Synthesis of Mixed-Layer Kaolinite/Smectite

Abstract Mixed-layer kaolinite/smectites containing 40–90% kaolinite layers have been synthesized from Wyoming smectite. Run times were 4 months at 156°C in solutions of A1C1 3 ∙6H 2 O and KCl or CaCl 2 . Similar KCl runs devoid of Al 3+ yielded mixed-layer illite/smectites. The supply of Al 3+ , rather than pK or pH, seems to control the alteration of smectite toward kaolinite or illite.