressure plasma jet with optimal Ar flow degraded dibutyl phthalate (DBP) by 96.6 % in 10 min. • Hydroxyl radicals play a significant role in DBP degradation. • Chemical probing and spectroscopic techniques revealed the liquid- and gas- phase hydroxyl radical concentration. • Cell viability is improved by 40% while dead cell population is substantially reduced, indicating notably reduced toxicity. Phthalate esters such as dibutyl phthalate (DBP) are widely used as plasticizers in various industries and are known to cause water pollution reaching 15.7 mgL -1 in freshwater and 0.01 mgL -1 in seawater. This study investigated the effectiveness of DBP degradation using an atmospheric-pressure plasma jet (APPJ). Variation in the argon (Ar) gas flow rate influenced the spatial distribution of the hydroxyl radicals (∙ O H) as it altered the laminar-to-turbulent flow transition. The highest density of ∙ O H was recorded to be 3.1 × 1016 cm−3 when the Ar flow rate was maintained at 2 standard liters per minute. Additionally, the ∙ O H concentration in plasma-activated water substantially increased to 35.5 μM with prolonged treatment. Similarly, the concentrations of H 2 O 2 , which is formed as a result of the recombination of the ∙ O H , gradually increased to 34.4 μM over 8 min of treatment time, and subsequently reduced to 32.6 μM after an additional 2 min of treatment. A degradation rate of 96.6 % was achieved within 10 min of treatment, as confirmed by a gas chromatography (GC)-flame ionization detector. GC-mass spectrometry was used to identify the intermediate products, and propose possible degradation pathways. However, a decline in the energy efficiency was observed because of reduced initial concentration over the extended treatment time. Furthermore, a 40 % increase in cell viability and a 45 % decrease in the percentage of the dead cell population were observed during the exposure of MRC5, astrocytes, and PC-3 cell lines to APPJ-treated DBP solution, indicating reduced toxicity of the contaminant. Thus, the proposed approach can effectively reduce the contamination of water resources by DBP. [ABSTRACT FROM AUTHOR]