Sonochemical degradation of ethyl paraben in environmental samples: statistically important parameters determining kinetics, by-products and pathwaysSonochemical degradation of ethyl paraben in environmental samples: statistically important parameters determining kinetics, by-products and pathways Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2018-10-102016enThe sonochemical degradation of ethyl paraben (EP), a representative of the parabens family, was investigated. Experiments were conducted at constant ultrasound frequency of 20 kHz and liquid bulk temperature of 30 °C in the following range of experimental conditions: EP concentration 250-1250 μg/L, ultrasound (US) density 20-60 W/L, reaction time up to 120 min, initial pH 3-8 and sodium persulfate 0-100 mg/L, either in ultrapure water or secondary treated wastewater. A factorial design methodology was adopted to elucidate the statistically important effects and their interactions and a full empirical model comprising seventeen terms was originally developed. Omitting several terms of lower significance, a reduced model that can reliably simulate the process was finally proposed; this includes EP concentration, reaction time, power density and initial pH, as well as the interactions (EP concentration) × (US density), (EP concentration) × (pHo) and (EP concentration) × (time). Experiments at an increased EP concentration of 3.5 mg/L were also performed to identify degradation by-products. LC-TOF-MS analysis revealed that EP sonochemical degradation occurs through dealkylation of the ethyl chain to form methyl paraben, while successive hydroxylation of the aromatic ring yields 4-hydroxybenzoic, 2,4-dihydroxybenzoic and 3,4-dihydroxybenzoic acids. By-products are less toxic to bacterium V. fischeri than the parent compound.http://creativecommons.org/licenses/by/4.0/Ultrasonics Sonochemistry3162-70 Papadopoulos Costas Frontistis Zacharias Antonopoulou Maria Venieri Danai Βενιερη Δαναη Konstantinou, Ioannis K Mantzavinos Dionysis Μαντζαβινος Διονυσης Elsevier Aqueous matrix Estrogenicity Factorial design Intermediates Micro-pollutants Sonodegradation