Sonochemical degradation of propylparaben in the presence of agro-industrial biocharSonochemical degradation of propylparaben in the presence of agro-industrial biochar Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2021-06-302020enThe degradation of propylparaben (PP) by 20 kHz ultrasound irradiation in the presence of biochar was investigated. The biochar was produced from rice husk and characterized exhaustively by several techniques. It contains high percentage of stable, amorphous carbon with a considerable number of aromatic moieties and about 60 % of ash content, exhibits a specific surface area of 70.6 m2/g and has a slightly basic surface with a pzc around 8. Batch experiments were performed with a horn-type sonicator, mainly in ultrapure water (UPW), while actual matrices such as bottled water, groundwater and treated wastewater were also tested to assess the effect of water constituents on degradation. The simultaneous use of ultrasound and biochar had a synergistic effect on PP degradation relative to the individual processes, i.e. silent adsorption and irradiation without biochar, resulting in about 60 % synergy. The pseudo-first order rate increased with increasing power density and biochar concentration (up to a certain value) and decreasing temperature and PP concentration, while basic or acidic conditions retarded degradation. Higher PP concentrations resulted in lower rate constants, thus pointing out that the production of radicals was the rate-determining step. Reactions in actual matrices were slower than in UPW (i.e. up to ten times) and this was ascribed to the various inorganic (i.e. bicarbonate, chloride) and organic (i.e. humic acid analogues) water constituents.http://creativecommons.org/licenses/by/4.0/Journal of Environmental Chemical Engineering84 Nikolaou Stavroula Vakros John Diamantopoulos Evaggelos Διαμαντοπουλος Ευαγγελος Mantzavinos Dionysis Μαντζαβινος Διονυσης Elsevier Adsorption Parabens Sonochemistry Synergy Waste valorization Water matrix