Kaolinite–potassium acetate intercalation compound (K-KAc complex) is subsequently calcined to produce metakaolin (MK).

Substrates / starting materials:

Raw kaolinitic clay (kaolin, K), containing kaolinite Al2[Si2O5](OH)4
Potassium acetate (KAc)
Ethanol (for washing)
Distilled water (for the KAc solution)

Reaction conditions for intercalation:

KAc concentration: 7.2 M aqueous solution
Solid-to-liquid ratio: 1:5
Temperature: 60 ℃
Time: 24 h
Stirring: exhaustive stirring under reflux
Post-treatment: filtration, drying at 105 ℃ for 2 days of ageing, then washing with ethanol to remove excess non-intercalated KAc

Products:

K-KAc complex (potassium acetate-intercalated kaolinite), with an intercalation ratio of approximately 89%
After calcination at 400, 450, 500, 550, or 600 ℃ for 2 h: calcined intercalated kaolinite / metakaolin-like product (KI-T series), in which acetate is removed and dehydroxylation of kaolinite occurs at lower temperatures than for non-intercalated kaolin.