Applied Sonochemistry

Mason, Timothy J.; Lorimer, J.P.

doi:10.1002/352760054x

Cited by 662 publications

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“…5 Ultrasonic waves are above the normal human hearing range (18-20 kHz). 6 The effect of ultrasonic waves on liquids has been discussed in detail by Suslick. 7 Others have explained non-spherical cavitation, 8 while more recently, some have studied multiphysical models involving ultrasonics and biodiesel production.…”

Section: Introductionmentioning

confidence: 99%

Enhancing Biodiesel Production from Soybean Oil Using Ultrasonics

Chand¹,

Chintareddy²,

Verkade³

et al. 2010

Energy Fuels

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Our objective was to determine the effect of ultrasonics on biodiesel production from soybean oil. In this study, ultrasonic energy was applied in two different modes: pulse and continuous sonication. Soybean oil was mixed with methanol and a catalytic amount of sodium hydroxide, and the mixture was sonicated at three levels of amplitude (60, 120, and 180 μm pp ) in pulse mode (5 s on/25 s off). In the continuous mode, the same reaction mixture was sonicated at 120 μm pp for 15 s. The reaction was monitored for biodiesel yield by stopping the reaction at selected time intervals and analyzing the biodiesel content by thermogravimetric analysis (TGA). The results were compared to a control group, in which the same reactant composition was allowed to react at 60 °C for intervals ranging from 5 min to 1 h without ultrasonic treatment. It was observed that ultrasonic treatment resulted in a 96% by weight isolated yield of biodiesel in less than 90 s using the pulse mode, compared to 30−45 min for the unsonicated control sample with comparable yields (83−86%). In the pulse mode, the highest yield (96%) was obtained by sonicating the mixture at 120 μm pp amplitude. In the continuous sonication mode, the highest biodiesel yield was 86% by weight, which was obtained in 15 s. Our objective was to determine the effect of ultrasonics on biodiesel production from soybean oil. In this study, ultrasonic energy was applied in two different modes: pulse and continuous sonication. Soybean oil was mixed with methanol and a catalytic amount of sodium hydroxide, and the mixture was sonicated at three levels of amplitude (60, 120, and 180 μm pp ) in pulse mode (5 s on/25 s off). In the continuous mode, the same reaction mixture was sonicated at 120 μm pp for 15 s. The reaction was monitored for biodiesel yield by stopping the reaction at selected time intervals and analyzing the biodiesel content by thermogravimetric analysis (TGA). The results were compared to a control group, in which the same reactant composition was allowed to react at 60°C for intervals ranging from 5 min to 1 h without ultrasonic treatment. It was observed that ultrasonic treatment resulted in a 96% by weight isolated yield of biodiesel in less than 90 s using the pulse mode, compared to 30-45 min for the unsonicated control sample with comparable yields (83-86%). In the pulse mode, the highest yield (96%) was obtained by sonicating the mixture at 120 μm pp amplitude. In the continuous sonication mode, the highest biodiesel yield was 86% by weight, which was obtained in 15 s.

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Section: Introductionmentioning

confidence: 99%

Enhancing Biodiesel Production from Soybean Oil Using Ultrasonics

Chand¹,

Chintareddy²,

Verkade³

et al. 2010

Energy Fuels

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“…14,15 The tendency for one or other species to prevail depends on the physical and chemical properties of the precursor, specially the hydrophobicity, vapour pressure, molar mass and concentration. 2,16 …”

Section: Resultsmentioning

confidence: 99%

“…Foi avaliada a dependência entre a produção de cloreto obtida pela sonicação de efluentes contendo organoclorados e o tempo de irradiação para CCl 4 , CHCl 3 , CH 2 Cl 2 e do inseticida Thiamethoxam ® . Sob condições de saturação pôde ser observada a maior produção de cloreto para CHCl 3 .…”

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“…1 The acoustic collapse of bubble produces T > 5200 K and P > 100 MPa, leading to homolitic cleavages of chemical bonds, giving rise to free radicals production. 2 The production of free radical can take place even in situations as simple as the ultrasonic irradiation of pure water. 3,4 In this way, the sonochemical generation of reagents can deal with primary species, such as the radicals H and OH, and/ or secondary species, such as H 2 O 2 produced by rearrangement of OH radicals.…”

Section: Introductionmentioning

confidence: 99%

“…1 Sonochemical processes are related to chemical effects produced during the irradiation of low frequency ultrasonic waves (between 20 and 1000 kHz) on liquids. 2 The ultrasound irradiation leads to the production of acoustic cavitation bubbles (i.e. transient bubbles) in a liquid bulk during the successive rarefaction and compression phases.…”

