Chem Sci Trans., 2013, 2(1), 5-12 Chemical Science Transactions DOI:10.7598/cst2013.188 ISSN/E-ISSN: 2278-3458/2278-3318 Simplified Synthesis of Swelling Na-4-Mica from Diatomite ORRANUCH KUNTHIYAJAI a , PHONGSAK LAOOT a , KUNWADEE RANGSRIWATANANON b and APHIRUK CHAISENA a* a Department of Applied Chemistry and Center for Innovation in Chemistry, Faculty of Science, Lampang Rajabhat University, Lampang 52100, Thailand b School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand a_chaisena@hotmail.com Received 21 May 2012 / Accepted 4 June 2012 Abstract: A swelling Na-4-mica (a highly charged fluorophlogopite) has recently attracted much attention because of its unique combination of high charge (four charges per unit cell) and swelling and cation exchange properties. Synthetic mica (ideal composition of Na 4 Mg 6 Al 4 O 20 F 4 .xH 2 O) was prepared by a simplified single-step synthetic process (NaCl-melt method) from diatomite at 900 0 C for 5 h. The obtained micas were characterized by powder X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and 29 Si and 27 Al magic-angle-spinning nuclear magnetic resonance (MAS-NMR) spectroscopy. Powder XRD and FT-IR data showed that the swelling Na-4-mica was obtained from diatomite (which serves as a cost-effective aluminosilicate source) with a small particle size (mean 2 μm) as revealed by SEM. The 29 Si and 27 Al MAS-NMR revealed the Si and Al nearest neighbor environment as well as the presence of impurities such as glassy phase. Keywords: Swelling Na-4-mica, Diatomite, Single-step synthetic process, Aluminosilicate Introduction Mica is representatives of the 2:1 phyllosilicates and consists of layers, composed of two sheets of Si-Al-O tetrahedral sandwiched between M-O and OH octahedral; the tetrahedral share corners of oxygen atoms. In contrast, two anion sites of the octahedral sheet shared only by other octahedral are oxygen atoms that are bound to hydrogen atoms forming OH groups, when not comprised of other anions such as F and Cl. Micas are distinguished from smectites or vermiculites by their higher layer charge density. The two main categories of micas based on layer charge density are: 1) true micas with 1 negative charges per formula unit and 2) brittle micas with 2 negative charges per formula unit 1 . Owing to their high charge density, naturally occurring micas do not normally swell in water and other polar solvents; as a result, exchange reactions with the interlayer cations do not readily occur. Synthetic micas, which swell in water, with cation exchange capacities of more than 200 mequiv (100 g) -1 , have been prepared and are of considerable interest 2-7 . In particular, Na- 4- mica is a very highly charged sodium fluorophlogopite mica of theoretical chemical composition RESEARCH ARTICLE