Microwave Radiation Effect On The Synthesis Of Cadmium Sulphide Nanoparticles In Water In Oil Microemulsion: A Preliminary Study At Different Frequencies

Caponetti, Eugenio; Pedone, Lucia; Massa, Rita

doi:10.1080/14328917.2004.11784826

Cited by 12 publications

(16 citation statements)

References 27 publications

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“…The variable sweep frequency mode gives rise (on average) to a more even microwave field distribution in the waveguide. [31] This may be the reason the crystallization rate for this synthesis at the frequency sweeping mode is closer to that at 2.45 GHz in which a single-mode distribution occurs. Altering the sweep rate from 10 to 100 sweeps min À1 (at 8.7$10.5 GHz frequency range) had no significant effect on this system.…”

Section: Applicator Typementioning

confidence: 94%

“…This is likely due to the lack of systems with variable frequencies (other than 2.45 GHz) commercially available. However, Caponetti et al [31] investigated the microwave radiation effect on the synthesis of cadmium sulfide. They employed several frequencies (2.45, 2.85, 8, 12 and 18 GHz) and found that the final particle size and morphology were dependent on the microwave frequency used.…”

Section: Introductionmentioning

confidence: 99%

“…Problems such as arcing are also eliminated with this type of operation since arcing occurs in the presence of an electric field in a standing wave at a constant frequency. [31] Antonio and Deam [35] studied the VFM technique. They reported that "The technique works by sweeping through a bandwidth of frequencies which are cycled through consecutively and launched into a cavity, resulting in different standing waves with many resonant modes.…”

Section: Introductionmentioning

confidence: 99%

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Microwave Synthesis of SAPO‐11 and AlPO‐11: Aspects of Reactor Engineering

et al. 2008

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AlPO-11 and SAPO-11 are synthesized using microwave heating. The effects of precursor volume, reaction temperature, reactor geometry, stirring, applicator type and frequency on the microwave synthesis of SAPO-11 and AlPO-11 are studied. The nucleation time and crystallization rate are determined from crystallization curves for SAPO-11 (and/or AlPO-11), for the various parameters investigated. Increasing volume of the reacting material decreases the reaction rate of SAPO-11 at 160 degrees C. In particular, the nucleation time increases with increase in the reaction volume. Increasing the reaction temperature increases the crystallization rate and decreases the nucleation time, however it decreases the particle size. Nucleation of SAPO-11 and AlPO-11 under microwave heating is strongly dependant on the reaction temperature. Using wider geometry vessel (33 mm compared to 11 mm diameter) enhances the reaction rate, producing larger crystals in the same reaction time, even though the crystallization rate is decreased. The crystallization rate is enhanced by applicator type in the following order CEM MARS-5 oven>CEM Discover "focused" system>monomode waveguide. Stirring the reacting solution during heating affects primarily the nucleation time. The effect of microwave frequency on the nucleation and growth of SAPO-11 shows a dependence on the applicator type more than the specific frequency, for the frequency range 2.45-10.5 GHz. The difference between the crystallization rate observed at higher frequencies and that at 2.45 GHz maybe due to the multimode nature of the waveguide at frequencies above 2.45 GHz. Sweeping the microwave frequency linearly between 8.7 and 10.5 GHz at rates of 10 min(-1) and 100 min(-1) shows an intermediate crystallization curve to that for fixed frequencies of 2.45 GHz and that for 5.8, 8.7 and 10.5 GHz.

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Section: Applicator Typementioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Microwave Synthesis of SAPO‐11 and AlPO‐11: Aspects of Reactor Engineering

et al. 2008

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“…This is likely owing to the fact that most microwave heating systems employ the standard magnetron at 2.45 GHz, and the use of other frequencies requires expensive and specialized equipment. However, Caponetti et al [168] investigated the effect of microwave frequency on the synthesis of CdS. These workers observed a greater positive increase in particle size in the sulfide particles produced at 12 GHz compared to 18, 8, 2.45 and 2.85 GHz.…”

Section: Microwave Frequency Effectsmentioning

confidence: 95%

Microwave Synthesis of Nanoporous Materials

2006

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Studies in the last decade suggest that microwave energy may have a unique ability to influence chemical processes. These include chemical and materials syntheses as well as separations. Specifically, recent studies have documented a significantly reduced time for fabricating zeolites, mixed oxide and mesoporous molecular sieves by employing microwave energy. In many cases, microwave syntheses have proven to synthesize new nanoporous structures. By reducing the times by over an order of magnitude, continuous production would be possible to replace batch synthesis. This lowering of the cost would make more nanoporous materials readily available for many chemical, environmental, and biological applications. Further, microwave syntheses have often proven to create more uniform (defect-free) products than from conventional hydrothermal synthesis. However, the mechanism and engineering for the enhanced rates of syntheses are unknown. We review the many studies that have demonstrated the enhanced syntheses of nanoporous oxides and analyze the proposals to explain differences in microwave reactions. Finally, the microwave reactor engineering is discussed, as it explains the discrepancies between many microwave studies.

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“…The microwave apparatus was a Sairem downstream microwave source working at 2.45 GHz [17]. The main characteristic of this set-up are: the homogeneous field distribution inside the sample holder; the ability to measure the microwave power absorbed by the sample; the simplicity of use.…”

Section: Microwave Apparatus and Proceduresmentioning

confidence: 99%

Effects of solvent‐free microwave extraction on the chemical composition of essential oil of Calamintha nepeta (L.) Savi compared with the conventional production method

Riela¹,

Bruno

Formisano

et al. 2008

J of Separation Science

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The essential oil of Calamintha nepeta has been obtained by solvent-free microwave extraction (SFME) and by classical hydrodistillation (HD). A comparative qualitative-quantitative study on the composition of the oils was carried out. A total of 38 compounds, constituting 97.6% of the oil, were identified in the oil obtained by SFME, whereas 46 compounds, representing 95.4% of the oil, were characterized in the HD oil. SFME-distilled oil is richer in lightly oxygenated monoterpenes (LOM) than HD oil. It also has a higher amount of sesquiterpenes and a lower quantity of hydrocarbon monoterpenes. HD oil seems to be affected by chemical changes more than SFME oil.

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Microwave Radiation Effect On The Synthesis Of Cadmium Sulphide Nanoparticles In Water In Oil Microemulsion: A Preliminary Study At Different Frequencies

Cited by 12 publications

References 27 publications

Microwave Synthesis of SAPO‐11 and AlPO‐11: Aspects of Reactor Engineering

Microwave Synthesis of SAPO‐11 and AlPO‐11: Aspects of Reactor Engineering

Microwave Synthesis of Nanoporous Materials

Effects of solvent‐free microwave extraction on the chemical composition of essential oil of Calamintha nepeta (L.) Savi compared with the conventional production method

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