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Sonophotocatalytic degradation of sodium diclofenac using low power ultrasound and micro sized TiO2.

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Title: Sonophotocatalytic degradation of sodium diclofenac using low power ultrasound and micro sized TiO2.
Authors: Meroni, Daniela1 (AUTHOR), Jiménez-Salcedo, Marta1,2 (AUTHOR), Falletta, Ermelinda1 (AUTHOR), Bresolin, Bianca M.3 (AUTHOR), Kait, Chong Fai4 (AUTHOR), Boffito, Daria C.5 (AUTHOR), Bianchi, Claudia L.1 (AUTHOR), Pirola, Carlo1 (AUTHOR) carlo.pirola@unimi.it
Source: Ultrasonics Sonochemistry. Oct2020, Vol. 67, pN.PAG-N.PAG. 1p.
Subjects: Diclofenac, Emerging contaminants, Micropollutants, Drinking water, Hydroxyl group, Wastewater treatment
Abstract: The nonsteroidal anti-inflammatory drug sodium diclofenac (DC) is an emerging water pollutant which resists conventional wastewater treatments. Here the sonophotocatalytic degradation of DC was carried out using micrometric TiO 2 (both pristine and Ag-decorated), UV-A irradiation and 20 kHz pulsed ultrasound. Sonophotocatalytic tests were compared with photolysis, sonolysis, sonophotolysis, sonocatalysis and photocatalysis data performed in the same conditions. A synergy index of over 2 was determined for tests with pristine TiO 2 , while values close to 1.3 were observed for Ag-TiO 2. Reaction intermediates were studied by HPLC–MS, showing degradation mechanisms activated by hydroxyl radicals. Similar pathways were identified for photocatalytic and sonophotocatalytic tests, although the latter led to more oxidized compounds. Different reactor configurations (static and dynamic set ups) were studied. Sequential and simultaneous application of UV light and ultrasound led to similar performance. The role of water matrix was investigated using ultrapure and drinking water, showing marked detrimental effects of electrolytes on the DC degradation. Overall, the combined treatment proved more efficient than photocatalysis alone especially in demanding working conditions, like in drinking water matrices. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:The nonsteroidal anti-inflammatory drug sodium diclofenac (DC) is an emerging water pollutant which resists conventional wastewater treatments. Here the sonophotocatalytic degradation of DC was carried out using micrometric TiO 2 (both pristine and Ag-decorated), UV-A irradiation and 20 kHz pulsed ultrasound. Sonophotocatalytic tests were compared with photolysis, sonolysis, sonophotolysis, sonocatalysis and photocatalysis data performed in the same conditions. A synergy index of over 2 was determined for tests with pristine TiO 2 , while values close to 1.3 were observed for Ag-TiO 2. Reaction intermediates were studied by HPLC–MS, showing degradation mechanisms activated by hydroxyl radicals. Similar pathways were identified for photocatalytic and sonophotocatalytic tests, although the latter led to more oxidized compounds. Different reactor configurations (static and dynamic set ups) were studied. Sequential and simultaneous application of UV light and ultrasound led to similar performance. The role of water matrix was investigated using ultrapure and drinking water, showing marked detrimental effects of electrolytes on the DC degradation. Overall, the combined treatment proved more efficient than photocatalysis alone especially in demanding working conditions, like in drinking water matrices. [ABSTRACT FROM AUTHOR]
ISSN:13504177
DOI:10.1016/j.ultsonch.2020.105123