Can “microwave effects” be explained by enhanced diffusion?

Antonio, Christian; Deam, Rowan

doi:10.1039/b617358f

Cited by 56 publications

(31 citation statements)

References 17 publications

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“…Microwave treatment of water can lead to a change in the equilibrium concentration of impurities due to a specific effect of microwaves on the border "water-air," where a large temperature gradient occurs and hence the diffusion processes intensify [4].…”

Section: Discussionmentioning

confidence: 99%

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Long-Term Structural Modification of Water under Microwave Irradiation: Low-Frequency Raman Spectroscopic Measurements

Yakunov

Biliy

Naumenko

2017

Advances in Optical Technologies

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Raman scattering has been used to study the influence of 2.45 GHz microwave on the structure of water. It has been shown that treatment of the distilled water samples by electromagnetic field leads to long-term changes in the vibrational density of states. It was established that the retention time of structural changes of the water samples depends on the sample volume. The experimental results have been interpreted on the basis of the percolation model. It has been suggested that the change in the chemical composition of the water treated by microwaves can lead to a change in the structure of the percolation cluster formed by the network of hydrogen bonds. The time of the equilibrium structure recovery of the percolation cluster after termination of the microwaves depends on the cluster size and is much slower than the recovery in the chemical composition of water.

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Section: Discussionmentioning

confidence: 99%

“…The first of them, although they have a thermal nature, cannot be reproduced in the common convection heater. These are (a) the effect of overheating, (b) selective heating, (c) the temperature gradients on the border, and so forth [4].…”

Section: Introductionmentioning

confidence: 99%

Long-Term Structural Modification of Water under Microwave Irradiation: Low-Frequency Raman Spectroscopic Measurements

Yakunov

Biliy

Naumenko

2017

Advances in Optical Technologies

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“…The sharp debate is still going on in the scientific community concerning the existence or non-existence of non-thermal microwave (MW) effects [1][2][3][4][5][6]. The benefits brought about by microwave irradiation some of the scientists ascribe to the totally thermal effects, arising from the dielectric heating mechanism, while the others incline towards the emergence of specific or non-thermal effects being the result of interactions between microwaves and matter, which are not directly connected to heating itself.…”

Section: Introductionmentioning

confidence: 99%

High-temperature microwave effects in liquid media

et al. 2015

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The heating behavior of high-boiling liquids under microwave (MW) irradiation was investigated.Linear and non-linear heating modes depending on the applied MW power level were observed.The non-linear interactions emerging at "high" power levels are ascribed to electromagnetic oscillations excitations resulting in non-linear heating speed growth and considerable decrease in energy input. The relationship between non-linearity degree and liquids' viscosity was established.The observed effects have been shown to apply not only to mere heating, but also to hightemperature chemical reactions. Future perspectives and practical applications of the work are also discussed. ________________________________________________________________________________

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“…As for the non-thermal effect, there exist many disputes currently (Antonio and Deam 2007;de la Hoz et al 2007;Reddy et al 2013), especially no final conclusion has yet been reached on the research results due to inaccuracy of material temperature measurement in the microwave field (Schmink and Leadbeater 2009;Gomaa et al 2013). The non-thermal effect has been seldom studied in the field of microwave desulfurization of coal.…”

Section: Non-thermal Effectmentioning

confidence: 99%

Progress of the technique of coal microwave desulfurization

Tao

Xie

et al. 2014

Int J Coal Sci Technol

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With the advantages of its fast speed, effective and moderate controllable conditions, desulfurization of coal by microwave has become research focus in the field of clean coal technology. Coal is a homogeneous mixture which consists of various components with different dielectric properties, so their abilities to absorb microwaves are different, and the sulfur-containing components are better absorbers of microwave, which makes them can be selectively heated and reacted under microwave irradiation. There still remain controversies on the principle of microwave desulfurization at present, thermal effects or non-thermal effects. The point of thermal effects of microwave is mainly base on its characters of rapidly and selectly heating. While, in view of non-thermal effect, direct interactions between the microwave electromagnetic field and sulfur containing components are proposed. It is a fundamental problem to determine the dielectric properties of coal and the sulfur-containing components to reveal the interaction of microwave and sulfur-containing compounds. However, the test of dielectric property of coal is affected by many factors, which makes it difficult to measure dielectric properties accurately. In order to achieve better desulfurization effect, the researchers employ methods of adding chemical additives such as acid, alkali, oxidant, reductant, or changing the reaction atmosphere, or combining with other methods such as magnetic separation, ultrasonic and microorganism. Researchers in this field have also put forward several processes, and have obtained a number of patents. Obscurity of microwave desulfurization mechanism, uncertainties in qualitative and quantitative analysis of sulfur-containing functional groups in coal, and the lack of special microwave equipment have limited further development of microwave desulfurization technology.

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Can “microwave effects” be explained by enhanced diffusion?

Cited by 56 publications

References 17 publications

Long-Term Structural Modification of Water under Microwave Irradiation: Low-Frequency Raman Spectroscopic Measurements

Long-Term Structural Modification of Water under Microwave Irradiation: Low-Frequency Raman Spectroscopic Measurements

High-temperature microwave effects in liquid media

Progress of the technique of coal microwave desulfurization

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