Enhancement of dye sonochemical degradation by some inorganic anions present in natural waters

Minero, Claudio; Pellizzari, Paolo; Maurino, Valter; Pelizzetti, Ezio; Vione, Davide

doi:10.1016/j.apcatb.2007.08.001

Cited by 121 publications

(64 citation statements)

References 41 publications

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“…It is well known that removal of organic pollutants depends on amounts of reactive species, with this, in turn, being dependent on the presence of additional substances in the reaction solution that can act as radical scavengers. Inorganic ions and organic substances are, in fact, well-known OH scavengers [30,31]. In a previous study [23], the ultrasonic degradation of bisphenol-A was also shown to be impacted upon negatively by humic acid.…”

Section: Resultsmentioning

confidence: 99%

Sonochemical Formation of Hydrogen Peroxide

Ziembowicz

Kida

Koszelnik

2017

The 2nd International Electronic Conference on Water Sciences

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Abstract:The work detailed in this study utilized 20 kHz ultrasonic irradiation as a mechanism of hydrogen peroxide production. The effects of various operating parameters were investigated, including ultrasonic intensity; solution pH; source of water; initial dibutyl phthalate concentration and the presence of hydrogen peroxide. During the irradiation, the H2O2 concentration was monitored. The results indicate that H2O2 is produced by cavitation during ultrasonic irradiation. An increase in ultrasonic intensity increases the amount of hydrogen peroxide produced. The initial pH of the solution does not affect the efficiency of processes substantially. H2O2 is regarded as one of the most effective additives enhancing the sonochemical production of hydroxyl radicals and hydrogen peroxide. Above a 0.1 mM dose of H2O2, the amount of H2O2 formed decreased as the concentration of H2O2 increased. Thus, the concentration of hydrogen peroxide plays a crucial role in the extent to which the effectiveness of the combined process is enhanced. The negative effect on reactions of the presence of additional components in the reaction solution was also confirmed. It was therefore concluded that the experimental evaluation of optimum parameters of hybrid processes is a matter of importance.

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Section: Resultsmentioning

confidence: 99%

Sonochemical Formation of Hydrogen Peroxide

Ziembowicz

Kida

Koszelnik

2017

The 2nd International Electronic Conference on Water Sciences

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“…In contrast, the production of Br 2 •-could be significant in bromine-rich aerosols, where bromide concentration is enhanced at the solution/vapour interface compared to chloride 46 . This is potentially very significant because bromine radicals take part to ozone depletion processes 24,47 and are very effective brominating agents in aqueous solution 48,49 , which could lead to the formation of environmentally persistent brominated secondary pollutants. Certainly, the real impact of 1NN depends on its concentration and on the inorganic composition of the media, but nevertheless we have demonstrated that the reaction of nitroPAHs with inorganic compounds (i.e.…”

Section: Discussionmentioning

confidence: 99%

Photochemistry of 1-Nitronaphthalene: A Potential Source of Singlet Oxygen and Radical Species in Atmospheric Waters

et al. 2010

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Abstract1-Nitronaphthalene (1NN) was used as a model of nitro-PAHs to investigate photosensitized reactions in aqueous solution in the presence of oxygen and halides. Laser Flash Photolysis (LFP) was employed to investigate electron transfer between halide anions and the triplet state of 1NN, leading to the formation of dihalogen radical anions (X 2 •-) in solution. The experiments were performed in the absence or presence of oxygen, showing a bimolecular quenching rate constant for the triplet state of 1NN ( 3 1NN) by oxygen of (1.95 ± 0.05) × 10 9 M -1 s -1 . The decay of 3 1NN was observed to strongly depend on the pH of the medium. At pH > 2, 3 1NN decayed with a pseudo-first order rate constant close to 6.0 × 10 5 s -1 . The rate constant was markedly enhanced at lower pHs, reaching 2.0 × 10 6 s -1 at pH ~ 0.1, which suggests formation of the protonated triplet state ( 3 1NNH + ) at low pHs. Furthermore, we showed that the photoreactions of 3 1NN in the presence of oxygen are potential sources of HO 2 • , 1 O 2 and possibly • OH in aqueous media. In Milli-Q water (pH ~ 6.5) and in the presence of halide anions the quenching rate constant of 3 1NN was evaluated to be (2.9 ± 0.4) × 10 4 M -1 s -1 for chloride, (7.5 ± 0.2) × 10 8 M -1 s -1 for bromide, and (1.1 ± 0.1) × 10 10 M -1 s -1 for iodide. Also in this case a pH-dependent reactivity was evidenced, and the quenching rate constant was (7.7 ± 1.2) × 10 5 M -1 s -1 with chloride at pH 1.1.

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“…36,48,49 Instances of anions functioning as enhancers of the degradation of pollutants also have been reported. 50 In this context, the effect of some of the commonly occurring anions in water, i.e. SO4…”

Section: Effect Of Dissolved Salts/anionsmentioning

confidence: 99%

MnO2 AND MnO2/TiO2 MEDIATED, PERSULPHATE ENHANCED PHOTOCATALYSIS FOR THE REMOVAL OF INDIGO CARMINE DYE POLLUTANT FROM WATER

Lekshmi¹,

Yesodharan²,

Yesodharan³

2017

ECB

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Heterogeneous photocatalysis using UV/VIS light or natural solar radiation as the energy source is one of the most efficient advanced oxidation processes (AOP) for the removal of chemical and bacterial pollutants from water. One of the least investigated oxides in this context, i.e. MnO2 and its combination MnO2/TiO2 are examined as potential photocatalysts for the removal of Indigo carmine (IC) dye pollutant from the water. The catalysts are characterized by XRD, FTIR, SEM, TEM, adsorption and surface area measurements. While MnO2 is very efficient for the decolorization of the dye, it is not effective enough for mineralization. MnO2 /TiO2 as the photocatalyst at the optimized ratio of 9:1 combines the advantages of both the oxides, i.e., rapid decolorization and efficient mineralization. Persulphate (S2O8 2-) enhances the degradation while H2O2 inhibits the same. The degradation is dependent on pH with higher degradation under extremely acidic conditions. The influence of dissolved salts/anions in the water on the degradation varies from 'moderate inhibition' to 'no effect' or even 'enhancement' depending on the chemistry of the anion and reaction conditions. Effect of various parameters such as reaction time, substrate concentration, catalyst dosage, the presence of O2, recycling of the catalyst, etc. on the efficiency of degradation is investigated. The results are critically analyzed, and a tentative mechanism is proposed.

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Enhancement of dye sonochemical degradation by some inorganic anions present in natural waters

Cited by 121 publications

References 41 publications

Sonochemical Formation of Hydrogen Peroxide

Sonochemical Formation of Hydrogen Peroxide

Photochemistry of 1-Nitronaphthalene: A Potential Source of Singlet Oxygen and Radical Species in Atmospheric Waters

MnO2 AND MnO2/TiO2 MEDIATED, PERSULPHATE ENHANCED PHOTOCATALYSIS FOR THE REMOVAL OF INDIGO CARMINE DYE POLLUTANT FROM WATER

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