title: Sonochemical degradation of naphthol blue black in water: Effect of operating parameters.
abstract: In this work, the sonochemical degradation of naphthol blue black (NBB), an acidic diazo dye, in water was investigated. The effects of several operating parameters such as initial NBB concentration, acoustic intensity, ultrasonic frequency, nature of the dissolved gas and solution pH on the degradation of the dye were carried out. The obtained results showed that ultrasound completely destroyed NBB (5 mg L(-1)) after 45 min of sonication and most of the chemical oxygen demand was eliminated after 90 min of treatment. It was found that the initial rate of sonolytic degradation increased with increasing the initial NBB concentration. The fitting of the experimental data by a heterogeneous Langmuir-kinetics model showed that NBB degraded mainly at the interfacial region of the bubble by hydroxyl radical (OH) attack. The degradation rate of the dye increased substantially with increasing acoustic intensity in the range of 0.44-3.58 W cm(-2) and decreased with increasing frequency in the range of 585-1140 kHz. The rate of NBB degradation decreased in the order of Ar>air>N2. The significant degradation was achieved in acidic conditions (pH 2) where the initial degradation rate was 1.37 and 1.66 higher than those observed at pH 6 and pH 10, respectively.
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.
authors.forename: Oualid
authors.initials: O
authors.lastname: Hamdaoui
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
keywords: Acoustic intensity; Dissolved gas; Hydroxyl radical; Naphthol blue black; Sonochemical degradation; Ultrasonic frequency