Removal of Sodium Montmorillonite from Cotton1

Abstract

Cotton fabric treated with aqueous sodium montmorillonite dispersions retains 0.12 ± 0.02% clay after three to at least ten washes with fresh portions of water. When fabric containing this tenaciously held clay is washed with solutions of deter gents and other chemicals, any reduction in the amount of retained clay must be due to the action of these chemicals. Polyoxyethylated nonionic detergents and polyethylene glycol were active, removing up to 70% of the clay. Cationic detergents were ineffective owing to their strong interaction with montmorillonite, which flocculates the clay and renders it hydro phobic; they also prevented or strongly reduced clay removal by nonionic detergents. Anionic detergents were ineffective because they are sorbed neither by montmorillonite nor by cotton: they did not interfere with clay removal by nonionic detergents. The irremovable sodium montmorillonite (approximately 0.04% ) is equal to the amount needed to completely cover the cotton surface with a clay layer consisting of elemental laniellae 9.4 A thick lying flat against the fibrils. Therefore, even non ionic detergents, which readily penetrate adjacent clay lamellae and separate them from each other, cannot detach the bottom lamellae of clay from the cotton substrate.