Thermal analysis of vermiculite using microwave heating

Zacarias, Joao R. A.; Forte, Gustavo G. S.; Fontgalland, Glauco; Carvalho, Joabson Nogueira de; Idalmir, S. Q.

doi:10.1109/i2mtc.2018.8409869

Cited by 2 publications

(1 citation statement)

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“…Structural changes of vermiculites induced by the above mentioned treatments provide evaluable information on the relationship between the structure of vermiculite and their industrial applications. In vermiculite applications as intumescent fire barriers [67][68][69] where exfoliation at low temperatures is required, the treatment type, in this case microwave irradiation, is more important than the structural change suffered by vermiculite. In the case of vacuum, not only the type of treatment but also the structural changes suffered by the vermiculite influence, since under pressure the vermiculite could act as a deposit mineral and host contaminating elements.…”

Section: Discussionmentioning

confidence: 99%

Structural Changes in Vermiculites Induced by Temperature, Pressure, Irradiation, and Chemical Treatments

Marcos¹

2021

Clay Science and Technology

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Depending on the treatment, the crystallinity increase of vermiculite may be accompanied by the enhancement of the majority starting phase, and the crystallinity loss may be accompanied by the appearance or disappearance of interstratified phases. Starting vermiculites with high K + content in the interlayer have more interstratified phases and lower water content and are less crystalline. The crystallinity loss of vermiculite and therefore the structural disorder increase are caused by the structural water loss. On the contrary, the crystallinity increase is produced by water gain. The vermiculite transformation by structural water loss occurs with temperature increase, vacuum, irradiation with microwaves or ultraviolet, and alcohol or acidic treatment. On the contrary, the transformation by water gain occurs in vermiculites treated with hydrogen peroxide and in those subjected to ionic metal exchange. These treatments provide evaluable information on the relationship between the structure of vermiculites and their industrial applications. The changes suffered by vermiculites due to the treatments applied could give light to ambiguities about their geological origin and hydrothermal and/or supergene processes.

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Section: Discussionmentioning

confidence: 99%