rhodamine B in pure water and a mineral water was reported at 300 kHz (Merouani
2010; Moumeni and Hamdaoui 2012). On the other hand, a slightly enhancement of
basic fuchsin degradation in a mineral water has been reported by Taamallah et al.
(2016) at 600 kHz. The sonochemical degradation of Basic Red 29 has been
investigated in mineral water, river water, and seawater and compared with that of
deionized water (Boutamine et al. 2017). The degradation rate followed the order:
mineral water > seawater > river water > pure water (Boutamine et al. 2017).
Interestingly, the sonochemical treatment of naphthol blue black at 1700 kHz was
strongly accelerated in mineral water and seawater as compared to data obtained in
pure water (Ferkous et al. 2016). All these enhancements were attributed to the
salting-out effect induced by the high concentration of anions in natural waters.
However, Ferkous et al. (2016) have suggested that the salting-out effect is frequency dependent.
5.8 Process Intensification Using Selected Additives
In addition to carbonate/bicarbonate and bromide, other inorganic and organic substances have been recently applied as intensifying agents for the sonochemical
treatment. In this section, only the most important agents have been highlighted.
5.8.1 CCl 4
The presence of CCl 4 in aqueous solutions of dyes drastically enhanced their
sonochemical removal. Ghodbane and Hamdaoui (2009b) have assessed the
sonochemical degradation of Acid Blue 25 in the presence of CCl 4 using a
1700 kHz ultrasonic device. The decolorization rate in the presence of 399 mg/L
of CCl 4 was 106 times greater than that calculated in the absence of CCl 4 . Additionally, the addition of 399 mg/L of CCl 4 at 1700 kHz results in an 87-fold increase
of the initial decolorization rate as compared with the frequency of 22.5 kHz. A
similar behavior has been reported by Merouani et al. (2010c) for the sonochemical
degradation of Rhodamine at 300 kHz. Gültekin et al. (2009) have reported that the
degradation rate of C.I. acid orange 8 at 300 kHz and 25 W increased by factors of
about 2, 3.5, and 4.66 with addition of CCl 4 at 0.5, 1, and 5 mM, respectively.
Similar findings have been reported for the degradation of two azo dyes at various
frequencies (Eren and Ince 2010) and for methyl orange in a 45 kHz ultrasonic
cleaning bath (Okitsu et al. 2008).
CCl 4 pyrolysis takes place inside cavitation bubbles, conducting to the release of
several chlorinated oxidizing agents (Eqs. 5.11, 5.12, 5.13, 5.14, 5.15, 5.16 and
5.17) that can react efficiently with dye molecules (Okitsu et al. 2008; Ghodbane and
Hamdaoui 2009b):
176
S. Merouani and O. Hamdaoui
2010; Moumeni and Hamdaoui 2012). On the other hand, a slightly enhancement of
basic fuchsin degradation in a mineral water has been reported by Taamallah et al.
(2016) at 600 kHz. The sonochemical degradation of Basic Red 29 has been
investigated in mineral water, river water, and seawater and compared with that of
deionized water (Boutamine et al. 2017). The degradation rate followed the order:
mineral water > seawater > river water > pure water (Boutamine et al. 2017).
Interestingly, the sonochemical treatment of naphthol blue black at 1700 kHz was
strongly accelerated in mineral water and seawater as compared to data obtained in
pure water (Ferkous et al. 2016). All these enhancements were attributed to the
salting-out effect induced by the high concentration of anions in natural waters.
However, Ferkous et al. (2016) have suggested that the salting-out effect is frequency dependent.
5.8 Process Intensification Using Selected Additives
In addition to carbonate/bicarbonate and bromide, other inorganic and organic substances have been recently applied as intensifying agents for the sonochemical
treatment. In this section, only the most important agents have been highlighted.
5.8.1 CCl 4
The presence of CCl 4 in aqueous solutions of dyes drastically enhanced their
sonochemical removal. Ghodbane and Hamdaoui (2009b) have assessed the
sonochemical degradation of Acid Blue 25 in the presence of CCl 4 using a
1700 kHz ultrasonic device. The decolorization rate in the presence of 399 mg/L
of CCl 4 was 106 times greater than that calculated in the absence of CCl 4 . Additionally, the addition of 399 mg/L of CCl 4 at 1700 kHz results in an 87-fold increase
of the initial decolorization rate as compared with the frequency of 22.5 kHz. A
similar behavior has been reported by Merouani et al. (2010c) for the sonochemical
degradation of Rhodamine at 300 kHz. Gültekin et al. (2009) have reported that the
degradation rate of C.I. acid orange 8 at 300 kHz and 25 W increased by factors of
about 2, 3.5, and 4.66 with addition of CCl 4 at 0.5, 1, and 5 mM, respectively.
Similar findings have been reported for the degradation of two azo dyes at various
frequencies (Eren and Ince 2010) and for methyl orange in a 45 kHz ultrasonic
cleaning bath (Okitsu et al. 2008).
CCl 4 pyrolysis takes place inside cavitation bubbles, conducting to the release of
several chlorinated oxidizing agents (Eqs. 5.11, 5.12, 5.13, 5.14, 5.15, 5.16 and
5.17) that can react efficiently with dye molecules (Okitsu et al. 2008; Ghodbane and
Hamdaoui 2009b):
176
S. Merouani and O. Hamdaoui