Sonophotocatalytic reactors for wastewater treatment: A critical review

Gogate, Parag R.; Pandit, Aniruddha B.

doi:10.1002/aic.10079

Cited by 171 publications

(80 citation statements)

References 180 publications

(234 reference statements)

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“…The pollutant and thus the sonophotocatalytic degradation rates will be maximum near the point of zero charge of the catalyst as 6.8. 27,28 This is in agreement with the higher COD Cr removal efficiency observed for the DDVP under sonophotocatalysis at pH 7.3. Considering that dichlorvos is a unionizable compound, the increase of the reaction at alkaline pH can be ascribed to the high hydroxylation of the surface of the catalyst due to the presence of a large quantity of OH − ions.…”

Section: Methodssupporting

confidence: 86%

Synthesis of Magnetic Sonophotocatalyst and its Enhanced Biodegradability of Organophosphate Pesticide

Meng¹,

Shi²,

Ming³

et al. 2014

Bulletin of the Korean Chemical Society

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A magnetic sonophotocatalyst Fe 3 O 4 @SiO 2 @TiO 2 is synthesized for the enhanced biodegradability of organophosphate pesticide. The as-prepared catalysts were characterized using different techniques, such as Xray diffraction (XRD) and transmission electron microscopy (TEM). The radial sonophotocatalytic activity of Fe 3 O 4 @SiO 2 @TiO 2 nanocomposite was investigated, in which commercial dichlorvos (DDVP) was chosen as an object. The degradation efficiency was evaluated in terms of chemical oxygen demand (COD) and enhancement of biodegradability. The effect of different factors, such as reaction time, pH, the added amount of catalyst on COD Cr removal efficiency were investigated. The average COD Cr removal efficiency reached 63.13% after 240 min in 12 L sonophotocatalytic reactor (catalyst 0.2 g L −1, pH 7.3). The synergistic effect occurs in the combined sonolysis and photocatalysis which is proved by the significant improvement in COD Cr removal efficiency compared with that of solo photocatalysis. Under this experimental condition, the BOD 5 / COD Cr ratio rose from 0.131 to 0.411, showing a remarkable improvement in biodegradability. These results showed that sonophotocatalysis may be applied as pre-treatment of pesticide wastewater, and then for biological treatment. The synthesized magnetic nanocomposite had good photocatalytic performance and stability, as when it was used for the fifth time, the COD Cr removal efficiency was still about 62.38%.

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Section: Methodssupporting

confidence: 86%

Synthesis of Magnetic Sonophotocatalyst and its Enhanced Biodegradability of Organophosphate Pesticide

Meng¹,

Shi²,

Ming³

et al. 2014

Bulletin of the Korean Chemical Society

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“…The difficulty of tailoring both frequency and amplitude at a time, together with the directional sensitive effect of ultrasound and its non-uniform volumetric energy density, are the main drawbacks of ultrasound cavitation that may complicate its scale-up [21][22][23][24]. A highintensity, bulk and multi-frequency type of excitation would be the ideal acoustic wave.…”

Section: Introductionmentioning

confidence: 99%

Shock-induced cavitation as a way of accelerating phenol oxidation in aqueous media

Dutilleul

Partaloglu

Costa

et al. 2017

Chemical Engineering and Processing: Process Intensification

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Graphical Abstract2 Highlights  Cavitation induced by the impact of a solid piston on liquid surface  Shock-waves of several bars amplitude exciting a wide frequency range  Phenol degradation initiated at ambient temperature and absence of oxidants  High phenol mineralization extents measured upon H2O2 addition  Accelerated active radical formation in the presence of shock-induced cavitation AbstractShock-induced cavitation phenomena, resulting from the propagation of the trail of shockwaves generated upon the impact of a solid piston on a liquid surface, was used as an innovative way of intensifying the oxidation of phenol in aqueous media. The amount of energy communicated by the impact was found to be proportional to the impact height, and was directly related to the maximal pressure attained, i.e. in the order of several tens of bars. This peak was followed by a rarefaction period that results in the origination of several cavitation phenomena, which continued upon piston rebound and further shock-wave generation and propagation. The multi-frequency nature of shock-induced cavitation, capable of exciting a wide range of frequencies between 1 kHz and 100 kHz, was confirmed by means of wavelet analysis. Under shock-induced cavitation conditions, phenol degradation was found to be possible even in the absence of any oxidizing agent. High extents of mineralization, i.e. 45.3 and 56.2% TOC elimination, 50 mg/L solution, neutral pH, were obtained in the presence of H2O2 (aprox. 10% vol.), pointing to an acceleration of the oxidation reaction based in a faster and more efficient creation of radical species.

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“…It has been reported that TiO 2 photocatalysis combined with ultrasound can be benefited [72,97,159,160] due to different factors like (a) an increase in the catalyst surface area due to the aggregation action of ultrasound, which enhances the performance of the photocatalytic system [161]; (b) an improvement of mass transfer of organic compounds between the liquid phase and the TiO 2 surface [162,163]; and (c) a reduction of charge recombination and promotion production of additional OH • due to the residual H 2 O 2 generated [162,163]. Also, the continuous cleaning of the TiO 2 surface by acoustic cavitation [164] might also have some role in modifying the photocatalytic rate. Tables 4-6 show that different amounts of catalyst ranging from 10 mg L −1 to 4 g L −1 yielded different degrees of organic degradation during the photocatalytic oxidation process under the experimental conditions stated.…”

Section: Influence Of Catalyst Concentrationmentioning

confidence: 99%

“…It has been reported that the adsorption of the organic compounds onto the TiO 2 surface is affected by the pH of the solution [97,160]. The pollutant and thus the rates of degradation will be maximum near the point of zero charge (pzc) of the catalyst [164]. The pzc of TiO 2 surface is at pH pzc between 6.25 and 7.1 [1,165,166], depending on the ionic strength [166].…”

Section: Influence Of Initial Pollutantmentioning

confidence: 99%

Recent Overview of Solar Photocatalysis and Solar Photo-Fenton Processes for Wastewater Treatment

Gutierrez-Mata

Velázquez-Martínez

Álvarez-Gallegos

et al. 2017

International Journal of Photoenergy

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This literature research, although not exhaustive, gives perspective to solar-driven photocatalysis, such as solar photo-Fenton and TiO 2 solar photocatalysis, reported in the literature for the degradation of aqueous organic pollutants. Parameters that influence the degradation and mineralization of organics like catalyst preparation, type and load of catalyst, catalyst phase, pH, applied potential, and type of organic pollutant are addressed. Such parameters may also affect the photoactivity of the catalysts used in the studied solar processes. Solar irradiation is a renewable, abundant, and pollution-free energy source for low-cost commercial applications. Therefore, these solar processes represent an environmentally friendly alternative mainly because the use of electricity can be decreased/avoided.

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Sonophotocatalytic reactors for wastewater treatment: A critical review

Abstract: The common optimum operating conditions for sonochemical and photocatalytic oxidation coupled with the similarity in the mechanism

Cited by 171 publications

References 180 publications

Synthesis of Magnetic Sonophotocatalyst and its Enhanced Biodegradability of Organophosphate Pesticide

Synthesis of Magnetic Sonophotocatalyst and its Enhanced Biodegradability of Organophosphate Pesticide

Shock-induced cavitation as a way of accelerating phenol oxidation in aqueous media

Recent Overview of Solar Photocatalysis and Solar Photo-Fenton Processes for Wastewater Treatment

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