Preparation of Kaolinite-Amino Acid Intercalates Derived from Hydrated Kaolinite

Makoto Sato
Department of Metallurgical and Inorganic Materials, Nagoya Municipal Industrial Research Institute, 3-4-41, Rokuban, Atsuta-ku, Nagoya, 456 Japan
E-mail of corresponding author: sato@nmiri.city.nagoya.jp

Abstract: Intercalation of amino acids into 10.0-Å hydrated kaolinite was studied by powder X-ray diffraction (XRD), differential thermal analysis-thermal gravimetry (DTA-TG), and infrared (IR) spectroscopy. Intercalation was found to be dependent on the chain-length, pH, and the concentration of the amino acid zwitterion. Near the isoelectric point, fully intercalated phases were obtained in solutions of concentration >0.5–1 M for glycine (Gly), 2–3 M for β-alanine (β-Ala), and 12 M for both γ-aminobutyric acid (γ-Aba) and δ-aminovaleric acid (δ-Ava). ∊-aminocaproic acid (∊-Aca) with a long chain (C = 6) was only partially intercalated. Intercalated amino acid formed a mono-molecular arrangement with the alkyl chain tilting toward the layer at an angle related to H2O content. The compositions of the intercalates of the Gly and β-Ala are Al2Si2O5(OH)4·(Gly)0.67·0.24H2O and Al2Si2O5(OH)4·(β-Ala)0.63·0.25H2O, respectively, based on TG data. From IR data, Gly and β-Ala molecules are found intercalated as zwitterions and these molecules form hydrogen bonds with both the Al-OH and Si-O surfaces of kaolinite. Washing the intercalate with water produced a hydrated kaolinite, which may form a second amino-acid intercalate of high order. Thus, hydrated kaolinite intercalates or deintercalates amino acids depending on concentration and conditions.

Key Words: Amino Acid • CMS Source Clay KGa-1 • Differential Thermal Analysis • Hydrated Kaolinite • Intercalation • Infrared Spectroscopy • Kaolinite • Thermogravimetric Analysis • Powder X-ray Diffraction

Clays and Clay Minerals; December 1999 v. 47; no. 6; p. 793-802; DOI: 10.1346/CCMN.1999.0470615
© 1999, The Clay Minerals Society
Clay Minerals Society (www.clays.org)