New aspect of the effect of liquid temperature on sonochemical degradation of nonvolatile organic pollutants in aqueous media

Chadi, Nor Elhouda; Merouani, Slimane; Hamdaoui, Oualid; Bouhelassa, Mohamed

doi:10.1016/j.seppur.2018.01.047

Cited by 31 publications

(9 citation statements)

References 46 publications

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“…Sonochemistry may be applied for frequency ranging from 20 kHz to 1 MHz, with an optimum frequency being around 300 kHz . However, higher sonochemical efficiency, as measured by chemical dosimetries or pollutants destruction, has also been reported for up to 1.7 MHz . To evaluate the influence of frequency and acoustic intensity on the inhibiting effect of CO 2 toward the production rate of • OH, numerical simulations of chemical reactions occurring inside a CO 2 bubble and an air bubble have been conducted for various frequencies (20, 140, 213, 355, 515, 647, 1000 and 1100 kHz) and different acoustic intensities (0.5, 0.75 and 1 W cm ‐2 ).…”

Section: Resultsmentioning

confidence: 99%

Toward understanding the mechanism of pure CO₂‐quenching sonochemical processes

Merouani¹,

Hamdaoui

Al‐Zahrani

2019

J of Chemical Tech & Biotech

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BACKGROUND: Carbon dioxide (CO 2 ) is a gas that has a distinguished effect on the sonochemical process. Dissolving pure CO 2 in solutions prevented sonochemical action in all laboratory-scale experiments, reported until know. The mechanism underlying the pure-CO 2 nullifying sonochemical treatment is until now under debate. RESULTS: Herein, thanks to confronting detailed numerical simulation results for single bubble sonochemistry with literature experimental observations, the mechanism of pure CO 2 -quenching sonochemical reaction was clarified. The acoustic generation of free radicals under CO 2 atmosphere was simulated for different conditions of frequency (20−1100 kHz), acoustic power (0.5−1 W cm -2 ), liquid temperature (20−50 ∘ C) and external pressure (0.6−1.6 atm) and compared with that generated for air-saturation, for the same conditions. Depending on the sonochemical parameters, it was found that CO 2 may enhance, decrease or completely suppress the acoustic generation of hydroxyl radicals. The effect of CO 2 was strongly operating conditions-dependent. CONCLUSION: Given that CO 2 nullified all sonolytic actions in aqueous solution, it was concluded that owing to its very high solubility in water (46-fold much higher than that of air), CO 2 could suppress the inertial cavitation bubbles responsible of all chemical actions. Gases of too higher solubility could favor the bubble-bubble coalescence rather than the production of inertial cavitation bubbles. The bubble-bubble coalescence in this case could be a suppressor of inertial cavitation. A high extent of bubbles coalescence could take place under CO 2 saturation provoking total disappearance of the chemical activity. Greek lettersSpecific heat ratio (c p /c v ) of the gas mixture. Surface tension of liquid water (N m -1 ). Density of liquid water (kg m -3 ).

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Section: Resultsmentioning

confidence: 99%

Toward understanding the mechanism of pure CO₂‐quenching sonochemical processes

Merouani¹,

Hamdaoui

Al‐Zahrani

2019

J of Chemical Tech & Biotech

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“…Pétrier et al [13] , examined the rate of phenol and carbon tetrachloride degradation over a range of ultrasonic frequencies from 20 to 800 kHz, where an optimal frequency of 200 kHz was determined for the maximal degradation of phenol, conversely, the decomposition of carbon tetrachloride increases proportionally with the frequency increase. In general, the effects of acoustic amplitude [14] , [15] , [16] , [17] , [18] , frequency [18] , [19] , [20] , [21] , [22] , saturating gas [18] , [23] , [24] , [25] , [26] , [27] , solution temperature [28] , [29] , static pressure [30] , [31] and other parameters have been widely investigated [32] .…”

