Salt Desorption from Halloysite

Abstract

ABNORMALLY high cation exchange capacities (40–70 m.equiv./100 gm.) have been reported for halloysite¹. Since isomorphous substitution is of inconsiderable magnitude in halloysite, White² has suggested that allophane, which sometimes is associated with halloysite, may account for these large values. The recent work of Wada³, however, shows that salts of potassium and ammonium can replace H₂O from between the layers of hydrated halloysite and form heat-stable complexes with the clay. The amount of salt so held is large (200–300 m.equiv./100 gm.).