Abstract

The exchangeable cations on natural clays can be replaced with different organocations by simple ion exchange. A variety of alkylammonium ions may be used in this regard to form organoclays that are effective adsorbents for removing organic contaminants from water. It has been found that when freshly dried organoclays (prepared from a natural clay) are heated at a regular temperature program, the organocation start to decompose at 523-553 K. However, to date, the thermal stability of organoclays prepared from Na- and autotransformed-clays using the alkylammonium method is unknown. Autotransformation means that H-smectite is converted spontaneously to (H, Al, Fe, Mg)-form upon ageing. Therefore, the aim of this work is to study the exchange of primary ammonium (n-alkylammonium chlorides), with a variable carbon chain length (ranging from C6 to C16), into Na-form clays (Na-clays) and autotransformed H-clays (An-clays) derived from SAz-1, SWa-1, ST and JP, and to determine whether autotransformation produces an improved thermal stability and to evaluate the decomposition process of the organoclays using thermogravimetry coupled with infrared spectroscopy.