Section: Introductionmentioning

confidence: 99%

Insight into the impact of excluding mass transport, heat exchange and chemical reactions heat on the sonochemical bubble yield: Bubble size-dependency

Dehane

Merouani²,

Hamdaoui

et al. 2021

Ultrasonics Sonochemistry

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Highlights Effects reactions heat and mass and heat transfer on chemical bubble yield are studied. The effect the three energetic mechanisms depend on ambient bubble radii, frequency and acoustic amplitude. The ignorance of thermal conduction improves the bubble energy and the chemical yield. Excluding chemical reactions heat accelerate notably the chemical bubble yield. Excluding mass transport of water vapor lowers the chemical bubble yield.

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“…In the research of Chardi et al, 50 °C was reported as the optimal temperature for Toluidine Blue in sonochemical degradation, which was the result of concurrence between the number of bubbles and the single bubble yield. 33 As the discharge temperature of dye wastewater is over 70 °C, 50 °C was selected as the water bath temperature in subsequent experiments. 34 The ion concentrations in the PS/Fe 3 O 4 @AC and US/PS/ Fe 3 O 4 @AC systems were determined to further investigate the difference of reaction progress in the two groups.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Degradation of Acid Red 73 by Activated Persulfate in a Heat/Fe₃O₄@AC System with Ultrasound Intensification

et al. 2020

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This work aimed to investigate the degradation efficiency of waste water with an azo dye, Acid Red 73 (AR73), by persulfate/heat/Fe3O4@AC/ultrasound (US). The introduction of ultrasound into the persulfate/heat/Fe3O4@AC system greatly enhanced the reaction rate because of the physical and chemical effects induced by cavitation. Various parameters such as temperature, initial pH, sodium persulfate dosage, catalyst dosage, initial concentration of AR73, ultrasonic frequency and power, and free-radical quenching agents were investigated. The optimal conditions were determined to be AR73 50 mg/L, PS 7.5 mmol/L, catalyst dosage 2 g/L, ultrasound frequency 80 kHz, acoustic density 5.4 W/L, temperature 50 °C, and pH not adjusted. Nearly, 100% decolorization was achieved within 10 min under optimal conditions. Different from some other similar research studies, the reaction did not follow a radical-dominating way but rather had 1O2 as the main reactive species. The recycling and reusability test confirmed the superiority of the prepared Fe3O4@AC catalyst. The research achieved a rapid decolorization method not only using waste heat of textile water as a persulfate activator but also applicable to a complex environment where common radical scavengers such as ethanol exist.

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New aspect of the effect of liquid temperature on sonochemical degradation of nonvolatile organic pollutants in aqueous media

Cited by 31 publications

References 46 publications

Toward understanding the mechanism of pure CO₂‐quenching sonochemical processes

Toward understanding the mechanism of pure CO₂‐quenching sonochemical processes

Insight into the impact of excluding mass transport, heat exchange and chemical reactions heat on the sonochemical bubble yield: Bubble size-dependency

Degradation of Acid Red 73 by Activated Persulfate in a Heat/Fe₃O₄@AC System with Ultrasound Intensification

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New aspect of the effect of liquid temperature on sonochemical degradation of nonvolatile organic pollutants in aqueous media

Cited by 31 publications

References 46 publications

Toward understanding the mechanism of pure CO2‐quenching sonochemical processes

Toward understanding the mechanism of pure CO2‐quenching sonochemical processes

Insight into the impact of excluding mass transport, heat exchange and chemical reactions heat on the sonochemical bubble yield: Bubble size-dependency

Degradation of Acid Red 73 by Activated Persulfate in a Heat/Fe3O4@AC System with Ultrasound Intensification

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Product

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Toward understanding the mechanism of pure CO₂‐quenching sonochemical processes

Toward understanding the mechanism of pure CO₂‐quenching sonochemical processes

Degradation of Acid Red 73 by Activated Persulfate in a Heat/Fe₃O₄@AC System with Ultrasound Intensification