Modification of montmorillonite by amino acids: Preparation and characterization

Montmorillonite (MMT) is a layered clay mineral. It has exchangeable cations between the aluminosilicate layers. Those interlayered cations are usually Na+, Ca2+ or K+ and they can be exchanged by organic cations. Cation of organic ammonium salts are most frequently used for MMT modification. Modified MMT can be used as the additive for preparation of green sand or for preparation of polymer nanocomposites by various methods. Intercalation of organic ammonium species into the interlayer space of montmorillonite was performed by the ion-exchange method. In this paper, we report on the preparation of organically modified montmorillonite (OMM) and its properties, using four different types of amino acids. The amino acids are: Glutamic acid, Ethylenediaminetetraacetic acid, 5-Aminoisophpthalic acid and 4-Amino-3-hydroxybenzoic acid. The cation exchange capacity (CEC) was determined by ammonium acetate method to be 84 meq/100 g. Montmorillonite and OMM were characterized by Attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR), X-ray diffraction analysis (XRD) and Thermogravimetric analysis (TGA). The cation exchange was determined by X-ray diffraction. After modifications interlayer basal spacing of organically modified montmorillonites increased. Infrared spectra confirm the presence of amino acids in OMM. The weight loss evident in TGA analysis after 1000°C is different for montmorillonite and organically modified montmorillonites. These results reveal the successful organic modification of montmorillonite with amino acids.