Removal of Fixed Ammonium from Clay Minerals by Cation Exchange Resins

Abstract

AMMONIUM in clay minerals that is not replaceable by K⁺ has been defined as fixed NH₄ ⁺. This fixed NH₄ ⁺ is replaceable to some extent by Na⁺ and H⁺, but the amount that can be replaced depends upon the extraction method used. Recent work^1,2 has shown that small amounts of K⁺ or NH₄ ⁺ in the extracting solution block the replacement of fixed NH₄ ⁺. Thus, the efficiency of an equilibrium extraction of fixed NH₄ ⁺ is decreased by the accumulation of displaced NH^{4 +} in the extracting solution². If a clay mineral containing fixed NH₄ ⁺ were equilibrated with a cation exchange resin instead of a soluble salt, there would be less soluble K⁺ or NH₄ ⁺ in the system. A comparison of these extraction methods was made, therefore, to determine if there was also less blocking and thus more fixed NH₄ ⁺ removed in a resin extraction.