A step ahead on efficient microwave heating for kaolinite

Abstract

The thermal evolution of kaolin clay under microwave radiation shows an unexpected large heating rate up to 500ºC/min for temperatures >650⁰C. Such heating rate is associated with a resistivity drop of >10 3 Ω.m observed after the dehydroxylation process. The high efficiency of the microwave heating effect is correlated with the presence of surface carriers that absorbs microwaves electromagnetic field and produces crystal heating by electron-phonon coupling or small polaron. The layered structure of the clay-based materials allows the appearance of charge carriers at the surface of the crystal lattice that is electromagnetically activated. This effect represents a breakthrough in the efficient use of microwaves energy in order to produce efficient thermal treatments in large volume of non-metallic minerals with a drastic reduction of the greenhouse gasses for mass production industries.

Microwave hybrid fast sintering of red clay ceramics

“…Considering the high amount of greenhouse gases generated by this industry, 1 studies have investigated clean technologies for the production of red ceramics, looking for a sustainable material with better physical and mechanical properties and a more refined microstructure, 2 in addition to lower energy consumption 3 …”

Temperature Assessment Of Microwave-Enhanced Heating Processes

“…Exploiting the many facets of microwave processing requires a thorough and comprehensive understanding of the underlying processes at atomic level for which new and complex instruments and measurement capabilities are needed. In this regard, several approaches have been developed for the in-situ monitoring of microwave reactions in combination with other characterization techniques for solid materials as X-Ray Diffraction, Neutron Scattering, FTIR or Raman Spectroscopy 13–16 . Schmink and Leadbeater 15 and Vaucher et al .…”

White and Red Brazilian São Simão’s Kaolinite–TiO2 Nanocomposites as Catalysts for Toluene Photodegradation from Aqueous Solutions

“…Reinosa et al [31] reported that the thermal treatment of kaolinite below 200 °C resulted in dehydrated kaolinite, near 500–580 °C the dehydroxylation of kaolinite led to metakaolinite phases (mixture of SiO 2 , Al 2 O 3 and other oxides present as isomorphic substituents), while at temperatures higher than 980 °C mullite and amorphous silica were obtained (spinel phase).…”