Attapulgite as a Thixotropic Suspending Agent

Abstract

Attapulgite is a hydrous magnesium aluminum silicate clay mineral with a unique structure made up of colloidal particles called spicules. Gellation takes place following dispersion when the spicules become attracted to each other, become entangled and form the matrix structure that thickens, entraps, and suspends solids. Proper dispersion and gelling is dependent on the amount of shear and length of time it is applied or the use of chemical means to facilitate dispersion. To achieve gellation chemically dispersed clay must come into contact with a chemical salt which causes spicules to associate with one another and the gel to instantly form. Attapulgite can also be used to structure organic systems with the proper use of a cationic surfactant. The basic advantages of attapulgite as a structuring agent are versatility, compatibility with a variety of liquid systems, functionality over a wide pH range, and resistance to attack by microorganisms. It is relatively economical and provides a thixotropic liquid system.