Sonochemical degradation of Basic Red 29 in aqueous media

Abstract

Abstract:In this work, the degradation of Basic Red 29 (BR29), an azo dye, was investigated using a high-frequency ultrasonic reactor (300 kHz). The influence of several parameters such as initial substrate concentration (5-200 mg L −1 ) , pH (3-10.1), ultrasonic power (20-80 W), and nature of the dissolved gas (Ar, air, and N 2) on the degradation of BR29was assessed. Additionally, the impact of natural matrices (seawater and natural and river waters) on the degradation rate of BR29 was clarified. Degradation experiments with radical scavengers, tert-butyl alcohol and glucose, showed that BR29 degraded mainly through HO• radical attack at the gas/liquid interface of the cavitation bubbles. The degradation of the dye was strongly sensitive to the operational conditions. The natural matrices enhanced the degradation of the dye. Ultrasonic mineralization and oxidation of the dye solution was significantly enhanced by addition of a low quantity of Fe 2+ (15 mg L −1 ) .

Ultrasound/Chlorine: A Novel Synergistic Sono-Hybrid Process for Allura Red AC Degradation

“…The obtained order of the saturating gases (Ar > air > N 2 ) for the US process is largely reported in the literature [58][59][60][61]. The measured accumulation rate of H 2 O 2 in water, as • OH quantifiers, were 6.4 µM•min −1 for Ar, 5.6 µM•min −1 for air and 3 µM•min −1 for N 2 .…”

“…Therefore, the effect of combining US and chlorine for ARAC degradation is additive for argon, synergistic for air and negative for N2. The obtained order of the saturating gases (Ar > air > N2) for the US process is largely reported in the literature [58][59][60][61]. The measured accumulation rate of H2O2 in water, as • OH (c) For the US/chlorine system, the resulting negative synergy under a nitrogen saturation atmosphere was due to the poor production rate of the generated reactive species from the acoustic bubbles, as stated below.…”

“…An interesting numerical investigation of how these gases affect the sonochemical activity was recently provided by Merouani et al [9,62]. Overall, thanks to its beneficial physical properties (i.e., a greater polytropic ratio (γ Ar = 1.66) and solubility (x Ar = 2.748 × 10 −5 ) and lower thermal conductivity (λ Ar = 0.018 W m −2 •K −1 ) than air and N 2 gases, which have the same γ and λ (γ = 1.41, λ = 0.026 W m −2 •K −1 ) and a slight differences in their solubility (x air = 1.524 × 10 −5 , x N2 = 1.276 × 10 −5 )), argon could produce the highest single-bubble yield ( • OH radical) and a greater number of bubbles than the other gases [60,63,64], allowing it to achieve the maximum sonochemical efficiency. The higher chemical efficiency in air-saturated solution than N 2 was mainly attributed to the internal bubble-chemistry [9,62].…”

Sonochemical reactor characterization in the presence of cylindrical and conical reflectors

“…Reactive species yields serve as representative indices for understanding the chemical consequences of sonolytic cavitation. Therefore, these yields have been evaluated in several experimental settings [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] and in theoretical and computational studies [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] . The impact of additives has also been investigated [31] .…”