Section: Introductionmentioning

confidence: 99%

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Production of chloride and hypochlorite for analytical purposes by sonochemical degradation of organochlorines

Korn¹,

Acevedo²,

Borges³

et al. 2005

J. Braz. Chem. Soc.

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Neste trabalho foram enfatizadas as potencialidades da geração sonoquímica de reagentes pela irradiação ultra-sônica de resíduos de organoclorados de efluentes laboratoriais com a produção de soluções de cloreto e hipoclorito para propósitos analíticos. Foi avaliada a dependência entre a produção de cloreto obtida pela sonicação de efluentes contendo organoclorados e o tempo de irradiação para CCl 4 , CHCl 3 , CH 2 Cl 2 e do inseticida Thiamethoxam ® . Sob condições de saturação pôde ser observada a maior produção de cloreto para CHCl 3 . O processo sonoquímico de geração de cloreto mostrou boa precisão (RSD < 10%). A extensão da geração sonoquímica de hipoclorito foi também avaliada quando conduzida em presença de concentrações diferentes de NaOH. O hipoclorito gerado pela degradação de resíduos foi monitorado pelo método de Berthelot, empregado para a determinação de NH 4 + . Os resultados da produção de azul de indofenol obtidos com soluções de hipoclorito geradas sonoquimicamente foram comparados, para diferentes concentrações de NH 4 + , com solução comercial do reagente e nenhuma diferença significativa (nível de confiança de 95%) foi constatada.This work was aimed at highlighting the potentialities of the reagent generation by ultrasonic irradiation to produce chloride and hypochlorite solutions for analytical purposes derived from the residues of organochlorines of laboratory effluents. The dependence between the production of chloride obtained from the sonication of effluents containing organochlorines and the irradiation time was evaluated for CCl 4 , CHCl 3 , CH 2 Cl 2 and Thiamethoxam ® . It was observed that under saturation conditions the production of chloride was highest for CHCl 3 . Additionally, good precision related to the sonochemical generation of chloride was achieved (RSD < 10%). The extent of sonochemical generation of hypochlorite was also evaluated in the presence of different NaOH concentrations. The hypochlorite generated by the degradation of CCl 4 residues was monitored by the reference Berthelot method for NH 4 + determination. The results obtained with hypochlorite solution sonochemically generated for different NH 4 + concentration were compared with the conventional reagent and no significant difference (95% confidence level) was found.

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Sonochemistry

Ashokkumar¹,

Mason²

2007

Kirk-Othmer Encyclopedia of Chemical Technology

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Sonochemistry is a relatively new term that arrived on the scene in the late 1970s and was then simply defined as the uses of ultrasound in chemistry and processing. Ultrasound is part of the overall sound spectrum, but is generally classified as sound beyond the frequency that can be detected by the human ear. Sometimes called “silent sound” it ranges from 20 kHz to 10 MHz within which it can be roughly subdivided into three main regions: low frequency, high power ultrasound (20–100 kHz); intermediate frequency, medium power ultrasound (100 kHz–1 MHz); and high frequency, low power ultrasound (1–10 MHz). The range from 20 kHz to 1 MHz is generally used in sonochemistry, whereas frequencies > 1 MHz are more commonly used in nondestructive testing and medicine. The driving force for sonochemistry is acoustic cavitation, which is the formation of small cavities in a fluid produced by ultrasound that undergo highly energetic collapse. A number of text books have been published that explore different aspects of sonochemistry. This article aims to provide the readers with a fundamental understanding of acoustic cavitation and its associated physical and chemical effects. Detailed information on the events that are involved in acoustic cavitation is discussed in the first section. Among the major effects generated by acoustic cavitation is Sonoluminescence and Sonochemistry, but only brief information is provided on the former since it is not the primary focus of this article. The majority of the discussion is focused upon Sonochemistry within which reactions have been subdivided into different categories, as suggested in the literature. Although sonochemistry is useful for a variety of applications, two areas that are particularly prominent are materials synthesis and the degradation of organic pollutants.

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Applied Sonochemistry

Cited by 662 publications

References 0 publications

Enhancing Biodiesel Production from Soybean Oil Using Ultrasonics

Enhancing Biodiesel Production from Soybean Oil Using Ultrasonics

Production of chloride and hypochlorite for analytical purposes by sonochemical degradation of organochlorines

Sonochemistry

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