Expansibility of vermiculites irradiated with microwaves

• Published in: Applied clay science 2011-01, Vol.51 (1-2), p.33-37
• Main Authors: Marcos, Celia, Rodríguez, Irene
• Format: Article
• Language: English
• Subjects: Contaminants; Diffraction; Earth sciences; Earth, ocean, space; Exact sciences and technology; Expansion; Flakes; Heating; Irradiation; Microwaves; Mineralogy; Nitrobenzenes; Scanning electron microscopy; Silicates; Thermogravimetry; Vermiculite; Vermiculites; X-ray diffraction
• ISSN: 0169-1317; 1872-9053
• DOI: 10.1016/j.clay.2010.10.019

The effect of microwave power on the expansion of vermiculites was studied at 800W for different microwave exposure times (from 10s to 600s) and compared with the changes after heating to 1000°C and dehydration in vacuum. The interlayer water molecules of the individual flakes were driven off quickly by microwave irradiation separating the layers. The changes were characterized by X-ray powder diffraction and scanning electron microscopy. Microwave irradiation reduced the time and energy required for the preparation of expanded vermiculite particles. Microwave-heated vermiculites may be useful for some applications, such as intumescent fire barriers. They could also be interesting materials for adsorption of contaminants, such as oil and aromatics compounds (benzene, toluene, chlorobenzene, nitrobenzene, etc.) or heavy metals ions from aqueous solutions, without the need of hydrophobic modification. ► Microwave-heated vermiculites suffered structural changes. ► Expansion time and energy were reduced.