title: Comprehensive experimental and numerical investigations of the effect of frequency and acoustic intensity on the sonolytic degradation of naphthol blue black in water.
abstract: In the present work, comprehensive experimental and numerical investigations of the effects of frequency and acoustic intensity on the sonochemical degradation of naphthol blue black (NBB) in water have been carried out. The experiments have been examined at three frequencies (585, 860 and 1140 kHz) and over a wide range of acoustic intensities. The observed experimental results have been discussed using a more realistic approach that combines the single bubble sonochemistry and the number of active bubbles. The single bubble yield has been predicted using a model that combines the bubble dynamics with chemical kinetics consisting of series of chemical reactions (73 reversible reactions) occurring inside an air bubble during the strong collapse. The experimental results showed that the sonochemical degradation rate of NBB increased substantially with increasing acoustic intensity and decreased with increasing ultrasound frequency. The numerical simulations revealed that NBB degraded mainly through the reaction with hydroxyl radical (OH), which is the dominant oxidant detected in the bubble during collapse. The production rate of OH radical inside a single bubble followed the same trend as that of NBB degradation rate. It increased with increasing acoustic intensity and decreased with increasing frequency. The enhancing effect of acoustic intensity toward the degradation of NBB was attributed to the rise of both the individual chemical bubble yield and the number of active bubbles with increasing acoustic intensity. The reducing effect of frequency was attributed to the sharp decrease in the chemical bubble yield with increasing frequency, which would not compensated by the rise of the number of active bubbles with the increase in ultrasound frequency.
authors.affiliation: Laboratory of Environmental Engineering, Department of Process Engineering, Faculty of Engineering, Badji Mokhtar - Annaba University, P.O. Box 12, 23000 Annaba, Algeria.
authors.forename: Hamza
authors.initials: H
authors.lastname: Ferkous
authors.affiliation: Laboratory of Environmental Engineering, Department of Process Engineering, Faculty of Engineering, Badji Mokhtar - Annaba University, P.O. Box 12, 23000 Annaba, Algeria; Department of Chemical Engineering, Faculty of Pharmaceutical Engineering Process, University of Constantine 3, Constantine, Algeria. Electronic address: s.merouani@yahoo.fr.
authors.forename: Slimane
authors.initials: S
authors.lastname: Merouani
authors.affiliation: Laboratory of Environmental Engineering, Department of Process Engineering, Faculty of Engineering, Badji Mokhtar - Annaba University, P.O. Box 12, 23000 Annaba, Algeria.
authors.forename: Oualid
authors.initials: O
authors.lastname: Hamdaoui
authors.affiliation: Laboratory of Applied Chemistry and Materials Technology, University of Oum El-Bouaghi, P.O. Box 358, 04000 Oum El Bouaghi, Algeria.
authors.forename: Yacine
authors.initials: Y
authors.lastname: Rezgui
authors.affiliation: Laboratory of Applied Chemistry and Materials Technology, University of Oum El-Bouaghi, P.O. Box 358, 04000 Oum El Bouaghi, Algeria.
authors.forename: Miloud
authors.initials: M
authors.lastname: Guemini
keywords: ()OH radical; Acoustic intensity; Frequency; Naphthol blue black (NBB); Numerical simulations; Sonochemical degradation